Anaesthesia
-
The role of vascular tone in determining cerebral perfusion pressure is increasingly being appreciated. It has been suggested that zero flow pressure, the arterial pressure at which blood flow ceases, represents the effective downstream pressure of the cerebral circulation. Nitrous oxide is a cerebral vasodilator and may therefore decrease zero flow pressure and increase cerebral perfusion pressure. ⋯ We studied eight healthy volunteers at normocapnia and studied the effects of the inhalation of nitrous oxide 50% on estimated cerebral perfusion pressure and zero flow pressure using transcranial Doppler ultrasonography. We found that nitrous oxide 50% significantly increased estimated cerebral perfusion pressure (p = 0.03), whilst decreasing zero flow pressure (p = 0.01). These results suggest that the vasomotor effects of nitrous oxide predominate in determining the effective downstream pressure of the cerebral circulation in healthy individuals.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the intubating laryngeal mask airway and laryngeal tube placement during manual in-line stabilisation of the neck.
We compared the placement of the laryngeal tube (LT) with the intubating laryngeal mask airway (ILMA) in 51 patients whose necks were stabilised by manual in-line traction. Following induction of anaesthesia and neuromuscular blockade, the LT and ILMA were inserted consecutively in a randomised, crossover design. Using pressure-controlled ventilation (20 cmH(2)O inspiratory pressure), we measured insertion attempts, time to establish positive-pressure ventilation, tidal volume, gastric insufflation, and minimum airway pressure at which gas leaked around the cuff. ⋯ Tidal volume was less for the LT (440 [290-670] ml) than for the ILMA (630 [440-750] ml, p = 0.013). Minimum airway pressure at which gas leak occurred and incidence of gastric insufflation were similar with two devices. In patients whose necks were stabilised with manual in-line traction, insertion of the ILMA was easier and quicker than insertion of the LT and tidal volume was greater with the ILMA than the LT.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Clinical comparison of three different anaesthetic depth monitors during cardiopulmonary bypass.
The lack of a gold standard complicates the evaluation and comparison of anaesthetic depth monitors. This randomised study compares three different depth-of-anaesthesia monitors during cardiopulmonary bypass (CPB) at 34 degrees C with fentanyl/propofol anaesthesia adjusted clinically and blinded to the monitors. Coronary artery bypass grafting patients (n = 21) were randomly assigned to all three possible paired combinations of three monitors: Bispectral Index (Aspect Medical), AAI auditory evoked potential (Danmeter), Entropy (Datex-Ohmeda). ⋯ Anaesthesia was classed as adequate, inadequate, or excessive according to recommended index values. Of the 255 paired indices recorded, 62% showed good agreement, 33% showed non-agreement, and 5% showed disagreement. Using good agreement between two monitors as a gold standard, a quarter of the measurements indicate inappropriate anaesthetic depth monitoring during CPB with clinically titrated anaesthetic depth.
-
Randomized Controlled Trial Clinical Trial
A programme for reducing smoking in pre-operative surgical patients: randomised controlled trial.
We assessed the efficacy of a comprehensive programme for stopping smoking in 210 smokers scheduled for surgery, before admission and 3 months after attending a pre-operative clinic. Participants were randomly allocated to receive an intervention incorporating nicotine replacement therapy for patients smoking more than 10 cigarettes per day ("dependent smokers"), or to a control group to receive usual care. Dependent smokers allocated to the intervention group were more likely to report abstinence before surgery than those allocated to receive usual-care (63 (73%) vs. 29 (56%), respectively; OR 2.2 (95% CI 1.0-4.8)), and 3 months after attendance (16 (18%) vs. 3 (5%), respectively; OR = 3.9 (95% CI 1.0-21.7).
-
Multicenter Study
Failed tracheal intubation in obstetrics: no more frequent but still managed badly.
In the South-West Thames region of the United Kingdom, during a 5-year period from 1999 to 2003, there were 20 failed tracheal intubations occurring in 4768 obstetric general anaesthetics (incidence 1 : 238). In half of the 16 cases for which the patient's notes could be examined there was a failure to follow an accepted protocol for failed tracheal intubation.