Evaluation of changes in tidal volume during mask ventilation following administration of neuromuscular blocking drugs

The practice of checking the ability to mask ventilate before administering neuromuscular blocking drugs remains controversial. We prospectively evaluated the changes in the expired tidal volume during pressure‐controlled ventilation (two‐handed mask ventilation technique) as a surrogate marker to assess the ease of mask ventilation following administration of rocuronium. After informed consent, 125 patients were anaesthetised using a standard induction technique consisting of fentanyl, propofol and rocuronium, with anaesthesia then maintained with isoflurane in oxygen. The mean (SD) expired tidal volume before administration of rocuronium increased by 61 (13) ml at 2 min following onset of neuromuscular block (p < 0.001). This supports the concept that neuromuscular blockade induced by rocuronium facilitates mask ventilation.     

Facemask ventilation and vocal cord angle following neuromuscular blockade: a prospective observational study#

Numerous studies support the idea that neuromuscular blockade facilitates facemask ventilation after induction of anaesthesia. Although improved airway patency or pulmonary compliance and a resolution of laryngospasm have been suggested as possible causes, the exact mechanism remains unclear. We aimed to assess whether neuromuscular blockade improves facemask ventilation and to clarify whether this phenomenon is associated with the vocal cord angle. This prospective observational study included patients aged between 20 and 65 years scheduled for elective surgery under general anaesthesia. After induction of anaesthesia, patients' lungs were ventilated with pressure-controlled ventilation using a facemask. During facemask ventilation, a flexible bronchoscope was inserted through a self-sealing diaphragm at the elbow connector attached to the facemask and breathing circuit and positioned to allow a continuous view of the vocal cords. The mean tidal volume and vocal cord angle were measured before and after administration of neuromuscular blocking drugs. Of 108 patients, 100 completed the study. Mean (SD) tidal volume ((11.0 (3.9) ml.kg^-1 vs. 13.6 (2.6) ml.kg^-1; p < 0.001) and mean (SD) vocal cord angle (17° (10°) vs. 26° (5°); p < 0.001) increased significantly after neuromuscular blockade. The proportional increase in mean tidal volume after neuromuscular blockade was positively correlated with vocal cord angle (Spearman's ρ = 0.803; p < 0.001). In conclusion, neuromuscular blockade facilitated facemask ventilation, and the improvement was correlated with further opening of the vocal cords.     

The effect of neuromuscular blockade on the efficiency of mask ventilation of the lungs

We conducted a two-part study to assess the practice of withholding neuromuscular blockade until the ability to ventilate the lungs using a bag and face mask (mask ventilation) has been established following induction of anaesthesia. The first part of the study consisted of a postal survey (71% response rate) of 188 anaesthetists in the Oxford region to assess their current practice. Thirty per cent of respondents always checked mask ventilation before administering a neuromuscular blocking drug, whereas 39% of respondents (all them consultants) never did this. A further 31% only did so in the case of known or anticipated difficulty with the airway. In the second part of the study, we measured inspired (V(TI)) and expired (V(TE)) tidal volumes before and after neuromuscular blockade in 30 patients undergoing general anaesthesia. The ratio V(TE)/V(TI) was used as a measure of the efficiency of ventilation. There was no difference in V(TE)/V(TI) before [mean (SD) 0.47 (0.13)] and after [0.45 (0.13)] neuromuscular blockade. We conclude that neuromuscular blockade does not affect the efficiency of mask ventilation in patients with normal airways.     

The effect of neuromuscular blockade on the efficiency of facemask ventilation in patients difficult to facemask ventilate: a prospective trial

Facemask ventilation of the lungs can be an important rescue intervention in a ‘cannot intubate’ scenario. We assessed the effect of neuromuscular blockade on expiratory tidal volumes in patients with expected difficulty in mask ventilation. The lungs of patients with at least three predictors of difficulty in mask ventilation were ventilated using a facemask held with two hands, with mechanical ventilation set in a pressure‐controlled mode. Tidal volumes were recorded before and after the establishment of complete neuromuscular block. In 113 patients, median (IQR [range]) tidal volume increased from 350 (260–492 [80–850]) ml initially, by 48% to 517 (373–667 [100–1250]) ml 30 s after rocuronium administration, (p < 0.001). After the onset of the complete neuromuscular block, a median tidal volume of 600 (433–750 [250–1303]) ml was observed, corresponding to an increase of 71% from baseline values (p < 0.001), and 16% from values obtained 30 s after rocuronium administration, respectively; p = 0.003). No decrease in the tidal volume during the measurements was observed. We conclude that the administration of rocuronium at a dose of 0.6 mg.kg^?1 was able to improve facemask ventilation in all cases with a potentially clinically relevant increase in tidal volume. The early use of a neuromuscular blocking agent can be considered as a therapeutic option in case of difficulty with mask ventilation.     

Successful use of sugammadex in a ‘can't ventilate’ scenario

A 53‐year‐old man with hypopharyngeal stenosis following curative chemoradiotherapy for a tongue base tumour presented three years later for an attempt at pharyngeal dilatation. The first attempt 6 months previously was abandoned when awake fibreoptic intubation failed due to partial airway obstruction and desaturation when the fibrescope was advanced. As mask ventilation was anticipated to be possible, a further attempt at intubation after induction of anaesthesia was judged appropriate. The backup plan was jet ventilation via a cricothyroid cannula sited pre‐induction. However, neither mask nor jet ventilation proved possible after the induction of anaesthesia and neuromuscular blockade with rocuronium. Swift administration of sugammadex on a background of thorough pre‐oxygenation allowed return of spontaneous breathing before the development of hypoxia and so avoided the need for surgical airway rescue. This case demonstrates the utility of sugammadex in restoring spontaneous respiration in a ‘can't ventilate’ scenario, provided that the airway has not been traumatised by instrumentation.     

Appropriate dosing of sugammadex to reverse deep rocuronium‐induced neuromuscular blockade in morbidly obese patients

In morbidly obese patients, the speed of reversal of neuromuscular blockade with sugammadex based on ideal body weight is still matter of debate. In this single‐center, randomised, double‐blinded study, neuromuscular blockade was monitored in 50 patients using acceleromyography at the adductor pollicis. At the end of surgery with deep rocuronium‐induced neuromuscular blockade, patients randomly received sugammadex 4 mg.kg⁻¹ (high dose group), 2 mg.kg⁻¹ (middle dose group), or 1 mg.kg⁻¹ (low dose group) of ideal body weight. After administration of the first dose of sugammadex, the mean (SD) recovery time (censored at 600 s) from deep neuromuscular blockade was significantly shorter (p < 0.001) in the high‐dose group (n = 14; 255 (63) s) vs the middle‐dose group (n = 13; 429 (102) s), or low‐dose group (n = 4; 581 (154) s). Success rate from neuromuscular blockade reversal defined by a train‐of‐four ≥ 0.9 within 10 min after sugammadex administration, were 93%, 77% and 22% for these high, middle and low‐dose groups respectively (p < 0.05 vs low‐dose group). In morbidly obese patients, 4 mg.kg⁻¹ of ideal body weight of sugammadex allows suitable reversal of deep rocuronium‐induced neuromuscular blockade. Monitoring remains essential to detect residual curarisation or recurarisation.     

Rocuronium versus vecuronium during fentanyl induction in patients undergoing coronary artery surgery.

OBJECTIVE: To evaluate the neuromuscular, ventilatory, and cardiovascular effects of rocuronium and vecuronium. DESIGN: Randomized, prospective, blinded study. SETTING: Tertiary care teaching center, single institution. PARTICIPANTS: Patients undergoing elective coronary artery bypass graft procedure. INTERVENTIONS: Patients received rocuronium, 1.0 mg/kg (n = 17), or vecuronium, 0.15 mg/kg (n = 15), during fentanyl induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Measures consisted of time to visual loss of orbicularis oculi twitches in response to facial nerve stimulation, ease of mask ventilation, hemodynamics, need for vasoactive drugs, and tracheal intubating conditions. Median time to twitch loss was faster (p < 0.05) after rocuronium (60 s) than after vecuronium (>84 s). Within 45 seconds, only 3 of 17 patients in the rocuronium group had moderate-to-severe difficulty with mask ventilation versus 12 of 15 patients in the vecuronium group (p < 0.05). Tracheal intubating conditions were excellent in all patients after rocuronium. In the vecuronium group, intubating conditions were excellent in 46%, good in 27%, and poor in 27% (p < 0.05 vrocuronium). Patients receiving vecuronium were more likely to require ephedrine and phenylephrine for hypotension (10/15 patients v 5/17 patients for rocuronium, p < 0.05). There were no clinically important differences in hemodynamic variables, oxygen metabolism, or myocardial ischemia between groups. CONCLUSION: During narcotic induction of anesthesia, rocuronium was associated with lower requirement for vasopressors, faster onset of neuromuscular blockade, and better conditions for mask ventilation and tracheal intubation compared with vecuronium.     

Prediction of difficult mask ventilation using a systematic assessment of risk factors vs. existing practice – a cluster randomised clinical trial in 94,006 patients

We compared implementation of systematic airway assessment with existing practice of airway assessment on prediction of difficult mask ventilation. Twenty‐six departments were cluster‐randomised to assess eleven risk factors for difficult airway management (intervention) or to continue with their existing airway assessment (control). In both groups, patients predicted as a difficult mask ventilation and/or difficult intubation were registered in the Danish Anaesthesia Database, with a notational summary of airway management. The trial's primary outcome was the respective incidence of unpredicted difficult and easy mask ventilation in the two groups. Among 94,006 patients undergoing mask ventilation, the incidence of unpredicted difficult mask ventilation in the intervention group was 0.91% and 0.88% in the control group; (OR) 0.98 (95% CI 0.66–1.44), p = 0.90. The incidence of patients predicted difficult to mask ventilate, but in fact found to be easy (‘falsely predicted difficult’) was 0.64% vs. 0.35% (intervention vs. control); OR 1.56 (1.01–2.42), p = 0.045. In the intervention group, 86.3% of all difficult mask ventilations were not predicted, compared with a higher proportion 91.2% in the control group, OR 0.61 (0.41–0.91), p = 0.016. The systematic intervention did not alter the overall incidence of unpredicted difficult mask ventilations, but of the patients who were found to be difficult to mask ventilate, the proportion predicted was higher in the intervention group than in the control group. However, this was at a ‘cost’ of increasing the number of mask ventilations falsely predicted to be difficult.     

Fentanyl versus sufentanil basic anesthesia. Hypnotic effect, muscle rigidity and efficacy of competitive muscle relaxants

As induction agents for cardioanesthesia, sufentanil (S) and fentanyl (F) are usually employed in combination with nondepolarizing muscle relaxants. We investigated potential interactions of these opioids with the relaxant component, paying special regard to the role of muscular rigidity and opioid-induced alterations of hemodynamics. Narcotic anesthesia was induced randomly in 45 coronary artery bypass patients with either F (20 micrograms/kg) or S (4 micrograms/kg). After 6 min, neuromuscular blockade was initiated within each group randomly with either vecuronium (V) or pancuronium (P) (0.01 mg/kg each). During opiate administration, the times for cessation of spontaneous respiration and loss of responsiveness to verbal and tactile stimuli were measured. The degree of opiate-induced muscular rigidity, simultaneous changes in arterial paCO2, cardiac indices (CI) prior to opioid and relaxant administration, onset and recovery from neuromuscular blockade (by electromyographic train-of-four registration), and motor response to laryngoscopy and intubation were recorded. The onset of spontaneous apnea (TK = time to breathing upon command only) and unresponsiveness (TM = time to controlled mask ventilation) was significantly faster with S than with F. Muscular rigidity was moderate in 25% of patients and severe in 35%-40%, during the administration of both narcotics. No significant differences between S and F were observed. During ventilation by face mask, patients with clinically apparent rigidity showed a statistically significant mean increase in paCO2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Remifentanil vs. alfentanil infusion in non-paralysed patients: a randomized, double-blind study

BACKGROUND AND OBJECTIVE: Remifentanil has a short duration of action and constant elimination, which allow administration of high doses, without prolonging recovery. Remifentanil has been compared to alfentanil, as part of a total intravenous anaesthetic technique, where remifentanil provided better anaesthetic conditions than alfentanil, without adverse effect on recovery. However, these results were obtained during anaesthesia involving neuromuscular blockade, which may mask both signs of insufficient anaesthesia and side-effects such as muscle rigidity. The aim of this study was to compare remifentanil with alfentanil for anaesthesia without neuromuscular blockade. METHODS: We performed a prospective, randomized, double-blind, four-centre study to compare remifentanil infusion 15 microg kg(-1) h(-1) and alfentanil infusion 60 microg kg(-1) h(-1), using a total intravenous technique for non-paralysed patients, and the laryngeal mask airway for airway management. We enrolled 192 patients, 18-65 yr of age with ASA I-II, undergoing minor surgery. The primary endpoint was the number of patients having pre-defined responses to surgical stimulation. A number of secondary criteria was evaluated to assess undesirable properties of the procedures. RESULTS: In the alfentanil group, 85% of patients responded to surgical stimulation, vs. 35% in the remifentanil group (P < 0.0001). No difference was found in recovery data, or in any other parameter than those related to insufficient anaesthesia. CONCLUSIONS: The remifentanil-based technique provided significantly better anaesthetic conditions than the alfentanil-based technique in the setting of this study, without causing any significant adverse effects.     

Oral clonidine does not alter vecuronium neuromuscular blockade in anaesthetized patients

Since clonidine, an α₂-agonist, inhibits the release of norepinephrine or acetylcholine which can decrease nondepolarizing muscle relaxant-induced neuromuscular blockade, the authors examined whether clonidine given as an oral preanaesthetic medication would alter the onset, duration or recovery of a vecuronium neuromuscular blockade in lightly anaesthetized patients. Thirty-eight patients (aged 20–73 yr) randomly received oral clonidine either approximately 5 μg · kg^?1 (n = 21) or none (n = 17), 90 min before arrival in the operating room. We measured acceleration of thumb contraction with ulnar nerve stimulation at the wrist to assess neuromuscular blockade. The onset time (the time from injection to decrease to 5% of baseline twitch height), duration (the time interval between injection and return of the first twitch to 25% of the baseline value), and recovery index (the time interval of the first twitch from 25% to 75% of the baseline value) of neuromuscular blockade from a single bolus of vecuronium 0.1 mg · kg^?1 iv were determined and compared between the clonidine-treated and control patients during lower abdominal or extremity surgery under epidural plus general anaesthesia with fentanyl and nitrous oxide in oxygen. No differences were noted between the control and clonidine groups in onset time (100 ± 6 sec (mean ± SE) vs 101 ± 6 sec), duration (44.5 ±2.7 min vs 42.9 ±2.7 min), or recovery index (21.6 ± 2.8 min vs 19.1 ± 1.9 min) of neuromuscular blockade from vecuronium, respectively. These results show that oral preanaesthetic medication of clonidine 5 μg · kg^?1 does not alter neuromuscular blockade induced with vecuronium 0.1 mg · kg^?1 in patients during combined epidural and fentanyl/nitrous oxide general anaesthesia.     

Effects of depth of neuromuscular block on surgical conditions during laparoscopic colorectal surgery: a randomised controlled trial

There have been few objective evaluations of the effects of deep neuromuscular blockade on intra‐operative conditions. In this prospective randomised controlled study, we evaluated the effects of deep neuromuscular block on surgical conditions during laparoscopic colorectal surgery. Patients were randomly allocated using a computer‐generated randomisation code to either moderate (train‐of‐four count 1–2 maintained and antagonised with neostigmine) or deep (post‐tetanic count 1–2 maintained and reversed with sugammadex) levels of neuromuscular blockade. The primary outcome measure was the number of abrupt increases in intra‐abdominal pressure intra‐operatively. Secondary outcome variables were intra‐operative restoration of spontaneous breathing, number of surgical requests for additional neuromuscular blockade, surgical rating of operating conditions and patient satisfaction. The surgeon who rated the surgical conditions score and investigator who checked the postoperative variables were blinded to patient allocation. In total, we recruited 70 patients of whom 64 (32 in each group) were analysed. Increases in intra‐abdominal pressure (14/32 vs. 6/32; p = 0.031), intra‐operative restoration of spontaneous breathing (16/32 vs. 2/32; p < 0.001) and request for additional neuromuscular blockade (21/32 vs. 8/32; p = 0.001) were more frequent in the moderate compared with the deep group. In patients undergoing elective laparoscopic colorectal surgery, deep neuromuscular blockade provided better surgical conditions than moderate neuromuscular blockade, as measured by a reduction in the incidence of intra‐abdominal pressure alarms.     

Edrophonium priming alters the course of neuromuscular recovery from a pipecuronium neuromuscular blockade

This study was designed to investigate the effect of divided administration of edrophonium on the course of neuromuscular recovery from a pipecuronium neuromuscular blockade. During thiopentone-nitrous oxide-halothane anaesthesia 48 patients were given pipecuronium 70 micrograms.kg-1. Patients were randomly assigned to one of four groups (n = 12 in each) to receive either edrophonium 1 mg.kg-1 (Groups I and II) or edrophonium 0.75 mg.kg-1 (Groups III and IV). In Groups I and III (single-dose groups), edrophonium was administered as a single bolus dose. In Groups II and IV (divided-dose groups) edrophonium was administered as an initial dose of 0.25 mg.kg-1 followed three minutes later by either 0.75 or 0.50 mg.kg-1 respectively. Reversal was attempted at 20% spontaneous recovery of twitch height. Administration of edrophonium in divided doses (Groups II and IV) accelerated the reversal of the pipecuronium neuromuscular blockade. At ten minutes post-reversal, train-of-four (TOF) ratio recovery reached 0.75 or more in 12 (100%) and in ten (83%) patients in Groups II and IV respectively. Similarly, times to attain a TOF of 0.75 (SEM) were shorter in the divided-dose groups than in the single-dose groups (P less than 0.05), being 354.5 (38.7) and 398.3 (49.1) sec in Groups II and IV vs 705.4 (66.6) and 651.2 (54.3) sec in Groups I and III respectively. Time was counted from the first administration of edrophonium. It is concluded that administration of edrophonium in divided doses produced a faster reversal of residual pipecuronium-induced neuromuscular blockade than single bolus administration. Also, administration in divided doses reduced the requirements of edrophonium needed for reversal of pipecuronium neuromuscular blockade.     

Placement of the intubating laryngeal mask is easier than the laryngeal mask during manual in-line neck stabilization

We have compared in 25 patients ease of placement of the conventional and intubating laryngeal masks while the patient's head and neck were stabilized by a manual in-line method, in a randomized, crossover study. After induction of anaesthesia and neuromuscular block, the masks were placed in turn. Adequacy of ventilation and ease of placement (using a 10-cm visual analogue scale (VAS)) were assessed; time for placement between removal of the face mask and connection of the laryngeal mask to the breathing system was measured. Adequate ventilation was always obtained after placement of the intubating laryngeal mask, whereas ventilation was adequate in 22 of 25 patients after placement of the conventional laryngeal mask. Placement of the intubating laryngeal mask was significantly easier (P < 0.001; 95% confidence intervals (CI) for median difference 8-31 mm in VAS) and faster (P << 0.001; 95% CI for mean difference 3.2-6.2 s) than that of the conventional mask.      

Ease of placement of the laryngeal mask during manual in-line neck stabilization

We studied 20 patients, in a randomized, cross-over study, to determine if manual in-line stabilization of the head and neck altered the ease of insertion of the laryngeal mask and its correct positioning. After induction of anaesthesia and neuromuscular block, the laryngeal mask was inserted and adequacy of ventilation assessed while the patient's head and neck were placed in the Magill and manual in-line positions, in turn. Ease of insertion of the mask was assessed using a 10-cm visual analogue scale (VAS) and position using a fibreoptic bronchoscope. Time for insertion of the mask was measured. The laryngeal mask was inserted and adequate ventilation obtained at the first attempt in all 20 patients in the Magill position and in 19 of 20 patients in the manual in-line position. Insertion was always more difficult (P << 0.001; 95% CI for difference in VAS 20-55 mm) and time for insertion longer (P << 0.001; 95% CI for difference 4.9-11.9 s) in the manual in-line position compared with the Magill position. The incidence of a suboptimal position was significantly higher for the manual in-line position (seven patients) than for the Magill position (15 patients) (P < 0.005). We conclude that in paralysed patients, manual in-line stabilization of the head and neck made insertion of the laryngeal mask and its correct positioning more difficult.      

Der Einfluss der Rocuroniumdosis auf die Effektivität der Maskenbeatmung

Background

Mask ventilation could improve after administration of muscle relaxants if there is a functional obstruction of the airway, such as laryngospasm, vocal cord closure or opioid-induced muscle rigidity. On the other hand, muscle relaxants could worsen mask ventilation because they induce upper airway collapse; however, clinical studies showed that rocuronium (Roc) improved mask ventilation or it remained unchanged. In most cases Roc 0.06?mg/kgBW was used.

Objective

The optimal dose of Roc has not been studied; therefore, we studied the quality of mask ventilation with three different doses of Roc (0.3, 0.6 and 0.9?mg/kgBW) and compared them with a control group receiving saline.

Material and methods

In this prospective clinical trial 200 patients were randomized into 4 groups: NaCl (saline), Roc03 (Roc 0.3?mg/kgBW), Roc06 (Roc 0.6?mg/kgBW) and Roc09 (Roc 0.9?mg/kgBW). Mask ventilation was performed to reach a tidal volume (TV) of >5.0?ml/kgBW; maximum ventilation peak pressure (p_peak) was limited to 25?mbar. If this TV was not reached, mask ventilation was improved by better mask position, head position or/and usage of a Guedel tube (oropharyngeal airway). During mask ventilation p_peak and TV were recorded and the quality of mask ventilation was assessed with the Han and Warters scores. The quality of mask ventilation between the four groups was compared for all patients and a subgroup analysis was performed for patients of the study groups, who had to be ventilated with a Guedel tube and for obese patients (body mass index ≥26?kg/m²). A sample size calculation revealed that at least 38 patients were necessary for each group to detect a statistically significant difference between groups; it was assumed that Roc improved the efficacy of mask ventilation by 20% compared to saline (α?=?0.05, 1?β?=?0.8).

Results

The administration of Roc significantly improved the TV/p_peak ratio compared to saline (p?=?0.04); however, this effect was irrespective of the dose. In patients who were ventilated with the Guedel tube the TV/p_peak ratio increased after Roc03 (p?≤?0.01) and after Roc06 (p?<?0.02) compared to the saline group. In obese patients who were ventilated with the Guedel tube the TV/p_peak ratio increased after Roc03 (p?≤?0.01), after Roc06 (p?=?0.03) and after Roc09 (p?=?0.02) compared to the saline group. There were no significant differences between the Roc groups; however, the effect was more pronounced in the Roc03 patients compared to the other Roc groups. The Han and Warters scores were not significantly different between the Roc groups and the saline group.

Conclusion

The efficacy of mask ventilation was equal or improved after administration of Roc but did not become worse. Patients who were ventilated with a Guedel tube had higher TV/p_peak ratios after Roc03 and Roc06 compared to saline. Higher dosages (>Roc06), however, had no advantages concerning quality of mask ventilation. In obese patients who had to be ventilated with a Guedel tube, Roc also improved the efficacy of mask ventilation. We conclude that administration of Roc is effective in improving mask ventilation and this effect was seen after 30–60?s even after Roc03.

     

Pressure support ventilation with the ProSeal laryngeal mask airway. A comparison of sevoflurane, isoflurane and propofol

BACKGROUND AND OBJECTIVE: There are no data about the influence of anaesthetics on cardiovascular variables during pressure support ventilation of the lungs through the laryngeal mask airway. We compared propofol, sevoflurane and isoflurane for maintenance of anaesthesia with the ProSeal laryngeal mask airway during pressure support ventilation. METHODS: Sixty healthy adults undergoing peripheral musculo-skeletal surgery were randomized for maintenance with sevoflurane end-tidal 2%, isoflurane end-tidal 1.1% or propofol 6 mg kg(-1) h(-1) in oxygen 33% and air. Pressure support ventilation comprised positive end-expiratory pressure set at 5 cmH2O, and pressure support set 5 cmH2O above positive end-expiratory pressure. Pressure support was initiated when inspiration produced a 2 cmH2O reduction in airway pressure. A blinded observer recorded cardiorespiratory variables (heart rate, mean blood pressure, oxygen saturation, airway occlusion pressure, respiratory rate, expired tidal volume, expired minute volume and end-tidal CO2), adverse events and emergence times. RESULTS: Respiratory rate and minute volume were 10-21% lower, and end-tidal CO2 6-11% higher with the propofol group compared with the sevoflurane or isoflurane groups, but otherwise cardiorespiratory variables were similar among groups. No adverse events occurred in any group. Emergence times were longer with the propofol group compared with the sevoflurane or isoflurane groups (10 vs. 7 vs. 7 min). CONCLUSION: Lung ventilation is less effective and emergence times are longer with propofol than sevoflurane or isoflurane for maintenance of anaesthesia during pressure support ventilation with the ProSeal laryngeal mask airway. However, these differences are small and of doubtful clinical importance.     

LMA-Classic™ and LMA-ProSeal™ are effective alternatives to endotracheal intubation for gynecologic laparoscopy

PURPOSE: To compare the laryngeal mask airways (LMA), LMA-Classic(TM) (LMA-C) and LMA-ProSeal(TM) (PLMA) with the endotracheal tube (ETT) with respect to pulmonary ventilation and gastric distension during gynecologic laparoscopy. METHODS: We stratified 209 women, aged > or = 18 yr, ASA physical status I-III, by body mass index as non-obese (< or = 30 kg x m(-2)) or obese (> 30 kg x m(-2)) and randomized them to LMA-C/PLMA or ETT groups for airway management. Anesthesia was induced with propofol, fentanyl and succinylcholine or rocuronium. In the LMA-C/PLMA group we used a size 4 LMA-C in non-obese patients and size 4 or 5 PLMA in obese patients. In the ETT group we used a cuffed 7.0 mm ETT in all patients. Anesthesia was maintained with isoflurane in nitrous oxide and 30-50% oxygen, fentanyl and neuromuscular blockade with mechanical ventilation (tidal volume 10 mL x kg(-1)). The staff surgeon, blinded to the type of airway, scored stomach size on an ordinal scale 0-10 at initial insertion of the laparoscope and immediately before the conclusion of the surgical procedure. RESULTS: There were no crossovers and no statistically significant differences between LMA-C/PLMA and ETT groups for SpO(2,) P(ET)CO(2) or airway pressure before or during peritoneal insufflation in short (< or = 15 min) or long (> 15 min) periods of peritoneal inflation. Differences between groups with respect to stomach size changes during surgery were not statistically significant. CONCLUSION: A correctly placed LMA-C or PLMA is as effective as an ETT for positive pressure ventilation without clinically important gastric distension in non-obese and obese patients.     

High frequency jet ventilation through a supraglottic airway device: a case series of patients undergoing extra-corporeal shock wave lithotripsy

High frequency jet ventilation has been shown to be beneficial during extra-corporeal shock wave lithotripsy as it reduces urinary calculus movement which increases lithotripsy efficiency with better utilisation of shockwave energy and less patient exposure to tissue trauma. In all reports, sub-glottic high frequency jet ventilation was delivered through a tracheal tube or a jet catheter requiring paralysis and direct laryngoscopy. In this study, a simple method using supraglottic jet ventilation through a laryngeal mask attached to a circle absorber anaesthetic breathing system is described. The technique avoids the need for dense neuromuscular blockade for laryngoscopy and the potential complications associated with sub-glottic instrumentation and sub-glottic jet ventilation. The technique was successfully employed in a series of patients undergoing lithotripsy under general anaesthesia as an outpatient procedure.     

Transnasal Humidified Rapid‐Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways

Emergency and difficult tracheal intubations are hazardous undertakings where successive laryngoscopy–hypoxaemia–re‐oxygenation cycles can escalate to airway loss and the ‘can't intubate, can't ventilate’ scenario. Between 2013 and 2014, we extended the apnoea times of 25 patients with difficult airways who were undergoing general anaesthesia for hypopharyngeal or laryngotracheal surgery. This was achieved through continuous delivery of transnasal high‐flow humidified oxygen, initially to provide pre‐oxygenation, and continuing as post‐oxygenation during intravenous induction of anaesthesia and neuromuscular blockade until a definitive airway was secured. Apnoea time commenced at administration of neuromuscular blockade and ended with commencement of jet ventilation, positive‐pressure ventilation or recommencement of spontaneous ventilation. During this time, upper airway patency was maintained with jaw‐thrust. Transnasal Humidified Rapid‐Insufflation Ventilatory Exchange (THRIVE) was used in 15 males and 10 females. Mean (SD [range]) age at treatment was 49 (15 [25–81]) years. The median (IQR [range]) Mallampati grade was 3 (2–3 [2–4]) and direct laryngoscopy grade was 3 (3–3 [2–4]). There were 12 obese patients and nine patients were stridulous. The median (IQR [range]) apnoea time was 14 (9–19 [5–65]) min. No patient experienced arterial desaturation < 90%. Mean (SD [range]) post‐apnoea end‐tidal (and in four patients, arterial) carbon dioxide level was 7.8 (2.4 [4.9–15.3]) kPa. The rate of increase in end‐tidal carbon dioxide was 0.15 kPa.min^?1. We conclude that THRIVE combines the benefits of ‘classical’ apnoeic oxygenation with continuous positive airway pressure and gaseous exchange through flow‐dependent deadspace flushing. It has the potential to transform the practice of anaesthesia by changing the nature of securing a definitive airway in emergency and difficult intubations from a pressured stop–start process to a smooth and unhurried undertaking.