The influence of fentanyl vs. s-ketamine on intubating conditions during induction of anaesthesia with etomidate and rocuronium:

Effect of esketamine on the EC50 of remifentanil for blunting cardiovascular responses to endotracheal intubation in female patients under general anesthesia: a sequential allocation dose-finding study

BACKGROUND

This study aimed to investigate the effect of esketamine on the dose-effect relationship between remifentanil and the cardiovascular response to endotracheal intubation during target-controlled infusion (TCI) of propofol.

METHODS

Patients underwent elective gynecological laparoscopic surgery under general anesthesia with endotracheal intubation, aged 18-65 years, American Society of Anesthesiologists class I or II, 18 kg/m2 ≤ body mass index ≤ 30 kg/m2, were randomly divided into the control (group C) and esketamine groups (group E). Before anesthesia induction, group E received an intravenous injection of 0.3 mg/kg of esketamine, while group C received an equal dose of physiological saline. TCI of propofol to the effect-site concentration (EC) of 3.0 μg/mL, and then TCI of remifentanil to the effect room and intravenous injection of rocuronium 0.6 mg/kg after MOAA/S was 0. Endotracheal intubation was performed after 2 min. Dixon's modified sequential method was used, and the initial EC of remifentanil was 3.0 ng/mL. The EC of remifentanil was determined according to the intubation response of the previous patient, with an adjacent concentration gradient of 0.3 ng/mL. The EC50 and EC95 values and their 95% confidence intervals (CIs) were determined using probit regression analysis.

RESULTS

The EC50 for cardiovascular response inhibition to endotracheal intubation using remifentanil was 3.91 ng/mL (95% CI: 3.59-4.33 ng/mL) and EC95 was 4.66 ng/mL (95% CI: 4.27-6.23 ng/mL) with TCI of propofol 3.0 μg/mL. After intravenous administration of 0.3 mg/kg of esketamine, the EC50 of remifentanil was 3.56 ng/mL (95% CI: 3.22-3.99 ng/mL) and EC95 was 4.31 ng/mL (95% CI: 3.91-5.88 ng/mL).

CONCLUSIONS

Combined with TCI of propofol 3.0 μg/mL for anesthesia induction, esketamine significantly reduced the EC50 and EC95 of remifentanil to inhibit the cardiovascular response to endotracheal intubation.

TRIAL REGISTRATION

The trial was registered in the Chinese Clinical Trials Registry ( www.chictr.org.cn ; registration number: ChiCTR2200064932; date of registration:24/10/2022).

Effects of adding low-dose esketamine to sufentanil and propofol sedation during cervical conization: a single-centre, randomized controlled trial

BACKGROUND

Cervical conization is a brief but painful procedure that can be performed under sufficient sedation with propofol and opioids. However, this sedation approach comes with a high risk of sedation-related adverse events (SRAEs). Esketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist, causes less cardiorespiratory depression than opioids. The aim of this study was to assess the efficacy and safety of adding a low dose of esketamine to propofol and sufentanil sedation as an opioid-reduced regimen.

METHODS

A total of 122 consecutive patients with ASA I-II, body mass index < 30, and STOP-BANG score < 3 who underwent cervical conization were enrolled and randomly divided into Group S and Group ES. Using a closed-loop target-controlled infusion (TCI) pump with a target bispectral index (BIS) value of 60 ± 5, patients in Group S were sedated with 0.2 mcg·kg-1 sufentanil and propofol, while patients in Group ES were sedated with 0.15 mg·kg-1 esketamine, 0.1 mcg·kg-1 sufentanil and propofol. The primary outcome was the incidence and severity of SRAEs, while the secondary outcomes included effectiveness of sedation, awakening time, psychotomimetic side effects, postoperative pain, postoperative nausea and vomiting, and patient and gynaecologist satisfaction.

RESULTS

Data from 120 patients were analysed. The incidence of composite SRAEs was significantly higher in Group S than in Group ES (85.0% vs. 56.7%, P < 0.05). Furthermore, the severity of SRAEs was higher in Group S than in Group ES (P < 0.001). There were no significant differences in the effectiveness of sedation, awakening time, psychotomimetic side effects, postoperative pain, postoperative nausea and vomiting, or patient and gynaecologist satisfaction between the two groups.

CONCLUSION

Adding low-dose esketamine to propofol and sufentanil sedation reduces the incidence and severity of SRAEs in patients undergoing cervical conization, with equal sedation efficacy, recovery quality, and no additional psychomimetic side effects.

TRIAL REGISTRATION

ChiCTR2000040457 , 28/11/2020.

Intubation Conditions following Rocuronium: Influence of Induction Agent and Priming

A small priming dose of rocuronium can shorten the onset time of neuromuscular blockade. Induction agents with less cardiovascular depression also reduce the onset time. We hypothesized that ketamine, compared to thiopentone, would reduce onset time and improve intubating conditions following priming. Sixty patients ASA I to II, randomized by computer-generated sequence to four groups were investigated in a double-blind controlled trial. In the two groups with priming, 0.04 mg/kg of rocuronium was followed by three minutes of priming interval. Induction was followed by an intubation dose of 0.4 mg/kg of rocuronium. After 30 seconds, intubation was attempted within a further 20 seconds. In the two control groups, the same sequence was repeated except sham priming (saline) was given. For induction, S-ketamine (1 mg/kg) or thiopentone (4 mg/kg) were administered. Intubating conditions were graded as excellent, good, poor, or not possible. Neuromuscular transmission was monitored by acceleromyography of the thumb. There were no measured differences in onset time of neuromuscular block or in haemodynamics between the groups. The proportion of good to excellent intubating conditions was higher when ketamine was preceded by priming compared to ketamine without priming (87% vs 20%; P<0.05). In both priming and control groups intubating conditions were improved when using ketamine compared to thiopentone (P<0.05). The mechanism of this effect was not clear from this study.

The effect of low dose ketamine and priming of cisatracurium on the intubating condition and onset time of cisatracurium

Background

Both ketamine and priming may accelerate the onset time of neuromuscular blocking agents. We investigate the effect of low dose ketamine and cisatracurium priming on the intubating condition and onset time of cisatracurium.

Methods

After Institutional Review Board approval, 120 consecutive patients undergoing general anesthesia were randomly assigned to one of 4 groups. All patients were injected one of normal saline (group C), cisatracurium 0.01 mg/kg (group P), ketamine 0.5 mg/kg (group K) and combination of cisatracurium 0.01 mg/kg, and ketamine 0.5 mg/kg (group PK) diluted into a 5 ml solution, followed 3 minutes later by cisatracurium 0.15 mg/kg in group C and K, and 0.14 mg/kg cisatracurium in priming group. Onset time was recorded the electromyographical responses using single twitch and intubating conditions were evaluated at 60 seconds after cisatracurium administration.

Results

The mean onset time was most significantly accelerated in Group PK and was also significantly more accelerated in Group P and K compared with Group C (P < 0.008). It was 112.7 ± 13.2, 91.4 ± 17.9, 84.9 ± 12.7 and 76.4 ± 8.3 seconds in Group C, P, K, and PK, respectively. Intubating conditions were significantly improved in Group P, K and PK than Group C (P < 0.008). Especially, Group PK showed most significant improvement of intubating conditions.

Conclusions

The combination of the low dose ketamine and cisatracurium priming accelerated the onset time and was improved the intubating conditions.

A review of etomidate for rapid sequence intubation in the emergency department

Etomidate is a sedative-hypnotic chemically unrelated to other induction agents. The pharmacological and safety profile of etomidate offers many advantages for induction during rapid sequence intubation (RSI) in the emergency department (ED). Its onset of action is within 5 to 15 seconds, and its duration of action is 5 to 15 minutes. Unlike thiopental, propofol, midazolam and, to a lesser extent, ketamine, etomidate has minimal respiratory or cardiovascular effects and can be safely used in patients with hemodynamic instability or cardiac ischemia. Etomidate is cerebroprotective, with the ability to decrease intracranial pressure and maintain cerebral perfusion, making it an ideal agent for patients with head injuries. Of the currently available induction agents, etomidate offers the most favourable safety profile and is the least likely to produce adverse effects in patients with unknown or untreated medical conditions. Etomidate may cause pain on injection, myoclonic movements on induction, hiccups, nausea and vomiting. Transient adrenal suppression has been reported, but not to a clinically significant degree, after single induction doses for ED RSI. Etomidate has been well studied in the ED and should be adopted for RSI in specific ED patient groups.

Scandinavian clinical practice guidelines on general anaesthesia for emergency situations

Emergency patients need special considerations and the number and severity of complications from general anaesthesia can be higher than during scheduled procedures. Guidelines are therefore needed. The Clinical Practice Committee of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine appointed a working group to develop guidelines based on literature searches to assess evidence, and a consensus meeting was held. Consensus opinion was used in the many topics where high-grade evidence was unavailable. The recommendations include the following: anaesthesia for emergency patients should be given by, or under very close supervision by, experienced anaesthesiologists. Problems with the airway and the circulation must be anticipated. The risk of aspiration must be judged for each patient. Pre-operative gastric emptying is rarely indicated. For pre-oxygenation, either tidal volume breathing for 3 min or eight deep breaths over 60 s and oxygen flow 10 l/min should be used. Pre-oxygenation in the obese patients should be performed in the head-up position. The use of cricoid pressure is not considered mandatory, but can be used on individual judgement. The hypnotic drug has a minor influence on intubation conditions, and should be chosen on other grounds. Ketamine should be considered in haemodynamically compromised patients. Opioids may be used to reduce the stress response following intubation. For optimal intubation conditions, succinylcholine 1-1.5 mg/kg is preferred. Outside the operation room, rapid sequence intubation is also considered the safest method. For all patients, precautions to avoid aspiration and other complications must also be considered at the end of anaesthesia.

Ketamine, but not priming, improves intubating conditions during a propofol-rocuronium induction

PURPOSE

Both ketamine and priming may shorten the onset time of rocuronium. This study investigates the effects of ketamine and priming as components of a propofol induction on intubating conditions and onset of neuromuscular block.

METHODS

This prospective randomized double-blind study was performed in 120 American Society of Anesthesiologists (ASA) I-II patients who were assigned to one of four groups of 30 patients each: control, priming, ketamine, and ketamine-priming. Ketamine 0.5 mg x kg(-1) or saline was given before priming and induction. Rocuronium 0.06 mg x kg(-1) or saline was injected 2 min before propofol 2.5 mg x kg(-1). This was followed by rocuronium 0.6 mg x kg(-1) or by rocuronium 0.54 mg x kg(-1) if priming was given. Intubation was performed one minute later. Intubating conditions were graded as excellent, good, or poor. Heart rate, noninvasive blood pressure, and train-of-four (TOF) response were monitored.

RESULTS

Intubating conditions were graded excellent in 20% of the control group, 30% of the priming group, 47% of the ketamine group, and 57% of the ketamine-priming group. Analysis using forward stepwise regression indicated that ketamine improved intubating conditions (P = 0.001) but priming did not (P = 0.35). Time to reach a TOF count of zero was shortened by ketamine (P = 0.001) but not by priming (P = 0.94): 216 +/- 20 s in the control group, 212 +/- 27 s in the priming group, 162 +/- 18 s in the ketamine group, and 168 +/- 22 s in the ketamine-priming group.

CONCLUSION

A low-dose ketamine used with a propofol-rocuronium induction improved intubating conditions and shortened onset time. Priming did not influence intubating conditions or onset time.

Effect of Remifentanil on Tracheal Intubation Conditions and Haemodynamics in Children Anaesthetised with Sevoflurane and Nitrous Oxide

This study examined the effect of remifentanil added to inhalation agents on intubating conditions in children (aged one to seven years). As is our routine, all patients were premedicated with 0.004 mg/kg glycopyrrolate intramuscularly 30 minutes before anaesthesia to prevent bradycardia and salivary secretion, and received intravenous 1 mg/kg ketamine prior to transfer into the operating room to facilitate separation of the child from the parents. Laryngoscopy was attempted after ventilation with 8% sevoflurane in 50% nitrous oxide and 50% oxygen for two minutes, and intravenous administration of either a placebo bolus of saline (Group S) or one of two doses of remifentanil, 1 μg/kg (Group R1) or 2 μg/kg (Group R2) given over 30 seconds, commenced at the beginning of the sevoflurane administration. Only 18 of 32 patients (56.3%) in Group S had acceptable intubating conditions compared with 31 of 32 patients (96.9%) in Group R1 and 32 of 32 patients (100%) in Group R2 (P <0.001). Mean blood pressure was lower in Group R1 and R2 compared with Group S (P <0.005). Our routine use of ketamine and glycopyrrolate may have influenced the relative lack of significant hypotension and bradycardia. Sevoflurane, nitrous oxide and remifentanil provided acceptable conditions for tracheal intubation in children and could be an acceptable alternative to intravenous induction and neuromuscular blocking agents.

The anaesthesiologist in the intensive care unit

PURPOSE OF REVIEW

This review focuses on recent knowledge in areas of anaesthesia expertise which are indispensable to intensive care unit management, including airway management, vascular access, regional analgesia and the treatment of status asthmaticus and status epilepticus.

RECENT FINDINGS

Etomidate as the sole agent for intubation in the intensive care unit has a 90% success rate, while in a prehospital setting, the addition of succinylcholine to etomidate results in a 99% success rate. In determining successful intubation, capnography and laryngoscopic/fibreoptic visualization are superior to auscultation, while auscultation is as effective as the self-inflating bulb or transillumination with the lightwand. The dorsalis pedis artery is an effective alternative to radial artery cannulation, while arterial cannulation itself can result in major adverse effects if complications arise. Ultrasound guidance in the placement of central catheters results in an improved insertion success rate. Internal jugular and subclavian lines have similar risk of haemothorax or pneumothorax, while subclavian lines are associated with the lowest incidence of infection. Midazolam, thiopentone and propofol have all been found to be efficacious in terminating refractory status epilepticus, with thiopentone resulting in a lower incidence of breakthrough seizures or treatment failure but an increased incidence of hypotension. Inhalational anaesthesia using isoflurane or desflurane has also been found to be successful in refractory status epilepticus. In the management of status asthmaticus, limiting minute volume while tolerating hypercapnia and acidosis as well as the use of inhalational anesthesia have proven effective strategies in a number of refractory cases.

SUMMARY

The anaesthesiologist's unique knowledge and skills are ideally suited to the practical management of patients in a critical care setting as well as in the treatment of the critical phases of many illnesses.

Airway Management in Critical Illness

Airway management in the ICU can be complicated due to many factors including the limited physiologic reserve of the patient. As a consequence, the likelihood of difficult mask ventilation and intubation increases. The incidence of failed airways and of cardiac arrest related to airway instrumentation in the ICU is much higher than that of elective intubations performed in the operating room. A thorough working knowledge of the devices available for the management of the difficult airway and recommended rescue strategies is paramount in avoiding bad patient outcomes. In this review, we will provide a conceptual framework for airway assessment, with an emphasis on assessment of the patient with limited cervical spine movement or injury and of morbidly obese patients. Furthermore, we will review the devices that are available for airway management in the ICU, and discuss controversies surrounding interventions like cricoid pressure and the use of muscle relaxants in the critically ill patient. Finally, strategies for the safe extubation of patients with known difficult airways will be provided.

Intubating conditions and hemodynamic effects of etomidate for rapid sequence intubation in the emergency department: an observational cohort study

OBJECTIVES

To describe and analyze the intubating conditions and hemodynamic effects of etomidate in patients undergoing rapid sequence intubation (RSI) in the emergency department.

METHODS

The authors conducted a prospective observational study of all patients who received etomidate for induction of RSI over a 42-month period in a large tertiary care teaching hospital. Intubating conditions were determined by the emergency physician for both sedation and paralysis and for technical difficulty using a five-point Likert scale. Hemodynamic effects were evaluated before, after, and every five minutes for 15 minutes following administration of etomidate.

RESULTS

Etomidate was used for induction of RSI in 522 patients, all of whom were included in the final efficacy analysis, while 491 were included in the analysis of hemodynamics. Lidocaine and fentanyl were used as pretreatment in 65.1% and 26.1% of patients, respectively, while succinylcholine was the paralytic in 94.3% of intubations. Sedation and paralysis were rated as excellent or good in 88.1% and 8.8% of patients, respectively, while technical difficulty was very easy or easy in 60.7% and 19.0% of patients, respectively. Mean (+/- SD) baseline systolic blood pressure (sBP), diastolic blood pressure (dBP), and heart rate were found to be 132.7 (+/- 35.4) mm Hg, 69.5 (+/- 21.2) mm Hg, and 96.1 (+/- 26.2) bpm, respectively. Overall, there was a clinically insignificant elevation in sBP (p < 0.0001), dBP (p = 0.0002), and heart rate (p < 0.0001) immediately postintubation. Elevations in sBP persisted at five minutes (p = 0.0230) and ten minutes (p = 0.0254) postintubation. Diastolic blood pressure and heart rate returned to baseline at five minutes after intubation and remained stable throughout the 15-minute postintubation assessment period. In the subgroup of 80 patients with a preintubation sBP < 100 mm Hg, there was a 12.1-mm Hg elevation in sBP (p < 0.0001) and a 7.3-mm Hg elevation in dBP (p = 0.0001) immediately postintubation. This elevation persisted throughout the 15-minute postintubation assessment period.

CONCLUSIONS

Etomidate appears to provide appropriate intubating conditions in a heterogeneous group of patients undergoing RSI in the emergency department. Hemodynamic stability appears to be present following administration of this agent, even in patients with low pre-RSI blood pressure. This attribute must be weighed against potential adverse effects of this agent, including adrenal suppression.