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Background: Impaired cerebral oxygenation, which is reflected by measuring jugular bulb oxygenation, is thought to play an important role in the development of neurological injury after cardiac operations with cardiopulmonary bypass (CPB). The effects of cardiopulmonary temperature and blood gas strategy on cerebral oxygenation are not fully appreciated., Methods: Sixty patients were randomly allocated into four equal groups (cold alpha-stat, cold pH-stat, warm alpha-stat and warm pH-stat) to compare the effect of these perfusion strategies on cerebral oxygenation monitored by jugular bulb oximetry [jugular bulb oxygen saturation (SjO(2)) and arterial-jugular bulb oxygen content difference (AjDO(2))]. Jugular bulb oxygen saturation and AjDO(2) were measured before CPB, after 5, 20, 40 min on CPB, at start and end of rewarming, 5 min before the end of CPB and 10 min after CPB. Two-way analysis of variance was used to model the lowest SjO(2) and highest AjDO(2) during CPB, with CPB temperature and blood gas management as contributing factors., Results: Significant changes in SjO(2) were only related to the type of blood gas management, with no significant difference between warm and cold CPB patients. In addition, during rewarming, desaturation (SjO(2)

Background: The effect of cardiopulmonary bypass temperature and blood gas management on the brain is still controversial. This study was designed to compare the changes in S100beta protein concentration and Mini-Mental State Examination in patients undergoing cold (28 degrees C) vs. warm (34 degrees C) cardiopulmonary bypass using different blood gas strategies (alpha-stat and pH-stat)., Methods: Sixty patients were randomly allocated to one of four equal groups (cold alpha-stat, cold pH-stat, warm alpha-stat, warm pH-stat). Serum S100beta concentrations were measured before CPB, directly after CPB, at 4.5 h and at 24 h after CPB. Mini-Mental State Examination was performed one day before surgery and on day five after the operation. Antegrade warm blood cardioplegia (37 degrees C) was used in all patients., Results: There was no significant difference in postoperative S100beta protein levels between the four groups. Also, there was no interaction between bypass temperature and type of blood gas strategy on S100beta levels after bypass (directly after bypass, 4.5 h and 24 h after bypass). Mini-Mental State Examination score was not affected by blood gas strategy but it was significantly lower in patients undergoing cold cardiopulmonary bypass surgery: median (range), 26 (12-29) vs. 27 (23-30) in warm patients, P = 0.014. There was no significant correlation between Mini-Mental State Examination score 5 days after CPB and S100beta levels at any of the studied time-points after CPB., Conclusion: These results support the use of warm CPB (34 degrees C) in patients undergoing coronary artery bypass surgery regardless of the type of blood gas strategy.

Seventy-one adult patients (31 male, 40 female) who presented for surgery underwent orotracheal intubation with Portex Blue Line standard cuff disposable tubes (9-mm for males, 8-mm for females). The tracheal tube cuff was inflated by a trained assistant using a syringe and the initial cuff pressure measured; the minimum cuff pressure required to prevent respiratory gas leakage was also measured and the cuff pressure maintained above this pressure throughout the operation by means of the Cardiff Cuff Controller. Initial cuff pressure values averaged 11.9 kPa for males and 13.5 kPa for females compared with minimum cuff pressure values of 5.2 and 1.2 kPa, respectively. The differences between initial and minimum pressures were statistically highly significant (p much less than 0.001). It is concluded that the present method of inflation may lead to gross overinflation of tracheal tube cuffs and that cuff pressure monitoring may be performed simply by means of an electropneumatic controller. The difference in minimum cuff pressure between males and females suggests that the difference in tracheal size between the sexes is greater than the 9-mm to 8-mm difference in tracheal tube size.

The central placement rate of central venous catheters inserted via the external jugular veins was assessed using two different types of catheter. In 50 patients a catheter-through-cannula design was used, in 50 a catheter-through-needle design; central placement rates were 72% and 60% respectively. Complications were few and never serious. The catheter-through-cannula design is recommended.

Difficulties were experienced in weaning a patient from a ventilator by means of intermittent mandatory ventilation (IMV). The difficulty was overcome by installing an alternative IMV system (Hudson "disposable IMV valve") through which the patient drew her spontaneous breaths. Laboratory measurements showed that the resistance of the ventilator breathing system was much higher than that of the alternative system, mainly as a result of the resistance of the humidifier. It was calculated from measurements with a preset pattern of simulated breathing that the extra, external, work of breathing through the ventilator breathing system was approximately 1.5 times the normal internal mechanical work of breathing for a normal patient; with the alternative system, the extra work was only 0.5 times the normal. It is stressed that the breathing systems of IMV ventilators should be judged with the same rigour as other systems through which the patient is required to breathe spontaneously. It is recommended that manufacturers should provide the necessary information.

Pulmonary and renal excretion of isoflurane and its metabolites was studied in nine surgical patients following administration of known quantitities of isoflurane. Uptake and pulmonary washout were predictable by a mathematical model for inert vapors. The agreement between predicted and experimental data supports the view that isoflurane is subject to little or no biotransformation. The average recovery in exhaled air was 95 per cent, SE 7 per cent. The postoperative increase of urinary excretion of fluoride and organic fluorine accounted for less than 0.2 per cent of fluorine administered as isoflurane. This small extent of biotransformation is probably biologically insignificant, but only after extensive clinical experience can the hazard of delayed toxic response be conclusively evaluated.

Two groups, each of 100 smokers, were compared in terms of reduction in cigarette consumption in the 5 days prior to elective surgery. One group was admitted to hospital in the routine way and information on preoperative cigarette consumption obtained by questioning each patient after recovery from anaesthesia. In the second group, a letter strongly advising the patient to stop smoking for 5 days preoperatively was enclosed with the admission letter. A proforma to record the daily cigarette consumption was also enclosed. By the day before surgery the mean cigarette consumption had fallen to 52% in Group I and 16% in Group II and 14 and 46 patients respectively had then stopped smoking completely. The differences were highly significant (P less than 0.001).

The pressure in the internal jugular vein was measured with the head in three different positions using, first, a short cannula and then a catheter with a round occluded end and two side-holes. These pressures were compared with the central venous pressure. In the horizontal position using the catheter, the two venous pressure measurements were similar. With the open-ended cannula, results could be unreliable with the head turned towards the side of cannulation.