Tracheal intubation without neuromuscular blocking agents: is there any point?

Why sedative hypnotics often fail in development

PURPOSE OF REVIEW

Drug development to support anaesthesia and sedation has been slow with few candidates emerging from preclinical discovery and limited innovation beyond attempted reformulation of existing compounds.

RECENT FINDINGS

The market is well supported by low-cost generic products and development compounds have not been shown to improve patient outcomes or possess other distinctive characteristics to justify the cost of development.

SUMMARY

To make progress in a large-volume, low margin and highly competitive environment requires meaningful advances in relevant basic science. Opportunities exist, but probably require bolder initiatives than further attempts at reformulation or fiddling with the structure of propofol. Extending development ambitions to include nonanaesthesiologist providers challenges professional boundaries but may facilitate cost-effective changes in patterns of care.

Administration of neostigmine after tracheal intubation shortens time to successful intraoperative neuromonitoring during thyroid surgery: a randomized controlled trial

This prospective, randomized controlled trial evaluated the effect of neostigmine for intraoperative neuromonitoring (IONM) during thyroid surgery. Forty subjects undergoing thyroidectomy with IONM, randomized into neostigmine administration after tracheal intubation (Group N, n = 20) or control treatment with normal saline (Group C, n = 20), completed the trial. Electromyography amplitudes of the vagus nerve (V1) were recorded before thyroid dissection. The time from the initial V1 signal check to successful V1 stimulation was recorded. In Group N, all the patients had a successful V1 signal at the first check, whereas ten (50%) patients in Group C had a time delay between the initial V1 check and successful V1 (p < 0.001). The mean delay time among the delayed patients in Group C was 11.2 ± 1.4 min. The mean time from skin incision to successful V1 stimulation was significantly shorter in Group N than in Group C (15.4 ± 2.4 min vs. 19.9 ± 5.7 min, p = 0.003). In Groups N and C, the mean V1 amplitudes were 962.2 ± 434.5 μV vs. 802.3 ± 382.7 μV (p = 0.225), respectively, and the mean R1 amplitudes were 1240.0 ± 836.5 μV vs. 1023.4 ± 455.8 μV (p = 0.316), respectively. There was one bucking event in Group N. In conclusion, neostigmine administration immediately after tracheal intubation can be useful to reverse neuromuscular blockade for successful IONM in thyroid surgeries.

Investigation of potential neuropharmacological activity of neostigmine-glycopyrrolate for intraoperative neural monitoring in thyroid surgery

Intraoperative neuromonitoring (IONM) is frequently used in thyroid surgery to reduce recurrent laryngeal nerve injury. The use of neuromuscular blockade agent to facilitate tracheal intubation, is a common cause of IONM failure. We performed a retrospective analysis to assess the efficacy of neostigmine-glycopyrrolate as a neuromuscular blockade reversal agent for IONM during thyroid surgery. Rocuronium (0.6 mg/kg) was administered for muscle relaxation. Neostigmine (2 mg) and glycopyrrolate (0.4 mg) were administered immediately after intubation. Cricothyroid muscle-twitch response upon external branch of superior laryngeal nerve stimulation and electromyography amplitudes of vagal and recurrent laryngeal nerves before (V1, R1) and after thyroid resection (V2, R2) were recorded. Fifty patients (23 males, 27 females) were included in the analysis. The diagnoses comprised 43 papillary thyroid carcinomas and seven benign diseases. The mean time between rocuronium injection and neostigmine-glycopyrrolate injection was 5.1 ± 1.2 min, and the mean time from neostigmine-glycopyrrolate injection to successful cricothyroid muscle twitching upon external branch of superior laryngeal nerve stimulation was 21.0 ± 4.5 min. All patients had V1 and R1 amplitudes of more than 500 μV each, with mean V1 and R1 amplitudes of 985.3 ± 471.6 μV and 1177.2 ± 572.7 μV, respectively. Neostigmine-glycopyrrolate was effectively used as a neuromuscular blockade reversal agent for IONM in thyroid surgeries without a significant increase in bucking events. Administration of neostigmine-glycopyrrolate immediately after intubation can be recommended for successful NMB reversal to facilitate IONM during thyroid surgery.

Current status of perioperative hypnotics, role of benzodiazepines, and the case for remimazolam: a narrative review

Anaesthesiologists and non-anaesthesiologist sedationists have a limited set of available i.v. hypnotics, further reduced by the withdrawal of thiopental in the USA and its near disappearance in Europe. Meanwhile, demand for sedation increases and new clinical groups are using what traditionally are anaesthesiologists' drugs. Improved understanding of the determinants of perioperative morbidity and mortality has spotlighted hypotension as a potent cause of patient harm, and practice must be adjusted to respect this. High-dose propofol sedation may be harmful, and a critical reappraisal of drug choices and doses is needed. The development of remimazolam, initially for procedural sedation, allows reconsideration of benzodiazepines as the hypnotic component of a general anaesthetic even if their characterisation as i.v. anaesthetics is questionable. Early data suggest that a combination of remimazolam and remifentanil can induce and maintain anaesthesia. Further work is needed to define use cases for this technique and to determine the impact on patient outcomes.

Low-Dose of Rocuronium During Thyroid Surgery: Effects on Intraoperative Nerve-Monitoring and Intubation

BACKGROUND

Intraoperative Neurophysiological Monitoring (IONM) reduces the incidence of Recurrent Laryngeal Nerve (RLN) injuries during thyroid surgery. To preserve nerve function, long acting neuromuscular blocking agents (NMBA) should be avoided. However, NMBA are necessary for laryngoscopy and endotracheal intubation. We designed this double-blinded, randomized, placebo-controlled trial to assess if a low-dose of rocuronium given at intubation would affect the IONM data recorded before the thyroid dissection.

METHODS

Hundred patients undergoing elective thyroid surgery were randomized to receive either 0.3 mg kg^-1 of low dose rocuronium (intervention) or no-NMBA (control). Intubation was performed with video-laryngoscopy. IONM was placed on RLN and nerve stimulation was performed before and after thyroid dissection. The presence of a valid amplitude prior to dissection was defined when the IONM signal was >100 μV. Occurrence of difficult laryngoscopy was reported together with intubation details including time, difficulty and failure. The lowest peripheral saturation (SpO₂) and the number of desaturation episodes during the intubation were also registered.

RESULTS

No patients showed impaired IONM signal before dissection in both groups. Cormack-Lehane grade was higher in the intervention group (1^1;2) compared to control one (1^1;1; P = 0.046). No-NMBA patients had increased number of difficult laryngoscopies (21% versus 6%, P = 0.041) and intubations (34% versus 8%; P = 0.003) as well as a longer time to intubation (78 [55; 175] versus 55 [31; 110] sec; P = 0.006). Lower values of peripheral SpO₂ during intubation attempt were registered in the no NMBA group (99 [97; 100] versus 99 [99; 100] %; P = 0.020). However, the number of intubation failure was similar between groups (p=0.495).

CONCLUSIONS

Low-dose of rocuronium does not compromise pre-dissection IONM signal and improves intubation condition when compared to a relaxant free strategy.

Mask Induction for an Intellectually Disabled Patient With Congenital Infiltrating Lipomatosis of the Face

Airway management for patients with craniofacial disorders poses many challenges. Congenital infiltrating lipomatosis of the face (CILF) is an extremely rare disorder in which mature lipocytes invade adjacent tissues in the head and neck. The manifestations are typically unilateral, often with associated hypertrophy of both the hard and soft tissues of the face. This is a case report regarding the anesthetic management for a 5-year-old intellectually disabled female with CILF involving the right side of her face who underwent a successful intubated general anesthetic for dental treatment. Awake fiber-optic intubations are recommended and routinely used for patients with suspected or confirmed difficult airways. In this case, substantial distortion of the normal facial anatomy was observed clinically with noted hypertrophy of the right maxilla, mandible, and right side of the tongue. Further complicating matters was the patient's inability to fully cooperate because of her intellectual disability, precluding the option of an awake fiber-optic intubation. To secure the airway following mask induction of anesthesia, spontaneous ventilation was carefully maintained using sevoflurane, nitrous oxide, and oxygen combined with the application of a nasopharyngeal airway. Despite compression of the oral cavity and upper pharyngeal space by the hypertrophic tissues due to CILF, the space in and around the glottis was preserved. Intubation was completed easily with the use of a fiber-optic scope without any serious complications.

Neuromuscular-blocking agents for tracheal intubation in pediatric patients (0-12 years): A systematic review and meta-analysis

BACKGROUND

The benefit of using neuromuscular-blocking agents to facilitate tracheal intubation in pediatric patients remains unclear due to variations in design, treatments, and results among trials. By combining the available evidence, we aimed to establish whether scientific findings are consistent and can be generalized across various populations, settings, and treatments.

METHODS

A systematic search for randomized controlled trials, related to the use of neuromuscular-blocking agents for tracheal intubation in American Society of Anesthesiologists class I-II participants (0-12 years), was performed. We considered all randomized controlled trials that studied whether intubation conditions and hemodynamics obtained by using neuromuscular-blocking agents were equivalent to those that were achieved without neuromuscular-blocking agents. We combined the outcomes in Review Manager 5.3 (RevMan, The Cochrane Collaboration) by pairwise random-effects meta-analysis using a risk ratio (RR) for intubation conditions and mean difference for hemodynamic values (mean [95% Confidence Intervals]). Heterogeneity among trials was explored using sensitivity analyses.

RESULTS

We identified 22 eligible randomized controlled trials with 1651 participants. Overall, the use of a neuromuscular-blocking agent was associated with a clinically important increase in the likelihood of both excellent (RR = 1.41 [1.19-1.68], I²  = 76%) and acceptable (RR = 1.13 [1.07-1.19], I²  = 68%) intubating conditions. There is strong evidence that both unacceptable intubation conditions (RR = 0.35 [0.22-0.46], I²  = 23%) and failed first intubation attempts (RR = 0.25 [0.14-0.42], I²  = 0%) were less likely to occur when a neuromuscular-blocking agent was used compared with when it was not. Higher systolic or mean arterial pressures (mean difference = 13.3 [9.1-17.5] mm Hg, I²  = 69%) and heart rates (mean difference = 15.9 [11.0-20.8] beats/min, I²  = 75%) as well as a lower incidence of arrhythmias were observed when tracheal intubation was facilitated by neuromuscular-blocking agents.

CONCLUSION

The use of a neuromuscular-blocking agent during light-to-moderate depth of anesthesia can improve the quality as well as the success rate of tracheal intubation and is associated with better hemodynamic stability during induction of anesthesia.

Neuromuscular blockade management for intraoperative neural monitoring

This article reviews the literature on development of neuromuscular blockade management in thyroid surgery with intraoperative neural monitoring (IONM) in the past decade. Neuromuscular blockade management includes the choice of neuromuscular blocking agents (NMBAs) and reversal of neuromuscular blockade by sugammadex. A series of animal study and clinical trials showed NMBAs effect on IONM in thyroid surgery. We summarized five NMBA regimens for IONM: (a) relaxant-free regimen, (b) depolarizing NMBA-succinylcholine, (c) titration of nondepolarizing NMBA, and (d) rocuronium combined with sugammadex. The proper management of neuromuscular blockade during IONM has greatly developed over the past decade. The misuse of NMBAs is associated with false IONM interpretations to surgeons. A detailed understanding of NMBAs and neuromuscular blockade management by sugammadex may optimize IONM quality in patients receiving monitored thyroid surgery.

Appropriate sevoflurane concentration to stabilize autonomic activity during intubation with rocuronium in infants: a randomized controlled trial

Background

In infants, sevoflurane is commonly used for induction of anesthesia, following which a muscle relaxant is administered to facilitate tracheal intubation. When rocuronium is used as the muscle relaxant, intubation may be performed before reaching an adequate depth of anesthesia because of its rapid onset. The purpose of this study was to investigate the optimal sevoflurane concentration that would minimize the impact of intubation on hemodynamics and autonomic nervous system (ANS) activity in infants.

Methods

Sixty-one infants aged 1–6 months, undergoing cleft lip repair, were enrolled. Patients were randomly assigned to three end-tidal sevoflurane concentration (E’_Sevo) groups, 3%, 4% and 5%. Anesthesia was induced with 5% sevoflurane with 100% oxygen, and rocuronium (0.6 mg/kg) was administered. The concentration of sevoflurane was adjusted to the predetermined concentration in each group. Mechanical pressure control ventilation via a face mask was commenced. Five minutes after E’_Sevo became stable at the predetermined concentration, tracheal intubation was performed. Immediately after tracheal intubation, ventilation was restarted at the same ventilator settings and continued for 150 seconds. Heart rate (HR) and mean arterial pressure (MAP) were measured 5 times in the 150 seconds after intubation. Normalized units (nu) of high frequency (HF: 0.04-0.15 Hz) and the ratio of low frequency (LF: 0.15-0.4 Hz) to HF components (LF/HF) of HR variability were calculated by MemCalc/Tonam2C™. Normalized units of HF (HFnu) and LF/HF reflect cardiac parasympathetic and sympathetic activity, respectively.

Results

After intubation, HR increased slightly in all groups and MAP increased by 9.2% in the E’_Sevo-3% group. LF/HF increased (p < 0.01) and HFnu decreased (p < 0.01) in all groups 30 seconds after intubation. HFnu was lower (p < 0.001) and LF/HF was higher (p = 0.007) in the E’_Sevo-3% group than in E’_Sevo-5% group. ANS responses to intubation were reduced in a dose-dependent manner.

Conclusions

Sympathomimetic and parasympatholytic responses to intubation in the E’_Sevo-3% group were much greater than those in the E’_Sevo-5% group. During tracheal intubation in infants, 4% or 5% sevoflurane is appropriate for prevention of sympathetic hyperactivation and maintenance of ANS balance as compared to 3% sevoflurane, when a muscle relaxant is co-administered.

Trial registration

The study was registered at UMIN-CTR (UMIN000009933).

The effect of adjuvant drugs on the quality of tracheal intubation without muscle relaxants in children: a systematic review of randomized trials

Intubation without prior administration of muscle relaxants is a common practice in children. However, succinylcholine may be considered as the golden standard for optimizing intubating conditions. We conducted a systematic review of the literature to identify drug combinations that included induction of anesthesia with sevoflurane or propofol. Our aim was to select drug combinations that yield excellent intubating conditions ≥80%; we identified six combinations in children aged 1-9 years. Sevoflurane with remifentanil (1 or 2 μg·kg(-1) ), lidocaine (2 mg·kg(-1) ), or propofol (2 mg·kg(-1) ) as the adjuvant shared the following characteristics: premedication with midazolam and/or ketamine, long sevoflurane exposure time, high inspired and endtidal sevoflurane concentration, and assisted ventilation. One combination using sevoflurane with propofol (3 mg·kg(-1) ) without premedication, with shorter sevoflurane exposure time, and spontaneous breathing indicated that propofol may be the adjuvant of choice for a rapid sevoflurane induction. The only adjuvant identified in propofol induction was remifentanil (4 μg·kg(-1) ). No serious adverse events were reported with these combinations.

Laryngeal morbidity after intubation with or without neuromuscular block in thyroid surgery using recurrent laryngeal nerve monitoring

OBJECTIVE

The avoidance of neuromuscular blocking agents (NMBA) for endotracheal intubation is associated with a higher incidence of laryngeal discomfort and lesions, but could impair effectiveness of intra operative recurrent laryngeal nerve monitoring (IONM).

METHODS

In a retrospective quality assessment study over a period of 30 months, a collective that had been intubated without NMBA was compared with a group, which had received NMBA. Endolaryngeal EMG was accomplished with a MagStim(®)-EMG-electrode.

RESULTS

Out of the 127 patients with 224 nerves at risk (NAR; NMBA 102 NAR, no NMBA 122 NAR), more than 90% received a total intravenous anaesthesia with propofol, and 88% had remifentanil. Laryngeal side effects and damage scores did not differ significantly.

CONCLUSIONS

In this special setting of IONM and thyroid surgery, avoidance of NMBA for endotracheal intubation seems not to increase the incidence of laryngeal side effects and lesions. If endotracheal intubation without NMBA is required, the authors suggest a standardized approach using induction agents as propofol and remifentanil.