Expiratory central airway collapse during positive pressure ventilation: a case report.

BACKGROUND: Physiologic narrowing of the central airway occurs during expiration. Conditions in which this narrowing becomes excessive are referred to as expiratory central airway collapse. Expiratory central airway collapse is usually managed by applying positive pressure to the airways, which acts as a pneumatic stent. The particularity of the case reported here included the patient's left main bronchus being permeable during spontaneous breathing but collapsing during general anaesthesia, despite positive pressure ventilation and positive end-expiratory pressure. CASE PRESENTATION: We present the case of a 55-year-old man admitted for the placement of a ureteral JJ stent. Rapid desaturation occurred a few minutes after the onset of anaesthesia. After excluding the most common causes of desaturation, fibreoptic bronchoscopy was performed through the tracheal tube and revealed complete collapse of the left main bronchus. The collapse persisted despite the application of positive end-expiratory pressure and several recruitment manoeuvres. After recovery of spontaneous ventilation, the collapse was lifted, and saturation increased back to normal levels. No evidence of extrinsic compression was found on chest X-rays or computed tomography scans. CONCLUSION: Cases of unknown expiratory central airway collapse reported in the literature were usually managed with positive pressure ventilation. This approach has been unsuccessful in the case described herein. Our hypothesis is that mechanical bending of the left main bronchus occurred due to loss of the patient's natural position and thoracic muscle tone under general anaesthesia with neuromuscular blockade. When possible, spontaneous ventilation should be maintained in patients with known or suspected ECAC.

Evaluation of the impact of deep neuromuscular blockade on surgical conditions for laryngeal microsurgery with High Frequency Jet Ventilation. A comparison with no block during intravenous general anesthesia with topical lidocaine.

OBJECTIVE: Laryngeal transoral surgery classically requires a neuromuscular block (NMB) to facilitate tracheal intubation and to improve surgical conditions. However, the short duration of most procedures and the potential complications of residual NMB lead to consider a no block approach. The hypothesis that intravenous anesthesia (remifentanil and propofol infusions) without NMB but including glottis topical lidocaine anesthesia would allow clinically acceptable laryngeal exposure and good surgical conditions was tested in the specific context of procedures undergone with High Frequency Jet Ventilation (HFJV). STUDY DESIGN: A prospective randomized clinical comparison. METHODS: 66 consenting patients were planned to receive 0.6 mg·kg-1 rocuronium or saline at random. The outcome measurements included the time and conditions to complete suspended laryngoscopy, and the surgical conditions rated by the surgeon. Any vocal cord movement or coughing was recorded. Data were compared using a Wilcoxon rank-sum test for numerical variables and chi-square test for categorical ones. Treatment failure was defined as an impossible laryngoscopy or a grade 4 surgical field occurring at any time during surgery and was compared to its null theoretical value by a general z-test. An interim analysis after completion of 50% patients was performed using Pocock boundaries at 0.0294 significance levels. RESULTS: A significant failure rate occurred in the non paralysed group (27%, p < 0.001). No coughing and no vocal cords movement occurred in the NMB group. Poorer surgical conditions were obtained without NMB (p = 0.011). CONCLUSION: Inducing a deep NMB ensured improved conditions during direct laryngeal microsurgery with HFJV.

The interest of 100 versus 200 Hz tetanic stimulations to quantify low levels of residual neuromuscular blockade with mechanomyography: a pilot study.

A more sensitive method than the train-of-four ratio seems required to detect low levels of residual neuromuscular blockade before tracheal extubation. The goal of the study was to determine the potential benefit of 5 s of 100 versus 200 Hz tetanic stimulation to quantify the residual block with mechanomyography in anesthetised patients. Twenty informed and consenting 18- to 80-year-old patients undergoing nose surgery were included. On the left hand, neuromuscular transmission was continuously monitored by acceleromyography. On the right side, a new mecanomyographic device (Isometric Thumb Force©) recorded the force of thumb adduction (N) developed during 5 s of 100- and 200 Hz tetanic stimulations of the ulnar nerve at three consecutive times: baseline before inducing the neuromuscular blockade, at the time of contralateral train-of-four ratio 0.9 recovery, and 3 min after additional sugammadex reversal. Tetanic Fade Ratios (TFR = F residual/F max) were compared between 100 and 200 Hz stimulations using Student's t test. At the time of TOF ratio 0.9 recovery, both 100 and 200 Hz TFR were significantly decreased compared to baseline (0.61 and 0.16 on average, respectively, p < 0.0001). The 200 Hz TFR was significantly lower than the 100 Hz TFR (p < 0.0001). There were no differences between baseline and post-reversal TFR. The 200 Hz TFR has the potential to better describe low levels of residual neuromuscular blockade than the TOF ratio and 100 Hz TFR and would benefit from further investigations. Retrospectively registered in the Australian and New Zealand Clinical Trials Registry ACTRN12619000273189.

Philips Intellivue NMT module: precision and performance improvements to meet the clinical requirements of neuromuscular block management.

The variability or inaccuracy of acceleromyographic measurements could interfere with the interpretation of the train-of-four (TOF) ratio during neuromuscular block (NMB) recovery. This study evaluated the precision and performance of the Philips Intellivue NMT module (NMT) before (part 1) and after (part 2) several technical upgrades (i.e., firmware upgrade, new cable, and hand adapter) that were recently available. Two cohorts of 30 patients who were scheduled to undergo rhino/septoplasty under general anesthesia were included in the study. TOF ratios were recorded simultaneously every 15 s on both hands with the NMT and a TOF-Watch SX installed inside a SL TOF-Tube (TWX). Before rocuronium was administered and once final responses were stabilized, the average of the four successive measurements that determined the baselines and repeatability coefficients were compared using a z test. Simultaneous measurements were recorded at different NMB stages: onset, depth of NMB after intubation, when TWX recovered TOF count 2, TOF ratios 0.5 and 0.9, and when NMT recovered TOF ratio 0.9. The results were compared using a Student t test; p < 0.05 was considered significant. The NMT repeatability coefficients obtained in part 1 were significantly higher than with the TWX, they were significantly lower in part 2. Initially, the NMT significantly overestimated NMB recovery at every stage. Conversely, in the second part of the study, no difference reached statistical significance. With the recent upgrades and the new hand adapter, the NMT provided similar results compared with the TWX, Their implementation should be recommended in clinical practice.

Performance of acceleromyography with a short and light TOF-tube compared with mechanomyography: a clinical comparison.

BACKGROUND: Disturbances in the thumb's movement interfere with the functioning of acceleromyography in many clinical settings. The short and light (SL) train-of-four (TOF)-Tube is a new version of a rigid tubular device that was designed to protect the thumb from external disturbances during surgery, even when the hand is not accessible by the anaesthesiologist. OBJECTIVE: To compare the precision and performance of acceleromyography performed with the aid of the SL TOF-Tube (AMGTT) with standard isometric mechanomyography (MMG). DESIGN: Simultaneous arm-to-arm comparison of both methods in the same anaesthetised patient. SETTING: A monocentric study, performed from September 2007 to June 2008. PATIENTS: Nineteen ASA I to II patients scheduled to undergo lower limb orthopaedic surgery under general anaesthesia. INTERVENTION: Neuromuscular transmission monitoring during baseline, onset and spontaneous recovery of rocuronium-induced neuromuscular block. MAIN OUTCOME MEASURES: Initial baseline and repeatability coefficients were assessed during 10 consecutive measurements of the first twitch height (T1) and TOF T4/T1 ratio and compared using a z test. The spontaneous recoveries of defined blockade levels (onset, T1 25% of initial calibration and TOF ratio 0.9) were compared in terms of duration and intensity. Agreement between both techniques was assessed by the Bland-Altman method. RESULTS: The mean ±â€ŠSD control TOF ratios were 98 ±â€Š1% (MMG) and 103 ±â€Š2% (AMGTT). The repeatability coefficients were higher (P < 0.001) and the onset was longer (mean 0.44 min) (P < 0.001) when they were measured by AMGTT. The recoveries of T1 25% and TOF ratio 0.9 were not significantly different between the two methods, and the limits of agreement were in the usual range of contralateral comparisons (-19 and +24% for TOF ratio 0.9). CONCLUSION: Compared with mechanomyography, acceleromyography performed with the aid of an SL TOF-Tube offered acceptable precision and equivalent performance during neuromuscular block recovery.

Deep neuromuscular block improves surgical conditions during laparoscopic hysterectomy: a randomised controlled trial.

BACKGROUND: The benefit of inducing deep neuromuscular block to improve laparoscopic surgical conditions is controversial. OBJECTIVE: The goal of this study was to determine the depth of neuromuscular block needed to guarantee excellent operating conditions during laparoscopic hysterectomy. DESIGN: A randomised controlled trial. SETTING: A single-centre study performed between February 2011 and May 2012. PATIENTS: One hundred and two women of ASA physical status 1 or 2 gave consent to participate and were allocated randomly to one of two groups. INTERVENTION: Under desflurane general anaesthesia, patients in Group S (shallow block), neuromuscular blockade was induced by administration of rocuronium 0.45 mg  kg-1 followed by spontaneous recovery or a rescue bolus dose of 5  mg if surgical conditions were unacceptable. In Group D (deep block), neuromuscular block was induced by administration of rocuronium 0.6 mg  kg-1 and maintained by bolus doses of 5  mg if the train-of-four count exceeded two, using adductor pollicis electromyography. MAIN OUTCOME MEASURES: With a stable pneumoperitoneum (13 mmHg), the surgeon scored the quality of the surgical field every 10  min as excellent (1), good but not optimal (2), poor but acceptable (3) or unacceptable (4). The groups were compared using the Cochran-Armitage trend test. The level of neuromuscular blockade was recorded each time the surgical field score exceeded 1. RESULTS: For groups S and D, respectively, the maximum surgical field scores were 1 in 21 and 34 patients, 2 in 11 and 11 patients, 3 in 4 and 5 patients and 4 in 14 and 0 patients. A trend towards higher scores was demonstrated in group S (P < 0.001). Surgical field scores of 2, 3 and 4 occurred only when the train-of-four count was at least 1, 2 and 3, respectively. CONCLUSION: Inducing deep neuromuscular block (train-of-four count <1) significantly improved surgical field scores and made it possible to completely prevent unacceptable surgical conditions.

Operating room discharge after deep neuromuscular block reversed with sugammadex compared with shallow block reversed with neostigmine: a randomized controlled trial.

OBJECTIVE: To determine if reversing a deep or moderate block with sugammadex, compared with a shallow block reversed with neostigmine, reduces the time to operating room discharge after surgery and the time spent in the postanesthesia care unit. DESIGN: A randomized controlled trial. SETTING: Monocentric study performed from February 2011 until May 2012. PATIENTS: One hundred consenting women with American Society of Anesthesiologists grade I or II were randomized into 2 groups. INTERVENTION: Laparoscopic hysterectomy was performed under desflurane general anesthesia. For the neostigmine (N) group, 0.45 mg · kg-1 rocuronium was followed by spontaneous recovery. A 5-mg rescue bolus was administered only if surgical evaluation was unacceptable. At the end of surgery, 50 µg · kg-1 neostigmine with glycopyrrolate was administered. For the sugammadex (S) group, a higher intubating rocuronium dose (0.6 mg · kg-1) was followed by 5-mg boluses each time the train-of-four count exceeded 2. Sugammadex (2-4 mg · kg-1) was administered to reverse the block. All patients were extubated after obtaining a train-of-four ratio of 0.9. MEASUREMENTS: The duration between the end of surgery and operating room discharge and the time spent in the postanesthesia care unit. MAIN RESULTS: The time till operating room discharge was shorter and more predictable in group S (9.15±4.28 minutes vs 13.87±11.43 minutes in group N; P=.005). The maximal duration in group S was 22 minutes, compared with 72 minutes in group N. The time spent in the postanesthesia care unit was not significantly different (group S: 47.75±31.77 minutes and group N: 53.43±40.57 minutes; P=.543). CONCLUSION: Maintaining a deep neuromuscular block during laparoscopic hysterectomy reversed at the end of the procedure with sugammadex enabled a faster and more predictable time till operating room discharge than did the classical combination of a shallower block reversed with neostigmine.

Postoperative analgesic effect of transcranial direct current stimulation in lumbar spine surgery: a randomized control trial.

BACKGROUND: Ultimately, the experience of pain derives from changes in brain excitability. Therefore, modulating the excitability of cortical areas involved in pain processing may become an attractive option in the context of multimodal analgesia during the postoperative period. Repetitive transcranial magnetic stimulation (rTMS) can reduce morphine consumption during the postoperative period after gastric bypass surgery. We tested the potential of another method of noninvasive brain stimulation, transcranial direct current stimulation (tDCS), to reduce morphine consumption or pain perception during the postoperative period. METHODS: Fifty-nine ASA I to II patients undergoing lumbar spine surgery were randomized to receive anodal (n=20), cathodal (n=20), or sham (n=19) tDCS in the recovery room in a double-blind manner. Morphine consumption administrated through patient-controlled analgesia (PCA) was the primary outcome; pain perception as measured by visual analog scale was the secondary outcome. RESULTS: There were no statistically significant differences between the 3 groups of patients, either for PCA morphine consumption or for pain scores. CONCLUSIONS: Several factors may explain the observed lack of impact of tDCS on PCA morphine consumption and pain perception: the method of brain stimulation (tDCS/rTMS), potential interactions with anesthetic drugs, differences in patients population (gastric bypass surgery/lumbar spine surgery), and the previous experience of pain and chronic consumption of analgesic drugs. Further studies with tDCS should be performed before concluding that tDCS is inefficient for postoperative pain control, because noninvasive brain stimulation methods, such as rTMS and tDCS, may become attractive in the setting of multimodal analgesia.