The laryngeal tube compared with the laryngeal mask: insertion,gas leak pressure and gastric insufflation

Background. We have compared the laryngeal tube and laryngealmask in 22 patients for the success rate of insertion, gas leakpressure and the incidence of gastric insufflation. Method. In a randomized, crossover design, the laryngeal tubeand laryngeal mask were inserted in turn after induction ofanaesthesia and neuromuscular block. The cuffs were inflateduntil the intracuff pressure reached 60 cm H₂O. We measuredadequacy of ventilation and the minimum airway pressure at whichgas leaked around the cuff. The presence or absence of gastricinsufflation was studied at an inflation pressure of 20 cm H₂O. Results. It was possible to ventilate through the laryngealtube in 21 patients and through the laryngeal mask in 21 patients.The mean leak pressure for the laryngeal tube (26 (SD 5) cmH₂O) was significantly greater than that for the laryngeal mask(19 (4) cm H₂O) (P<0.01; 95% confidence intervals for meandifference: 5.3–10.2 cm H₂O). Gastric insufflation didnot occur when the laryngeal tube was used and was noted inthree patients when the laryngeal mask was used. Conclusion. The laryngeal tube provides a better seal in theoropharynx than the laryngeal mask. Br J Anaesth 2002; 89: 729–32     

Predicted values of propofol EC50 and sevoflurane concentration for insertion of laryngeal mask Classic and ProSeal

Background. A new laryngeal mask airway, the ProSeal^TM (PLMA),is said to be more difficult to insert than the laryngeal maskairway Classic^TM (CLMA) using propofol anaesthesia. Therefore,we expected a greater dose of propofol and sevoflurane to berequired to insert the PLMA compared with the CLMA. We determinedthe effective concentration 50% (EC₅₀) of propofol and end-tidalsevoflurane to allow insertion of the PLMA and the CLMA. Methods. Seventy-six elective female patients (aged 20–60yr and ASA I–II) were randomly assigned to one of fourgroups. Either a PLMA or a CLMA was inserted using either propofoltarget controlled infusion or sevoflurane. Both propofol andsevoflurane targets were determined with a modified Dixon’sup-and-down method. After equilibration between the predeterminedblood and effect site concentrations, which had been held steadyfor more than 10 min, LMA insertion was attempted without neuromuscularblock. Results. The predicted EC_50CLMA and EC_50PLMA for propofol were3.14 (0.33) and 4.32 (0.67) µg ml^–1. E'_CLMAand E'_PLMA of sevoflurane (mean (SD)) were 2.36 (0.22) and 2.82(0.45)% (P<0.01 and 0.05, respectively). Conclusions. The estimated concentration of propofol and thesevoflurane concentration needed to allow insertion of the ProSeal^TMare respectively 38 and 20% greater than those needed for insertionof the Classic LMA. Br J Anaesth 2004; 92: 242–5     

Size 2 ProSeal laryngeal mask airway: a randomized, crossover investigation with the standard laryngeal mask airway in paediatric patients

Background. One of the main concerns with the use of the standardlaryngeal mask airway (SLMA) in small infants is that its low-pressureseal might be inadequate for positive pressure ventilation sothat there is a risk of gas leakage into the stomach with thesubsequent risk of regurgitation. The new ProSeal^TM LMA (PLMA)has been shown to form a more effective seal than the SLMA andto facilitate gastric tube placement in adults. The first paediatricsize PLMA became available recently. Methods. Thirty anaesthetized, non-paralysed children aged 46(19) months, weighing 16 (10–21) kg, were studied. TheSLMA and PLMA were inserted in random order into each patient.Airway leak pressure and maximum tidal volume were measured.Ease of insertion, quality of initial airway and fibreopticposition were also determined. Gastric tube placement was assessedfor the PLMA. Results. The airway leak pressure and maximum tidal volume weresignificantly higher for the PLMA (P=0.001). Ease of insertionand quality of initial airway were similar for both devices.Air entry into the stomach occurred more frequently with theSLMA (P=0.005). Gastric tube placement was possible in all patients. Conclusions. The size 2 PLMA offered some advantages over thesame size of SLMA in this crossover investigation. The highreliability of gastric tube placement and the significantlyincreased airway leak pressure might have important implicationsfor use of this device for positive pressure ventilation ininfants.      

Use of a ProSeal laryngeal mask airway for airway maintenance during emergency Caesarean section after failed tracheal intubation

We report the use of the ProSeal^TM laryngeal mask airway toestablish and maintain the airway during emergency Caesareansection when tracheal intubation had failed with conventionallaryngoscopy and mask ventilation was difficult. The ProSeal^TMlaryngeal mask allowed controlled ventilation without gas leakand facilitated drainage of the stomach. Br J Anaesth 2004; 92: 144–6     

A Randomized Controlled Trial Comparing the ProSeal™ Laryngeal Mask Airway with the Laryngeal Tube Suction in Mechanically Ventilated Patients

Background: The ProSeal(TM) Laryngeal Mask Airway (PLMA) (Laryngeal Mask Company, Henley-on-Thames, United Kingdom) is a new laryngeal mask with a modified cuff designed to improve its seal and a drain tube for gastric tube placement. Similarly, the Laryngeal Tube Suction (LTS) (VBM Medizintechnik Gmbh, Sulz a.N, Germany) is a new laryngeal tube that also has an additional channel for gastric tube placement. This study compared the placement and functions of these two devices.

Methods: One hundred fifty patients undergoing general anesthesia for elective surgery were randomly allocated to the PLMA (n = 75) or LTS (n = 75). Oxygenation and ventilation, ease of insertion, fiberoptic view, oropharyngeal leak pressure, ventilatory data, ease of gastric tube insertion, and postoperative airway morbidity were determined.

Results: After successful insertion of the devices in 96% of patients with the PLMA and in 94.4% with the LTS it was possible to maintain oxygenation, ventilation, and respiratory mechanics during the entire duration of surgery. Successful first and second attempt insertion rates were 57 patients (76%) and 15 patients (20%), respectively, for the PLMA and 60 patients (80%) and 11 patients (14.6%), respectively, for the LTS. Airway placement was unsuccessful with the PLMA in three patients and with the LTS in four patients. Time to achieve an effective airway was 36 +/- 24 s with the PLMA versus 34 +/- 25 s with the LTS. Gastric tube insertion was possible in 97.3% of patients with the PLMA and in 96% with the LTS.     

A randomized controlled trial comparing the ProSeal Laryngeal Mask Airway with the Laryngeal Tube Suction in mechanically ventilated patients

BACKGROUND: The ProSeal Laryngeal Mask Airway (PLMA) (Laryngeal Mask Company, Henley-on-Thames, United Kingdom) is a new laryngeal mask with a modified cuff designed to improve its seal and a drain tube for gastric tube placement. Similarly, the Laryngeal Tube Suction (LTS) (VBM Medizintechnik Gmbh, Sulz a.N, Germany) is a new laryngeal tube that also has an additional channel for gastric tube placement. This study compared the placement and functions of these two devices. METHODS: One hundred fifty patients undergoing general anesthesia for elective surgery were randomly allocated to the PLMA (n = 75) or LTS (n = 75). Oxygenation and ventilation, ease of insertion, fiberoptic view, oropharyngeal leak pressure, ventilatory data, ease of gastric tube insertion, and postoperative airway morbidity were determined. RESULTS: After successful insertion of the devices in 96% of patients with the PLMA and in 94.4% with the LTS it was possible to maintain oxygenation, ventilation, and respiratory mechanics during the entire duration of surgery. Successful first and second attempt insertion rates were 57 patients (76%) and 15 patients (20%), respectively, for the PLMA and 60 patients (80%) and 11 patients (14.6%), respectively, for the LTS. Airway placement was unsuccessful with the PLMA in three patients and with the LTS in four patients. Time to achieve an effective airway was 36 +/- 24 s with the PLMA versus 34 +/- 25 s with the LTS. Gastric tube insertion was possible in 97.3% of patients with the PLMA and in 96% with the LTS. CONCLUSIONS: With respect to both physiologic and clinical function, the PLMA and LTS are similar and either device can be used to establish a safe and effective airway in mechanically ventilated anesthetized adult patients.     

Relation between fentanyl dose and predicted EC50 of propofol for laryngeal mask insertion

Background. This study sought to determine the effective concentrationfor 50% of the attempts to secure laryngeal mask insertion (predictedEC_50LMA) of propofol using a target-controlled infusion (Diprifusor^TM)and investigated whether fentanyl influenced these requiredconcentrations, respiratory rate (RR) and bispectral index (BIS). Methods. Sixty-four elective unpremedicated patients were randomlyassigned to four groups (n = 16 for each group) and given saline(control) or fentanyl 0.5, 1 or 2 µg kg^–1.Propofol target concentration was determined by a modificationof Dixon’s up-and-down method. Laryngeal mask airway insertionwas attempted without neuromuscular blocking drugs after equilibrationhad been established for >10 min. Movement was defined aspresence of bucking or gross purposeful muscular movement within1 min after insertion. EC_50LMA values were obtained by calculatingthe mean of 16 patients in each group. Results. Predicted EC_50LMA of the control, fentanyl 0.5, 1 and2 µg kg^–1 groups were 3.25 (0.20), 2.06 (0.55),1.69 (0.38) and 1.50 (0.54) µg ml^–1 respectively;those of all fentanyl groups were significantly lower than thatof control. RR was decreased in relation to the fentanyl doseup to 1 µg kg^–1. BIS values after fentanyl1 and 2 µg kg^–1 were significantly greaterthan in the control and 0.5 µg kg^–1 groups. Conclusions. A fentanyl dose of 0.5 µg kg^–1is sufficient to decrease predicted EC_50LMA with minimum respiratorydepression and without a high BIS value. Br J Anaesth 2004; 92: 238–41     

Effects of sevoflurane and propofol on left ventricular diastolic function in patients with pre-existing diastolic dysfunction

Background. The effects of anaesthetics on left ventricular(LV) diastolic function in patients with pre-existing diastolicdysfunction are not well known. We hypothesized that propofolbut not sevoflurane will worsen the pre-existing LV diastolicdysfunction. Methods. Of 24 randomized patients, 23 fulfilled the predefinedechocardiographic criterion for diastolic dysfunction. Theyreceived general anaesthesia with sevoflurane 1 MAC (n=12) orpropofol 4 µg ml^–1 (n=11). Echocardiographic examinationswere performed at baseline and in anaesthetized patients underspontaneous breathing and under positive pressure ventilation.Analysis focused on peak early diastolic velocity of the mitralannulus (E_a). Results. During spontaneous breathing, E_a was higher in thesevoflurane than in the propofol group [mean (95% CI) 7.0 (5.9–8.1)vs 5.5 (4.7–6.3) cm s^–1; P<0.05], reflectingan increase of E_a from baseline only in the sevoflurane group(P<0.01). Haemodynamic findings were similar in both groups,but the end-tidal carbon dioxide content was more elevated inthe propofol group (P<0.01). During positive pressure ventilation,E_a was similarly low in the sevoflurane and propofol groups[5.3 (4.2–6.3) and 4.4 (3.6–5.2) cm s^–1, respectively]. Conclusions. During spontaneous breathing, early diastolic functionimproved in the sevoflurane but not in the propofol group. However,during positive pressure ventilation and balanced anaesthesia,there was no evidence of different effects caused by the twoanaesthetics.     

Combination of external chest wall oscillation with continuous positive airway pressure

We studied the effects of continuous positive airway pressure(CPAP) on pulmonary gas exchange during external chest walloscillation (ECWO), and the relationship with obesity, in ninepatients with normal body weight (group ‘N’) and10 obese patients (group ‘O’). During ECWO withCPAP 5, Pa_CO2 decreased in group ‘O’ (6.0 (SD 0.8)to 5.6 (0.5) kPa, P<0.05), whereas it increased in group‘N’ at all levels (P<0.01). Arterial PO₂ (P<0.001)was greater and Pa_CO2 (P<0.01) less in group ‘N’during CPPV and ECWO plus CPAP. We also compared the haemodynamiceffects of ECWO plus CPAP with those of continuous positivepressure ventilation (CPPV). ECWO plus CPAP and CPPV were appliedfor 30 min to 6 ASA III patients. Cardiac output (CI 2.7 (0.5)vs 2.1 (0.2) litre min^–1 m^–2, P<0.05) and strokevolume (SVI 49 (9) vs 32 (6) ml m^–2, P<0.05) were greaterduring ECWO plus CPAP than with CPPV. ECWO is less effectivein obese individuals than in those with normal body weight,and the effect of CPAP in overweight individuals is small. Br J Anaesth 2001; 87: 441–6     

The proseal laryngeal mask: results of a descriptive trial with experience of 300 cases

Background. The ProSeal laryngeal mask airway (PLMA) is a newlaryngeal mask device with a modified cuff and a drainage tube. Methods. We assessed the PLMA in 300 anaesthetized adults eitherparalysed or breathing spontaneously. We assessed insertioncharacteristics, airway seal pressures, haemodynamic responseto insertion, ease of gastric tube placement, gastric insufflation,and postoperative sore throat. Results. Insertion was successful in 294 patients (98%) andgraded as easy in 274 patients (91%). We found no differencein ease of insertion or success rate with either the introduceror the finger insertion method, or in paralysed or non-paralysedpatients. Mean airway seal pressure was 29 cm H₂O, and 59 patients(20%) had seal pressures greater than 40 cm H₂O. No gastricinsufflation was detected. Gastric tube placement was successfulin 290 of 294 patients (98.6%). There was no cardiovascularresponse to insertion, with a small reduction in heart rate5 min after insertion and significant decreases in mean arterialpressure at 1 and 5 min after insertion. Sore throat was notedin 23% patients after operation and in 16% of patients after24 h, with 90% of the sore throats described as mild. Conclusions. The PLMA is a reliable airway management devicethat can give an effective glottic seal in paralysed and non-paralysedpatients. The device allows the easy passage of a gastric tube,causes a minimal haemodynamic response to insertion, and anacceptable incidence of sore throat. Br J Anaesth 2002; 88: 534–9     

Evaluation of the CTrach--an intubating LMA with integrated fibreoptic system

Background. The laryngeal mask airway CTrach^TM (CTrach) is avariant of the intubating laryngeal mask airway. It providesvisualization of the larynx during intubation and is designedto increase the success rates of ventilation and tracheal intubation. Methods. Sixty healthy anaesthetized and paralysed patientswith normal airways were studied. The success rates of ventilationand intubation using CTrach^TM were determined. Laryngeal viewscoring ranged from grade I (full view of arytenoids and glottis),II (arytenoids and glottis partly visible), III (view of arytenoids,glottis or epiglottis blurred, or view clear with only epiglottisvisible) to IV (no part of larynx identifiable). Adjusting manoeuvreswere undertaken to improve the laryngeal view in grades II orworse. Results. CTrach insertion and ventilation was possible in allpatients. Initial views were scored as grade I in 22 (36.7%),grade II in 14 (23.3%), grade III in 7 (11.7%) and grade IVin 17 (28.3%) patients. Adjusting manoeuvres were undertakenin 38 patients with grade II and worse (63.3%), resulting inimproved views of grade I in 33 (55.0%), grade II in 18 (30.0%),grade III in 4 (6.7%) and grade IV in 5 (8.3%) patients. Trachealintubation was successful in 58 (96.6%) patients at first attemptand in one at second. Tracheal intubation failed once. Conclusions. In 60 patients with normal airways, the CTrachwas used successfully for ventilation, with successful trachealintubation in 59 patients. Tracheal intubation can be successfuldespite grade III or IV views.      

Randomized study comparing the effects of hydroxyethyl starch solution with Gelofusine on pulmonary function in patients undergoing abdominal aortic aneurysm surgery

Background. Restoring blood flow to ischaemic tissue can causelung damage with pulmonary oedema. Hydroxyethyl starch (HES)solution, when used for volume replacement, may modify and reducethe degree of ischaemia–reperfusion injury. We comparedthe effects of HES solution with those of Gelofusine solutionon pulmonary function, microvascular permeability and neutrophilactivation in patients undergoing elective infrarenal abdominalaortic aneurysm surgery. Methods. Forty patients were randomized into two groups. Theanaesthetic technique was standardized. Lung function was assessedwith the PO₂/FI_O2 ratio, respiratory compliance, chest x-rayand a score for lung injury. Microvascular permeability wasdetermined by measuring microalbuminuria. Neutrophil activationwas determined by measurement of plasma elastase. Results. Four hours after surgery, the median (quartile values)PO₂/FI_O2 ratio was 40.3 (37.8, 53.1) kPa for the HES-treatedpatients compared with 33.9 (31.2, 40.9) kPa for the Gelofusine-treatedpatients (P<0.01, Mann–Whitney test). The respiratorycompliance was 80 (73.5, 80) ml cm^–1 H₂O inthe HES-treated patients compared with 60.1 (50.8, 73.3) mlcm^–1 H₂O in the Gelofusine-treated patients (P<0.01,Mann–Whitney test). The lung injury score 4 h after surgerywas less for the patients treated with HES compared with thepatients treated with Gelofusine (0.33 vs 0.71, P=0.01, Wilcoxonrank sum test). Mean (SD) plasma elastase was less in the HES-treatedpatients on the first postoperative day (1.96 (0.17) vs 2.08(0.24), P<0.05). The log mean microalbuminuria was less inthe HES-treated patients (0.41 vs 0.91 mg mmol^–1,P<0.05). This difference in microvascular permeability wasassociated with different volumes of colloid required to maintainstable cardiovascular measurements in the two groups of patientsstudied (3000 vs 3500 ml, P<0.01, Mann–Whitney test). Conclusion. Compared with Gelofusine, the perioperative pulmonaryfunction of patients treated with HES after abdominal aorticaneurysm surgery was better. Br J Anaesth 2004; 92: 61–6     

Increased carbon dioxide absorption during retroperitoneal laparoscopy

Background. Retroperitoneoscopy for renal surgery is now a commonprocedure. We compared carbon dioxide absorption in patientsundergoing retroperitoneoscopy for adrenal or renal surgerywith that of patients undergoing laparoscopic cholecystectomy. Methods. We measured carbon dioxide elimination with a metabolicmonitor in 30 anaesthetized patients with controlled ventilation,undergoing retroperitoneoscopy (n=10), laparoscopy (n=10) ororthopaedic surgery (n=10). Results. Carbon dioxide production increased by 38, 46 and 63%at 30, 60 and 90 min after insufflation (P<0.01) in patientshaving retroperitoneoscopy. Carbon dioxide production (mean(SD)) increased from 92 (21) to 150 (43) ml min^–1 m^–260–90 min after insufflation and remained increased afterthe end of insufflation. During laparoscopy, V^·_CO2 increasedless (by 15%) (P<0.05 compared with retroperitoneoscopy)and remained steady throughout the procedure. Conclusion. Retroperitoneal carbon dioxide insufflation causesmore carbon dioxide absorption than intraperitoneal insufflation,and controlled ventilation should be increased if hypercapniashould be avoided. Br J Anaesth 2003; 91: 793–6     

Comparison of the Laryngeal Tube Suction and the Proseal laryngeal Mask Airway in anesthetized patients

BACKGROUND: The Laryngeal Tube Suction (LTS : Smith Medical, Tokyo) is a new laryngeal tube that has an additional channel for gastric tube placement. Similarly, the Proseal Laryngeal Mask Airway (PLMA) also has a drain tube for gastric tube placement. This study compared the functions of these two devices. METHODS: Forty patients undergoing general anesthesia were randomly allocated to the group LTS (n = 20) or group PLMA (n = 20). Ease of insertion, quality of airway seal, ease of gastric tube insertion, fiberoptic view of the glottis through each device after placement, and postoperative sorethroat/hoarseness were investigated. RESULTS: There were no differences in patient characteristics and anesthetic background data for both groups. No differences concerning handling, quality of airway seal, ease of gastric tube insertion, and postoperative airway morbidity were detected between LTS and PLMA. In economical terms, LTS was more reasonable compared with PLMA. CONCLUSIONS: With respect to clinical function, the LTS and PLMA were similar and either device can be used to establish an effective airway in anesthetized patients.     

Comparison of the standard laryngeal mask airway and the ProSeal laryngeal mask airway in obese patients

Background. The ProSeal^TM laryngeal mask airway (PLMA) may haveadvantages over the laryngeal mask airway (LMA     

The effect of bi-level positive airway pressure mechanical ventilation on gas exchange during general anaesthesia

Background. Atelectasis may occur and ventilation–perfusionmismatch may increase during general anaesthesia with neuromuscularparalysis and mechanical ventilation, though preservation ofsome intermittent muscle contraction might mitigate this process.There is still no ideal manoeuvre to minimize such mismatchor atelectasis. Bi-level positive airway pressure (BiPAP) ventilationadjusts to extra breaths and improves gas exchange during recoveryof diaphragm function after neuromuscular paralysis. We hypothesizethat BiPAP ventilation may limit the development of pulmonaryshunt and may improve ventilation–perfusion mismatch whencompared with standard IPPV, with or without PEEP when neuromuscularparalysis has been used during surgery. Methods. Twenty ventilated patients either on BiPAP or IPPVwith or without PEEP were studied randomly using the multipleinert gas elimination technique (MIGET) at 60 and 120 min afterrocuronium at induction and after 60 min. Non-invasive cardiacoutput (NICO^®) monitoring and plasma concentrations of rocuroniumwere measured. We compared the data of MIGET, gas exchange,haemodynamic variables and pulmonary mechanics measurementsbetween the different ventilatory modes. Results. Intrapulmonary shunt (blood flow to ) did not increase at 60 min of anaesthesia in anyof the different ventilation modes compared with the shunt valuebefore anaesthesia. Log standard deviation of perfusion increasedin IPPV, with and without PEEP groups, compared with the baseline(P<0.05) but did not increase in the BiPAP group. BiPAP ventilationgenerated a higher level of Pa_O2 than IPPV with or without PEEP(P<0.05). Conclusion. BiPAP ventilation was beneficial in decreasing ventilation–perfusionmismatch and improving oxygenation when compared with conventionalIPPV (with or without PEEP). ³Present address: Department of Anaesthesia, Guangzhou MedicalCollege, Guangzhou, China     

吸引型喉导管与食管引流型喉罩在腹腔镜手术麻醉中的应用

目的：探讨吸引型喉导管与食管引流型喉罩用于腹腔镜手术麻醉通气的效果。方法：择期腹腔镜胆囊切除术患者32例,随机分为吸引型喉导管组（LTS组）与食管引流型喉罩组（PLMA组）,进行麻醉中通气。结果：LTS组与PLMA组气腹前后,放气腹前后pH、PaCO2各组内与本组间比较无明显差异（P〉0.05）。PETCO2、SpO2于气腹前后无明显差异（P〉0.05）。Ppeak、VT于气腹前后差异明显（P〈0.05）,Ppeak于放气腹前后也有明显差异（P〈0.05）。结论：LTS与PLMA用于全麻腹腔镜手术通气,气腹建立时VT由8mL/kg调整为10mL/kg,可避免CO2气腹引起的PaCO2升高,通气效果可维持稳定。     

Isocapnic hyperpnoea accelerates recovery from isoflurane anaesthesia

Background. Hyperventilation should speed up elimination ofvolatile anaesthetic agents from the body, but hyperventilationusually results in hypocapnia. We compared recovery from isofluraneanaesthesia in patients allowed to recover with assisted spontaneousventilation (control) and those treated with isocapnic hyperpnoea. Methods. Fourteen patients were studied after approximately1 h of anaesthesia with isoflurane. Control patients were allowedto recover in the routine way. Isocapnic hyperpnoea patientsreceived 2–3 times their intraoperative ventilation usinga system to maintain end tidal PCO₂ at 45–50 mm Hg. Wemeasured time to removal of the airway and rate of change ofbispectral index (BIS) during recovery. Results. With isocapnic hyperpnoea, the time to removal of theairway was markedly less (median and interquartile range valuesof 3.6 (2.7–3.7) vs 12.1 (6.8–17.2) min, P<0.001);mean (SD) BIS slopes during recovery were 11.8 (4.4) vs 4.3(2.7) min^–1 (P<0.01) for isocapnic hyperpnoea and controlgroups, respectively. Isocapnic hyperpnoea was easily appliedin the operating room. Conclusions. Isocapnic hyperpnoea at the end of surgery resultsin shorter and less variable time to removal of the airway afteranaesthesia with isoflurane and nitrous oxide. Br J Anaesth 2003; 91: 787–92     

Randomized evaluation of the performance of single-use laryngoscopes in simulated easy and difficult intubation

Background. Single-use laryngoscopes are becoming used morewidely. Methods. We compared six types of single-use laryngoscope withthe standard Macintosh laryngoscope using the Laerdal SimMan^TMpatient simulator. Twenty anaesthetists attempted to intubatethe simulator with standardized airway settings allowing a fullview of the vocal cords (‘easy intubation’). Theairway settings were then changed so that only the posteriorpart of the glottis was visible (‘difficult intubation’)and the anaesthetists were asked to intubate the simulator again. Results. The time to intubate with the standard laryngoscopewas less in both easy (P<0.05) and difficult (P<0.01)intubations. The performance of five laryngoscopes during easyintubation (P<0.01) and four during difficult intubation(P<0.001) was significantly worse than that of the Macintosh.There was a significant difference in Cormack and Lehane gradingbetween the laryngoscopes tested in both easy (P<0.05) anddifficult (P<0.05) intubation. The percentage of glotticopening visible (POGO score) also differed between laryngoscopesin both the easy (P<0.01) and difficult (P<0.001) groups.The highest POGO scores were obtained with the Macintosh laryngoscope.During the difficult intubation simulation, the reusable Macintoshlaryngoscope needed less use of a bougie and had fewer failedintubations than the single-use laryngoscopes, but these differencesdid not reach statistical significance. Conclusions. Of the laryngoscopes tested, the standard reusableMacintosh laryngoscope performed best. The Europa^TM was thebest single-use laryngoscope. Some single-use laryngoscopestested were significantly inferior to the Macintosh. This raisesconcern over their use in clinical practice, particularly ifintubation is difficult. Br J Anaesth 2003; 90: 8–13     

Skin conductance monitoring compared with bispectral index monitoring to assess emergence from general anaesthesia using sevoflurane and remifentanil

Background. Changes in skin conductance have previously beenreported to correlate well with plasma levels of stress hormonesand awakening stimuli. In this study, monitoring of skin conductanceduring emergence from general anaesthesia was compared withthe monitoring of bispectral index (BIS). Methods. Twenty-five patients undergoing minor elective surgerywere investigated. The number of fluctuations in mean skin conductance(NFSC), BIS and haemodynamic parameters were recorded simultaneously.The performance of the monitoring devices to predict and distinguishbetween the clinical states ‘steady-state anaesthesia’,‘first reaction’ and ‘extubation’ werecompared using the method of prediction probability (P_K) calculation. Results. Both monitors showed similar performance in distinguishingbetween ‘steady-state anaesthesia’ vs ‘firstreaction’ (P_K NFSC 0.89; BIS^® 0.94) and ‘steady-stateanaesthesia’ vs ‘extubation’ (P_K NFSC 0.96;BIS^® 0.96). The response times of the monitors, to indicatethe likelihood of ‘first reaction’, were not significantlydifferent. Conclusions. NFSC, as a parameter of skin conductance, performedsimilarly to BIS in patients waking after a general anaesthetic.