Category: Circulation

Physiologically Difficult Airway – Metabolic Acidosis

Physiologically Difficult Airway - Metabolic Acidosis
~ Jule Santos, Brasil ~ Leave a comment

Case Presentation

A 32-year-old male with insulin-dependent diabetes mellitus came to your emergency department for shortness of breath. He was referred to the suspected COVID-19 area. His vitals were as follows: Blood pressure, 100/55 mmHg; pulse rate, 135 bpm; respiratory rate, 40/min; saturation on 10 liters of oxygen per minute, 91%; body temperature, 36.7 C. His finger-prick glucose was 350 mg/dl.

The patient reported that he had started to feel ill and had an episode of diarrhea 1 week ago. He developed a dry cough and fever in time. He started to feel shortness of breath for 2 days. He sought out the ER today because of the difficulty breathing and abdominal pain.

The patient seemed alert but mildly agitated. He was breathing effortfully and sweating excessively. On physical examination of the lungs, you noticed fine crackles on the right. Despite the patient reported abdominal pain, there were no signs of peritonitis on palpation.

An arterial blood gas analysis showed: pH 7.0, PCO2: 24, pO2: 56 HCO3: 8 Lactate: 3.

The point-of-care ultrasound of the lungs showed B lines and small foci of subpleural consolidations on the right.
At this point, what are your diagnostic hypotheses?

Two main diagnostic hypotheses here are:

  • Diabetic ketoacidosis (Hyperglycemia + metabolic acidosis)
  • SARS-CoV2 pneumonia

We avoid intubating patients with pure metabolic decompensation of DKA if possible, as they respond to hydration + insulin therapy + electrolyte replacement well and quickly. 

But in this scenario, the patient is extremely sick and has complicating medical issues, such as an acute lung disease decompensating the diabetic condition, probably COVID19. Considering these extra issues may complicate the recovery time and increase the risk of respiratory failure, you decide to intubate the patient in addition to the treatment of DKA.

You order lab tests and cultures. You start hydration and empirical antibiotics while starting preoxygenation and preparing for intubation.

Will this be a Difficult Airway?

Evaluating the patient for the predictors of a difficult airway is a part of the preparation for intubation. Based on your evaluation, you should create an intubation plan. 

This assessment is usually focused on anatomical changes that would make it difficult to manage the airway (visualization of the vocal cords, tube passage, ventilation, surgical airway), thereby placing the patient at risk.

“Does this patient have any changes that will hinder opening the mouth, mobilizing the cervical region, or cause any obstruction for laryngoscopy? Does this patient have any changes that hinder the use of Balloon-Valve-Mask properly, such as a large beard? What about the use of the supraglottic device? Does this patient have an anatomical alteration that would hinder emergency cricothyroidotomy or make it impossible, like a radiation scar? ”

So the anatomically difficult airway is when the patient is at risk if you are unable to intubate him due to anatomical problems.

The physiologically difficult airway, however, is when the patient has physiological changes that put him at risk of a bad outcome during or shortly after intubation. Despite intubation. Or because of intubation, because of its physiological changes due to positive pressure ventilation.

These changes need to be identified early and must be mitigated. You need to recognize the risks and stabilize the patient before proceeding to intubation or be prepared to deal with the potential complications immediately if they happen.

5 main physiological changes need attention before intubation are: hypoxemia, hypotension, severe metabolic acidosis, right ventricular failure, severe bronchospasm.

Back to our patient: Does he have physiologically difficult airway predictors?

  • SI (Shock Index): 1.35 (Normal <0.8) – signs of shock
  • P / F: 93 (Normal> 300) – Severe hypoxemia
  • pH: 7.0: Severe metabolic acidosis – expected pCO2: 20 (not compensating)
  • qSOFA: 2 + Lactate: 3 (severity predictor)

Physiologically Difficult Airway

"Severely critical patients with severe physiological changes who are at increased risk for cardiopulmonary collapse during or immediately after intubation."

Sakles JC, Pacheco GS, Kovacs G, Mosier JM. The difficult airway refocused.

Severe Metabolic Acidosis

In this post, we will focus only on the compensation of the metabolic part, but do not forget that this is a patient who needs attention on oxygenation and hemodynamics as well. That is, this is intubation with very difficult predictions.

What happens during the rapid sequence of intubation in severe metabolic acidosis?

To perform the procedure, the patient needs to be in apnea. During an apnea, pulmonary ventilation is decreased and the CO2 is not “washed” from the airway. These generate an accumulation of CO2, an acid, decreasing blood pH. In a patient with normal or slightly altered pH, this can be very well-tolerated, but in a patient with a pH of 7.0, an abrupt drop in this value can be ominous.

We know that the respiratory system is one of the most important compensation mechanisms for metabolic acidosis and it starts its action in seconds, increasing the pH by 50 to 75% in 2 to 3 minutes, guaranteeing the organism time to recover. So, even seconds without your proper actions can be risky for critical patients.

In addition, it must be remembered that increased RF is the very defense for the compensation of metabolic acidosis, and most of the time the organism does this very well. So if after the intubation the NORMAL FR and NORMAL minute volume are placed in the mechanical ventilator parameters, again there is an increase in CO2 and a further decrease in pH.

And what’s wrong? After all, a little bit of acidosis even facilitates the release of oxygen in the tissues because it deflects the oxyhemoglobin curve to the right, right?

Severe metabolic acidosis (pH <7.1) can have serious deleterious effects:

  • Arterial vasodilation (worsening shock)
  • Decreased myocardial contractility
  • Risks of arrhythmias
  • Resistance to the action of DVAs
  • Cellular dysfunction

What to do?

Always the primary initial treatment is: treating the underlying cause! In patients with severe metabolic acidosis, it is best to avoid intubation! Especially in metabolic ketoacidosis, which as hydration and insulin intake improves, there is a progressive improvement in blood pH.

Sodium bicarbonate

The use of sodium bicarbonate to treat metabolic acidosis is controversial, especially in non-critical acidosis values ​​(pH> 7.2). If you have acute renal failure associated, its use may be beneficial by postponing the need for renal replacement therapy (pH <7.2).

As for DKA, where sodium bicarbonate is used to the ketoacidosis formed by erratic metabolism due to the lack of insulin and no real deficiency is present, its use becomes limited to situations with pH <6.9.

The dose is empirical, and dilution requires a lot of attention (avoid performing HCO3 without diluting!)

NaHCO3 100mEq + AD 400ml

Run EV in 2h

If K <5.3: Associate KCl 10% 2amp

I would make this solution and leave it running while proceeding with the intubation preparations.

Attention: Remember, according to the formula below, that HCO3 is converted to CO2, and if done in excess, is associated with progressive improvement of the ketoacidosis and recovery of HCO3 from the buffering molecules. In a patient already with limited ventilation, its increase can cause deviation of the curve for the CO2 increase, which is also easily diffused to the cells and paradoxically decrease the intracellular pH, in addition to carrying K into the cell.

H + + HCO3 – = H2CO3 = CO2 + H2O

Mechanical ventilation

I think the most important part of the management of these patients is the respiratory part.

If you choose the Rapid Sequence Intubation: Prepare for the intubation to be performed as quickly as possible: Use your best material, choose the most experienced intubator, put the patient in ideal positioning, decide and apply medications skillfully, to ensure the shortest time possible apnea.

You will need personnel experienced in Mechanical Ventilation and you must remember to leave the ventilatory parameters adjusted to what the patient needs and not to what would be normal!

I found this practice very interesting: First, you calculate what the expected pCO2 should be for the patient, according to HCO3:

Winter’s Equation (Goal C02) = 1.5 X HCO3 + 8 (+/- 2)

And then, according to this table, you try to reach the VM Volume Minute value.
Goal CO2 Minute Ventilation
40 mmHg
6-8 L
30 mmHg
12-14 L
20 mmHg
18-20 L

These are just initial parameters. With each new blood gas analysis repeated in 30 minutes to an hour, you re-make fine adjustments using the formula below:

Minute volume = [PaCO2 x Minute volume (from VM)] / CO2 Desired

With the treatment of ketoacidosis, new parameters should be adjusted, hopefully for the better.

Another safer option for these patients would be to use the Awake Patient Intubation technique so that you would avoid the apnea period. However, Awake Patient Intubation Technique is contraindicated in suspected or confirmed COVID-19 cases due to the risk of contamination.

That’s it, folks, send your feedback, your experiences, and if you have other sources!

Further Reading

  1. Frank Lodeserto MD, “Simplifying Mechanical Ventilation – Part 3: Severe Metabolic Acidosis”, REBEL EM blog, June 18, 2018. Available at: https://rebelem.com/simplifying-mechanical-ventilation-part-3-severe-metabolic-acidosis/.
  2. Justin Morgenstern, “Emergency Airway Management Part 2: Is the patient ready for intubation?”, First10EM blog, November 6, 2017. Available at: https://first10em.com/airway-is-the-patient-ready/.
  3. Salim Rezaie, “How to Intubate the Critically Ill Like a Boss”, REBEL EM blog, May 3, 2019. Available at: https://rebelem.com/how-to-intubate-the-critically-ill-like-a-boss/.
  4. Salim Rezaie, “RSI, Predictors of Cardiac Arrest Post-Intubation, and Critically Ill Adults”, REBEL EM blog, May 10, 2018. Available at: https://rebelem.com/rsi-predictors-of-cardiac-arrest-post-intubation-and-critically-ill-adults/.
  5. Salim Rezaie, “Critical Care Updates: Resuscitation Sequence Intubation – pH Kills (Part 3 of 3)”, REBEL EM blog, October 3, 2016. Available at: https://rebelem.com/critical-care-updates-resuscitation-sequence-intubation-ph-kills-part-3-of-3/.
  6. Lauren Lacroix, “APPROACH TO THE PHYSIOLOGICALLY DIFFICULT AIRWAY”, https://emottawablog.com/2017/09/approach-to-the-physiologically-difficult-airway/
  7. Scott Weingart. The HOP Mnemonic and AirwayWorld.com Next Week. EMCrit Blog. Published on June 21, 2012. Accessed on July 15th 2020. Available at [https://emcrit.org/emcrit/hop-mnemonic/ ].
  8. IG: @pocusjedi: “Pocus e Coronavirus: o que sabemos até agora?”https://www.instagram.com/p/B-NxhrqFPI1/?igshid=14gs224a4pbff

References

  1. Sakles JC, Pacheco GS, Kovacs G, Mosier JM. The difficult airway refocused. Br J Anaesth. 2020;125(1):e18-e21. doi:10.1016/j.bja.2020.04.008
  2. Mosier JM, Joshi R, Hypes C, Pacheco G, Valenzuela T, Sakles JC. The Physiologically Difficult Airway. West J Emerg Med. 2015;16(7):1109-1117. doi:10.5811/westjem.2015.8.27467
  3. Irl B Hirsch, MDMichael Emmett, MD. Diabetic ketoacidosis and hyperosmolar hyperglycemic state in adults: Treatment. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. https://www.uptodate.com (Accessed on July 15, 2020.)
  4. Cabrera JL, Auerbach JS, Merelman AH, Levitan RM. The High-Risk Airway. Emerg Med Clin North Am. 2020;38(2):401-417. doi:10.1016/j.emc.2020.01.008
  5. Guyton AC, HALL JE. Tratado de fisiologia medica. 13a ed. Rio de Janeiro(RJ): Elsevier, 2017. 1176 p.
  6. Kraut JA, Madias NE. Metabolic acidosis: pathophysiology, diagnosis and management. Nat Rev Nephrol. 2010;6(5):274-285. doi:10.1038/nrneph.2010.33
  7. Calvin A. Brown III, John C. Sakles, Nathan W. Mick. Manual de Walls para o Manejo da Via Aérea na Emergência. 5. ed. – Porto Alegre: Artmed, 2019.
  8. Smith MJ, Hayward SA, Innes SM, Miller ASC. Point-of-care lung ultrasound in patients with COVID-19 – a narrative review [published online ahead of print, 2020 Apr 10]. Anaesthesia. 2020;10.1111/anae.15082. doi:10.1111/anae.15082
Cite this article as: Jule Santos, Brasil, "Physiologically Difficult Airway – Metabolic Acidosis," in International Emergency Medicine Education Project, November 25, 2020, https://iem-student.org/2020/11/25/physiologically-difficult-airway-metabolic-acidosis/, date accessed: April 25, 2024

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Question Of The Day #21

question of the day
~ Joseph Ciano, USA ~ Leave a comment
qod21

Which of the following is the most appropriate next step in management for this patient’s condition?

  • A) Watch the cardiac monitor for a rhythm change
  • B) Continue chest compressions
  • C) Administer intravenous adrenaline
  • D) Check for a pulse

This patient experienced a witnessed cardiac arrest at home, after which pre-hospital providers initiated cardiopulmonary resuscitation (CPR, or “chest compressions”) and Advanced Cardiovascular Life Support (ACLS). ACLS includes the tenets of Basic Life Support (BLS), such as early initiation of high-quality CPR at a rate of 100-120 compressions/minute, compressing the chest to a depth of 5 cm (2 inches), providing 2 rescue breaths after every 30 compressions (30:2 ratio), avoiding interruptions to CPR, and allowing for adequate chest recoil after each compression. In the ACLS algorithm, intravenous epinephrine is administered every 3-5 minutes and a “pulse check” is performed after every 2 minutes of CPR. The patient’s cardiac rhythm, along with the clinical history, helps decide if the patient should receive defibrillation (“electrical shock”) or additional medications. The ACLS algorithm divides management into patients with pulseless ventricular tachycardia (pVT) or ventricular fibrillation (VF) and patients with pulseless electric activity (PEA) or asystole.

The cardiac rhythm seen during the pulse check for this patient is a wide complex tachycardia with a regular rhythm. In the setting of cardiac arrest, chest pain prior to collapse, and a history of acute coronary syndrome, ventricular tachycardia is the most likely cause. The ACLS algorithm advises unsynchronized cardioversion at 150-200 Joules for patients with pVT or VF. Watching the cardiac monitor for a rhythm change (Choice A) or checking for a pulse (Choice D) are not recommended after defibrillation. A major priority of both BLS and ACLS is to avoid interruptions to CPR, so the best next step in management is to continue CPR (Choice B) after defibrillation. Administration of intravenous adrenaline (Choice C) is helpful for cardiac arrests to initiate shockable rhythm and should be repeated every 3-5 minute or every 2 cycle of CPR, particularly valuable in asystole patients. Calcium gluconate is another drug that can be used in patients with hyperkalemia and indicated in a patient with known kidney disease, missed hemodialysis sessions, or a history of usage of medications that can cause hyperkalemia. Magnesium can be used for patients who show polymorphic VT, particularly Torsades de Pointes. The next best step in this scenario is to continue CPR, regardless of the etiology of the cardiac arrest. Correct Answer: B.

Want Another Question?

References

Cite this article as: Joseph Ciano, USA, "Question Of The Day #21," in International Emergency Medicine Education Project, November 13, 2020, https://iem-student.org/2020/11/13/question-of-the-day-21/, date accessed: April 25, 2024

Push Th(d)ose Vasopressors

Push Th(d)ose Vasopressors
~ Neha Hudlikar, UAE ~ Leave a comment

Background

Since Scott Weingart first advocated for using push-dose pressors in the Emergency Department (ED) over a decade ago(1), push-dose vasopressors, also known as bolus-dose vasopressors have seemingly found their way into many EDs. However, recent studies have sought to ask more questions regarding its use and safety in the Emergency Department.

Vasopressors such as epinephrine and norepinephrine are commonly used for regulating and maintaining adequate blood pressure or mean arterial pressure (MAP). While these are usually administered as a continuous infusion via central access, administering them as a small bolus through peripheral access came to be known as push-dose vasopressor in practice.

Traditionally, this small bolus strategy was used in the operating room (OR) by anesthetists to treat transient hypotension due to sedating agents or spinal anesthesia. Multiple studies have supported the safety and efficacy of push-dose vasopressors in this clinical setting/patient population (2).

Swensen, et al. (3) studied the safety of bolus-dose phenylephrine for hypotension in the Emergency Department, however, data on the efficacy and safety of push-dose pressors remains sparse in ED and in-patient settings. Studies published in the past few years have questioned the lack of evidence regarding the safety and efficacy of push-dose pressor use in ED settings and highlighted some negative consequences of its use (4). To understand the concerns, it’s important we first understand the vasopressors, indications for use, and preparation in the ED.

Push-dose pressors in the Emergency Department

The two common vasopressors used as push-dose pressors in the Emergency Department are Epinephrine and Phenylephrine. Patients needing emergency airway, traumatic brain injury, and post-cardiac arrest with the return of spontaneous circulation may all experience hypotension which could lead to adverse outcomes. Push-does pressors have been proposed as a temporary measure to limit the hypotension while a vasopressor infusion/definitive treatment is being set up (5).

phenilephrine vs epinephrine
push dose epinephrine
push dose phenilephrine

Clinical settings in the ED where the use of push-dose pressor is proposed:

  1. Airway management: Hypotension prior, during, and post-intubation could be treated with bolus-dose vasopressors. Panchal et al. (6) did a retrospective chart review of intubated hypotensive patients in which phenylephrine was used. Bolus-dose phenylephrine demonstrated an increase in systolic blood pressure and the authors recommended further studies to understand the best use of phenylephrine for post-intubation hypotension.
  2. Return of spontaneous circulation (ROSC): In patients with ROSC, bolus-dose pressors may aid in the maintenance of end-organ perfusion, which is often impaired after ROSC (7).
  3. Traumatic brain injury: By rapidly increasing mean arterial pressure and thus cerebral perfusion pressure, bolus-dose vasopressors may help to prevent secondary brain injury.

What are the concerns regarding the use of push-dose pressors in the ED?

Acquisto and Bodkin (8) cited a few dosing errors while using push-dose pressors and highlighted that emergency physicians are less familiar with the practice of medication preparation/manipulation and hence dosing errors are expected, inadvertently causing patients more harm than benefit. They also emphasized on the lack of evidence in the literature regarding the efficacy and safety of push-dose pressors in a stressful environment like the ED.

Rotando and Picard et al. (9) in their prospective observational study of 146 patients receiving push-dose pressors in the ICU had thirteen (11.2%) patients have a dose-related medication error and seventeen (11.6%) adverse events. They concluded while push-dose pressors where efficacious, they were associated with adverse drug events and medication errors.

Cole et al (10). performed a retrospective analysis of 249 patients receiving push-dose pressors and found a higher incidence of adverse hemodynamic effects (39%) and human errors (19%). They emphasized the need for further studies to question whether push-dose pressors improve outcomes, and if so, how to safely implement them in practice.

Another concern raised is whether physicians may bypass standard resuscitation practices of fluid boluses in favor of using push-dose pressors. Schwartz et al. (11) found that only 34% of patients received an appropriate fluid challenge before using push-dose pressors in a retrospective chart review of 73 patients receiving push-dose pressors for acute hypotension in the ED. Furthermore, it appeared that patients who did not receive an appropriate fluid bolus needed more doses of bolus-dose pressors followed by the need for continuous vasopressor infusion within 30 minutes of bolus-dose pressor use.

Emergency physicians work in stressful environments which raises concerns on the ability of the physician to perform accurate dose calculations under duress (4). The prepared syringe also contains multiple individual doses, and using more concentrated solutions potentially increases the risk of overdose and extravasation injury (12).

Conclusion

While the practice of using push-dose pressors has found its way into the Emergency Department, it is crucial to acknowledge that evidence regarding its safety and benefits is limited. However, rather than disregarding the practice, high-quality research should be encouraged, which could potentially be practice-changing. Holden et al. (12) offer a framework of operational and safety considerations for the use of push-dose pressors in the ED and is a must-read for all using push-dose pressors in their current practice.

References

  1. Scott Weingart. EMCrit Podcast 6 – Push-Dose Pressors. EMCrit Blog. Published on July 10, 2009. Accessed on September 25th 2020. Available at [https://emcrit.org/emcrit/bolus-dose-pressors/ ].
  2. Lee A, Ngan Kee WD, Gin T. A quantitative, systematic review of randomized controlled trials of ephedrine versus phenylephrine for the management of hypotension during spinal anesthesia for cesarean delivery. Anesth Analg. 2002 Apr;94(4):920-6, table of contents. doi: 10.1097/00000539-200204000-00028. PMID: 11916798.
  3. Swenson K, Rankin S, Daconti L, Villarreal T, Langsjoen J, Braude D. Safety of bolus-dose phenylephrine for hypotensive emergency department patients. Am J Emerg Med. 2018 Oct;36(10):1802-1806. doi: 10.1016/j.ajem.2018.01.095. Epub 2018 Feb 19. PMID: 29472039.
  4. Cole JB. Bolus-Dose Vasopressors in the Emergency Department: First, Do No Harm; Second, More Evidence Is Needed. Ann Emerg Med. 2018 Jan;71(1):93-95. doi: 10.1016/j.annemergmed.2017.05.039. Epub 2017 Jul 26. PMID: 28754354.
  5. Weingart S. Push-dose pressors for immediate blood pressure control. Clin Exp Emerg Med. 2015;2(2):131-132. Published 2015 Jun 30. doi:10.15441/ceem.15.010
  6. Panchal AR, Satyanarayan A, Bahadir JD, Hays D, Mosier J. Efficacy of Bolus-dose Phenylephrine for Peri-intubation Hypotension. J Emerg Med. 2015 Oct;49(4):488-94. doi: 10.1016/j.jemermed.2015.04.033. Epub 2015 Jun 20. PMID: 26104846.
  7. Gottlieb M. Bolus dose of epinephrine for refractory post-arrest hypotension. CJEM. 2018 Oct;20(S2):S9-S13. doi: 10.1017/cem.2016.409. Epub 2017 Jan 10. PMID: 28069098.
  8. Acquisto NM, Bodkin RP, Johnstone C. Medication errors with push dose pressors in the emergency department and intensive care units. Am J Emerg Med. 2017 Dec;35(12):1964-1965. doi: 10.1016/j.ajem.2017.06.013. Epub 2017 Jun 7. PMID: 28625533.
  9. Rotando A, Picard L, Delibert S, Chase K, Jones CMC, Acquisto NM. Push dose pressors: Experience in critically ill patients outside of the operating room. Am J Emerg Med. 2019 Mar;37(3):494-498. doi: 10.1016/j.ajem.2018.12.001. Epub 2018 Dec 3. PMID: 30553634.
  10. Cole JB, Knack SK, Karl ER, Horton GB, Satpathy R, Driver BE. Human Errors and Adverse Hemodynamic Events Related to “Push Dose Pressors” in the Emergency Department. J Med Toxicol. 2019 Oct;15(4):276-286. doi: 10.1007/s13181-019-00716-z. Epub 2019 Jul 3. PMID: 31270748; PMCID: PMC6825064.
  11. Schwartz MB, Ferreira JA, Aaronson PM. The impact of push-dose phenylephrine use on subsequent preload expansion in the ED setting. Am J Emerg Med. 2016 Dec;34(12):2419-2422. doi: 10.1016/j.ajem.2016.09.041. Epub 2016 Sep 22. PMID: 27720568.
  12. Holden D, Ramich J, Timm E, Pauze D, Lesar T. Safety Considerations and Guideline-Based Safe Use Recommendations for “Bolus-Dose” Vasopressors in the Emergency Department. Ann Emerg Med. 2018 Jan;71(1):83-92. doi: 10.1016/j.annemergmed.2017.04.021. PMID: 28601272.
Cite this article as: Neha Hudlikar, UAE, "Push Th(d)ose Vasopressors," in International Emergency Medicine Education Project, November 11, 2020, https://iem-student.org/2020/11/11/push-thdose-vasopressors/, date accessed: April 25, 2024

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Drop the Beat! – Adenosine in SVT

Drop the Beat! – Adenosine in SVT
~ Mohammad Anzal Rehman, UAE ~ Leave a comment

Supraventricular tachycardia (SVT) is defined as a dysrhythmia that originates proximal to (or ‘above’) the atrioventricular (AV) node of the heart. It commonly manifests as a regular, narrow complex (QRS interval < 120ms) tachycardia in affected patients. It is most frequently attributable to re-entrant electrical conduction through accessory pathways in the heart, with typical Electrocardiogram (ECG) findings depicting ventricular rates of 150 to 250 beats/min without the preceding P wave usually seen in sinus tachycardias. [1,2]

In the stable adult patient presenting with SVT, where no ‘red flags’ such as shock, altered mental state, ischemic chest pain or hypotension are present, management typically begins with an attempt to convert the rhythm back to its baseline sinus state using vagal manoeuvres.[3] Vagal manoeuvres such as the carotid sinus massage and the Valsalva manoeuvre are effective first-line therapies, terminating approximately 25% of spontaneous SVTs,[4] with the newer, modified Valsalva manoeuvre showing even greater efficacy of 43% conversion.[5] When these fail or are otherwise not feasible to use in patients, management involves the administration of a drug called Adenosine.

The Evolution of Adenosine Use for SVT

In 1927, studies found that the injection of extracts from cardiac tissue into animals appeared to decrease heart rates and that this effect was attributable to an ‘adenine compound’.[6] This compound was later identified as Adenosine, comprised of the purine-based nucleobase Adenine attached to a ribose sugar. Fifty years after its initial discovery, Adenosine began to emerge as a treatment for stabilizing SVTs and has remained a mainstay in its management ever since.[7]

Current guidelines recommend Adenosine for the management of SVT, usually administered through a peripheral intravenous (IV) access initially as a 6 mg bolus. Adenosine has an extremely short half-life (less than 10 seconds) and is therefore rapidly metabolized soon after it enters the body.[8] Therefore, IV dosage is commonly followed by a 20 mL rapid saline flush to facilitate the drug’s transport to cardiac tissue where it can act before being broken down into inactive metabolites. If the 6mg dose does not convert the SVT back to sinus rhythm, subsequent doses are given at 12 mg, also followed by 20-mL saline for rapid infusion.

Pro-Tip: Single syringe technique

Before we dive into the concept of the single syringe method of administering Adenosine, take a look at the segment above. How would you give 6 mg of Adenosine through an IV site, making sure a total of 20 mL saline follows right after, in enough time to make sure you don’t waste that precious 10-second half-life of Adenosine? In many places, one of the two methods are used to make this happen:

  1. Use an IV line to push Adenosine > remove syringe > push 10 mL saline using a pre-filled syringe > remove syringe > push 10mL saline using a second pre-filled syringe.
  2. Fancier places use what’s known as a stopcock, a device usually with 3 ports attached to the IV site. Adenosine syringe is attached to one port and a 10 mL saline flush is attached at a separate port. The process looks something like this: Push adenosine through stopcock port > turn stopcock to open saline port’s access to IV site > push 10 mL saline flush > push an additional 10 mL saline using second syringe or remainder of a 20 mL prefilled syringe.

Now we all know that nurses are indistinguishable from ninjas at times when handling IV medication. However, even the most experienced practitioner is not immune to the occasional stumble when switching between the various syringes and swivels required in the methods above. In fact, a study in 2018 found that, in pediatric patients, adenosine given using the stopcock method delivered suboptimal doses.[9]

In an attempt to improve administration time, a potential work-around was proposed where adenosine could be combined with the flush solution in one 20 mL syringe and pushed altogether.[10] This potentially eliminates any time wasted changing syringes and manipulating stopcocks, but does it still work the same? Fortunately, a few studies have demonstrated the feasibility of the single syringe method, with non-inferior efficacy compared to standard methods of drug administration.[11,12]

Caveats: Coffee Conundrums

Let’s talk a bit about dosage. We mentioned above that guidelines recommend starting at 6 mg and moving to 12 mg for subsequent dosages. These dosages assume uninhibited action of adenosine at its receptors which, unfortunately, may not always be the case in patients. What would inhibit adenosine’s activity, I hear you ask? You’ll want to put down that Caramel Macchiato because the answer (pause for dramatic effect) … is coffee – caffeine to be exact.

Caffeine is known to work by antagonizing adenosine receptors, thereby decreasing adenosine’s biologic effect.[13] A component in many frequently consumed beverages, such as coffee, tea, energy drinks and sodas, and with a half-life of approximately 4-5 hours, caffeine is very likely to be present in the bloodstreams of many Emergency Department patients (and doctors). A 2010 multi-centre study in Australia found that recent ingestion of caffeine less than 4 hours prior to a 6 mg adenosine bolus significantly reduced its effectiveness in treating SVT. [14]

This makes it all the more important to not only include information on any known recent beverage consumption during history taking for patients presenting with SVT, but also to potentially increase dosage for patients with a confirmed or suspected recent ingestion of caffeine. In such cases, it would be reasonable to start at 12 mg adenosine as the first dose, followed by 18 mg subsequent dosages to manage SVT.[15]

A 2010 multi-centre study in Australia found that recent ingestion of caffeine less than 4 hours prior to a 6 mg adenosine bolus significantly reduced its effectiveness in treating SVT.

A. Rehman Tweet

References and Further Reading

  1. Bibas, L., Levi, M., & Essebag, V. (2016). Diagnosis and management of supraventricular tachycardias. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne, 188(17-18), E466–E473. https://doi.org/10.1503/cmaj.160079
  2. Mahtani, A. U., & Nair, D. G. (2019). Supraventricular Tachycardia. The Medical clinics of North America, 103(5), 863–879. https://doi.org/10.1016/j.mcna.2019.05.007
  3. Advanced Cardiac Life Support Provider Manual, American Heart Association, Mesquite 2016
  4. Lim, S. H., Anantharaman, V., Teo, W. S., Goh, P. P., & Tan, A. (1998). Comparison of Treatment of Supraventricular Tachycardia by Valsalva Maneuver and Carotid Sinus Massage. Annals of emergency medicine, 31(1), 30–35.
  5. Appelboam, A., Reuben, A., Mann, C., Gagg, J., Ewings, P., Barton, A., Lobban, T., Dayer, M., Vickery, J., Benger, J., & REVERT trial collaborators (2015). Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT): a randomised controlled trial. Lancet (London, England), 386(10005), 1747–1753. https://doi.org/10.1016/S0140-6736(15)61485-4
  6. Drury, A. N., & Szent-Györgyi, A. (1929). The physiological activity of adenine compounds with especial reference to their action upon the mammalian heart. The Journal of physiology, 68(3), 213–237. https://doi.org/10.1113/jphysiol.1929.sp002608
  7. Delacrétaz E. (2006). Clinical practice. Supraventricular tachycardia. The New England journal of medicine, 354(10), 1039–1051. https://doi.org/10.1056/NEJMcp051145
  8. Kazemzadeh-Narbat, M., Annabi, N., Tamayol, A., Oklu, R., Ghanem, A., & Khademhosseini, A. (2015). Adenosine-associated delivery systems. Journal of drug targeting, 23(7-8), 580–596. https://doi.org/10.3109/1061186X.2015.1058803
  9. Weberding, N. T., Saladino, R. A., Minnigh, M. B., Oberly, P. J., Tudorascu, D. L., Poloyac, S. M., & Manole, M. D. (2018). Adenosine Administration With a Stopcock Technique Delivers Lower-Than-Intended Drug Doses. Annals of emergency medicine, 71(2), 220–224. https://doi.org/10.1016/j.annemergmed.2017.09.002
  10. Hayes, B.D. (2019). ‘Trick of the Trade: Combine Adenosine with the Flush’. Academic Life in Emergency Medicine Blog Post https://www.aliem.com/trick-of-trade-combine-adenosine-single-syringe/
  11. Choi, S.C., Yoon, S.K., Kim, G.W., Hur, J.M., Baek, K.W., & Jung, Y.S. (2003). A Convenient Method of Adenosine Administration for Paroxysmal Supraventricular Tachycardia. Journal of the Korean society of emergency medicine, 14, 224-227.
  12. McDowell, M., Mokszycki, R., Greenberg, A., Hormese, M., Lomotan, N., & Lyons, N. (2020). Single-syringe Administration of Diluted Adenosine. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine, 27(1), 61–63. https://doi.org/10.1111/acem.13879
  13. Ribeiro, J. A., & Sebastião, A. M. (2010). Caffeine and adenosine. Journal of Alzheimer’s disease : JAD, 20 Suppl 1, S3–S15. https://doi.org/10.3233/JAD-2010-1379
  14. Cabalag, M. S., Taylor, D. M., Knott, J. C., Buntine, P., Smit, D., & Meyer, A. (2010). Recent caffeine ingestion reduces adenosine efficacy in the treatment of paroxysmal supraventricular tachycardia. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine, 17(1), 44–49. https://doi.org/10.1111/j.1553-2712.2009.00616.x
  15. Hayes, B.D. (2012). ‘Is the 6-12-12 adenosine approach always correct?’ Academic Life in Emergency Medicine Blog Post https://www.aliem.com/is-6-12-12-adenosine-approach-always/
Cite this article as: Mohammad Anzal Rehman, UAE, "Drop the Beat! – Adenosine in SVT," in International Emergency Medicine Education Project, September 14, 2020, https://iem-student.org/2020/09/14/adenosine-in-svt/, date accessed: April 25, 2024

Anaphylaxis in a Nutshell

anaphylaxis in a nutshell
~ Neha Hudlikar, UAE ~ Leave a comment

Anaphylaxis can be broadly defined as a severe, life-threatening, generalized or systemic hypersensitivity reaction. Literature suggests that anaphylaxis is not always easily recognized in the Emergency Department (ED). One study indicates around 50% of cases being misdiagnosed and up to 80% do not receive appropriate first-line treatment.

Triggers

The most commonly identified triggers of anaphylaxis include food, drugs and venom, but it is important to note that 30% of the cases can be idiopathic. Among drugs, muscle relaxants, antibiotics, NSAIDs and aspirin are the most commonly implicated.

Which patients are at an increased risk of anaphylaxis severity and mortality?

Extremes of age

Co-morbid conditions (asthma, COPD, cardiovascular disease)

Concurrent use of beta-blockers and ACE inhibitors

While the overall prognosis of anaphylaxis is good, the key to avoiding adverse outcomes is by prompt recognition and initiation of appropriate interventions. Below are key points to guide your management of anaphylaxis in the ED.

Recognizing Anaphylaxis in the ED

Anaphylaxis reactions vary significantly in duration and severity and a single set of criteria will not identify all anaphylactic reactions. The World Allergy Organization (WAO) has suggested the following criteria to help ED physicians be more consistent in their recognition of anaphylaxis.

Anaphylaxis is highly likely when any one of the following three criteria is fulfilled

1. Acute onset of an illness (minutes to several hours) with involvement of the skin, mucosal tissue, or both (eg, generalized urticaria, itching or flushing, swollen lips-tongue-uvula) AND AT LEAST ONE OF THE FOLLOWING

  • Respiratory compromise (eg, dyspnea, wheeze-bronchospasm, stridor, reduced PEF, hypoxemia)
  • Reduced blood pressure or associated symptoms of end-organ dysfunction (eg. hypotonia [collapse], syncope, incontinence) OR

2. Two or more of the following that occur rapidly after exposure to a likely allergen for that patient (minutes to several hours)

  • Involvement of the skin-mucosal tissue (eg, generalized urticaria, itch-flush, swollen lips-tongue-uvula)
  • Respiratory compromise (eg, dyspnea, wheeze-bronchospasm, stridor, reduced PEF, hypoxemia)
  • Reduced blood pressure or associated symptoms (eg, hypotonia [collapse], syncope, incontinence)
  • Persistent gastrointestinal symptoms (eg, crampy abdominal pain, vomiting) OR

3. Reduced blood pressure after exposure to known allergen for that patient (minutes to several hours)

  • Infants and children: low systolic blood pressure (age-specific) or greater than 30% decrease in systolic blood pressure
  • Adults: systolic blood pressure of less than 90 mm Hg or greater than 30% decrease from that person’s baseline

Management Algorithm of Anaphylaxis in the ED

Anaphylaxis algorithm
Anaphyaxis algorithm 2

Key Points in Management

  • Early and prompt recognition of the anaphylaxis/severe allergic reaction is key to appropriate management. Anticipate deterioration of clinical status/airway and an early call for help.
  • Initial systematic assessment using an ABCDE approach. The most important step in the management of anaphylaxis is the early administration of epinephrine intramuscularly. Do not delay this step while securing IV access/airway. There are no absolute contradictions to the use of epinephrine in the management of anaphylaxis.
  • Be prepared for a surgical cricothyroidotomy especially in a patient who is rapidly deteriorating despite epinephrine.
  • In patients on beta-blockers, the key is to give glucagon 1mg - 3mg IV every 5 minutes and titrate for resolution of hypotension (be prepared for vomiting).
  • Remember that antihistamines and corticosteroids do NOT play a role in the management of the acute reaction.
  • Serum tryptase levels are elevated in anaphylaxis but diagnosis is clinical and laboratory tests are not helpful in acute settings.
  • Patients who respond to treatment and have complete resolution of symptoms can be discharged after an observation period of 4 – 8 hours. However, up to 20% of the patients can have a biphasic reaction, which usually occurs within 8 hours but has been reported to occur as far as 72 hours. Consider extended observation for patients who presented with protracted anaphylaxis, hypotension or airway management.
  • Patients with anaphylaxis due to insect stings or unknown/unavoidable triggers should be prescribed an epinephrine autoinjector pen on discharge and timely follow up with an allergist.

References and Further Reading

Cite this article as: Neha Hudlikar, UAE, "Anaphylaxis in a Nutshell," in International Emergency Medicine Education Project, January 31, 2020, https://iem-student.org/2020/01/31/anaphylaxis-in-a-nutshell/, date accessed: April 25, 2024

Clinical examination of the hemodynamically unstable patient

Clinical examination of the hemodynamically unstable patient
~ Job Guillen, Mexico ~ Leave a comment

Authors: Job Rodríguez Guillén. Chief of Emergency Department. Hospital H+ Querétaro. México and Paola Rivero Castañeda. Medical Intern, Anahuac Querétaro University, Mexico. 

Introduction

Clinical examination accounts as a fundamental part in the management of most critical scenarios. Although there are few publications and it remains controversial, its value considered as limited by 50% of medical practicioners (1). None of the well-known semiology books include any section about the physical examination in the critically ill patient (2). Nonetheless, an adequate clinical evaluation at the patient’s bedside may save lives in the context of a serious situation.

Clinical Examination Objectives

The main objectives are identifying and discerning from types of shock, emphasizing in the identification of life-threatening conditions, clinical signs of organic hypoperfusion, as well as to evaluate treatment response regarding therapies employed, and risk stratifying.

Identify hemodynamic instability

  • Life-threatening conditions (Tension pneumothorax, Cardiac tamponade, Pulmonary thromboembolism, Active hemorrhage, etc.)
  • Organ hypoperfusion
    (Altered mental state, decreased uresis, mottled skin, prolonged CFT, etc.)

Evaluate treatment response

  • Vital signs and normalization of the clinical state
    (Mental state improvement, diminished skin mottling, improved uresis, normalization of prolonged capillary filling time, etc.)

Risk stratifying

  • Scale and prognostic scores calculation. Prognostic scores use a combination of clinical and/or laboratoy variables (SOFA: Squential Organ Failure Assessment; APACHE: Acute Physiology and Chronic Health Evaluation; SAPS: Simplified Acute Physiology Score; MPM: Mortality Probability Models, etc.)

Clinical Exam Systematization

The clinician must be able to do a quick and efficient clinical examination to recognize different states of shock as early as possible, or even situations that may compromise organic perfusion. At a given time, it’s suggested to check out the clinical history, re-interrogate the patient and his/her family members, as well as patient’s family/regular physician (or even look for their previous medical notes), in order to help clinical integration, and so for decision making.

Systematization of the evaluating process, based on the previously proposed objectives, can be identified with the following mnemonic: PROA.

PROA - Summary

P - Probabilistic thinking

  • Think about any probability.
  • Look for intentionally.
  • Analyze clinical context and individualize.

R - Risk of dying

Identify life-threatening causes: Cardiac tamponade, Tensionpneumothorax, Pulmonary thromboembolism, Active hemorrhage, etc.

O - Organic hypoperfusion

Cutaneous perfusion signs: examine mottled skin and capillary filling time.

A - Approach of the clinical examination

Clinical exam by regions. Some components may not be relevant for all patients, even requiring other physical maneuvers. Even though laboratory and imaging are not part of the clinical exam, their interpretation must be integrated with the examination findings.

Probabilistic Thinking

Medicine is a science of uncertainty and an art of probability.

— William Osler

Clinical decision making in the emergency department begins with the estimation of the probability of a determined patient to have or do not have specific conditions (Bayesian reasoning or pretest probability).

Example; the probability of septic shock in a young patient after having a car crash is very low compared to the high probability of presenting with hemorrhagic or obstructive shock.

Proposed decisions related to initial probabilistic thinking vary in clinical relevance depending on the patient’s condition. It should always be re-evaluated through available additional data (posttest probability) (Figure 1).

Relationship between probability thresholds and decision‐making zones
Figure 1: Relationship between probability thresholds and decision‐making zones (3).

Risk of Dying

Shock is a momentary pause in the act of death.

— John Collins Warren

Currently, there are four types of shock, all with a common pathophysiological pathway: acute circulatory insufficiency associated with cell oxygen utilization dysfunction (altered-balance between oxygen input and consumption: DO2/VO2 dysfunction), a central situation that takes part in the development of multiorgan dysfunction (4-5).

Initial physical examination should be directed to the identification of immediate life-threating pathologies such as obstructive shock (Tension pneumothorax, cardiac tamponade, pulmonary thromboembolism), hemorrhagic shock etc.

These pathologies require immediate action. Otherwise, early multi-organ dysfunction and death may occur. The Point of Care Ultrasound (PoCUS), is a fundamental tool used for the evaluation of patients with hemodynamic instability of unknown origin.

Organ Hypoperfusion

When assessing the damage an earthquake or fire has caused inside a building, one looks through the windows. Using this analogy, it would be useful to be able to see inside the body to view the damage caused by the shock process.

— Jean-Louis Vincent

The initial approach to clinical examination begins with the skin. It is essential to remember that microcirculation cannot be globally defined through its dependency with macrocirculation, autoregulation mechanisms and organ interactions. Moreover, the availability of devices to evaluate it remains limited. Therefore, the evaluation is done from clinical, biochemical and hemodynamic data integration (6) (Figure 2)

Figure 2: three windows of shock

The correct way of measuring capillary filling time

Approach of The Clinical Examination

Clinical exam is not an art, is an essential ability.

— Leonel Martínez-Ramírez

During the initial evaluation, multiple situations can affect the accomplishment of a detailed physical examination. Therefore, it is recommended to follow a structured exploration method, looking at every main organ system and region. Documenting its results would allow avoiding the inclusion of essential data, and would permit to identify tendencies or any change in the patient’s clinical status.

Clinical examination approach in the critically-ill patient.

7Clinical examination approach emphasized in the critically-ill patient. This examination is realized based on every region in the body. Some components may not be relevant for all patients, or even some other maneuvers shall be executed in the physical examination. The verification list should be modified to be adapted to each patient’s circumstances. Laboratory and other studies analysis does not conform part of the clinical examination, although, their interpretation should be added to exploration findings (7).

  • General appearance

    Introduce yourself to the patient. Evaluate general appearance, physical state, complexity or the presence of particular face patterns, etc.

  • Head

    Inspect pupils' symmetry and reactiveness to light. Look for facial asymmetry and signs of bleeding in nostrils and oropharynx. Inspect lips, mouth and tongue, searching for lesions or signs of ulceration.

  • Neck

    Evaluate neck symmetry, venous distension and tracheal positioning. Palpate searching for adenopathies, subcutaneous emphysema, etc.

  • Thorax

    Expose the thorax, inspect the use of accessory respiratory muscles, diaphragmatic movement, and type of respiration. Also, look for ecchymosis or hematomas. Palpate searching for subcutaneous emphysema or bone crepitations. Auscultate respiratory sounds bilaterally, as well as heart sounds, noting the physiological splitting of the second heart sound, murmurs, friction and gallop rhythm or third heart sound.

  • Upper extremities

    Evaluate upper extremities symmetry. Inspect all arterial and venous line catheters. Evaluate for presence of mottled skin, peripheral pulses and perfusion through capillary filling time.

  • Abdomen

    Take into consideration the diaphragmatic movement during ventilation. Evaluate distension and tympanic sounds during the percussion of the abdomen. Palpate for any rigidity or involuntary guarding. Evaluate abnormal growth of spleen and liver, palpable masses, murmurs or other intestinal sounds.

  • Lower extremities

    Evaluate all sites of vascular accesses and palpate pulses. Evaluate mottled skin, peripheral perfusion and edema.

  • Central Nervous System and Mental State

    Evaluate if the patient is able to follow orders and if his/her four extremities can move equally. Evaluate plantar response as well as withdrawal to pain stimuli. Check pupils and facial symmetry if they were not previously evaluated.

  • Devices and Incisions

    Every possible surgical site should be evaluated, as well as the entrance of every device, including endotracheal tubes, vascular accesses, thoracic tubes, enteral probes and urinary catheters. It should be taken into consideration the characteristics and quantity of urine in the Foley bag.

  • Monitors and waveforms

    The mode, pressures, ventilation per minute and waveforms, hemodynamic monitor (venous pressure, arterial pressure), telemetry and vital signs, as well as any other type of bedside monitor, should be inspected in order to detect any qualitative or quantitative alteration/abnormality.

  • Posterior region

    Exam executed when the patient is in a prone position. Inspect looking for lesions or penetrating wounds. Pressure ulcer appearance should be evaluated.

  • Environment

    Family’s or visitors' moods should be taken into consideration. Light quality, ambient temperature, etc. should be evaluated.

Conclusions

Clinical integration of initial clinical history and the physical examination should be added to the biochemical complementation as well as advanced hemodynamic monitoring parameters, when these are available. Even so, if clinical examination answers raised questions during the initial evaluating process, the clinician must act according to physiological principles. There is no ideal hemodynamic monitoring, meaning that all parameters have to be individualized for each patient and his/her clinical context. Therefore, clinical examination systematization results are an excellent aid for the clinician regarding his/her clinical practice.  

References and Further Reading

  1. Vazquez R, Vazquez Guillamet C, Adeel Rishi M, Florindez J, Dhawan PS, Allen SE, Manthous CA, Lighthall G.  Physical examination in the intensive care unit: opinions of physicians at three teaching hospitals. Southwest J Pulm Crit Care. 2015;10(1):34-43. DOI: http://dx.doi.org/10.13175/swjpcc165-14
  2. Cook CJ, Smith GB. Do textbooks of clinical examination contain information regarding the assessment of critically ill patients?Resuscitation. 2004;60:129–136.
  3. Zehtabchi S, Kline J.A. The Art and Science of Probabilistic Decision‐making in Emergency Medicine. Academic Emergency Medicine, 17:521-523. DOI: http://doi.org/10.1111/j.1553-2712.2010.00739.x
  4. Weil MH, Shubin H. Proposed reclassification of shock states with special reference to distributive defects. Adv Exp Med Biol.1971 Oct;23(0):13-23.
  5. Ince C. The microcirculation is the motor of sepsis. Crit Care. 2005;9 Suppl 4:S13-9. DOI: 1186/cc3753
  6. Vincent JL, Ince C, Bakker J. Clinical review: Circulatory shock–an update: a tribute to Professor Max Harry Weil.Crit Care. 2012 Nov 20;16(6):239. DOI: 10.1186/cc11510.
  7. Metkus TS, Kim BS. Bedside Diagnosis in the Intensive Care Unit. Is Looking Overlooked?. Ann Am Thorac Soc.2015 Oct;12(10):1447-50. DOI: 10.1513/AnnalsATS.201505-271OI.
Cite this article as: Job Guillen, Mexico, "Clinical examination of the hemodynamically unstable patient," in International Emergency Medicine Education Project, December 6, 2019, https://iem-student.org/2019/12/06/clinical-examination-of-the-hemodynamically-unstable-patient/, date accessed: April 25, 2024