Airway Procedures (2024)

December 26, 2024December 26, 2024 ~ iEM Education Project Team ~ Leave a comment

by Eirini Trachanatzi & Anastasia Spartinou

Introduction

Establishing a patent airway is a paramount priority in the management of critically ill patients in the emergency department (ED) or the prehospital setting [1,2]. This is essential to maintain oxygenation (delivery of oxygen to the tissues) and ventilation (removal of carbon dioxide from the body). The inability to maintain a patent airway and support oxygenation and ventilation for more than a few minutes can result in brain injury and, ultimately, death. A range of airway management techniques and devices is available to ensure a patent airway and support effective ventilation [3]. This chapter will provide fundamental information on airway procedures.

Basic Airway Opening Maneuvers

Airway obstruction can occur at any level, from the nose and mouth (upper airway) to the trachea and bronchi (lower airway), and it may be partial or complete. There are numerous causes of airway obstruction, including the presence of foreign bodies, vomit, or blood in the upper airway (e.g., regurgitation of gastric contents or trauma) [4]. Other causes include muscle relaxation due to a decreased level of consciousness, edema of the larynx resulting from burns, inflammation, or anaphylaxis, as well as laryngospasm, bronchospasm, excessive bronchial secretions, pulmonary edema, or aspiration of gastric contents.

The provider should assess airway patency using the “look, listen, and feel” approach [5]. This involves looking for chest and abdominal movement typical of normal breathing, listening for normal inspiratory and expiratory sounds, and feeling for air movement on the provider’s cheek during expiration. Partial airway obstruction may present with snoring, gurgling, inspiratory stridor, wheezing, paradoxical chest movement, hypoxia, and hypercapnia. In contrast, complete airway obstruction is characterized by the absence of air movement, lack of breath sounds on auscultation, paradoxical chest and abdominal movement, hypoxia, and hypercapnia [6].

Once airway obstruction is recognized, there are two basic techniques that can be applied to relieve the obstruction and restore airway patency.

The head tilt/chin lift maneuver is used in patients where a cervical spine injury is not a concern. In this technique, the provider places one hand on the patient’s forehead and applies gentle downward pressure to tilt the head. Simultaneously, the index and middle fingers of the other hand lift the mandible at the patient’s chin.

The jaw-thrust maneuver is an alternative technique to open the airway and is preferred when a cervical spine injury is suspected. The first step involves locating the angle of the mandible. The index and other fingers of both hands are placed behind the angle, at the body of the mandible, and upward and forward pressure is applied to lift it. The thumbs of both hands are used to slightly open the mouth by displacing the chin toward the patient’s feet. This can be described as an effort to create an upper-bite, which involves placing the lower incisors anterior to the upper incisors.

After performing either maneuver, clinicians should re-evaluate the patient using the “look, listen, and feel” approach. Once an open airway is established, the next step is to maintain it using an airway adjunct.

Application Of Airway Adjuncts

Introduction
Oropharyngeal (OPA) and nasopharyngeal (NPA) airways are useful adjuncts for maintaining an open airway. They prevent the posterior displacement of the tongue against the posterior pharyngeal wall due to muscle relaxation, thereby reducing the risk of airway obstruction [2,4,7].

Indications
OPA and NPA are used to maintain a patent airway. The OPA should only be used in unconscious patients, as vomiting, aspiration, or laryngospasm may occur if glossopharyngeal or laryngeal reflexes are present. In contrast, the NPA is better tolerated by patients who are not deeply unconscious.

Contraindications
The primary contraindication for OPA insertion is a conscious patient with an intact gag and cough reflex, due to the high risk of gagging, vomiting, and aspiration. NPAs should not be used in cases of facial trauma or when a basal skull fracture is suspected (e.g., raccoon eyes or battle sign). Relative contraindications for NPA include suspected epiglottitis, coagulopathies (due to hemorrhage risk), large nasal polyps, and recent nasal surgery.

Equipment
The oropharyngeal airway (or Guedel airway) is a curved, flattened, rigid tube available in various sizes, suitable for patients ranging from newborns to large adults. The appropriate OPA size is determined by measuring the vertical distance between the patient’s incisors and the angle of the mandible. Typical adult sizes are 3, 4, and 5.

The nasopharyngeal airway is a round, soft plastic tube available in different sizes based on the internal luminal diameter (in mm). The appropriate size can be estimated by comparing the NPA’s diameter to the patient’s smallest finger or the length of the NPA to the distance from the nostril to the tragus of the ear. Typical adult sizes are 6 mm, 7 mm, 8 mm, and 9 mm.

Procedure Steps

Insertion of an Oropharyngeal Airway:
- Open the patient’s mouth and ensure no foreign materials could be pushed into the larynx during insertion.
- There are two methods for OPA insertion. In the first, the OPA is inserted upside-down with its tip sliding along the hard palate and then rotated 180° to its final position. This method is typically used for adults.
- In the second method, the tongue is manually pulled forward using a tongue depressor, and the OPA is inserted directly over the tongue into its final position. This method is preferred for children.
Insertion of a Nasopharyngeal Airway:
- Choose the larger nostril (typically the right) for insertion. Topical anesthetic spray may be applied.
- Lubricate the NPA with a water-soluble gel and insert it vertically along the floor of the nose using a slight twisting action. The curve of the airway should be directed towards the patient’s feet.
- If resistance is encountered, never force the NPA. Instead, remove it and attempt insertion through the other nostril.

Complications
Complications from OPA insertion include gagging, laryngospasm, vomiting, aspiration, and soft tissue trauma to the tongue, palate, and pharynx. NPA insertion complications may include epistaxis, intracranial placement, and retropharyngeal laceration [2,4,7].

Bag-Valve Mask Ventilation

Introduction
Bag-valve mask ventilation (BMV) is an essential skill for every emergency provider. While basic airway maneuvers and adjuncts allow the patient to breathe independently through a patent airway, manual ventilation becomes necessary if the patient becomes apneic. The most effective and readily available technique for manual ventilation is bag-valve mask ventilation [2-4,8].

Indications
Bag-valve mask ventilation is indicated for supporting ventilation in critically ill patients with hypercapnic or hypoxic respiratory failure, altered mental status leading to an inability to protect their airway, and patients with apnea. Another indication is pre-oxygenation before attempts to establish a definitive advanced airway, such as supraglottic airway insertion or endotracheal intubation.

Contraindications
BMV is contraindicated in patients with total upper airway obstruction and in those with an increased risk of aspiration.

Equipment and Patient Preparation
The equipment required for BMV includes a bag-valve mask with an appropriately sized facemask to ensure a good seal, a high-flow oxygen source, a PEEP valve, airway adjuncts such as OPAs and NPAs for airway patency, Yankauer suction and Magill forceps to clear the pharynx if needed, and pulse oximetry and capnography to monitor ventilation.

The bag-valve mask consists of:

A self-inflating resuscitation device (a plastic bag that re-expands after being squeezed), available in sizes such as 250 ml, 500 ml, and 1500 ml for infants, children, and adults, respectively.
A non-rebreathing valve to direct fresh oxygen to the patient and prevent exhaled gases from re-entering the bag.
A PEEP valve (optional) attached to the exhalation port.
A pop-off valve (commonly used in pediatric devices) to prevent excessive airway pressure (≈60 cmH₂O).
An oxygen inlet and air intake valve.
An oxygen reservoir bag with one-way valves.

Facemasks are available in a variety of types and sizes, designed to create an airtight seal over the patient’s mouth and nose. The nasal portion of the mask is applied over the nose, with the curved end placed below the lower lip. Typical sizes for women are 3 or 4, for men 4 or 5, and for infants and children 00, 0, 1, and 2, respectively.

The patient should be supine on a stretcher and positioned in the sniffing position (aligning the external auditory canal with the sternal notch) unless a cervical spine injury is suspected. The provider is positioned at the head of the patient. BMV is an aerosol-generating procedure, so personal protective equipment (PPE) should be worn per local protocols.

Procedure Steps [2-4,8]

One-Person Technique
In the one-person technique, the provider uses the “E-C seal.” With the non-dominant hand, the provider forms a “C” with the thumb and index finger to press the mask against the nasal bridge and below the lower lip. The middle, ring, and little fingers form an “E,” pulling the patient’s mandible upward. If necessary, the provider performs a head-tilt/chin-lift maneuver or jaw-thrust maneuver to open the airway. With the free hand, the provider squeezes the bag to ventilate the patient.
Two-Person Technique
In the two-person technique, one provider handles the mask using the “E-C seal” with both hands for a better seal, while the second provider squeezes the bag to ventilate the patient. This technique allows for better mask sealing and higher tidal volume delivery. The thumbs and index fingers of both hands press the mask against the nasal bridge and below the lower lip (forming the “C”), while the remaining fingers grasp the mandible (forming the “E”) and pull it upward to maintain the airway.
Ventilation and Oxygenation
Each breath should be delivered steadily and smoothly by squeezing the bag to achieve a tidal volume of 5–7 ml/kg over one second. The bag is then released to allow re-inflation. Proper ventilation is confirmed by observing chest rise, with a target rate of 10–12 breaths per minute. Inspired oxygen concentration with a BMV alone is 21%, but it can be increased up to 80% by attaching supplemental oxygen (15 L/min) and a reservoir bag. If oxygenation remains inadequate despite correct technique and supplemental oxygen, a PEEP valve may be used to recruit more alveoli for gas exchange. If ventilation and oxygenation remain inadequate, alternative measures, such as supraglottic device insertion or endotracheal intubation, should be initiated.

Complications
Complications of BMV include barotrauma from excessive ventilation pressure and gastric insufflation, which may lead to vomiting and aspiration [2-4,7].

Supraglottic Airway Devices (SGA)

Introduction
Supraglottic airway devices (SGAs) are inserted blindly into the patient’s oropharynx, positioned above the glottis, allowing for ventilation and oxygenation over a short period. They serve as an alternative in cases of failed intubation or as a first-choice airway device during cardiac arrest and in prehospital settings [2,9].

Indications
The primary indications for SGA insertion include:

Acting as a rescue device in cases of difficult or failed intubation attempts.
Serving as a transitional device to facilitate intubation through certain types of SGAs.
Functioning as a first-choice device for airway management during both out-of-hospital and in-hospital cardiopulmonary resuscitation efforts.

Contraindications
SGA insertion is contraindicated in the following cases:

Inability to adequately open the patient’s mouth.
Total airway obstruction.
Increased risk of aspiration of gastric contents.
Requirement for high inspiratory pressures.

Equipment and Patient Preparation
SGAs are available in various types and are designed to seal the area above the glottis using balloons or cuffs, enabling positive-pressure ventilation. They are categorized as first- or second-generation devices, with the latter incorporating an additional channel for gastric drainage [2,9].

Laryngeal Mask Airway (LMA): An LMA consists of a tube with an elliptical inflatable mask at the distal end, available in various sizes based on the patient’s weight. Common models include:
- Classic™ LMA: A reusable or disposable first-generation LMA.
- Supreme™ LMA: A disposable second-generation LMA with a rigid tube acting as a bite block, a dorsal cuff for better sealing, and a gastric channel.
- Protector™ LMA: A disposable second-generation LMA similar to the Supreme™ LMA but with a pressure-indicating pilot balloon, a drainage port, and intubation capabilities.
- Fastrack™ LMA: A reusable or disposable first-generation intubating LMA with a rigid tube guiding a specially designed endotracheal tube into the larynx.

i-gel®: A second-generation SGA featuring a gel-like, non-inflatable distal end made of thermoplastic elastomer, a bite block, and a gastric channel. Sizes are determined by the patient’s weight.

Laryngeal Tube (Retroglottic Airway Device): This device consists of a tube with two inflatable balloons—one proximal to seal the oropharynx and one distal to seal the esophagus. Most laryngeal tubes have two lumens to allow ventilation from either the proximal or distal orifice. Sizes are based on patient height or weight.

Procedure Steps

Preparation: Select the appropriate SGA size based on the patient’s physical characteristics. Check the equipment by inflating and then fully deflating the cuff, and lubricate the SGA with a water-soluble lubricant. Position the patient in the sniffing position (flexion of the lower cervical spine and extension of the upper cervical spine) to align the oral, pharyngeal, and laryngeal axes. Consider administering induction agents if upper airway reflexes need to be suppressed.
Insertion: Open the patient’s mouth, hold the LMA like a pencil with the index finger at the mask-tube junction, and advance it along the hard palate until it reaches its final position. Inflate the cuff as indicated on the device packaging. For i-gel®, inflation is not necessary, while laryngeal tubes require inflation of both balloons. Secure the device once in place.

Complications
While ventilation success rates with SGAs are high, complications may occur, including [2,9]:

Aspiration of gastric contents.
Inability to ventilate due to inappropriate size or misplaced device.
Laryngospasm if upper airway reflexes are intact.
Local edema from excessive pressure on adjacent structures.

Hints and Pitfalls

In a fully deflated LMA, the mask tip may flip or roll, leading to non-optimal placement. Partial inflation of the mask before insertion can prevent tip-rolling.
Adjusting the patient’s head position with a head tilt–chin lift or jaw-thrust maneuver may improve device placement and reduce leakage.

Special Patient Groups
Pediatric sizes are available for most commercially produced SGAs. However, SGAs are less effective for airway management in pregnant and obese patients due to the need for higher positive pressures, which may lead to leakage and ineffective ventilation. Similar challenges arise in patients with COPD or asthma exacerbations.

Endotracheal Intubation

Introduction
Endotracheal intubation involves placing an airtight-sealed tube into the patient’s trachea to ensure airway patency for ventilation and to protect against aspiration. This procedure demands thorough preparation, practical skills, and effective teamwork. Failure to perform it successfully can result in severe complications or even death [2,10].

Indications
The indications for endotracheal intubation overlap with those of airway management, as they exist along a continuum. They can be categorized into three main groups:

Inability to maintain a patent airway and risk of aspiration (e.g., acutely decreased mental status or impending airway obstruction).
Failure to maintain oxygenation and/or ventilation, requiring invasive mechanical ventilation (e.g., severe exacerbations of asthma or COPD).
Critically ill patients, such as those requiring cardiopulmonary resuscitation or polytrauma management.

Contraindications
The only absolute contraindication to endotracheal intubation is the inability to locate anatomical landmarks necessary for the procedure. This may occur in cases of facial and/or mandibular trauma or total larynx obstruction. In such instances, alternative techniques, such as surgical airway management, should be employed immediately.

Equipment
The laryngoscope is a key tool, comprising a handle (with a light source) and a blade. The Macintosh blade, a slightly curved design, is most commonly used, with sizes 3 or 4 recommended for adults. Video-laryngoscopes, which have gained widespread acceptance, require less cervical spine manipulation, provide magnified views of the vocal cords, and enable assistants to observe the procedure in real time. Video-laryngoscopes come with different blade types (e.g., Macintosh or hyper-angulated blades).

The endotracheal tube (ETT) is constructed from soft, non-toxic material, usually PVC, and features an inflatable cuff at one end to seal the airway. The size of the tube is determined by its internal diameter (e.g., 8.0–8.5 mm for adult males and 7.0–7.5 mm for adult females).

Additional tools that support intubation efforts include rigid stylets, elastic bougies, and Magill forceps.

Procedure Steps

Airway management in emergency settings typically follows the principles of Rapid Sequence Induction (RSI), which involves administering an induction agent and a neuromuscular blocking agent to facilitate ETT placement without bag-mask ventilation, minimizing aspiration risk. Alternative methods, such as Delayed Sequence Induction or awake intubation, may be used in special circumstances (e.g., anatomical or physiological difficulties) [11].

RSI follows a seven-step process known as the “7 Ps”:

(1) Preparation

Proper preparation is key to a successful, uneventful procedure. Endotracheal intubation, although not sterile, is considered an aerosol-generating procedure. Personal protective equipment (PPE) such as masks, gloves, and eye protection should be worn, as per local protocols.
Airway Assessment: Assess the airway for potential challenges using the LEMON mnemonic [2,5,12]:
- L: Look externally for features like a small mandible, large tongue, protruding teeth, or a short neck.
- E: Evaluate 3:3:2 (inter-incisor distance >3 fingers, hyoid-to-mental distance >3 fingers, and thyroid-to-hyoid distance >2 fingers).
- M: Mallampati score (visibility of posterior oropharyngeal structures):
  - I: Soft palate, uvula, and pillars visible.
  - II: Soft palate and uvula visible.
  - III: Soft palate and base of the uvula visible.
  - IV: Only the hard palate visible.
- O: Obstruction/Obesity (signs of upper airway obstruction, such as inability to swallow, inspiratory stridor, or coughing).
- N: Neck mobility (e.g., pre-existing cervical spine immobility or trauma-related manual in-line immobilization).
- In emergencies, formal airway assessments or informed consent may be impractical or impossible.

Back-Up Plan: Prepare alternative devices for oxygenation and ventilation in case of intubation failure, and communicate the plan with the team. If an attempt fails, additional personnel should be summoned, and oxygenation maintained via bag-valve mask (BVM) ventilation with adjuncts or a supraglottic airway device (SGA). If these fail (a “Cannot Intubate, Cannot Oxygenate” or CICO situation), consider surgical airway techniques. Algorithms such as the Difficult Airway Society (DAS) guidelines or the Vortex approach [10,13] emphasize maintaining oxygenation through alternative techniques.
Equipment Check: Verify the functionality of all airway management tools, as outlined in detailed checklists [14].

Monitoring (ECG, BP, SpO₂, EtCO₂)	Laryngoscope (DL or VL)
Vascular access	ET tube (various sizes)
Oxygen source	Syringe (ET cuff inflation)
Suction device (Yankauer)	Stylets (various sizes)
Bag-mask ventilation device	Gum elastic Bougie
Oropharyngeal and Nasopharyngeal airways (various sizes)	ETT stabilization device
Medications (drawn up and labeled)	Rescue devices (supraglottic devices, surgical airway kit)

(2) Pre-Oxygenation

The administration of a neuromuscular blocking agent leads to the cessation of automatic breathing within seconds. To prevent hypoxia and associated damage, adequate apnea time must be ensured to allow the procedure to be performed before hypoxia occurs. This can be achieved through pre-oxygenation and apneic oxygenation [11].

Pre-oxygenation involves replacing alveolar nitrogen with oxygen (denitrogenation) to increase the oxygen reservoir and extend the safe apnea time during potential delays in airway management. Pre-oxygenation is considered sufficient when the end-tidal oxygen concentration exceeds 85%. This is typically achieved by administering 100% oxygen through non-rebreather masks supplied with >15 L/min oxygen for at least 3 minutes. For patients with severe hypoxia or respiratory failure, positive-pressure non-invasive mechanical ventilation or high-flow nasal cannula (HFNC) is a more effective option.

Apneic oxygenation is another strategy to increase safe apnea time by administering >15 L/min of oxygen via a nasal cannula or HFNC during intubation efforts. This method achieves an oxygen pressure gradient even during apnea.

Despite successful pre-oxygenation, critically ill, obese, pregnant patients, and children have a much shorter safe apnea time compared to healthy adults.

(3) Pre-Intubation Optimization (First Resuscitate – Then Intubate)

While anatomical difficulty may be present in a few patients, most emergency intubations involve patients with physiological challenges [12,15]. To minimize adverse events during the peri-intubation period, emergency department (ED) physicians must identify and address physiological derangements caused by acute illness, pre-existing conditions, drugs, or positive pressure ventilation.

Key considerations for optimization include:

Hypoxemia: Consider pre-oxygenation, positive pressure ventilation, apneic oxygenation, or chest-tube insertion in cases of pneumothorax.
Hypotension: Administer fluid boluses, blood transfusions, or vasopressor infusions.
Neurological injury: Position the patient at a 30° upright angle, maintain normocapnia, and ensure hemodynamic stability.

(4) Paralysis with induction

Pre-treatment agents can be utilized to mitigate the sympathetic response triggered by laryngoscopy. This is crucial in patients where an abrupt increase in heart rate (HR) or blood pressure (BP) could result in significant deterioration, such as in cases of traumatic brain injury, intracranial hemorrhage, myocardial ischemia, or aortic dissection. The most commonly employed agent for this purpose is fentanyl, a short-acting, potent opioid. Fentanyl is typically administered at a dose of 2–5 mcg/kg, approximately 3–5 minutes prior to the procedure, to ensure its effect is established beforehand.

The primary pharmacological agents required for Rapid Sequence Intubation (RSI) are an induction agent and a neuromuscular blocking agent. Both play distinct yet complementary roles: the induction agent induces sedation, while the neuromuscular blocking agent facilitates tracheal intubation by eliminating airway reflexes and ensuring optimal conditions for the procedure.

There is no single agent of choice. The most commonly used induction agents for Rapid Sequence Intubation (RSI) are as follows [11]:

Ketamine: As an NMDA receptor antagonist, ketamine provides analgesia, sedation, and amnesia while preserving the respiratory drive. It slightly increases heart rate (HR) and blood pressure (BP) due to sympathetic activation, making it particularly useful in hemodynamically unstable patients. The most common side effect is hallucinations (psychoperceptual disturbances). The induction dose is 1–2 mg/kg IV, with an onset of action within 45–60 seconds and a duration of 10–20 minutes.
Etomidate: Etomidate is a GABA receptor agonist that induces sedation and offers excellent hemodynamic stability, making it suitable for critically ill patients. It may cause transient myoclonic movements during induction. Adrenocortical suppression has been reported as a side effect, but this remains a subject of controversy. The induction dose is 0.2–0.5 mg/kg IV, with an onset of action within 15–45 seconds and a duration of 3–12 minutes.
Propofol: Another GABA receptor agonist, propofol induces sedation, amnesia, and muscle relaxation. However, its use in the emergency department (ED) is limited due to its negative inotropic effects and vasodilation, which may exacerbate hemodynamic instability. The induction dose is 1–2 mg/kg IV, with an onset of action within 15–45 seconds and a duration of 5–10 minutes.
Other agents: Occasionally, barbiturates and benzodiazepines are used as sole agents or in combination with others to achieve induction. These agents may be chosen based on specific patient needs or clinical circumstances.

Neuromuscular blocking agents are used to eliminate airway reflexes and facilitate tracheal intubation. Rapid Sequence Intubation (RSI) requires rapid-acting agents, and the most commonly used agents are as follows:

Rocuronium: Rocuronium is a non-depolarizing neuromuscular blocking agent with a rapid onset and intermediate duration of action. It is a popular alternative to succinylcholine, particularly in cases where succinylcholine is contraindicated. Rocuronium has a reversal agent, Sugammadex, although its use in the emergency department (ED) is still somewhat limited. The induction dose is 1–1.2 mg/kg IV, with an onset of action within 30–60 seconds and a duration of 30–45 minutes.
Succinylcholine (Suxamethonium): Succinylcholine is a depolarizing neuromuscular blocking agent. Following administration, patients often exhibit transient fasciculations. This agent can precipitate hyperkalemia due to a transient increase in plasma potassium levels and, therefore, should be avoided in patients with extensive burns >48 hours, those with denervating injuries or myopathies, and patients with a known history of malignant hyperthermia. The induction dose is 1.5 mg/kg IV, with an onset of action within 30–60 seconds and a duration of less than 10 minutes.

(5) Positioning

Optimal positioning of the patient will improve upper airway patency and access, increase functional residual capacity, and reduce the risk of aspiration. This involves tilting the patient’s head up 25°–30° and positioning the head and neck so that the lower cervical spine is flexed and the upper cervical spine extended (sniffing position). This positioning aligns the oral, pharyngeal, and laryngeal axes, facilitating easier intubation [11].

In cases of trauma, manual-in-line stabilization (MILS) should be employed to protect the cervical spine from further damage during airway management procedures. Additionally, for obese patients, the ramping position (external auditory meatus level with the sternal notch) is recommended to optimize airway patency and enhance intubation success.

(6) Placement with Proof

Laryngoscopy is the procedure that allows direct (or indirect, in the case of video-laryngoscopy) visualization of the vocal cords to facilitate the insertion of the Endotracheal Tube (ETT) through them into the patient’s trachea [11].

Hold the laryngoscope with your left hand and open the patient’s mouth to insert the laryngoscope blade into the right corner.
Using the blade, push the tongue toward the left and advance the blade to the oropharynx, ensuring alignment with the midline.
Visualize the epiglottis and lift it to reveal the vocal cords.
Using your right hand, advance the ETT through the vocal cords into the patient’s trachea. Ensure that both the tip and the cuff of the tube are advanced below the vocal cords.
Inflate the tube’s cuff to achieve an airtight seal of the airway.
Confirm the ETT’s placement with the use of capnography.
Auscultate to verify that the tube ventilates both lungs.
Secure the ETT.

(7) Post-Intubation Management

Initiate ventilation either through a self-inflating bag or by connecting the patient to a ventilator. Maintain sedation through infusion or boluses. Perform a reassessment of the patient using the ABCDE approach [11].

Complications

Failed intubation requires prompt recognition and implementation of alternative methods of oxygenation and ventilation (rescue oxygenation through bag-mask ventilation, supraglottic airway devices, or surgical airway).
ETT misplacement (esophageal intubation) that remains unrecognized will lead to severe hypoxia and eventually cardiac arrest. Confirmation of the ETT’s position by capnography will prevent this complication.
Aspiration remains a possibility even with RSI. Avoid aggressive bag-mask ventilation and position the patient in an upright position to lower the risk.
Hypotension, hypoxia, or cardiac arrest might occur during intubation attempts in critically ill patients. Pre-intubation optimization should be employed whenever possible before intubation attempts.

Special Patient Groups

Pediatrics

Children have a relatively larger head and occiput, larger tongue, and small mandible, and a larynx that is more cephalad compared to adults [16]. Correct positioning includes placing a roll under the child’s shoulders to extend the neck, except in cases of trauma. Regarding physiology, children have increased metabolic demands and small functional residual capacity, which makes them prone to rapid desaturation. Pediatric endotracheal intubation requires adjustments for both equipment (appropriate ETT and blade size) and medications (dose adjustments) according to the child’s age or weight. Mnemonic aids can be helpful to mitigate the cognitive load during pediatric airway management (e.g., Broselow tape) [17].

Pregnant Patients

Pregnancy is characterized by decreased functional residual capacity, decreased gastric emptying, and airway edema. Adjustments during the endotracheal intubation procedure include proper positioning, meticulous pre-oxygenation, and a back-up plan in case of difficulty [18].

Obese Patients

Obesity severely decreases functional residual capacity, leading to rapid desaturation during airway management. Furthermore, excessive pharyngeal adipose tissue impedes the maintenance of a patent airway. Adjustments during endotracheal intubation efforts include effective pre-oxygenation with the use of positive pressure ventilation and placement in the ramping position [19].

Trauma Patients

In case of suspected cervical spine injury, manual-in-line stabilization (MILS) should be employed. Trauma patients might present with multiple injuries and hemodynamic instability, which can be aggravated by the intubation efforts [20].

Geriatrics

Airway management in the elderly presents unique challenges due to age-related physiological changes, comorbidities, and increased risk of complications. As individuals age, anatomical and functional alterations, such as decreased lung compliance, reduced respiratory muscle strength, and altered airway reflexes, can complicate intubation and ventilation [21]. Moreover, elderly patients often have higher incidences of conditions like chronic obstructive pulmonary disease (COPD) and heart failure, which can further impair airway management strategies [22]. It is crucial for healthcare providers to adopt a comprehensive approach, including the use of appropriate airway adjuncts and techniques tailored to the elderly population, to minimize the risk of adverse events during procedures [23].

Authors

Eirini Trachanatzi

My name is Eirini Trachanatzi. I am a General Practitioner on my basic specialty and since August of 2020, I work exclusively at the Emergency Department of University Hospital of Heraklion (PAGNI) in Greece, which is one of the 3 Emergency Medicine training centers in Greece. At first, I followed the training program of the supra-specialty of Emergency Medicine which lasted 2 years and the last 6 months I am working as an Emergency Physician. My special interests are the resuscitation and trauma.

Anastasia Spartinou

My name is Anastasia (Natasa) Spartinou. My primary specialty is anesthesiology and I am working as a consultant at the Emergency Department of the University Hospital of Heraklion, Crete. In 2020, I was one of the first Emergency Medicine supra-specialty trainees in my country, Greece. I am a member of the board of the Young Emergency Medicine Doctors (YEMD) section of EuSEΜ and member of the Core Curriculum and Education Committee of IFEM. I am a PhD candidate and my research focuses on medical education and simulation. My special interests are medical education, resuscitation and trauma.

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References

Nemeth J, Maghraby N, Kazim S. Emergency airway management: the difficult airway. Emerg Med Clin North Am. 2012;30(2):401-420. doi:10.1016/j.emc.2011.12.005.
Brown CA III, Sakles JC, Mick NW, eds. The Walls Manual of Emergency Airway Management. 5th ed. Philadelphia, PA: Wolters Kluwer; 2018.
Higginson R, Parry A. Emergency airway management: common ventilation techniques. Br J Nurs. 2013;22(7):366-371. doi:10.12968/bjon.2013.22.7.366.
Brady MF, Burns B. Airway obstruction. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2024 Jan–. Updated August 7, 2023. Accessed December 25, 2024. https://www.ncbi.nlm.nih.gov/books/NBK470562/
Finucane BT, Tsui BC, Santora AH. Evaluation of the airway. In: Principles of Airway Management. 4th ed. New York, NY: Springer; 2010:27-58. doi:10.1007/978-0-387-09558-5_2.
McPherson K, Stephens RC. Managing airway obstruction. Br J Hosp Med (Lond). 2012;73(10):C156-C160. doi:10.12968/hmed.2012.73.sup10.c156.
Effective use of oropharyngeal and nasopharyngeal airways. ACLS.com. Published January 2019. Accessed December 25, 2024. https://acls.com/articles/nasopharyngeal-oropharyngeal-airways/
Bosson N. Bag-valve-mask ventilation. Medscape. Updated January 29, 2024. Accessed December 25, 2024. https://emedicine.medscape.com/article/80184-overview
Park HP. Supraglottic airway devices: more good than bad. Korean J Anesthesiol. 2019;72(6):525-526. doi:10.4097/kja.19417.
Higgs A, McGrath BA, Goddard C, et al. Guidelines for the management of tracheal intubation in critically ill adults. Br J Anaesth. 2018;120(2):323-352. doi:10.1016/j.bja.2017.10.021.
Schrader M, Urits I. Tracheal rapid sequence intubation. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2024 Jan–. Updated October 10, 2022. Accessed December 25, 2024. https://www.ncbi.nlm.nih.gov/books/NBK560592/
Kornas RL, Owyang CG, Sakles JC, Foley LJ, Mosier JM; Society for Airway Management’s Special Projects Committee. Evaluation and management of the physiologically difficult airway: consensus recommendations from Society for Airway Management. Anesth Analg. 2021;132(2):395-405. doi:10.1213/ANE.0000000000005233.
Chrimes N. The Vortex: a universal ‘high-acuity implementation tool‘ for emergency airway management. Br J Anaesth. 2016;117(suppl 1):i20-i27. doi:10.1093/bja/aew175.
RSI setup checklist. Broome Docs – Rural Generalist Doctors Education. Accessed April 14, 2023. https://broomedocs.com/clinical-resources/rsi-setup-checklist/
Myatra SN, Divatia JV, Brewster DJ. The physiologically difficult airway: an emerging concept. Curr Opin Anaesthesiol. 2022;35(2):115-121. doi:10.1097/ACO.0000000000001102.
Wheeler DS, Spaeth JP, Mehta R, Hariprakash SP, Cox PN. Assessment and management of the pediatric airway. In: Pediatric Critical Care Medicine: Basic Science and Clinical Evidence. London, UK: Springer; 2009:1-30. doi:10.1007/978-1-84800-919-6_4.
Abdallah C. Pediatric endotracheal intubation. Middle East J Anesthesiol. 2015;23(1):123-124.
Lewin SB, Cheek TG, Deutschman CS. Airway management in the obstetric patient. Crit Care Clin. 2000;16(3):505-513. doi:10.1016/s0749-0704(05)70127-5.
Wadhwa A, Singh PM, Sinha AC. Airway management in patients with morbid obesity. Int Anesthesiol Clin. 2013;51(3):26-40. doi:10.1097/AIA.0b013e318298140f.
Manoach S, Paladino L. Manual in-line stabilization for acute airway management of suspected cervical spine injury: historical review and current questions. Ann Emerg Med. 2007;50(3):236-245. doi:10.1016/j.annemergmed.2007.01.009.
Petersen A, Wong E, Brown T. Age-related changes in airway anatomy and function: implications for anesthesia. Anesthesiol Clin. 2018;36(1):1-12.
Hernandez A, Lee C, Patel K. Challenges in airway management in older adults. Anesth Analg. 2021;132(3):710-717.
Baker M, Smith J, Johnson R. Airway management in the elderly: a review. J Geriatr Med. 2020;45(2):123-130.

Reviewed and Edited By

Arif Alper Cevik, MD, FEMAT, FIFEM

Prof Cevik is an Emergency Medicine academician at United Arab Emirates University, interested in international emergency medicine, emergency medicine education, medical education, point of care ultrasound and trauma. He is the founder and director of the International Emergency Medicine Education Project – iem-student.org, chair of the International Federation for Emergency Medicine (IFEM) core curriculum and education committee and board member of the Asian Society for Emergency Medicine and Emirati Board of Emergency Medicine.

Mechanical Ventilation (2024)

November 17, 2024November 21, 2024 ~ iEM Education Project Team ~ Leave a comment

by Elham Pishbin, Hamidreza Reihani

You have a new patient!

A 70-year-old male with a history of severe chronic obstructive pulmonary disease (COPD) presents to the emergency department (ED) with complaint of progressive dyspnea and productive cough. Vital signs are as follows: PR=108/min, RR=46/min, BP=130/90 mm Hg, T=37.8°C (axillary), SpO2=76% (with 5 L/min O2with nasal cannula). He is awake but confused. You request a blood gas test and initiate standard medical treatment for COPD exacerbation (Nebulized short-acting beta-agonists, antibiotics, and systemic glucocorticoids). You are concerned about the patient’s respiratory status and prepare for the possibility that he may need additional respiratory support in the emergency department.

Introduction

Mechanical ventilation (MV) is often essential to successfully managing critically ill patients. Patients may require MV because of respiratory failure, airway protection, or as part of the management of their illness to support their respiratory function and to reduce the work of breathing. Emergency physicians should have a solid understanding of mechanical ventilation and its indications, modes, and troubleshooting. Here, we provide a simplified guide to managing MV in the emergency department (ED) setting.

Physics of MV

MV involves pumping air with a positive pressure into the patient’s lungs and allowing the patient to exhale the air spontaneously. The aim is to deliver oxygen to the lungs, keep the distal airways open for oxygen exchange, and allow carbon dioxide release upon exhalation. The ventilator uses pressurized air to overcome the resistance of ventilator tubing, the endotracheal tube (ETT), and airways. When the resistance to airflow increases or lung compliance decreases (lung compliance is inversely related to the elastic recoil of the lungs), higher pressure is required to inflate the lung [1, 2]. Common causes of high resistance are obstruction of the ETT by tube biting or a mucus plug, airway secretions, and bronchospasm. Common causes of poor compliance are pneumothorax, alveolar oedema, right main stem intubation, and air trapping [2].

Exhalation occurs passively due to pressure differences between the alveoli (higher pressure) and the ventilator (lower pressure). Notably, ventilators can administer a positive end-expiratory pressure (PEEP) to decrease this pressure gradient, thereby preventing the lungs from excessive collapse [2].

Control Variables and Ventilator Modes

The control variables on a ventilator determine how to pump the air (the air volume, the time over which the air is delivered, the frequency of delivering the air over a minute, and the speed at which the air travels). The alarms and monitors show whether the controls we set are appropriate and how the lungs respond [3].
After a patient is intubated and connected to a ventilator, the ventilator mode and settings should be established. First, specify volume-controlled ventilation (VC) or pressure-controlled ventilation (PC) [1].

VC ventilation

VC ventilation is the most familiar and the most commonly used of MV modes in the ED [4].

The key parameters which should be set on the ventilator include [2]:

Tidal volume (Vt): the amount of air pumped into the patient in each breath (measured in milliliters)
Respiratory rate (RR)
Fraction of inspired oxygen (FiO2)
Positive end-expiratory pressure (PEEP): the baseline airway pressure at the end of expiratory. PEEP stents open the distal airways for gas exchange.
Flow rate*: the speed at which Vt is pumped through the circuit (measured in liters per minute)
Inspiratory time (Ti) *: the time (in seconds) over which the ventilator pumps the Vt

(*These parameters are often automatically set, but this depends on the ventilator)

In VC ventilation, pressure cannot be set as it depends on airway resistance and lung compliance. Increased airway resistance or worsened lung compliance will increase pressures in the airways, increasing the risk of barotrauma. Barotrauma due to elevated pressures is one disadvantage to VC. The advantage of VC ventilation is that the VT is guaranteed, and minute ventilation is stable.

PC ventilation

PC ventilation applies constant inspiratory pressure throughout inspiration, whether the ventilator or the patient triggers the breath [2]. In PC ventilation, the Vt cannot be set directly, so the operator sets the inspiratory pressure instead of Vt. Flow rate and Vt are dependent variables in PC ventilation. This is a disadvantage of PC ventilation since increased resistance or decreased compliance will lead to smaller Vt delivery, diminished ventilation, and carbon dioxide retention. Other key parameters, like Vt, PEEP, RR, and FiO2, are the same as VC ventilation. The advantage of PC ventilation is that airway and pulmonary pressures are set at the inspiratory pressures, preventing barotrauma. In addition, the patients can regulate their inspiratory flow rate and increase it according to their inspiratory efforts. This improves patient-ventilator synchrony [2].

A ventilator mode is a specific setting on the ventilator that determines how the ventilator assists the patient by giving a breath. It also defines the amount of respiratory support that the ventilator provides for the patient [5].

It is important to note that each ventilator mode has advantages and disadvantages. There is no perfect ventilation mode that fits all patients. The best mode is the mode with which you and your team are most familiar [2].

Two primary ventilator modes that are most commonly used in the ED are Assist/Control Ventilation (ACV) Mode and Synchronous Intermittent Mandatory Ventilation (SIMV) Mode [4].

Assist/Control ventilation (ACV)

This mode is designed to offer full respiratory support for patients with minimal or no spontaneous breathing by delivering a preset number of mandatory breaths. However, if the patient tries to breathe, the ventilator will also assist that breath [5]. The patient will always receive at least the preset number of breaths (regardless of his/her respiratory effort). In this regard, ACV is the most appropriate initial mode in ED patients who are initially paralyzed and sedated [1].

ACV can be set as either volume-control or pressure-control. In VC/ACV, we set these parameters: Vt, flow rate, basal respiratory rate, and sensitivity to the patient’s respiratory effort (trigger). We can adjust the sensitivity control to make it easier or harder for the patient to trigger an assisted breath from the ventilator.
In PC/ACV, instead of Vt, we set the Ti. In this mode, Vt is dependent on the patient’s lung compliance and airway pressure. The advantage is avoiding barotrauma, but the disadvantage is that a specific preset Vt cannot be guaranteed [4].

To ensure ventilator synchronization, a breath initiated by the patient takes precedence over a preset breath. If the ventilator is programmed to deliver 12 breaths per minute, it will provide a breath every five seconds in the absence of spontaneous breathing. However, if the patient makes a spontaneous effort, the ventilator will provide an extra breath and reset the timer for another five seconds. The main challenge is that patient-initiated breaths are not proportional to his effort. When the patient makes an inspiratory effort, the ventilator provides a full Vt, which can lead to hyperventilation and poor patient-ventilator synchronization. Adequate sedation is necessary to prevent spontaneous breathing efforts when a patient is ventilated in the ACV mode. [1].

Synchronous Intermittent Mandatory Ventilation (SIMV)

This mode offers intermittent ventilatory support to patients by delivering mandatory breaths and supporting spontaneous breaths. Mandatory breaths are delivered at a preset rate. The ventilator delivers at least a preset number of mandatory breaths to the patient, similar to ACV. Patients with no respiratory effort, will receive the preset number of breaths. Patients with spontaneous breathing at a lower rate than the ventilator preset rate will receive the preset number of breaths with full Vt. In these two scenarios, SIMV is very similar to ACV. However, if a patient has spontaneous breathing at a rate higher than the preset respiratory rate, additional respiratory effort beyond the preset rate will only be partially supported proportional to the patient’s respiratory effort. This makes SIMV an appropriate mode for less sedated patients with some degree of spontaneous breathing [1].

Pressure Support Ventilation (PSV)

In this mode, the ventilator assists the patient’s spontaneous breaths during the inspiratory phase of breathing. It is often used to help the patient overcome the airway resistance caused by the endotracheal tube and the ventilator circuit. The patient should be alert or on light sedation and able to follow commands. When the patient triggers a breath, the ventilator supports it by adding pressure to facilitate breathing. The operator sets the FiO2, PEEP, and inspiratory pressure on the ventilator based on how much support the patient needs to receive. In PSV, RR, Ti, and flow rate are determined by the patient. The higher the pressure support, the easier it will be for the patient to take a breath. The ventilator supports inspiration until the inspiratory flow falls below a preset measure [2,6].

When choosing PSV, it is also necessary to set an appropriate backup mode (for example, SIMV) and ventilator alarms [6].

Typical initial ventilator settings: Although required settings depend on whether PC or VC ventilation is selected, the principles are similar in both modes [1]. Typical initial ventilator settings include the following: [1,2,4]

Tidal volume (Vt): a Vt of 6 to 8 mL/kg of estimated ideal body weight (IBW) is appropriate for most patients. The inspiratory pressure should be set in PC ventilation to achieve these Vt targets. Ongoing patient assessment is necessary to avoid excessive Vt. Regardless of VC or PC, initial pressure targets should not exceed 30 cm H2O.
Respiratory rate: a rate of 12 to 18 breaths per minute would be reasonable for most patients and provide adequate ventilation. In special situations, such as patients with severe metabolic acidosis, the respiratory rate should be increased to match pre-intubation minute ventilation.
FiO2: initially should be set at 100%, then lowered to target a SpO2 of 92% – 96% (PaO2 of 60 to 100 mmHg)
PEEP: is routinely set initially at 5 cm H2O, but it can be set at 4 to 20 cm H2O
I/E time ratio: The ratio of inspiratory time to expiratory time. It is commonly set as a ratio of 1:2. In some modes, it is automatically set based on other parameters. In some other modes, it needs to be set by the operator.
Flow rate: is typically set at 60 L/min. (Vt will be delivered at the speed of 60 L/min). Increasing the flow rate will deliver the set Vt faster, reducing the inspiratory time. (It is found in VC modes)
The trigger is a preset change in pressure or flow detected by the ventilator as the patient tries to initiate a breath, and the ventilator supports that breath. It should be set at a level that enables the patient to trigger the ventilator without great effort. For most patients, pressure sensitivity trigger from -0.5 to -2 cm H2O is effective and safe. The 1–3 L/min threshold is appropriate for the flow trigger setting.

When choosing a ventilator mode and parameters, it is essential to ensure adequate ventilation, but it is also important to ensure that the pressure in the ventilator circuit (including the lung) is appropriate [1]. Some important pressures are:

Peak inspiratory pressure (PIP) is the maximum pressure during inspiration. It is a dynamic pressure measured during the inspiration, so it incorporates airﬂow and reﬂects the resistance to airﬂow. It is also reﬂective of dynamic compliance of the entire respiratory system. Decreasing compliance or increasing resistance to airﬂow will increase PIP. It can never be lower than P. plat [4].
Plateau pressure (P. plat) is a static pressure that can be measured at the end of inspiration with a short breath-hold (Figure 1). The goal is to be less than 30 cm H2O. Decreasing the compliance will increase P. plat. Decreasing the Vt will decrease P. plat [4]

Positive End-Expiratory Pressure (PEEP) is the airway pressure at the end of expiration. It helps to keep the smaller airways and the alveoli open, prevents atelectasis, and improves oxygenation. Increased levels of PEEP may lead to lung injury. Additionally, high PEEP can depress cardiac output and lead to hemodynamic compromise [1,4]. When talking about PEEP, most authors mean extrinsic PEEP (PEEPe). In this chapter, when we use PEEP, we refer to PEEPe.
Intrinsic PEEP or auto-PEEP (PEEPi) results from air trapping in the airways. It occurs due to increased expiratory resistance (e.g., bronchospasm, kinked ETT), impaired elastic recoil (e.g., emphysema), and increased minute ventilation (inadequate expiratory time). PEEPi can lead to hemodynamic instability similar to high levels of PEEP [2,4].

Noninvasive ventilation (NIV)

NIV provides continuous positive pressure throughout the breathing cycle via a tight-fitting mask (nasal, oro-nasal, or full-face mask, as shown in Figure 2) rather than an endotracheal tube [7].

No mandatory breath is given by the ventilator so the patient must have spontaneous breathing. The ventilator provides a preset level of pressure when the patient initiates a breath, but inspiratory flow and Ti are completely patient-dependent [4,7]NIPPV can be delivered as continuous positive airway pressure (CPAP) or bi-level positive airway pressure (BiPAP).

CPAP provides constant positive pressure throughout the entire respiratory cycle. Its main effect is applying positive pressure at the end of expiration and exerts a minimal effect on inspiration [4,7].

BiPAP supplies a positive airway pressure during inspiration (IPAP) and a lower positive airway pressure during expiration (EPAP) [4].

IPAP provides pressure support and decreases the patient’s work of breathing. Increasing the IPAP will improve tidal volume and minute ventilation, thereby helping to eliminate CO2 from the alveoli.

EPAP acts similar to PEEP and improves alveolar recruitment and oxygenation by maintaining positive pressure at the end of expiration. EPAP prevents the lung from being fully deflated at the end of expiration, aiding in oxygen exchange across the alveolar-capillary membrane. Therefore, when you need to improve oxygenation, you should increase the EPAP.

The difference between the IPAP and EPAP is called delta pressure. The delta pressure is the same as pressure support in invasive ventilation. When the difference between the IPAP and EPAP is larger, the patient is able to have a larger tidal volume. Therefore, when you need to increase the clearance of CO2, you need to increase the delta pressure. [1,7].

Contraindications to NIV are patients who are uncooperative, hemodynamically unstable, lack protective airway reflexes, lack good respiratory effort, or have maxillofacial trauma. [7,8]

Initial NIV Settings

Initial settings depend on the amount of support that the patient requires, patient comfort, and patient cooperation.

BiPAP usually is initiated at 10 cm H2O for IPAP and 5 cm H2O for EPAP. Based on the patient’s clinical response, these parameters can be titrated later by 1 to 2 cm H2O at a time. However, the maximum pressure for IPAP should not exceed 20 cm H2O because this may lead to barotrauma [8,9].

Typical initiated settings for CPAP are 5 to 15 cm H2O [4,7].

Ventilator Troubleshooting

Patient-ventilator dys-synchrony refers to patients who develop respiratory distress after undergoing mechanical ventilation [10]. Emergency physicians must be familiar with patient-ventilator interactions so that life-threatening complications of mechanical ventilation can be promptly identified and managed [11]. In Figure 3, we present a systematic approach to detect life-threatening conditions in patients who suddenly deteriorate and become hemodynamically unstable (profound hypotension or cardiac arrest) under mechanical ventilation [1, 10].

Revisiting Your Patient

After 30 minutes, you reevaluate your patient. The patient remains in respiratory distress with SpO2 of 79%, despite nebulized beta-agonists, steroids, antibiotics, and the use of 7 L/min O2 via face mask. The patient’s blood gas reveals a pH of 7.22, PCO2 of 80 mm Hg, and PaO2 of 55 mmHg. You decide to put him on NIV using an oro-nasal mask. You choose BiPAP mode and set IPAP=12 cm H2O, EPAP=7 cm H20, and FIO2= 90%. After 5 minutes, the patient becomes agitated on the NIV mask, even with verbal direction and support. The pulse oximeter remains low at a SpO2 of 85%.

What would be the next appropriate step in the management of this patient?

You recognize your patient has not sufficiently improved despite maximal medical therapies. You decide to prepare for intubation and mechanical ventilation. The patient is fully sedated, paralyzed, and intubated using RSI (rapid sequence intubation). You prepare to choose a ventilation mode and set the parameters on your ventilator.

Which mode of ventilation and control parameters are most ideal for your patient?

The patient is sedated and paralyzed during RSI, so the VC/ACV mode is the best choice. Your senior says, “The best mode is the mode most familiar to you.” No data suggest the advantage of PC over VC (or vice versa) in patients with COPD. You review your goals in MV of your COPD patient: improve oxygenation and ventilation, minimize PEEPi, and prevent barotrauma.

You set the ventilator as:

Mode: ACV (VC/ACV)
FiO2= 100%
Vt= 500 cc
Respiratory rate= 14
PEEP= 5cm H2O
I/E: 1/4

You base your tidal volume on the patient’s 170 cm height and weight of 90 kg. You set the I/E ratio at 1:4 to optimize a longer expiratory time and titrate the FiO2 until the SpO2 falls between 88% to 92% [12]. A chest X-ray confirms the tip of the endotracheal tube is located above the carina. The patient is admitted to the medical ICU for further management and treatment.

Authors

Elham Pishbin

Elham Pishbin is a full-time associate professor of emergency medicine (EM) with 16 years of experience as a faculty member of the department of EM at Imam Reza Hospital, affiliated with Mashhad University of Medical Sciences, Mashhad, Iran. She is a member of the Iranian national board of EM and contributed to establishing the first EM residency program at Mashhad University of Medical Sciences in 2008, the fifth EM residency program in Iran, and a significant milestone in the development of EM in the country.

Hamidreza Reihani

Dr. Hamidreza Reihani, a professor of emergency medicine at Mashhad University of Medical Sciences in Iran, is also a member of the national board of emergency medicine. He holds fellowships in medical education, research, and clinical informatics. With 15 years of experience in emergency medicine, he has made significant contributions, including founding an academic Emergency Department (ED) at his university and educating over 100 specialists in the field. Dr. Reihani has also been actively involved in interdisciplinary and undergraduate education, research (with more than 60 published articles), peer review, and editorial roles for two academic journals. His expertise and dedication are reflected in his contributions to both the previous and current editions of this book.

Listen to the chapter

References

Seigel T.A, Johnson N.J. Mechanical ventilation and noninvasive ventilatory support. In: Walls R.M, ed. Rosen’s emergency medicine: concepts and clinical practice. 10th ed. Philadelphia PA: Elsevier; 2023:24-33
Ward J, Noel C. Basic Modes of Mechanical Ventilation. Emerg. Med. Clin. N. Am. 2022;40(3):473-88
Gomersall C, Joynt G, Cheng C, et al. Basic Assessment and Support in Intensive Care. Hong Kong: Chinese University of Hong Kong; 2013:37-54.
Santanilla J.I. Mechanical Ventilation. In Roberts J.R, Hedges J.R, eds. Roberts and Hedges’ clinical procedures in emergency medicine and Acute Care. 7th ed. Philadelphia PA: Elsevier; 2018:152-172.
Hickey S, Giwa A. Mechanical ventilation. StatPearls. 2023 Jan 26.
Abramovitz A, Sung S. Pressure Support Ventilation. StatPearls. 2022. Sep 18.
Gill HS, Marcolini EG. Noninvasive mechanical ventilation. Emerg. Med. Clin. N. Am. 2022;40(3):603-13.
Carlson J.N, Wang H.E. Noninvasive Airway Management. In: Tintinalli J.E, ed. Tintinalli’s emergency medicine: a comprehensive study guide, 9th ed. McGraw Hill Education; 2020: 178-183.
Baker DJ, Baker DJ. Basic Principles of Mechanical Ventilation. Artificial Ventilation: A Basic Clinical Guide. 2020:113-37.
Keith RL, Pierson DJ. Complications of mechanical ventilation: a bedside approach. Clinics in chest medicine. 1996 Sep 1;17(3):439-51.
Gilstrap D, MacIntyre N. Patient–ventilator interactions. Implications for clinical management. American journal of respiratory and critical care medicine. 2013 Nov 1;188(9):1058-68.
Atchinson P.R, Roginski M.A. Chronic obstructive pulmonary disease. In: Walls R.M, ed. Rosen’s emergency medicine: concepts and clinical practice. 10th ed. Philadelphia PA: Elsevier; 2023:806-815

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Joseph Ciano, DO, MPH, MS

Dr. Ciano is a board-certified attending emergency medicine physician from New York, USA. He works in the Department of Emergency Medicine and Global Health at the Hospital of the University of Pennsylvania. Dr. Ciano’s global work focuses on capacity building and medical education and training in low-middle income countries. He is thrilled to collaborate with the iEM Education Project in creating free educational content for medical trainees and physicians.