Austrian syndrome.

The authors present a case of Austrian syndrome, the triad of pneumococcal pneumonia, endocarditis and meningitis, in a 49-year-old woman, who developed severe acute heart failure due to aortic valve destruction. The patient required imminent valve surgery, but eventually recovered.

The early IL-6 and IL-10 response in trauma is correlated with injury severity and mortality.

BACKGROUND: Trauma has previously been shown to influence interleukin (IL)-6 and IL-10 levels, but the association of injury severity and mortality with IL-6 and IL-10 responses in the early phase of accidental trauma remains to be investigated. We wished to describe serum levels of IL-6 and IL-10 in the first 24 h after trauma and to assess the relationship with severity of injury and mortality. METHODS: Prospective, descriptive cohort study in a Level 1 trauma centre, Copenhagen, Denmark. We included 265 consecutive adult trauma patients admitted directly from the accident scene during an 18-month period. Serum levels of IL-6 and IL-10 were measured upon arrival and at 6, 12, and 24 h after admittance using an enzyme-linked immunosorbent assay. Correlation analysis was used to assess the relationship between Injury Severity Score (ISS) and levels of IL-6 and IL-10. Analysis of variance was used to describe the IL-6 and IL-10 concentrations in relation to 30-day mortality in a mixed-effect model repeated measures analysis. RESULTS: Mortality was 10.9% (29/265) at 30 days. A significant increase of both IL-6 and IL-10 concentrations was found over time, and a significant correlation was found between ISS and the levels of both IL-6 and IL-10 at all sampling points. Serum concentrations of IL-6 and IL-10 were significantly higher in patients not surviving 30 days (P<0.0001). CONCLUSION: The early systemic inflammatory response measured as IL-6 and IL-10 in serum is correlated with injury severity and 30-day mortality following trauma.

Lactic acidosis in the rectal lumen of patients with septic shock measured by luminal equilibrium dialysis.

BACKGROUND: Gut ischaemia may contribute to morbidity in sepsis, but little is known about the metabolic state of the gut mucosa in such patients. METHODS: Nine patients with abdominal septic shock treated with norepinephrine, and ten healthy subjects, were subjected to equilibrium dialysis with a rectal balloon. pH, PCO(2) and concentrations of L-lactate were measured by auto-analyser. RESULTS: In rectal dialysis fluid from patients with septic shock, acidosis was present (pH 7.23, 95% CI 7.11-7.36) and concentrations of L-lactate were approximately five times greater than controls (2.5-5.8 vs 0.5-1.2 mmol litre(-1)). The lactate concentration was related to the dose of norepinephrine (P<0.001). In contrast, values of dialysate PCO(2) did not differ significantly between patients and controls (6.4-11.0 vs 8.9-13.8 kPa). CONCLUSIONS: The results suggest that, either lactic acidosis in rectal mucosa is related to shock severity, or that norepinephrine causes mucosal ischaemia. In any case, metabolic dysfunction is present in the rectal mucosa in patients with abdominal septic shock treated with norepinephrine.

Splenectomy impairs lymphocytosis during maximal exercise.

To evaluate the role of the spleen for the exercise-induced lymphocytosis, six splenectomized subjects and six matched control subjects cycled for 12 min at two submaximal work rates corresponding to 50 and 75% of their maximal work capacity, followed by a supramaximal intensity maintained until exhaustion (16 +/- 1 min; mean +/- SE). Venous blood samples were taken before, during, and 2 h after the maximal load. In both groups, the concentration of lymphocytes became elevated during exercise, but the increase from the level at rest was impaired in the splenectomized subjects compared with that of the controls (118 +/- 34 vs. 238 +/- 38%; P < 0.05). This was reflected in several lymphocyte subsets: cluster designation (CD) 3+ cells (pan T lymphocytes), 69 +/- 19 vs. 204 +/- 37%; CD8+ cells (T lymphocyte subset), 164 +/- 41 vs. 467 +/- 68%; CD16+ cells [natural killer (NK) cells], 291 +/- 88 vs. 870 +/- 177%; CD56+ cells (NK cells), 301 +/- 108 vs. 753 +/- 187%. Also, the specific NK cell lysis of target cells (NK cell activity) during exercise was lower for the splenectomized subjects (30 +/- 7%) than that of the control subjects (52 +/- 10%), but evaluation of lytic units indicates that this was due to a reduced number of NK cells in the assay rather than insufficient cell lysis. Plasma catecholamines reached the same level in the splenectomized subjects and control subjects, which was taken to reflect that the activity of the sympathetic nervous system was similar in the two groups of subjects. Thus the major finding of this study is that the spleen is important for lymphocytosis during exercise, accounting for two-thirds of the increase in T lymphocytes and NK cells.

Lower body impedance for the evaluation of venovenous bypass flow.

Inferior vena cava (IVC) clamping during liver transplantation causes venous congestion in the splanchnic and IVC beds. A venovenous bypass relieves congestion and improves cardiac output (CO), but the bypass flow required for adequate drainage of the vascular beds is controversial. In this study we evaluated the bypass flow necessary to compensate for the IVC clamping. Lower body impedance (BI) is inversely related to tissue fluid content and was used to reflect congestion. A venovenous bypass was successfully applied to 59 of 62 patients. BI was measured across the left buttock and related to bypass flow, CO, bypass flow ratio (bypass flow/CO before IVC clamping; n = 62), and right femoral venous pressure (n = 8). The bypass flow was 1.7 (0.0-3.0) L.min-1 (median and range). BI decreased (delta BI; -2.2 [-10.3-1.1)] omega) as the femoral venous pressure increased (29 [21-49] mm Hg; r = -0.81; P < .05), and the femoral venous pressure correlated inversely to bypass flow (r = -0.35; P < .01). The change in CO at IVC clamping (delta CO; -2.3 [-6.3-1.6] L.min-1) related to bypass flow ratio (0.25 [0-0.51]; r = 0.57, P < .01), whereas delta BI related only minimally to bypass flow or bypass flow ratio (r = 0.37; P < .05). In conclusion the median bypass flow of 1.7 L.min-1 was too small to prevent fluid accumulation in the lower caval region, and extrapolation of data suggests that bypass flow should have approached 3.5 L.min-1 or 50% of CO in order to prevent fluid accumulation in the lower caval region. However the minimal correlation between lower BI and bypass flow indicates that bypass flow per se is not the only determinant of lower body fluid accumulation.

Plasma noradrenaline and ageing: effects of smoking habits.

We tested the hypothesis that long-term smoking is responsible for increased plasma noradrenaline (NA) in elderly healthy subjects. Thirty-nine subjects were studied both at rest and during exercise: 10 young non-smokers (median age 24 years, range 21-33), 10 young smokers (30.5 years, 27-36), 10 elderly non-smokers (64 years, 52-75) and nine elderly smokers (62 years, 56-68). The young and elderly subjects had smoked for an average of 15 years and 46.8 years respectively. Plasma NA was significantly elevated in elderly long-term smokers compared with elderly non-smokers, young non-smokers and young smokers in both supine and sitting positions (supine: 1.06 +/- 0.24 vs. 0.71 +/- 0.22, 0.53 +/- 0.12, and 0.70 +/- 0.29 nmol L-1 respectively; sitting: 3.01 +/- 0.83 vs. 2.07 +/- 0.77, 1.89 +/- 0.52 and 2.25 +/- 0.47 nmol L-1 respectively). Plasma adrenaline did not differ among the groups. At submaximal exercise (60 W), plasma NA was significantly elevated in the elderly smokers compared with the other groups, owing to the elevated basal values. Increments in plasma NA at 60, 100 and 140 W were correlated with the relative exertion and not influenced by smoking. Plasma NA increased more in young subjects than in the elderly during maximal work load (21.7 +/- 8.0 vs. 13.4 +/- 5.4 nmol L-1) and correlated with the peak O2 uptake. Total blood volume was not different among the four groups and correlated inversely with basal plasma NA. It is concluded that long-term smoking may contribute to increased basal plasma NA concentrations and probably also increased sympathetic nerve activity in elderly healthy subjects, whereas smoking has little if any effect on plasma NA responses induced by exercise. Interindividual variability in basal plasma NA concentrations may in part be explained by differences in blood volume.

Basal and exercise-induced changes in plasma catecholamines: relationship to age, smoking habits and sampling times.

Contrary to earlier investigations, we have previously shown that the initial increase in venous plasma noradrenaline (NA) during exercise did not differ in young and elderly non-smoking subjects exercising at the same relative workload (75%), and that the greatest increase at maximal workload was observed in the young subjects. In order to determine whether the observed discrepancy could be explained by long-term smoking, plasma NA and adrenaline (A) were evaluated in eight elderly male smokers (mean age 67 years). The results were compared with data reported previously [Jensen et al. (1994) Exercise-induced changes in plasma catecholames and neuropeptide Y: relation to age and sampling times. J Appl Physiol, 76, 1269-1273] in seven young (mean age 27 years) and seven elderly (mean age 61 years) non-smoking male subjects. As shown earlier, basal plasma NA was significantly increased in elderly smokers compared to young and elderly non-smokers. During exercise at 75% of maximal work capacity, no difference was observed between elderly smokers and non-smokers. No difference in plasma A was found between elderly smokers and non-smokers either at rest or during exercise. These findings indicate that the exercise-induced increase in plasma NA did not differ in elderly smokers and non-smokers despite increased resting levels in the former group, and that the increase in the elderly subjects was not augmented compared to that in young subjects.

Increased transcapillary escape rate of albumin in elderly subjects due to long-term smoking habits.

Transcapillary escape rate of albumin (TER) expressed as percentage decrease in specific activity of plasma albumin per hour was measured in 44 healthy male subjects, 10 young non-smokers (median age 24.0 years, range 21-33), 10 young smokers (30.5 years, range 27-36), 10 elderly non-smokers (64.0 years, range 51-75) and 14 elderly smokers (61.5 years, range 54-69). In addition urinary albumin excretion rates were measured in 15 of the elderly subjects. The subjects were investigated after overnight fasting and abstention from tobacco. Median TER was 7.33% (interquartile range 5.82-9.90) in the elderly smoking subjects. This value was significantly elevated as compared to elderly non-smokers, 4.47% (2.93-5.83), young non-smokers, 3.70% (2.24-6.30) and young smokers, 4.25% (2.80-4.44). A statistically non-significant (P = 0.064) tendency of a higher urinary albumin excretion rate was observed in elderly smokers. This agrees with other investigations showing slightly increased albuminuria in smokers compared with non-smokers. The differences were not related to differences in blood pressure, plasma cholesterol, weight, or abuse of alcohol in the elderly subjects. Diabetic subjects with an increased TER to levels comparable with levels in long-term smokers have increased urinary albumin excretion rates, which seems to be greater than in long-term smoking subjects. It is suggested that increased TER in long-term smokers may indicate a vascular dysfunction affecting either capillary permeability or endothelial surface area.

Comparison of cardiac output measurement techniques: thermodilution, Doppler, CO2-rebreathing and the direct Fick method.

Simultaneously measured cardiac output obtained by thermodilution (TD), transcutaneous suprasternal ultrasonic Doppler (DOP), CO2-rebreathing (CR) and the direct Fick method (FI) were compared in eleven healthy subjects in a supine position (SU), a sitting position (SI), and during sitting exercise at a workload of 50 W (EX). The agreements between the techniques, two by two, were expressed as the bias calculated as the averaged differences between the techniques. Precision was expressed as the standard deviation of the bias. The overall agreement (bias +/- precision) between TD, DOP and CR respectively and FI were 2.3 +/- 1.6, -0.1 +/- 1.4, and -0.2 +/- 1.1 l/min. TD overestimated cardiac output consistently in SU, SI and EX. DOP was in-accurate during EX and agreed well with FI in SU and SI. CR agreed closely with FI in SI and EX, but values were underestimated in SU. The overall agreement between DOP and CR, respectively, and TD were 2.5 +/- 2.2 and 2.6 +/- 1.6 l/min. The overall agreement between DOP and CR was 0.1 +/- 1.6 l/min. In conclusion, TD overestimated cardiac output compared to the other techniques and the poor agreement has to be taken into consideration especially in measures of low values. The precision of DOP and CR against FI seems to be within clinically acceptable limits, and these methods may provide interchangeable alternatives to the invasive Fick method.

Exercise-induced changes in plasma catecholamines and neuropeptide Y: relation to age and sampling times.

Plasma norepinephrine (NE), epinephrine (E), and neuropeptide Y (NPY) were evaluated in seven young (median age 29 yr, range 21-31) and seven elderly (median age 61 yr, range 51-72) healthy subjects. They were all nonsmokers and had never smoked. Basal values and the initial increase in plasma NE and E during exercise at 75% of maximal work load were identical in the two groups. After 5 min of exercise at this load, plasma NE and E remained constant in the elderly but were still increasing in the young subjects. Plasma NE and E increased to significantly higher values after 15 min in the young subjects: 1.68 +/- 0.18 vs. 0.92 +/- 0.11 ng/ml (NE) and 0.136 +/- 0.012 vs. 0.061 +/- 0.013 ng/ml (E). Basal plasma NPY was highest at rest and increased only during exercise in the young subjects. Our results demonstrate that in nonsmokers aging is not associated with increased plasma NE levels. The blood pressure response to exercise was the same in both groups, suggesting that the increase in the sympathetic activity was adequate in the elderly. Alternatively, the higher increase in sympathetic activity in the young subjects may be attributed to their higher work capacity.

Dopamine, dobutamine, and dopexamine. A comparison of renal effects in unanesthetized human volunteers.

BACKGROUND: Recently, dopexamine (DX), which acts via adrenergic beta 2 and dopaminergic DA1 receptors, has been introduced in the treatment of low cardiac output states. However, the renal effects of DX have not been compared to those produced by equipotent inotropic doses of dopamine (DA), which predominantly stimulates DA1 and DA2 receptors, and of dobutamine (DB), which stimulates beta 1 but not DA receptors. The current study tested the null hypothesis that, with equal increases in cardiac output, DX, DA, and DB would have similar effects on renal function. METHODS: Each drug was given for 2 h on three different occasions to eight normal subjects in doses adjusted to produce a similar 30-35% increase in cardiac output. Effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) were measured as renal clearances of 131I-hippuran and 99mTc-DTPA, respectively. Lithium clearance (CLi) was used as an index of proximal tubular outflow. RESULTS: Doses of DA, DX, and DB were 2.90 +/- 0.19, 1.00 +/- 0.02, and 4.92 +/- 0.40 microgram.kg-1.min-1, respectively. Dopamine and DX increased ERPF by 23% and 10%, respectively, whereas ERPF remained unchanged during DB. The increase in ERPF was smaller during DX compared with DA. The GFR remained unchanged during DA and DB, but increased during DX (7%). The CLi increased by 35% and 30% during DA and DX, respectively, but was not changed by DB. Calculated absolute proximal reabsorption rate (APR = GFR--CLi) decreased by 13% during DA, but remained unchanged during DB and DX. Dopamine increased sodium clearance (CNa) by 103%, but the changes during DX and DB were not significant. Only DA decreased fractional distal reabsorption (FDRNa = 1--CNa/CLi). CONCLUSIONS: The findings are consistent with a specific, renal-vasodilating effect of DA and DX. However, in the current doses, this effect of DX was of lesser magnitude compared with that of DA. Only DA significantly increased CNa, and the decreases in APR and FDRNa indicate that an effect on tubular reabsorption rate contributed to the natriuresis.

Perioperative monitoring with pulse oximetry and late postoperative cognitive dysfunction.

In a randomized, blinded clinical study, we have used objective and subjective measures to determine if perioperative monitoring with pulse oximetry--by virtue of its potential to lessen hypoxaemia--would decrease late postoperative cognitive dysfunction. We investigated 736 adult patients undergoing elective procedures (other than cardiac, neurosurgical or for cancer) under regional or general anaesthesia, allocated randomly to undergo (group I) or not to undergo (group II) pulse oximetry monitoring in the operating theatre and recovery room. Cognitive function was evaluated using the Wechsler memory scale (WMS) and continuous reaction time (RT) test the day before surgery, and on the 7th day after operation or at discharge if that occurred before postoperative day 7. A questionnaire sent 6 weeks after surgery elicited patients' subjective perceptions regarding cognitive abilities. There were no significant differences between the two groups in either the total WMS score, the score for each WMS subtests or RT test. The questionnaire revealed that 7% in group I and 11% in group II believed cognitive abilities had decreased (ns). For the 40 patients whose WMS scores were 10 points less after than before operation, a follow-up study was undertaken 3 months after surgery. At that time, the median WMS score had returned to the preoperative value. We conclude that, for these 736 patients, subjective and objective measures did not indicate less postoperative cognitive impairment after perioperative monitoring with pulse oximetry.

Randomized evaluation of pulse oximetry in 20,802 patients: I. Design, demography, pulse oximetry failure rate, and overall complication rate.

BACKGROUND: Although pulse oximetry is currently in widespread use, there are few data documenting improvement in patient outcome as a result of the use of oximetry. The authors describe the study design, patient demographic findings, data validation, pulse oximetry failure rate, and overall postoperative complication rates in the first large prospective randomized multicenter clinical trial on perioperative pulse oximetry monitoring. METHODS: In five Danish hospitals, by random assignment, monitoring did or did not include pulse oximetry for patients 18 yr of age and older, whether scheduled for elective or emergency operations, or for regional or general anesthesia, except during cardiac and neurosurgical procedures. Operational definitions were established for perioperative events and postoperative complications. The data were collected preoperatively, during anesthesia, in the postanesthesia care unit, and until the day of discharge from the hospital or the seventh postoperative day. RESULTS: Of 20,802 patients, 10,312 were assigned to the oximetry group and 10,490, to the control group. In general, the demographic data, patient factors, and anesthetic agents used were distributed evenly. A slight intergroup difference was found in the distribution of age, duration of surgery, some types of surgery, and some types of anesthesia. The total failure rate of the oximetry was 2.5%, but it increased to 7.2% in patients with American Society of Anesthesiologists physical status 4 (P < 0.00001). In 14.9% of the patients, one or more events occurred in the operating room and 13.5% in the postanesthesia care unit. The overall postoperative complication rate was 9.7%. The total rates of cardiovascular and respiratory complications were 2.78% and 3.50%, respectively. Within the first seven postoperative days, 0.47% of the patients died. Anesthesia was not thought to have been solely responsible for any death, but in 7 patients (1 per 3,365), it was a possible contributory factor. CONCLUSIONS: Despite the finding of a few significant inter-group differences, the randomization was well balanced with a high validity of data. The overall postoperative complication rate was similar to that in other recent morbidity and mortality studies.

Randomized evaluation of pulse oximetry in 20,802 patients: II. Perioperative events and postoperative complications.

BACKGROUND: The authors describe the effect of pulse oximetry monitoring on the frequency of unanticipated perioperative events, changes in patient care, and the rate of postoperative complications in a prospective randomized study. METHODS: The study included 20,802 surgical patients in Denmark randomly assigned to be monitored or not with pulse oximetry in the operating room (OR) and postanesthesia care unit (PACU). RESULTS: During anesthesia and in the PACU, significantly more patients in the oximetry group had at least one respiratory event than did the control patients. This was the result of a 19-fold increase in the incidence of diagnosed hypoxemia in the oximetry group than in the control group in both the OR and PACU (P < 0.00001). In the OR, cardiovascular events were observed in a similar number of patients in both groups, except myocardial ischemia (as defined by angina or ST-segment depression), which was detected in 12 patients in the oximetry group and in 26 patients in the control group (P < 0.03). Several changes in PACU care were observed in association with the use of pulse oximetry. These included higher flow rate of supplemental oxygen (P < 0.00001), increased use of supplemental oxygen at discharge (P < 0.00001), and increased use of naloxone (P < 0.02). The rate of changes in patient care as a consequence of the oximetry monitoring increased as the American Society of Anesthesiologists physical status worsened (P < 0.00001). One or more postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group (difference not significant). The two groups did not differ significantly in cardiovascular, respiratory, neurologic, or infectious complications. The duration of hospital stay was a median of 5 days in both groups (difference not significant). An equal number of inhospital deaths were registered in the two groups. Questionnaires, completed by the anesthesiologists at the five participating departments, revealed that 18% of the anesthesiologists had experienced a situation in which a pulse oximeter helped to avoid a serious event or complication and that 80% of the anesthesiologists felt more secure when they used a pulse oximeter. CONCLUSIONS: This study demonstrated that pulse oximetry can improve the anesthesiologist's ability to detect hypoxemia and related events in the OR and PACU and that the use of the oximeter was associated with a significant decrease in the rate of myocardial ischemia. Although monitoring with pulse oximetry prompted a number of changes in patient care, a reduction in the overall rate of postoperative complications was not observed.

Sublingual premedication with brotizolam.

This randomized, double-blind and double-dummy study was carried out in order to compare the perioperative sedation after premedication with either brotizolam 0.25-0.50 mg sublingually or diazepam 5-10 mg orally. Sixty-two patients aged 18-60 years scheduled for minor gynaecological surgery in general anaesthesia were included. Assessments were: 1. auditory continued response time (ACRT); 2. coma scale; 3. anxiety scale; and 4. final patient questionnaire. One hour after premedication the brotizolam group was more sedated, based on ACRT (P < 0.01) and the coma scale (P < 0.05). The final questionnaire showed (P < 0.05) that the brotizolam group was more satisfied with the effect of the premedication. Seven hours after the premedication the ACRT scores in both groups were similar to those before premedication and all the patients could walk about freely. In conclusion, as a premedicant in outpatients sublingual brotizolam appears to be a good alternative to diazepam.

Hypoxaemia is reduced by pulse oximetry monitoring in the operating theatre and in the recovery room.

To determine the impact of pulse oximeter monitoring on the incidence, severity and duration of hypoxaemia in the operating theatre (OT) and in the recovery room (RR), we investigated 200 patients in a randomized study. The extent of hypoxaemia in the OT was compared with that in the RR. Adult inpatients were allocated randomly to two groups: group I, pulse oximeter data and alarms "available"; group II, these data "unavailable" to the anaesthesia team and RR staff. Hypoxaemia was graded into four values of oxyhaemoglobin saturation (SpO2). The incidence of hypoxaemia was reduced significantly in group I in both OT and RR. In the OT, five patients in group II suffered SpO2 less than 76% compared with none in group I (P less than 0.02). In group II in the RR, seven patients suffered SpO2 less than 81%; three of these had SpO2 less than 76%. No patients in group I exhibited such small values of saturation. The smallest recorded SpO2 in the OT and the RR was significantly greater in group I. The cumulative duration of hypoxaemia was significantly less in group I in the RR, but not in the OT. The incidence and severity of hypoxaemia in the OT and in the RR were comparable, whereas the cumulative duration of hypoxaemia was significantly greater in the RR than in the OT. The occurrence of hypoxaemia in an individual patient in the OT significantly increased this patient's risk of suffering hypoxaemia in the RR. We conclude that the extent of hypoxaemia, especially in the RR, may be reduced significantly by pulse oximeter monitoring, but even with the information provided, some patients still develop hypoxaemia.

Age-related changes of exercise-induced plasma catecholamines and neuropeptide Y responses in normal human subjects.

Age-related plasma noradrenaline and neuropeptide Y were evaluated in seven young (mean +/- SD, 28 +/- 3 years) and seven elderly (64 +/- 8 years) normal subjects during rest and different work loads on a cycle ergometer. In the supine and the sitting position plasma noradrenaline and neuropeptide Y were almost identical in the two groups. Plasma neuropeptide Y did not increase during exercise at 100 W for 15 min. At this load plasma noradrenaline levels were higher in the older subjects (mean +/- SEM, 0.97 +/- 0.12 vs. 0.60 +/- 0.09 ng ml-1). There was a significant correlation between plasma noradrenaline and the relative work load at 100 W (r = 0.794, P = 0.0007). At 75% of maximal work load plasma noradrenaline and neuropeptide Y were higher in the young group (1.84 +/- 0.16 vs. 1.26 +/- 0.13 ng ml-1 (noradrenaline) and 38 +/- 4 vs. 22 +/- 5 pmol l-1 (neuropeptide Y)). In the elderly group plasma neuropeptide Y did not increase during exercise and showed a tendency to fall below basal level 5 min post-exercise. It is concluded, that plasma noradrenaline does not increase more in older subjects during exercise when correcting for the generally lower physical fitness in this group compared to younger subjects, and that plasma neuropeptide Y does not increase during exercise in older subjects, suggesting an age-reduced capacity in this system.

Hypoxaemia during anaesthesia--an observer study.

We have investigated 296 inpatients in a single-blind observer study to determine the incidence, degree and duration of hypoxaemia during anaesthesia. The clinical recognition of hypoxaemia, period of time until recognition and risk factors were studied. Oxygen saturation (Spo2) was monitored continuously with a pulse oximeter (Ohmeda, model 3700). One or more episodes of mild hypoxaemia (Spo2 86-90%) were recorded in 53% of patients. Severe hypoxaemia with Spo2 values less than 81% were recorded in 20% of patients. The mild hypoxaemic episodes lasted up to 34.6 min (mean 2.3 min) and 70% were not detected by the anaesthetist. In the remaining 30% of episodes, the anaesthetist diagnosed the complication with a mean time delay of 70 s. After intervention a mean time delay of 57 s was recorded until Spo2 exceeded 90%. Utilizing a stepwise multiple logistic regression analysis, we found that risk factors associated with a greater incidence of hypoxaemia were patient age (P less than 0.005) and anaesthetic technique (P less than 0.00001). We conclude that hypoxaemic episodes in our operating rooms are common during anaesthesia and suggest preoxygenation in all patients in addition to administration of supplementary oxygen during arousal from anaesthesia and during transfer to the recovery room.