Anaesthesia
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Randomized Controlled Trial Clinical Trial
Reshaping the Macintosh blade using biomechanical modelling. A prospective comparative study in patients.
It has been demonstrated that during routine use of the Macintosh blade, great forces are exerted on the maxillary incisors. The aim of this study was, by using biomechanical modelling, to modify a standard Macintosh blade in order to reduce these forces. ⋯ The mean (SD) maximal forces exerted on the maxillary incisors were 12.7 (8.8) N in patients in the modified Macintosh group compared to 25.5 (17.8) N in the standard Macintosh group (p = 0.008). These results demonstrate that reducing the proximal step of the Macintosh laryngoscope results in a reduction of the forces exerted on the teeth and suggest that laryngoscope blades with a high proximal step might be more traumatic than blades in which the proximal step is reduced.
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Comparative Study Clinical Trial Controlled Clinical Trial
The peri-operative use of the oesophageal Doppler monitor in patients undergoing coronary artery revascularisation. A comparison with the continuous cardiac output monitor.
This study was carried out to evaluate the ease of use and reliability of cardiac output estimations performed by an oesophageal Doppler monitor and to compare its use with that of a continuous cardiac output pulmonary flotation catheter. Measurements were made during and after surgery in 16 patients scheduled to undergo coronary revascularisation. Both devices suffered significant intra-operative problems which led us to question their suitability as operating theatre monitors. After surgery the continuous cardiac output monitor provided stable results while the oesophageal Doppler monitor required the continuous presence of an experienced anaesthetist to ensure comparable cardiac output estimations.
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A study was undertaken to compare the size of tracheal tube used for paediatric anaesthesia derived from either the diameter of the distal phalanx of the little or index finger, or from a standard formula (age in years/4 + 4.5 mm). The results showed that the diameter of the terminal phalanx was a poor predictor of the external diameter of the tube that provided the best fit. ⋯ The mean (SD) figures were 5.61 (0.75) and 5.70 (0.67) mm for the formula and the chosen tracheal tube, respectively. The use of the diameter of the terminal phalanx of either the little or the index finger is an unreliable measurement for the prediction of the tracheal tube size in paediatrics.
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When volatile anaesthetics are used in a closed breathing system it is usually assumed that inflow of anaesthetic to the system matches uptake by the patient. Early laboratory reports on the interactions between sevoflurane and soda lime cast doubt on that assumption. We have measured the loss of sevoflurane, desflurane and isoflurane from a closed breathing system and found no differences of consequences.
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Splanchnic ischaemia is thought to be of central importance in the development of multi-organ failure and hence death in critically ill patients. It has been suggested that the arterial to gastric intramucosal pH gradient and the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood are more sensitive markers of splanchnic ischaemia than gastric intramucosal pH itself and thus should be predictors of mortality in the critically ill. We studied 62 critically ill patients within 6 h of admission to the intensive care unit and found no significant difference at 0, 12 or 24 h after admission to the study in either the arterial to gastric intramucosal pH gradient or the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood between survivors and nonsurvivors. We conclude that in contrast to gastric intramucosal pH neither the arterial to gastric intramucosal pH gradient nor the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood distinguish survivors from nonsurvivors.