British journal of anaesthesia
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Major surgery is still associated with undesirable sequelae such as pain, cardiopulmonary, infective and thromboembolic complications, cerebral dysfunction, nausea and gastrointestinal paralysis, fatigue and prolonged convalescence. The key pathogenic factor in postoperative morbidity, excluding failures of surgical and anaesthetic technique, is the surgical stress response with subsequent increased demands on organ function. ⋯ To understand postoperative morbidity it is therefore necessary to understand the pathophysiological role of the various components of the surgical stress response and to determine if modification of such responses may improve surgical outcome. While no single technique or drug regimen has been shown to eliminate postoperative morbidity and mortality, multimodal interventions may lead to a major reduction in the undesirable sequelae of surgical injury with improved recovery and reduction in postoperative morbidity and overall costs.
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Clinical Trial
Assessment of cardiovascular changes during laparoscopic hernia repair using oesophageal Doppler.
We have used an oesophageal Doppler to measure aortic blood flow velocity before, during and after induction of carbon dioxide pneumoperitoneum in 10 consecutive patients, mean age 58 yr, undergoing laparoscopic hernia repair. Derived values for stroke distance, minute distance and systemic vascular resistance showed considerable interpatient variation indicating unpredictable haemodynamic responses. ⋯ There was a corresponding increase in the index of systemic vascular resistance from 1092 (747) to 2079 (400) (P < 0.05) which persisted after deflation of the abdomen. Oesophageal Doppler can provide continuous online haemodynamic data with a rapid response to acute changes and may have a role in non-invasive haemodynamic monitoring during laparoscopic procedures in older patients with cardiovascular disease.
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Clinical Trial
Can prolonged expiration manoeuvres improve the prediction of arterial PCO2 from end-tidal PCO2?
We have studied, in 16 patients undergoing thoracoabdominal oesophagectomy, if two prolonged expiration manoeuvres improve prediction of arterial PCO2 (PaCO2) from end-tidal PCO2 (PE' CO2). PE' CO2, PCO2 at the end of a simple prolonged expiration (PE1 CO2), and PCO2 at the end of a prolonged expiration preceded by sustained hyperinflation of the lungs (PE2 CO2), were measured during laparotomy, in the lateral thoracotomy position during two-lung ventilation, and after transition to one-lung ventilation. (PaCO2-PE' CO2) was 1.3 (SD 0.4) kPa during laparotomy and this remained stable throughout the study. ⋯ However, PE1 CO2 and PE2 CO2 did not agree more closely with PaCO2 than PE' CO2 at any stage of the study. We conclude that these manoeuvres did not improve estimation of PaCO2 from PE' CO2.
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We have assessed a range of high volume, low pressure (HVLP) cuffed tracheal tubes in a benchtop model, for leakage of fluid from above the cuff to the model trachea below, during various ventilatory modes. Rapid leakage occurred in the model during all modes of ventilation, unless tracheal pressure was greater than the height of fluid in the column above the cuff. This leakage occurred preferentially down longitudinal folds that occur in the HVLP cuff wall. This model suggests that, if a longitudinal fold within the cuff wall is patent, then the possibility exists of subglottic to tracheal leakage.