Should etomidate be used for rapid-sequence intubation induction in critically ill septic patients?

A systematic review and meta-analysis of the hemodynamic effects of etomidate versus other sedatives in patients undergoing rapid sequence intubation

INTRODUCTION

Rapid sequence intubation is an airway rescue and protection technique in which different sedatives are used to perform orotracheal intubation. Etomidate, due to its pharmacokinetic and pharmacodynamic qualities, particularly hemodynamic stability, is the most widely used sedative in this scenario. However, its superiority over other sedatives is controversial.

MATERIALS AND METHODS

We performed a meta-analysis using a pre-designed protocol and PRISMA guidelines to evaluate the mean difference between systolic blood pressure before and after administration of the sedative. We also analyzed the relative risks of hypotension.

RESULTS

Ten studies were included. The incidence of hypotension in patients receiving etomidate ranged from 6.4% to 75.2%, and between 24.0% and 65.9% in patients receiving other sedatives. No significant differences were found in the mean difference in systolic blood pressure during pre-intubation 0.01 mm Hg (95% CI: -0.90; 0.92) or in post-intubation 0.98 mmHg (95% CI: -0.24; 2.20). The relative risk analysis showed that the risk of hypotension is equal to an RR of 1.19 (95% CI: 0.92-1.54) between those who received etomidate and those who received the other sedatives.

CONCLUSIONS

The risk of hypotension after rapid intubation sequence with etomidate does not differ significantly compared to other sedatives. However, the studies included in this review were heterogeneous.

Ketamine is not associated with more post-intubation hypotension than etomidate in patients undergoing endotracheal intubation

INTRODUCTION

Emergency department (ED) patients undergoing emergent tracheal intubation often have multiple physiologic derangements putting them at risk for post-intubation hypotension. Prior work has shown that post-intubation hypotension is independently associated with increased morbidity and mortality. The choice of induction agent may be associated with post-intubation hypotension. Etomidate and ketamine are two of the most commonly used agents in the ED, however, there is controversy regarding whether either agent is superior in the setting of hemodynamic instability. The goal of this study is to determine whether there is a difference in the rate of post-intubation hypotension who received either ketamine or etomidate for induction. Additionally, we provide a subgroup analysis of patients at pre-existing risk of cardiovascular collapse (identified by pre-intubation shock index (SI) > 0.9) to determine if differences in rates of post-intubation hypotension exist as a function of sedative choice administered during tracheal intubation in these high-risk patients. We hypothesize that there is no difference in the incidence of post-intubation hypotension in patients who receive ketamine versus etomidate.

METHODS

A retrospective cohort study was conducted on a database of 469 patients having undergone emergent intubation with either etomidate or ketamine induction at a large academic health system. Patients were identified by automatic query of the electronic health records from 1/1/2016-6/30/2019. Exclusion criteria were patients <18-years-old, tracheal intubation performed outside of the ED, incomplete peri-intubation vital signs, or cardiac arrest prior to intubation. Patients at high risk for hemodynamic collapse in the post-intubation period were identified by a pre-intubation SI > 0.9. The primary outcome was the incidence of post-intubation hypotension (systolic blood pressure < 90 mmHg or mean arterial pressure < 65 mmHg). Secondary outcomes included post-intubation vasopressor use and mortality. These analyses were performed on the full cohort and an exploratory analysis in patients with SI > 0.9. We also report adjusted odds ratios (aOR) from a multivariable logistic regression model of the entire cohort controlling for plausible confounding variables to determine independent factors associated with post-intubation hypotension.

RESULTS

A total of 358 patients were included (etomidate: 272; ketamine: 86). The mean pre-intubation SI was higher in the group that received ketamine than etomidate, (0.97 vs. 0.83, difference: -0.14 (95%, CI -0.2 to -0.1). The incidence of post-intubation hypotension was greater in the ketamine group prior to SI stratification (difference: -10%, 95% CI -20.9% to -0.1%). Emergency physicians were more likely to use ketamine in patients with SI > 0.9. In our multivariate logistic regression analysis, choice of induction agent was not associated with post-intubation hypotension (aOR 1.45, 95% CI 0.79 to 2.65). We found that pre-intubation shock index was the strongest predictor of post-intubation hypotension.

CONCLUSION

In our cohort of patients undergoing emergent tracheal intubation, ketamine was used more often for patients with an elevated shock index. We did not identify an association between the incidence of post-intubation hypotension and induction agent between ketamine and etomidate. Patients with an elevated shock index were at higher risk of cardiovascular collapse regardless of the choice of ketamine or etomidate.

Effect of Propofol or Etomidate as General Anaesthesia Induction on Gastric Cancer: A Retrospective Cohort Study with 10 Years' Follow-Up

Objective

The aim is to study the effect of intraoperative application of propofol and etomidate on the long-term prognosis of patients with gastric cancer at the same tumor stage.

Methods

A total of 1018 patients who underwent radical gastric cancer surgery at the First Affiliated Hospital of Anhui Medical University from January 2010 to December 2010 were selected and divided into the propofol and etomidate groups according to the different anesthetic induction drugs.

Results

Among 244 patients in TNM stage IIIA, survival times were 36.10 and 41.79 for etomidate and propofol, respectively, which were statistically different (p < 0.05). Among the 82 patients in TNM stage IIIC, survival times were 26.57 and 35.20 for etomidate and propofol, respectively, which were statistically different (p < 0.05).

Conclusion

In patients undergoing radical gastric cancer surgery, the application of propofol during induction of anaesthesia is more beneficial in improving the postoperative survival time compared to the application of etomidate at a specific TNM stage.

Effects of etomidate combined with dexmedetomidine on adrenocortical function in elderly patients: a double-blind randomized controlled trial

Etomidate has been advocated to be used in anesthesia for the elderly and the critically ill patients due to its faint effect on cardiovascular system. But the dose-dependent suppression of etomidate on adrenal cortex function leads to the limitation of its clinical application. Clinical research showed that dexmedetomidine could reduce the dose requirements for intravenous or inhalation anesthetics and opioids, and the hemodynamics was more stable during the operation. The objective was to observe the effect of etomidate combined with dexmedetomidine on adrenocortical function in elderly patients. 180 elderly patients scheduled for elective ureteroscopic holmium laser lithotripsy were randomly allocated to PR group anesthetized with propofol-remifentanil, ER group anesthetized with etomidate-remifentanil, and ERD group anesthetized with dexmedetomidine combined with etomidate-remifentanil. Patients in each group whose operation time was less than or equal to 1 h were incorporated into short time surgery group (PR₁ group, ER₁ group and ERD₁ group), and whose surgical procedure time was more than 1 h were incorporated into long time surgery group (PR₂ group, ER₂ group and ERD₂ group). The primary outcome was the serum cortisol and ACTH concentration. The secondary outcomes were the values of SBP, DBP, HR and SpO₂, the time of surgical procedure, the dosage of etomidate and remifentanil administered during surgery, the time to spontaneous respiration, recovery and extubation, and the duration of stay in the PACU. The Serum cortisol concentration was higher at t_1~2   in ERD₁ group compared to ER₁ group (P < 0.05). The Serum cortisol concentration at t_1~3   was higher in ERD₂ group than in ER₂ group (P < 0.05). The Serum ACTH concentration was lower at t_1~2  in ERD₁ group compared to ER₁ group (P < 0.05). The Serum ACTH concentration at t_1~3  was lower in ERD₂ group compared to ER₂ group (P < 0.05). The SBP at T₁ and T₃ were higher in ER₂ and ERD₂ group than in PR₂ group (P < 0.05). The DBP in ER₁ and ERD₁ group were higher at T₁ compared to PR₁ group (P < 0.05). The dosage of etomidate was significantly lower in ERD₁ group and ERD₂ group than in ER₁ group and ER₂ group (P < 0.05), respectively. The administration of dexmedetomidine combined with etomidate can attenuate the inhibition of etomidate on adrenocortical function in elderly patients and maintain intraoperative hemodynamic stability.

Ketamine Versus Etomidate and Peri-intubation Hypotension: A National Emergency Airway Registry Study

BACKGROUND

The hemodynamic impact of induction agents is a critically important consideration in emergency intubations. We assessed the relationship between peri-intubation hypotension and the use of ketamine versus etomidate as an induction agent for emergency department (ED) intubation.

METHODS

We analyzed ED intubation data for patients aged >14 years from the National Emergency Airway Registry performed in 25 EDs during 2016 through 2018. We excluded patients with preintubation hypotension (systolic blood pressure <100 mm Hg) or cardiac arrest prior to intubation. The primary outcome was peri-intubation hypotension. Secondary outcomes included interventions for hypotension (e.g., intravenous fluids or vasopressors). We report adjusted odds ratios (aOR) from multivariable logistic regression models controlling for patient demographics, difficult airway characteristics, and intubation modality.

RESULTS

There were 738 encounters with ketamine and 6,068 with etomidate. Patients receiving ketamine were more likely to have difficult airway characteristics (effect size difference = 8.8%, 95% confidence interval [CI] = 5.3% to 12.4%) and to undergo intubation with video laryngoscopy (8.1%, 95% CI = 4.4% to 12.0%). Peri-intubation hypotension incidence was 18.3% among patients receiving ketamine and 12.4% among patients receiving etomidate (effect size difference = 5.9%, 95% CI = 2.9% to 8.8%). Patients receiving ketamine were more likely to receive treatment for peri-intubation hypotension (effect size difference = 6.5%, 95% CI = 3.9% to 9.3%). In logistic regression analyses, patients receiving ketamine remained at higher risk for peri-intubation hypotension (aOR = 1.4, 95% CI = 1.2 to 1.7) and treatment for hypotension (aOR = 1.8, 95% CI = 1.4 to 2.0). There was no difference in the aOR of hypotension between patients receiving ketamine at doses ≤1.0 mg/kg versus >1.0 mg/kg or patients receiving etomidate at doses ≤0.3 mg/kg versus >0.3 mg/kg.

CONCLUSIONS

Pending additional data, our results suggest that clinicians should not necessarily prioritize ketamine over etomidate based on concern for hemodynamic compromise among ED patients undergoing intubation.

Etomidate as an Induction Agent in Sepsis

Sepsis is a life-threatening response to infection often times requiring endotracheal intubation in critically ill patients. Etomidate is routinely used as an intravenous induction agent to provide sedation and amnesia before placing an endotracheal tube. Although etomidate has many favorable qualities, there is a major concern regarding the predictable adrenal insufficiency that follows its use. Controversy continues to this day as to whether etomidate should be avoided in the setting of sepsis or septic shock.

Advancing novel anesthetics: pharmacodynamic and pharmacokinetic studies of cyclopropyl-methoxycarbonyl metomidate in dogs

BACKGROUND

Cyclopropyl-methoxycarbonyl metomidate (CPMM, also known as ABP-700) is a second-generation "soft" (i.e., metabolically labile) etomidate analogue. The purpose of this study was to characterize CPMM's pharmacology in beagle dogs in preparation for potential first in human phase 1 clinical trials.

METHODS

CPMM's and etomidate's hypnotic activity and duration of action were assessed using loss of righting reflex and anesthesia score assays in three or four dogs. Their pharmacokinetics were defined after single bolus administration and single bolus followed by 2-h infusion. Adrenocortical recovery times after single bolus followed by 2-h infusion of CPMM, propofol, etomidate, and vehicle were measured using an adrenocorticotropic hormone stimulation test.

RESULTS

Compared with etomidate, CPMM was half as potent as a hypnotic (ED50 approximately 0.8 mg/kg), was more rapidly metabolized, and had a shorter duration of sedative-hypnotic action. Recovery times after CPMM administration were also independent of infusion duration. After hypnotic infusion, adrenocorticotropic hormone-stimulated plasma cortisol concentrations were 4- to 27-fold higher in dogs that received CPMM versus etomidate. Adrenocortical recovery was faster in dogs after CPMM infusion versus etomidate infusion (half-time: 215 vs. 1,623 min, respectively). Adrenocortical responsiveness assessed 90 min after CPMM infusion was not significantly different from that after propofol infusion.

CONCLUSION

The studies in dogs confirm that CPMM has hypnotic and adrenocortical recovery profiles that are superior than those of etomidate, supporting the continued development of CPMM as a clinical sedative-hypnotic to be used as a single bolus and by continuous infusion to induce and maintain general anesthesia or procedural sedation.

Effects of different etomidate doses on intraoperative somatosensory-evoked potential monitoring

BACKGROUND

Somatosensory-evoked potentials (SSEPs) are widely used for intraoperative spinal cord monitoring. Although many general anesthetics inhibit SSEPs, etomidate has been reported to boost SSEPs. This clinical study aimed to test whether etomidate doses less than 0.3 mg/kg amplify SSEP monitoring.

METHODS

Patients were divided into four groups: A, B, C, and D. Etomidate doses of 0.1, 0.2, and 0.3 mg/kg were infused into patients in groups A, B, and C, respectively, after baseline SSEPs were obtained. Group D patients were infused with saline. In the subsequent 15 min, the amplitudes and latencies of SSEPs were recorded and compared.

RESULTS

Etomidate exhibited amplification effects on SSEPs, and this effect increased with dose escalation. The amplitude changes in groups A, B, and C were significantly different (P = 0.002, P = 0.000, and P = 0.000, respectively) from that of group D. The amplitude change was largest in group C and significantly greater than those in groups A and B (P = 0.006, P = 0.000). Latency was not significantly affected (P < 0.05) by etomidate.

CONCLUSION

Small doses of etomidate that were less than 0.3 mg/kg had dose-related amplification effects on SSEP monitoring.

Does etomidate increase vasopressor requirements in patients needing mechanical ventilation?

BACKGROUND

Single-dose etomidate is used as an induction agent for rapid-sequence intubation and is associated with transient adrenal insufficiency. There is ongoing debate as to the clinical consequences of this transient adrenal insufficiency for critically ill patients.

OBJECTIVE

To determine if the use of etomidate is associated with higher requirements for a vasopressor, relative to other induction agents, at a single time point (24 h after administration of the induction agent) in patients needing mechanical ventilation.

METHODS

In this retrospective observational study utilizing electronic health records, a convenience sample of 50 patients who had undergone intubation in the emergency department with etomidate were matched (1:1) with patients who had received other induction agents. Matching was based on primary admitting diagnosis relating to the cause of shock, APACHE II (Acute Physiology and Chronic Health Evaluation II) score, age, and sex. All patients were subsequently admitted to critical care areas for management. As a surrogate marker of hemodynamic instability, the vasopressor dose was recorded 24 h after intubation. Vasopressor doses were converted to norepinephrine equivalents for comparison.

RESULTS

The mean dose of vasopressors, in norepinephrine equivalents, was 4 μg/min(-1) for patients receiving etomidate and 3 μg/min(-1) for the control group (mean difference 0.7 μg min(-1), 95% confidence interval [CI] -1.9 to 3.2 μg min(-1), p = 0.61). Twelve of the patients in the etomidate group and 16 of those in the control group required the use of vasopressors at 24 h following intubation (odds ratio 2.3, 95% CI 0.53 to 13.99, p = 0.34).

CONCLUSIONS

Single-dose etomidate does not adversely affect hemodynamic stability, as measured by the dose of vasopressors required at 24 h after administration.

Differential effects of etomidate and its pyrrole analogue carboetomidate on the adrenocortical and cytokine responses to endotoxemia

OBJECTIVE

We developed a novel pyrrole analog of etomidate, (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate), which retains etomidate's desirable anesthetic and hemodynamic properties but lacks its potent inhibitory affect on adrenocorticotropic hormone-stimulated steroid synthesis. The objective of this study was to test the hypothesis that in contrast to etomidate, carboetomidate neither suppresses the adrenocortical response to endotoxemia nor enhances the accompanying production of proinflammatory cytokines.

DESIGN

Animal study.

SETTING

University research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

For both single and multiple anesthetic dose studies, rats were injected with Escherichia coli lipopolysaccharide immediately followed by a hypnotic dose of etomidate, carboetomidate, or vehicle alone (dimethyl sulfoxide) as a control. For single-dose studies, no additional anesthetic (or vehicle) was administered. For multiple anesthetic dose studies, additional doses of anesthetic (or vehicle) were administered every 15 mins for a total of eight anesthetic (or vehicle) doses.

MEASUREMENTS AND MAIN RESULTS

Plasma adrenocorticotropic hormone, corticosterone, and cytokine concentrations were measured before lipopolysaccharide administration and intermittently throughout the 5-hr experiment. In single anesthetic dose studies, plasma adrenocorticotropic hormone and cytokine concentrations were not different at any time point among the etomidate, carboetomidate, and vehicle groups, whereas plasma corticosterone concentrations were briefly (60-120 mins) reduced in the etomidate group. In multiple anesthetic dose studies, plasma corticosterone concentrations were persistently lower and peak plasma interleukin-1β and interleukin-6 concentrations were higher in the etomidate group vs. the carboetomidate and control groups. Peak plasma interleukin-10 concentrations were similarly elevated in the etomidate and carboetomidate groups vs. the control group.

CONCLUSIONS

Compared with etomidate, carboetomidate produces less suppression of adrenocortical function and smaller increases in proinflammatory cytokine production in an endotoxemia model of sepsis. These findings suggest that carboetomidate could be a useful alternative to etomidate for maintaining anesthesia for a prolonged period of time in patients with sepsis.

In vivo and in vitro pharmacological studies of methoxycarbonyl-carboetomidate

BACKGROUND

We previously developed 2 etomidate analogs that retain etomidate's favorable hemodynamic properties but whose adrenocortical effects are reduced in duration or magnitude. Methoxycarbonyl (MOC)-etomidate is rapidly metabolized and ultrashort acting whereas (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate) does not potently inhibit 11β-hydroxylase. We hypothesized that MOC-etomidate's labile ester could be incorporated into carboetomidate to produce a new agent that possesses favorable properties individually found in each agent. We describe the synthesis and pharmacology of MOC-(R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (MOC-carboetomidate), a "soft" analog of carboetomidate.

METHODS

MOC-carboetomidate's octanol:water partition coefficient was determined chromatographically and compared with those of etomidate, carboetomidate, and MOC-etomidate. MOC-carboetomidate's 50% effective concentration (EC(50)) and 50% effective dose for loss of righting reflexes (LORR) were measured in tadpoles and rats, respectively. Its effect on γ-aminobutyric acid A (GABA(A)) receptor function was assessed using 2-microelectrode voltage clamp electrophysiological techniques and its metabolic stability was determined in pooled rat blood using high performance liquid chromatography. Its duration of action and effects on arterial blood pressure and adrenocortical function were assessed in rats.

RESULTS

MOC-carboetomidate's octanol:water partition coefficient was 3300 ± 280, whereas those for etomidate, carboetomidate, and MOC-etomidate were 800 ± 180, 15,000 ± 3700, and 190 ± 25, respectively. MOC-carboetomidate's EC(50) for LORR in tadpoles was 9 ± 1 μM and its EC(50) for LORR in rats was 13 ± 5 mg/kg. At 13 μM, MOC-carboetomidate enhanced GABA(A) receptor currents by 400% ± 100%. Its metabolic half-life in pooled rat blood was 1.3 min. The slope of a plot of the duration of LORR in rats versus the logarithm of the hypnotic dose was significantly shallower for MOC-carboetomidate than for carboetomidate (4 ± 1 vs 15 ± 3, respectively; P = 0.0004123). At hypnotic doses, the effects of MOC-carboetomidate on arterial blood pressure and adrenocortical function were not significantly different from those of vehicle alone.

CONCLUSIONS

MOC-carboetomidate is a GABA(A) receptor modulator with potent hypnotic activity that is more rapidly metabolized and cleared from the brain than carboetomidate, maintains hemodynamic stability similar to carboetomidate, and does not suppress adrenocortical function.

Outcomes of etomidate in severe sepsis and septic shock

BACKGROUND

The use of single-dose etomidate to facilitate intubation in critically ill patients has recently been debated given its suppression of steroidogenesis with possible resultant adverse outcomes. Our objective was to assess the effects of single-dose etomidate used during rapid-sequence intubation (RSI) on various measures of outcome, such as mortality, vasopressor use, corticosteroid use, ICU length of stay (ICU-LOS), and number of ventilator days.

METHODS

A retrospective 18-month cohort study was performed in a multidisciplinary ICU of an academic tertiary care institution. Consecutive patients with severe sepsis or septic shock who were intubated and mechanically ventilated were identified and grouped as having received single-dose etomidate during intubation or not. Hospital mortality, ICU length of stay, number of ventilator days, corticosteroid use, vasopressor use, and demographic and clinical variables were recorded.

RESULTS

Two hundred twenty-four patients were identified; 113 had received etomidate. The mean Acute Physiology and Chronic Health Evaluation II scores in the etomidate and nonetomidate groups were 21.3 ± 8.1 and 21.9 ± 8.3, respectively (P = .62). The relative risks for mortality and vasopressor use were 0.92 (CI, 0.74-1.14; P = 0.51) and 1.16 (CI, 0.9-1.51; P = .31), respectively, in the etomidate group. There were no significant differences in ICU-LOS (mean, 14 vs 12 days; P = .31) or number of ventilator days (mean, 11 vs 8 days; P = .13) between the etomidate and nonetomidate groups, respectively. The relative risk for corticosteroid use in the etomidate group was 1.34 (CI, 1.11-1.61; P = .003). Multivariate analysis using logistic regression demonstrated no significant association of etomidate with mortality (OR, 0.9; CI, 0.45-1.83; P = .78).

CONCLUSION

Single-dose etomidate used during RSI in critically ill patients with severe sepsis and septic shock was not associated with increased mortality, vasopressor use, ICU-LOS, or number of ventilator days. Patients intubated with etomidate had an increased incidence of subsequent corticosteroid use, with no difference in outcomes.