Evaluation of the Pentax-AWS(®) and the Macintosh laryngoscope in difficult intubation: a manikin study.

BACKGROUND: The Pentax-AWS (AWS(®)), a new video laryngoscope, has been shown to be useful in cases of difficult intubation. We hypothesized that the AWS(®) would be more useful in the settings of a narrow upper airway than the Macintosh laryngoscope. We compared each device in simulated scenarios of representative difficulty of tracheal intubation using a manikin. The primary endpoint was the rate of successful intubation. METHODS: With each device, 23 anesthesiologists performed tracheal intubation in a SimMan(®) manikin in the following scenarios: (1) normal airway, (2) tongue edema, (3) cervical spine rigidity, (4) pharyngeal obstruction, (5) jaw trismus, (6) tongue edema with pharyngeal obstruction. The intubation time and success rate were measured. Each participant was asked to rate the difficulty of intubation (1=very easy; 5=very difficult). RESULTS: In the scenarios of tongue edema and tongue edema with pharyngeal obstruction, the AWS(®) yielded a higher success rate (100% vs. 34.8%; P<0.001, 65.2% vs. 21.7%; P=0.006), a shorter intubation time [14.6 (7.0) vs. 33.4 (13.0) s; P<0.001, 24.5 (12.0) vs. 37.6 (11.9); P=0.047; mean (standard deviation)], and a lower difficulty score [2 (1-4) vs. 5 (1-5); P<0.001, 4 (2-5) vs. 5 (3-5); P<0.001; median (range)], compared with the Macintosh laryngoscope. CONCLUSION: The AWS(®) has an advantage over the Macintosh laryngoscope in simulated tongue edema and tongue edema with pharyngeal obstruction. Further studies in a clinical setting are necessary to confirm these findings.

Comparison of haemodynamic responses to tracheal intubation using the Airway Scope(®) and Macintosh laryngoscope in normotensive and hypertensive patients.

We compared the effects of the Airway Scope(®) on haemodynamic responses during tracheal intubation with those of direct laryngoscopy in normotensive and hypertensive patients. The systolic blood pressure, diastolic blood pressures and heart rate were recorded: (a) before anaesthesia; (b) immediately before intubation; (c) at intubation; and (d) 1, 2, 3, 4 and 5 min after intubation. In normotensive patients, the increase in blood pressure and heart rate over time were significantly lower with the Airway Scope than with the Macintosh laryngoscope (p < 0.003). In hypertensive patients, however, there was no difference in the changes over time in any of these haemodynamic measures between the two devices (p > 0.05). We conclude that the Airway Scope attenuates haemodynamic responses to tracheal intubation in comparison with the laryngoscope in normotensive but not in hypertensive patients. You can respond to this article at http://www.anaesthesiacorrespondence.com.

A simple fibreoptic assisted laryngoscope for paediatric difficult intubation: a manikin study.

The fibreoptic assisted laryngoscope is a new airway device. We compared the fibreoptic assisted laryngoscope with the Bullard laryngoscope, Macintosh laryngoscope and fibreoptic bronchoscope in a manikin with a simulated Cormack and Lehane Grade 4 laryngoscopic view. Eighteen anaesthetists intubated the manikin's trachea using these devices and the success rate of intubation was measured. They were then asked to rate the subjective difficulty of intubation. The success rate (95% confidence interval) was 100% (94.6-100) with the fibreoptic assisted laryngoscope, 88.9% (80.5-97.3) using the Bullard laryngoscope, 37.0% (24.1-49.9) with the Macintosh laryngoscope, and 22.2% (11.1-33.3) using the fibreoptic bronchoscope. Tracheal intubation using the fibreoptic assisted laryngoscope or Bullard laryngoscope is easier than that using the Macintosh laryngoscope or fibreoptic bronchoscope by subjective difficulty score. All of the intubations were successful with the fibreoptic assisted laryngoscope without practice. These results suggest that fibreoptic assisted laryngoscope may be a useful tool for paediatric difficult intubation.

[A successful perioperative anticoagulation therapy and monitoring of a patient with hereditary plasminogen abnormality undergoing aortic valve replacement].

During perioperative period, plasminogen abnormality can result in unusual or unexplained clotting that occurs spontaneously or after minor trauma. However, there has been no report on perioperative anticoagulation therapy and monitoring in patients with hereditary plasminogen abnormality undergoing cardiac surgery. We performed a successful perioperative anticoagulation therapy and monitoring of a patient with hereditary plasminogen abnormality undergoing cardiac surgery. A 48-year-old male patient with severe aortic valve stenosis, who had had no episode of thrombosis, was scheduled for aortic valve replacement Preoperative laboratory screenings detected his abnormal plasminogen activity (7.6% normal), and he was diagnosed as hereditary plasminogen abnormality. Anesthetic course was uneventful until the initiation of cardiopulmonary bypass (CPB). During CPB, heparin level was monitored every 30 minutes by Hepcon/HMS (Medtronic Hemotec, Parker, CO). No thrombus was observed in the CPB circuit. Plasminogen activity, fibrin degradation products (FDP) and D-dimer were not elevated during perioperative period. Protamine dosage was determined by protamine titration method, and protamine was administrated after the termination of CPB. No major bleeding was observed after protamine administration. When the patient was admitted to ICU, anticoagulation therapy was started immediately. During perioperative period, no episode suggesting thrombosis was observed. In conclusion, we consider that this successful anticoagulation therapy and monitoring during CPB has been achieved by use of Hepcon/HMS.

Evaluation of the Airway Scope, a new video laryngoscope, in tracheal intubation by naive operators: a manikin study.

BACKGROUND AND AIM: The Airway Scope (AWS) is a new video laryngoscope. The purpose of this study was to compare the AWS and Macintosh laryngoscopes with regard to their usefulness for beginners in tracheal intubation. METHODS: Thirty-one nurses with no previous experience of tracheal intubation used each device 10 times to intubate the trachea of a manikin (Laerdal Airway Managemant Trainer, Laerdal, Stavanger, Norway). Intubation correctly completed within 30 s was regarded as successful. The intubation time, success rate, number of esophageal intubations and dental clicks, and subjective evaluation of difficulty of intubation [rated from 1 (extremely easy) to 5 (extremely difficult)] were recorded. RESULTS: The average intubation time was significantly shorter for AWS than for the Macintosh laryngoscope (16.7 +/- 11.0 s vs. 23.2 +/- 24.9 s; mean +/- standard deviation; P = 0.0297), and the success rate with AWS was significantly greater (91.3% vs. 79.4%; P < 0.001). In the total of 310 intubation attempts for each device, the number of esophageal intubations (0/310 with AWS vs. 20/310 with the Macintosh laryngoscope) and dental clicks (0/310 with AWS vs. 40/310 with the Macintosh laryngoscope) differed significantly (P < 0.001). AWS was rated as easier to use than the Macintosh laryngoscope (P < 0.001). CONCLUSION: AWS is more useful for beginners as it provides quicker and easier tracheal intubation.

Comparison of the Airway Scope, gum elastic bougie and fibreoptic bronchoscope in simulated difficult tracheal intubation: a manikin study.

We compared the Airway Scope with a gum elastic bougie and fibreoptic bronchoscope in a manikin with a simulated Cormack and Lehane Grade 3 laryngoscopic view. Twenty-seven anaesthetists intubated the trachea of the manikin with these devices and the time required for intubation was measured. They were then asked to rate the subjective difficulty of intubation (1 = very easy; 5 = very difficult). Mean (SD) intubation times were 16.6 (11.2) s with the Airway Scope, 29.4 (10.9) s with the gum elastic bougie (p < 0.0001), and 30.6 (20.0) s with the fibreoptic bronchoscope (p < 0.0001). The median (range) difficulty was 2 (1-4) with the Airway Scope, 3 (2-4) with the gum elastic bougie (p < 0.001), and 2 (1-5) with the fibreoptic bronchoscope (p = 0.014). In Cormack and Lehane grade 3 laryngoscopic views, the Airway Scope may enable faster and easier tracheal intubation than does a Macintosh laryngoscope with a gum elastic bougie or a fibreoptic bronchoscope.

Influence of head and neck position on cuff position and oropharyngeal sealing pressure with the laryngeal mask airway in children.

We studied how head and neck position affect the cuff position and oropharyngeal sealing pressures of the laryngeal mask airways (LMAs) in children. We studied 39 non-paralyzed healthy children aged 1.5-8.0 yr, weighing 10.3-27.0 kg, managed with size 2 or 2.5 LMAs during elective surgery. Head and neck movements did not adversely affect airway patency in 97% of patients. One child developed apparent airway obstruction with head and neck flexion, which was relieved in the neutral position. Oropharyngeal sealing pressure was significantly greater during neck flexion compared with the neutral position (P<0.02). Fibreoptic examination revealed that the epiglottis covered a larger area of the LMA aperture during neck flexion, compared with the neutral position (P<0.02).

Opposite effects of depressant and convulsant barbiturate stereoisomers on acetylcholine release from the rat hippocampus in vivo.

BACKGROUND: It has been shown that the R(-) isomer of 1-methyl-5-phenyl-5-propyl barbituric acid (MPPB) induces loss of the righting reflex (LRR), while S(+)-MPPB causes pure excitatory effects, including convulsions, in vivo. METHODS: We studied the effects of the depressant and convulsant MPPB stereoisomers on rat hippocampal acetylcholine (ACh) release in vivo, using a brain microdialysis technique in freely moving animals. RESULTS: R(-)-MPPB 60 and 90 mg x kg(-1) i.p. decreased ACh release from the rat hippocampus by 44.1 (8.2)% and 60.8 (8.2)%, respectively. In the hippocampus, the local application of bicuculline, a gamma-aminobutyric acid (GABA)(A) receptor antagonist, 1 micromol litre(-1) antagonized the inhibitory effects of R(-)-MPPB 90 mg x kg(-1) i.p. In contrast, R(-)-MPPB, S(+)-MPPB 60 and 90 mg x kg(-1) i.p. increased ACh release to 151.8 (6.8)% and 169.6 (11.1)% of the basal release, respectively. CONCLUSIONS: Our results demonstrated that R(-)-MPPB decreased, while S(+)-MPPB increased, rat hippocampal ACh release and that the inhibitory effects of R(-)-MPPB may involve the GABA(A) receptor in vivo. These data imply that changes in hippocampal ACh due to these agents may be related to their central inhibitory and stimulatory actions in vivo.

Chronic ethanol consumption does not affect action of propofol on rat hippocampal acetylcholine release in vivo.

BACKGROUND: The aim of this study was to examine ethanol-consumption-related changes in the effects of propofol on rat hippocampal acetylcholine (ACh) release. METHODS: Male Sprague-Dawley rats received a solution of ethanol (20% v/v) for 24 weeks while controls received tap water. The effects of propofol were examined by in vivo microdialysis, with ACh release from the hippocampal regions determined by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). RESULTS: Propofol 50 mg kg(-1) i.p. significantly decreased basal hippocampal ACh release in ethanol-treated and control rats by 50.4 (sem 4.7)% and 38.3 (11.1)%, respectively. Propofol 100 mg kg(-1) i.p. significantly decreased basal hippocampal ACh release in ethanol-treated and control rats by 67.5 (3.7)% and 55.9 (7.4)%, respectively. The reduction in hippocampal ACh release induced by 50 or 100 mg kg(-1) i.p. propofol was not significantly different between ethanol-treated and control rats. There was no significant difference in the duration of sleep between the two groups. CONCLUSIONS: These results demonstrate that chronic ethanol consumption does not augment the inhibitory actions of propofol on rat hippocampal ACh release. These findings appear to be inconsistent with the notion that chronic ethanol intake enhances the propofol-induced inhibition of the hippocampal cholinergic system and related mental dysfunction.