Hemodynamic stability during induction of anesthesia and tracheal intubation with propofol plus fentanyl, ketamine, and fentanyl-ketamine

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 prone position without volume expansion on pulse pressure variation in spinal surgery : a prospective observational study

Background : Pulse pressure variation (PPV) is a predictor of fluid responsiveness in supine patients under mechanical ventilation. Its use has also been validated in the prone position. The aim of this study was to assess changes in PPV induced by prone position in patients undergoing spinal surgery. Methods : Ninety-six patients aged 12 to 75 years, scheduled for elective spinal surgery were included. Patients were excluded if they had clinical signs related to any organ failure, or if they required vasoactive drugs and/or volume expansion during the early stages of anesthesia. Patients received a standardized anesthesia protocol. Fluid expansion was not allowed from induction until 10 minutes after positioning. Hemodynamic measurements recorded before the induction of anesthesia (T0) included : arterial pressure (systolic (SAP) diastolic (DAP) and mean (MAP)) and heart rate (HR). Radial artery was cannulated after intubation and measurements, as well as PPV, were noted in supine position (T1). Patients were then placed in prone position hemodynamics and PPV measurements were repeated (T2). Results : Forty-eight patients completed the study. Anesthesia induction induced a significant decrease in SAP, DAP, and MAP with no effect on HR. Prone position did not induce any significant changes in SAP, MAP, DAP, and HR. A significant difference was found between PPV values in supine (Mean=10.5, SD=4.5) and prone positions (Mean=15.2, SD=7.1) ; t=-4.15 (p<0.001). The mean increase in PPV was 4.7%. Conclusion : Prone position without prior volume expansion induces a significant increase in PPV prior to any modification in arterial blood pressure and heart rate.

Effect of low-dose ketamine versus fentanyl on attenuating the haemodynamic response to laryngoscopy and endotracheal intubation in patients undergoing general anaesthesia: a prospective, double-blinded, randomised controlled trial

BACKGROUND

The use of drugs to attenuate the haemodynamic response to laryngoscopy and endotracheal intubation is the standard of care during elective surgery. Current evidence is conflicting concerning the best agent and optimal dose for this purpose. In the majority of cases, fentanyl is widely utilized to attenuate haemodynamic responses. Ketamine, an established available drug, has been scarcely studied in this regard at low doses and against varying doses of other common agents.

OBJECTIVE

To compare the overall occurrence of hypertension and tachycardia immediately pre-intubation (post-induction) until 10 minutes post intubation between the study group receiving fentanyl at 1.0 µg/kg and the other receiving ketamine at 0.5 mg/kg, to compare the occurrence of post-induction hypotension and the occurrence of neuropsychiatric phenomena during emergence between the two groups.

METHODS

One hundred and eight ASA I and II patients aged 18-65 years scheduled for elective surgery under general anaesthesia were randomized into two groups: Control group: received fentanyl 1.0 µg/kg intravenously. Intervention group: received ketamine 0.5 mg/kg intravenously. General anaesthesia was standardized in both groups. The patients and physicians administering anaesthesia were blinded to the study. Haemodynamic responses were evaluated by determining heart rate and blood pressure immediately before laryngoscopy and at 2.5, 5, 7.5 and 10 minutes. Neuropsychiatric phenomena were assessed upon recovery from anaesthesia.

RESULTS

One hundred and eight ASA I and II patients scheduled to undergo elective surgery were included in this study, 54 participants (50%) in the fentanyl arm and 54 (50%) in the ketamine arm. Baseline demographic characteristics were similar between the groups. There were more hypertensive episodes in the ketamine arm (11%) compared to the fentanyl arm (1.85%), but not achieving statistical significance: Fisher's exact test, p=0.06. There was no significant difference in the number of episodes of tachycardia between the Ketamine group 7/54 (13%) and the fentanyl group, 6/54 (11%); x2=0.05, p=0.82. Hypotensive episodes were more common in those who received Fentanyl, 41/54 (76%), compared to ketamine recipients, 21/54 (39%), X2=16.9, p<0.001. The use of Ketamine was associated with less episodes of hypotension, adjusted odds ratio = 0.18 (95% confidence interval 0.07, 0.45).

CONCLUSION

We conclude, based upon findings in this study group, that there is no difference in the occurrence of hypertension with the use ketamine at 0.5 mg/kg in combination with Propofol at 2.0 mg/kg. In this regard, ketamine provides a viable alternative to fentanyl at 1.0 µg/kg for attenuating the pressor response to laryngoscopy and endotracheal intubation. Additionally, our results suggest that ketamine may protect against post-induction (pre-laryngoscopy) hypotension.

Postintubation Hypotension in General Anesthesia: A Retrospective Analysis

BACKGROUND

Postintubation hypotension (PIH) is an adverse event associated with poor outcomes in emergency department endotracheal intubations. Study objective was to determine the incidence of PIH and its impact on outcomes following tracheal intubation in a general anesthesia population.

METHODS

Structured chart audit of adult patients intubated for a vascular surgery procedure at a tertiary care center over a 3-year period. Outcomes included in-hospital mortality, extended intensive care unit length of stay (ICU LOS), and requirement for postoperative (postop) hemodialysis or mechanical ventilation.

RESULTS

Incidence of PIH was 60% (837 of 1395). Patients who developed PIH had increased mortality (8.8% PIH vs 5.2% no-PIH; P = .014), extended ICU LOS (7.9% PIH vs 2.0% no-PIH; P < .001), and postop mechanical ventilation requirement (20.7% PIH vs 3.8% no-PIH; P < .001). When controlling for confounding factors, PIH was associated with extended ICU LOS (odds ratio [OR] 2.55, 95% confidence interval [CI] 1.01-6.62, P = .049), postop ventilation (OR 2.43, 95% CI 1.27-4.74, P = .008), and a composite end point (OR 1.72, 95% CI 1.02-2.92, P = .043).

CONCLUSIONS

Development of PIH occurs in 60% of patients undergoing intubation for vascular surgery and was associated with adverse outcomes including extended ICU LOS and postop ventilation requirement.

Peri-operative challenges in post myocardial infarction ventricular septal rupture: A case series and review of literature

Ventricular septal rupture (VSR) is a life threatening complication of myocardial infarction (MI). The incidence of post-MIVSR varied from 1% to 3% in the pre-thrombolytic era. There is almost a 10-fold decrease in the reported incidences (0.2-0.3%) of MIVSR today. The mortality in such an event is as high as 50-90%. Prognosis of post-MIVSR depends on prompt echo diagnosis and proactive surgical therapy. The peri-operative challenges during management of such a case can be enormous.

Comparison of ketamine with fentanyl as co-induction in propofol anesthesia for short surgical procedures

Background and Objective:

A prospective randomized control study was conducted to compare and evaluate quality of anesthesia with ketamine or fentanyl as co-induction with propofol.

Materials and Methods:

Sixty ASA I or II, 18–50 year old patients who were scheduled for minor surgeries of short duration (<30 min anticipated duration) were selected. The patients were randomly allocated to group I and group II comprising 30 patients each. The patients of group I were given ketamine injection 0.5 mg/kg and group II patients fentanyl injection (1.5 μg/kg) as co-induction agent. Two minutes later, induction of anesthesia was given with inj propofol (2.5 mg/kg) and appropriate-sized laryngeal mask airway was inserted. The anesthesia was maintained with 60% N₂O in O₂ and intermittent bolus of inj propofol (0.5 mg/kg) after observing significant changes in the heart rate, blood pressure, lacrimation, sweating, and abnormal movements.

Results:

There was significant decrease (P<0.05) in the pulse rate, systolic and diastolic blood pressure at 1, 3, and 5 min in group II (fentanyl group) whereas the change was insignificant (P>0.05) at 10 min.

Conclusion:

It was observed that ketamine as premedicant was better than fentanyl with respect to hemodynamic stability and caused less adverse effects intraoperatively and postoperatively.

Anesthesia for repair of ventricular septal rupture after acute myocardial infarction

A surgical patient with ventricular septal rupture after acute myocardial infarction is presented. The primary concern of general anesthesia was in the maintenance of systemic arterial pressure and reduction of afterload. General anesthesia was induced with a combination of fentanyl, ketamine, and propofol, which successfully suppressed fluctuations of hemodynamic variables associated with induction of anesthesia and tracheal intubation. Intravenous milrinone was used for inotropic support and reduction of systemic vascular resistance. The ventricular septal rupture was successfully repaired.

Comparison of propofol and isoflurane anesthesia in orthotopic pig-to-baboon cardiac xenotransplantation

BACKGROUND

Orthotopic pig-to-baboon xenogeneic heart transplantation (oXHTx) is the only accepted preclinical animal model for cardiac xenotransplantation. We compared the hemodynamic stability of a propofol- and isoflurane-based anesthetic regimen during oXHTx.

METHODS

Hearts from 12 hDAF or hCD46 transgenic pigs (Sus scrofa; body weight 7 to 32 kg) were transplanted into baboons (Papio anubis and Papio hamadryas; body weight 9 to 26 kg) in the orthotopic life-supporting position. Animals received a propofol-based intravenous regimen or inhalation anesthesia with isoflurane. Analgesia was achieved with fentanyl in both groups. Systemic hemodynamic variables were measured before, during and after cardiopulmonary bypass (CPB) and the need for inotropic or vasoactive pharmacological support was compared before and after CPB.

RESULTS

Global hemodynamic variables [i.e. heart rate, mean arterial pressure (MAP) and cardiac output] were not significantly different in propofol-anesthetized baboons compared to baboons anesthetized with isoflurane. Baboons anesthetized with isoflurane showed a trend towards less pharmacological support required to achieve an adequate MAP of >60 mmHg after CPB (propofol: epinephrine 0.13 [0.05; 0.16] and norepinephrine 0.15 [0.02; 0.16] microg/kg/min vs. isoflurane: epinephrine 0.05 [0.02; 0.08] and norepinephrine 0.06 [0.02; 0.19] microg/kg/min; no significant difference).

CONCLUSIONS

Propofol and isoflurane appear to provide equal hemodynamic stability in orthotopic cardiac pig-to-baboon xenotransplantation prior to the start of CPB. The trend of a reduced catecholamine support needed after CPB, however, suggests that isoflurane may be the preferred drug for maintenance of anesthesia in this primate model.