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Dantrolene is known to have a low solubility in water. Studies have demonstrated that it dissolves more rapidly in warm water. However, the overall benefit of warming has not been measured. This study evaluated the overall time benefit of warming.The first step was to measure how long it took to warm the 10 ml plastic ampoules of sterile water from ambient temperature (20°C) to 45°C. We found that when immersed in a water bath held at 45°C, this required a minimum of seven minutes. Therefore the ampoules used for the study were kept immersed in a water bath held at 45°C for at least 10 minutes.It took an average of 82.6 seconds to draw 60 ml (six ampoules) of water into a 60 ml syringe. Squirting the water into the dantrolene vial and mixing until dissolved took 102.8 seconds (SD 8.3) for the warmed water and 129.0 seconds (SD 14.6) for the ambient temperature water (P=0.009). Redrawing the dantrolene solution into the syringe took an average of 32 seconds for the warmed water and 35.2 seconds for the ambient temperature water. After the redrawing phase the average temperature of the warmed solution was 32.2°C. The average total preparation time for the warmed solution was 217.4 seconds (SD 20.0) and for the ambient temperature preparation was 243.0 seconds (SD 11.7) (P=0.038).Thus the time difference in preparation was about 256 seconds, which is the time that could be saved in preparing the standard dose of 10 vials of dantrolene using water at 45°C. However, as it required about seven minutes to initially warm the sterile ampoules, there would be a net increase, not decrease in the time required. These findings indicate that warming is of no benefit in speeding dantrolene preparation.

Anesthesiologists in the operating room vigilantly monitor their patient's vital signs during surgical procedures. The vital signs are displayed on a monitor that may be located in an awkward position and out of view of the anesthesiologist (who may be busy performing procedures on the patient). A head-mounted display (HMD) can help anesthesiologists monitor the patient's vital signs no matter where they are, or where they are looking, in the operating room. HMDs have been tested in simulated and real operating rooms, but no study has investigated whether the worsened inattentional blindness phenomenon found with head-up displays in aviation would also affect HMDs in anesthesia. Experiment 1 shows that the HMD did not worsen participants' ability to report unexpected events, but it did let them look towards the simulated patient for longer. Experiment 2 shows that participants using the HMD are slower to detect a change in a waveform and quicker to detect a change in numbers when working with a simulated patient. Experiment 3, a clinical trial, replicated the finding that the HMD lets participants look towards the patient for more time. We assess the prospects for HMDs in clinical contexts.

In this paper we outline considerations that went into designing and executing a full-scale simulator-based summative evaluation of four different display configurations for presenting information about anesthetized patients to an anesthesiologist. Although patient simulators appear to provide a “natural laboratory” for evaluating medical device innovations and equipment interface concepts, the software underlying patient simulators can be unequal to the challenges posed by the need for good representation of patient physiology and good experimental control. Moreover, the opportunities that full-scale patient simulators can offer for completely interactive, event-driven scenarios can present problems for experimental control and can promote participant hypervigilance. We describe the design of our experimental scenarios, the challenges our scenarios posed for simulator software and how we overcame those challenges, the design of a distractor task, and the methodology used to ensure we collected behavioral data sensitive to the manipulations of interest. Our adaptations in the face of challenges posed by the full-scale simulator context let us design an experiment that was highly informative about the advantages and disadvantages of the display configurations of interest.

Theoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial saturation should improve as the venous oxygen extraction per ml of blood decreases if the total oxygen consumption remains constant. Previous work demonstrated that this was not achieved with adrenaline or isoprenaline as increased shunting negated any benefit from improved cardiac output and mixed venous oxygen content. However, pharmacological stimulation of cardiac output and venous oxygen without any increase in shunt should achieve the goal of improved arterial oxygenation. To test this hypothesis, seven pigs were subjected to one-lung ventilation and infused on separate occasions, with dopamine and with dobutamine in random order to increase the cardiac output. The mixed venous oxygen content, shunt fraction, oxygen consumption and arterial oxygen saturation were measured. With both dopamine and dobutamine there was a consistent rise in venous oxygen content. However, with dopamine, the mean shunt rose from 28% to 42% and with dobutamine, the mean shunt rose from 45% to 59% (both changes P It is concluded that any benefit to arterial saturation which might occur from a dopamine- or dobutamine-induced increase in mixed venous oxygen content during one-lung ventilation is offset by increased shunting. During one-lung anaesthesia, there would appear to be no benefit to arterial saturation in increasing cardiac output with an infusion of either dopamine or dobutamine.

Accidental bronchial intubation was examined in the first 3947 cases reported to the Australian Incident Monitoring Study and was found to have accounted for 154 (3.7%) of the total incidents reported. Most incidents were detected in the operating theatre (93.5%) and during maintenance of anaesthesia (77.9%), by unexplained oxygen desaturation alone (63.6%). Capnography remained normal or unremarkable during 88.5% of the episodes. One-third of cases were associated with head or neck surgery and possible flexion of the patient's head. A RAE tube was used in 20% of incidents, a greater frequency than occurred in the study overall. A third party was implicated in 36 (23.4%) of cases. Ninety per cent of cases were considered preventable. Major morbidity occurred in three cases and unplanned intensive care admission was required in a further five. Almost two-thirds (61.1%) of the incidents might have been avoided by the proposed markings on the tracheal tube. We conclude that when arterial desaturation occurs at any stage during anaesthesia the possibility of bronchial intubation must be considered. Asymmetrical ventilation may be difficult to detect clinically and in most cases there is no change in capnography.

Tissue irritation, as evidenced by phlebitis, associated with Optiva™ (Johnson & Johnson Medical) and Insyte™ (Becton Dickinson) polyurethane cannulae was studied. The integrity of the cannulae on removal, the incidence of infection at the cannula site and the factors which influence phlebitis were also examined. One thousand and eight patients had a polyurethane cannula placed for induction of anaesthesia for cardiac surgery. After surgery, the cannula was examined every 24 hours. If evidence of phlebitis occurred, the cannula was removed and sent for culture. All remaining cannulae were removed at 72 hours and the site examined daily for a further three days. There were 503 Optiva™ and 505 Insyte™ cannulae studied. The distributions between the two cannulae with respect to patient characteristics, gauge of cannula, number of attempts and difficulty of insertion, cannula site and anaesthetist inserting were similar. The early removal rate for both groups was 47%. Overall phlebitis rate with Optiva™ was 31% and Insyte™ 33%. This difference is not statistically significant. The cumulative phlebitis rate increased with time but did not differ between the two types of cannulae. Minor tip distortion or shaft kinking of the cannulae occurred in 16.2% of Optiva™ and 23.5% of Insyte™. This difference is statistically significant and may relate to the slightly more acute taper at the Optiva™ cannula tip. Both cannulae were similar in clinical performance.

Summary The clinical pharmacodynamics of temazepam were investigated in patients who received spinal anaesthesia. Total plasma and cerebrospinal fluid temazepam concentrations were measured and correlated with the clinical effects. Sedation was measured by three separate methods. None, including an aggregated score of all three measures, was correlated closely with either the plasma or the cerebrospinal fluid levels (p = 0.86 and 0.12 respectively). Anxiety was measured before and after premedication. The two scores were correlated but the change in anxiety after premedication did not correlate with either the plasma or the cerebrospinal fluid concentrations (p = 0.11 and 0.45 respectively). Short-term memory was measured before and after premedication. The decline in short-term memory ability was moderately well correlated with both the plasma and the cerebrospinal fluid levels (p = 0.0005 and 0.013 respectively). With temazepam, the variation in sedative and anxiolytic effects between subjects is explained not by differences in pharmacokinetics but rather by differences in the pharmacodynamic response. Because sedative and anxiolytic effects are poorly correlated, but the amnesic effect is well correlated with temazepam concentrations, different sites of action for these effects are suggested.

We audited patients with anaphylaxis to muscle relaxants during anaesthesia referred to the Department of Anaesthesia at the Royal Adelaide Hospital between the start of 2000 and the end of 2009. Of the 220 patients tested during this period, 43 had a positive intradermal test to the muscle relaxant given during their anaesthetic. The majority of these were to rocuronium and suxamethonium. Where rocuronium was the index agent, 65% of patients cross-reacted with another relaxant and 29% of patients with suxamethonium as their index agent demonstrated cross-reaction with another relaxant.

Lungs that have been hypoxic and hypoperfused because of atelectasis and the resulting decrease in pulmonary arterial blood flow develop specific decreases in manganese superoxide dismutase (MnSOD) activity and are sensitive to oxidant injury during reoxygenation. Since the MnSOD protein is concentrated in mitochondria of alveolar epithelial type II cells (ATII), we hypothesized that expression of MnSOD would be decreased in these cells also as a result of hypoxia. To investigate whether regulation of MnSOD expression occurred before or after transcription, we determined whether MnSOD protein content or steady-state mRNA level changed after hypoxia as well. ATII cells were isolated by elastase digestion from lungs of adult rabbits after right lungs had been hypoxic and hypoperfused for 7 days because of unilateral atelectasis. MnSOD activity was measured by inhibition of cytochrome c reduction in the presence of 1 mM KCN, MnSOD protein content was measured on immunoblots, and MnSOD mRNA was quantified on slot blot autoradiograms. MnSOD activity was 8.4 +/- 1.9 U/mg protein in ATII cells from control lungs and 6.8 +/- 1.5 U/mg protein in ATII cells from hypoxic and hypoperfused lungs (n = 9, P = 0.037). MnSOD protein content was 5.1 +/- 1.4 micrograms/mg protein in ATII cells from control and 4.1 +/- 1.2 micrograms/mg protein in ATII cells from hypoxic and hypoperfused lungs (P = 0.021). ATII cell MnSOD mRNA/18S ribosomal RNA (ratio of arbitrary absorbance units) determined by RNA slot blots was 2.18 +/- 1.26 in ATII cells from control lungs and 2.94 +/- 0.88 in ATII cells from hypoxic lungs (n = 7, P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

There were 19 cases of air embolism (1%) among the first 2000 incidents reported to the Australian Incident Monitoring Study. No embolism-induced fatalities were reported. Serious acute systemic effects occurred in 14 incidents; one circulatory arrest required electrical counter-shock. The surgical field was the entry route for the air in 63% of the incidents; 47% of the cases occurred during head and neck surgery. Capnography was the most successful first detector (26%) and it confirmed the diagnosis in another 26%. Invasive blood pressure monitoring, the electrocardiograph and the pulse oximeter played a useful role in detecting and/or confirming air embolism. Doppler monitoring was not reported in this series. A successful first response for management included head-down posture, manual ventilation, 100% oxygen and control of the air entry site. Cerebral arterial gas embolism may induce vascular endothelial damage and possible delayed neurological sequelae; hyperbaric oxygen therapy should be considered.

The role of monitors in patients undergoing general anaesthesia was studied by analysing the first 2000 incidents reported to the Australian Incident Monitoring Study; 1256 (63%) were considered applicable to this study. In 52% of these a monitor detected the incident first; oximetry (27%) and capnography (24%) detected over half of the monitor detected incidents, the electrocardiograph 19%, blood pressure monitors 12%, a low pressure (circuit) alarm 8%, and the oxygen analyser 4%. Of the other monitors used, 5 first detected 1–2% of incidents, and the remaining 8 less than 0.5% each. The oximeter would have detected over 40% of the monitor detected incidents had its more informative modulated pulse tone always been relied upon instead of the “bleep” of the ECG. A theoretical analysis was then carried out to determine which of an array of 17 monitors would reliably have detected each incident had each monitor been used on its own and had the incident been allowed to evolve. To facilitate “scoring” of monitors, the incidents were categorized empirically into 60 clinical situations; 40% of applicable incidents were accounted for by only 5 clinical situations, 60% by 10 and nearly 80% by 20. 98% were accounted for by the 60 situations. A pulse oximeter, used on its own, would theoretically have detected 82% of applicable incidents (nearly 60% before any potential for organ damage). These figures for capnography are 55% and 43 % and for oximetry and capnography combined are 88% and 65%, respectively. With the addition of blood pressure monitoring these become 93% and 65%, and of an oxygen analyser, 95 and 67%. Other monitors, including the ECG, each increase the yield by by less than 0.5%. The international monitoring recommendations and those of the Australian and New Zealand College of Anaesthetists are thoroughly vindicated by the patterns revealed in this study. The priority sequence of monitor acquisition for those with limited resources should be stethoscope, sphygmomanometer, oxygen analyser if nitrous oxide is to be used, pulse oximeter, capnograph, high pressure alarm, and, if patients are to be mechanically ventilated, a low pressure alarm (or spirometer with alarm); an ECG, a defibrillator, a spirometer and a thermometer should be available.

The first 2000 incidents reported to the Australian Incident Monitoring Study (AIMS) were analysed with respect to the role of the electrocardiograph (ECG). Of these, 138 (7%) were first detected by the ECG. Of the 1256 incidents which occurred in association with general anaesthesia (GA incidents) 48% were “human detected” and 52% “monitor detected”, the ECG was ranked third and detected 121 (19%) of these monitor detected GA incidents. However over 98% of incidents first detected by the ECG were heart rate changes; they would also have been detected by a pulse meter or pulse oximeter which would have supplied additional information about the adequacy of peripheral perfusion. The ECG is a “first-line” monitor in situations with the potential for myocardial ischaemia, complex dysrhythmias or altered myocardial conduction and should be used in all critically ill patients as well as those at significant risk of these problems. The ECG frequently detects incidents involving minor physiological trespass, such as simple heart rate and rhythm changes associated with anaesthetic agents. These incidents are generally detected relatively early in their evolution. AIMS data has confirmed, however, that the ECG has such poor sensitivity for serious physiological changes such as hypoxia, hypercarbia and hypotension that it cannot even be regarded as a useful “back-up” monitor for these problems. Indeed a “normal” ECG in a dangerous situation may lead to a degree of complacency. Because the anaesthetist cannot differentiate between these minor and serious causes of ECG changes, it was decided, for a theoretical analysis, that although the ECG used on its own would have detected 55% of the 1256 GA incidents, had they been allowed to evolve, it could not be assumed that it would do so without potential for organ damage. The ECG may be regarded as an adjunct to, but does not replace, an oxygen analyser, pulse oximeter, capnograph, or high pressure alarm. An ECG should always be available but need not be used for young fit patients unless specifically indicated.

A review of the first 2000 incidents reported to the Australian Incident Monitoring Study found 317 incidents which involved problems with ventilation. The major portion (47%) were disconnections; 61% of these were detected by a monitor. Monitor detection was by a low circuit pressure alarm in 37% but this alarm failed to warn of non-ventilation in 12 incidents (in 6 because it was not switched “on” and in 6 because of a failure to detect the disconnection). Failure of detection was usually with ventilator bellows descending in expiration. Complete failure to ventilate occurred in 143 incidents, most commonly because of a disconnection. Disconnection was associated, in one-third of the cases, with interference to the anaesthetic circuit by a third party and in nearly half with surgery on the head and neck. Leaks affected ventilation in 129 incidents, but in only 19 was ventilation totally lost; leaks associated with seal failure of the absorber were common. Misconnections occurred in 36 incidents, most commonly involving the scavenging system. The frequency of a complete failure to check an anaesthetic machine was greater when an induction room was involved than when only the operating theatre was the site of the incident. These incidents suggest that meticulous checking and monitoring for failure of ventilation, preferably using at least two separate, self-activating systems is highly desirable. The Australian and New Zealand College of Anaesthetists’ policy on low circuit pressure alarms, oximetry and capnography is vindicated by these reports.

Human error is a pervasive and normal part of everyday life and is of interest to the anaesthetist because errors may lead to accidents. Definitions of, and the relationships between, errors, incidents and accidents are provided as the basis to this introduction to the psychology of human error in the context of the work of the anaesthetist. Examples are drawn from the Australian Incident Monitoring Study (AIMS). An argument is put forward for the use of contemporaneous incident reporting (eliciting relevant contextual information as well as details of use to cognitive psychologists), rather than the use of accident investigation after the event (with the inherent problems of scant information, altered perception and outcome bias). A classification of errors is provided. “Active” errors may be classified into knowledge-based, rule-based, skill-based and technical errors. Different strategies are required for the prevention of each type and it may now be useful to place more emphasis in anaesthetic practice on categories to which little attention has been directed in the past. “Latent” errors make an enormous contribution to problems in anaesthesia and several categories are discussed (e.g. environment, physiological state, equipment, work practices, personnel training, social and cultural factors). An approach is provided for the prevention and management of errors, incidents and accidents which allows clinical problems to be categorized, the relative importance of various contributing factors to be established, and appropriate preventative strategies to be devised and implemented on the basis of priorities determined from the AIMS data. Accidents cannot be abolished; however, an understanding of the factors underlying them can lead to the rational direction of resources and effort to prevent them and minimise their effects.

The first 2000 incidents reported to the Australian Incident Monitoring Study were analysed with respect to problems with the endotracheal tube; 189 (9%) were reported. The most common problem was endobronchial intubation which accounted for 42% of these 189 reports; endobronchial intubation was the most common cause of arterial desaturation in the 2000 incidents. Obstructions and oesophageal intubation each accounted for 18% of the 189 problems with tubes. The remainder was made up of disconnections and leaks (7% each), misplacements other than endobronchial or oesophageal (4%), inappropriate choice of tube (3%), cuff herniation (1%), failure to deflate the cuff and foreign body in the tube (0.5% each). The pulse oximeter and capnograph first detected 58% of these incidents; a further 25% were detected clinically. The pulse oximeter is the “front-line” monitor for endobronchial intubation, and the capnograph the “front-line” monitor for oesophageal intubation, disconnection and obstruction. Recommendations are made for how to prevent problems and how to determine the nature of those that do occur.

There were 57 reports of possible allergic reactions in the perioperative period in the first 2000 incidents reported to the Australian Incident Monitoring Study. These were examined and classified with respect to presentation, clinical course, agents implicated and management strategies employed. Reactions were graded as to probability of allergic aetiology and severity of systemic disturbance. Two deaths were reported. A method of determining an “allergy score” was devised as an indication of which reactions may be most deserving of further investigation.

The IL482 CO-Oximeter uses four wavelengths of visible light to analyze blood samples for the relative percentages of oxy-, carboxy-, reduced, and met-hemoglobin. In the analysis, the absorption at each of the wavelengths is multiplied by a matrix of four coefficients to derive the quantities of the four hemoglobin types. The normal settings of the CO-Oximeter coefficients are those for adult human hemoglobin. However, animal blood can be measured provided that the appropriate matrix of coefficients is available. Instrumentation Laboratory has provided sets of coefficients for several animal species. The company has also published a protocol for determining coefficients for other animal species. This protocol was examined using sheep hemoglobin-A blood and found to be inaccurate. The IL482 protocol is unsatisfactory because, if the initial error is large, successive iterations to determine the coefficient matrix through revision of the estimates of residual hemoglobin types do not converge. With sheep type-A hemoglobin, the use of human coefficients for the initial estimate gave a value of 6%, whereas, by chromatography, the carboxyhemoglobin (COHb) was 0.12% (i.e., a better initial estimate would be zero). When this was done, the final COHb estimate on "as-drawn" blood was within 1% of the COHb measured independently by gas chromatography. Revision of the protocol gave a markedly better accuracy, within 2% for COHb over the whole range when tested against mixtures of CO and O2 tonometered blood.(ABSTRACT TRUNCATED AT 250 WORDS)

A 37-year-old woman sustained a ruptured pericardium and two lacerations of the left atrial appendage in an automobile accident. Simple suture repair of the atrial appendage was achieved after clamping the base of the left atrium to control the bleeding.

When the vectors of force required to close the ideal surgical wound arc analysed, it is apparent that suture tension varies with the pattern of suture. For a given closing force, perpendicular interrupted sutures have the least tension. Symmetrical continuous sutures require greater suture tension, and this increases the more the suture is aligned with the direction of the wound. Asymmetrical (perpendicular/diagonal) continuous suturing requires more tension than interrupted sutures but this never exceeds 200%. Symmetrical suturing has slightly less tension than asymmetrical suturing when the spacing is about equal to the width of the suture. However, as the spacing ratio increases to greater than 2, the tension in the symmetrical suture rises very sharply. At a length: width ratio of 4. the symmetrical suture tension is about 70% greater than the same asymmetrical suturing.

Summary Hyperkalaemic periodic paralysis is the rarer of the two forms of potassium-associated familial paralysis. We report a family with hyperkalaemic periodic paralysis with paramyotonia and the anaesthetic management of four affected members. In three of these, paralytic episodes had been precipitated by previous anaesthesia, but this was avoided in the anaesthetics described. We conclude from our experiences that with depletion of potassium before surgery, prevention of carbohydrate depletion, avoidance of potassium-releasing anaesthetic drugs and maintenance of normothermia, patients with hyperkalaemic periodic paralysis can be anaesthetised without complications. We have no evidence that they exhibit abnormal sensitivity to nondepolarising neuromuscular relaxants.

Summary Twenty-six patients received oral temazepam and subsequently spinal anaesthesia. Blood and lumbar cerebrospinal fluid temazepam levels were measured together with the degree of sedation. The plasma and cerebrospinal fluid concentrations correlated well with the temazepam dose but even better with the weight standardised dose (r = 0.65, p = 0.0003 and r = 0.75, p = p = 0.00001 respectively). Both the plasma and cerebrospinal fluid concentrations of temazepam were correlated with the patient's sedation (r = 0.42 p = 0.037, and r = 0.46 p = 0.021 respectively), but neither was strong. Thus, although the drug concentration at the receptor may be a major factor in producing sedation, others factors, possibly the receptor population or their responsiveness, are also important contributors.

A new technique is described to aid in achieving a correct blind insertion of an endobronchial tube. The tube is selected by length to fit the distance from the patient's mouth to carina. As the tube is inserted, the position of the endobronchial cuff is monitored. This is done by inflating the bronchial cuff in the trachea and after each breath, advancing the tube down the trachea until only one lung is inflated. This accurately identifies the bronchial cuff as just beyond the carina, at the entrance to the main bronchus. From here, the tube can be advanced precisely into the bronchus to give the optimal conditions for isolation of the right and left lungs.

The effect of intermittent positive airway pressure to the non-ventilated lung was assessed in 10 patients who desaturated during one-lung ventilation. Once their saturation fell below 95% they were given a slow inflation of 2 l/min of oxygen into the non-ventilated lung for two seconds. This was repeated every 10 seconds for five minutes or until the saturation rose to 98%, whichever was sooner. The initial mean SpO2, was 89.3% ±4.2%. All 10 patients had an increase in saturation. The mean saturation following intermittent positive airway pressure was 96.5%±1.6% (P Intermittent positive airway pressure should be considered for patients who desaturate while undergoing one-lung ventilation.

Profound hypotension and cardiac arrest after commencement of combined spinal and general anaesthesia in a patient for knee replacement surgery raised the suspicion of anaphylaxis. This seemed to be confirmed when a mast cell tryptase test taken about 90 minutes after the onset of the hypotension was elevated. However, subsequent intradermal skin testing twelve weeks later did not identify a causal drug. Repeat mast cell tryptase at the time showed the same elevation, which led to the correct diagnosis of mastocytosis and a secondary diagnosis that the patient's hypotension and cardiac arrest were the result of her spinal anaesthesia. If the serum tryptase is elevated during the event but no allergic agent can be identified, a further serum tryptase should be taken several weeks later to exclude a persistent elevation due to mastocytosis.

The left tracheobronchial double-lumen tube is the commonest device to separate the left and right lungs for differential ventilation. With the appropriate tube, the left bronchial cuff is positioned in the bronchus so that the cuff is beyond the carina but the tip of the tube does not occlude the aperture of the left upper lobe bronchus. The difference between the length of the left main bronchus and the length of the cuff and tip of the bronchial segment of the tube has been termed “the margin of safety” by Benumof. If the length of the cuff plus the tip exceeds that of the left main bronchus, there will be occlusion of the left upper lobe bronchus. The bronchial cuff and bronchial tip lengths were measured on two hundred and twenty left tracheobronchial (double-lumen) tubes from four manufacturers. The largest cuff-tip length was 40 mm with a Portex 41Fr tube but some 41Fr tubes from all manufacturers had cuff-tip lengths of 33 mm or greater which exceed the length of the shortest left main bronchus measured by Benumof. There was also a marked variation in cuff-tip lengths of the same size tube from the same manufacturer. The largest variation was 18 mm for the Portex 41 but substantial variation of 8 mm or more was found in at least one French size of all manufacturers. Users must be aware that significant cuff-tip length variation occurs and match the selected tube to the patient to ensure an adequate margin of safety.

We examined the effect of no music, classical music or rock music on simulated patient monitoring. Twenty-four non-anaesthetist participants with high or low levels of musical training were trained to monitor visual and auditory displays of patients' vital signs. In nine anaesthesia test scenarios, participants were asked every 50-70 s whether one of five vital signs was abnormal and the trend of its direction. Abnormality judgements were unaffected by music or musical training. Trend judgements were more accurate when music was playing (p = 0.0004). Musical participants reported trends more accurately (p = 0.004), and non-musical participants tended to benefit more from music than did the musical participants (p = 0.063). Music may provide a pitch and rhythm standard from which participants can judge changes in vital signs from auditory displays. Nonetheless, both groups reported that it was easier to monitor the patient with no music (p = 0.0001), and easier to rely upon the auditory displays with no music (p = 0.014).

We reviewed the use of advanced display technologies for monitoring in anesthesia. Researchers are investigating displays that integrate information and that, in some cases, also deliver the results continuously to the anesthesiologist. Integrated visual displays reveal higher-order properties of patient state and speed in responding to events, but their benefits under an intensely timeshared load is unknown. Head-mounted displays seem to shorten the time to respond to changes, but their impact on peripheral awareness and attention is unknown. Continuous auditory displays extending pulse oximetry seem to shorten response times and improve the ability to time-share other tasks, but their integration into the already noisy operative environment still needs to be tested. We reviewed the advantages and disadvantages of the three approaches, drawing on findings from other fields, such as aviation, to suggest outcomes where there are still no results for the anesthesia context. Proving that advanced patient monitoring displays improve patient outcomes is difficult, and a more realistic goal is probably to prove that such displays lead to better situational awareness, earlier responding, and less workload, all of which keep anesthesia practice away from the outer boundaries of safe operation.

Residual muscle weakness after general anaesthesia, assessed using handgrip strength, was audited in a teaching hospital. The relationships between residual weakness, the use of muscle relaxants and patient characteristics were examined. Handgrip strength was measured preoperatively, one hour postoperatively and one day postoperatively using a hand dynamometer in 151 patients having general anaesthesia. Forty-nine patients received no muscle relaxant, 34 patients received vecuronium and 68 received rocuronium. Patients were managed by their anaesthetist according to that anaesthetist's clinical choice. All patients who received muscle relaxants received neostigmine. One hour postoperatively, there was a decline in handgrip strength of 16% for the no relaxant group, 24% for vecuronium and 29% for rocuronium. The degree of weakness for the relaxant groups was unrelated to age (P=0.89) but was strongly influenced by the patient's sex. Almost all of the increased weakness with relaxants was found in the female patients. The mean decline in handgrip strength in the male patients who received either vecuronium or rocuronium was similar to that seen when relaxants had not been used (P=0.40). One hour postoperatively, female patients showed a marked decrease in handgrip strength after both vecuronium and rocuronium (32% and 34% respectively, combined P=0.01). These results suggest that in usual clinical practice at our institution, female patients are more likely to have residual weakness after muscle relaxants.

The aim of this study, during one-lung ventilation, was to evaluate if oxygenation could be improved by use of a simple oxygen reservoir or application of 5 cmH2O continuous positive airway pressure (CPAP) to the non-ventilated lung compared with an open airway. Twenty-three patients with lung malignancy, undergoing thoracotomy requiring at least 60 minutes of one-lung ventilation before lung lobe excision, were studied. After routine induction and establishment of one-lung ventilation, the three treatments were applied in turn to the same patient in a sequence selected randomly. The first treatment was repeated as a fourth treatment and these results of the repeated treatment averaged to minimize the effect of slow changes.Arterial oxygenation was measured by an arterial blood gas 15 minutes after the application of each treatment. Twenty patients completed the study. Mean PaO2(in mmHg) was 210.3 (SD 105.5) in the “OPEN” treatment, 186.0 (SD 109.2) in the “RESERVOIR” treatment, and 240.5 (SD 116.0) in the “CPAP” treatment. This overall difference was not quite significant (P=0.058, paired ANOVA), but comparison of the pairs showed that there was a significant better oxygenation only with the CPAP compared to the reservoir treatments (t=2.52, P=0.021). While the effect on the surgical field was not apparent in most patients, in one patient surgery was impeded during CPAP. Our results show that the use of a reservoir does not give oxygenation better than an open tube, and is less effective than the use of CPAP 5 cmH2O on the non-ventilated lung during one-lung ventilation.

Patients sometimes notice an onion or garlic taste before losing consciousness with thiopentone. An assessment of 113 patients revealed that 42% of patients noticed this taste. The effect was observed less in older patients. There was no statistically significant difference in the incidence between men and women. Premedicated patients had a lower incidence, but this was explained by the greater proportion of older patients receiving a premedication. If the taste effect of thiopentone is genetically determined then it is a different gene to thiocarbamate which has about 75% tasters.

The diameter of the left main bronchus is the determining dimension when selecting the size of a left tracheobronchial (double-lumen) tube for lung separation. However, this information is not given by any manufacturer, either on the tube or in the package insert. This paper describes the lengths and diameters of the deflated bronchial cuff segment of left tracheobronchial tubes in common use. One hundred and seventy-one left tracheobronchial tubes ranging in size from 28 to 41 nominal French gauge from four manufacturers were measured. There was wide variation between tubes of the same nominal size from the same manufacturer. For tubes of the same size from the same manufacturer, the diameter of the segment with the deflated bronchial cuff varied by more than 1 mm in diameter in some instances.The diameter of the bronchial cuff segment did not consistently decrease as the nominal size decreased even for the same manufacturer. There was major overlap in diameters of the bronchial segments between Fr 41, Fr 39, and Fr 37 tubes from most manufacturers, so that some of the Fr 39 tubes have a bronchial cuff segment diameter as much as 0.5 mm larger than the Fr 41 tube. It is concluded that the current French gauge markings on left tracheobronchial tubes are of very limited value in determining the appropriate size to be selected for a patient. More accurate and consistent dimensions of tracheobronchial tubes are required to improve clinical selection.

A recent change from Haemaccel® to Gelofusin® as the preferred colloid for resuscitation in our region caused us to review patients who were known to be allergic to Haemaccel. As Gelofusin and Haemaccel are both modified gelatine, it seemed likely that cross reactivity could occur. Two patients who had been diagnosed previously as having had anaphylactic reactions to Haemaccel were tested intradermally with dilutions of 1/100 of Haemaccel and Gelofusin. Both patients showed similar positive reactions to each agent. It appears that patients who are known to be allergic to Haemaccel are probably allergic also to Gelofusin. Both patients have been given new Medic Alert bracelets stating “Allergic to Haemaccel and Gelofusin”.

Previous studies using animal models have demonstrated that carbon dioxide (CO2) pneumoperitoneum during laparoscopy is associated with adverse physiological, metabolic, immunological and oncological effects, and many of these problems can be avoided by the use of helium insufflation. The present study was performed in patients to compare the effect of helium and CO2 insufflation on intraperitoneal markers of immunological and metabolic function.Eighteen patients undergoing elective upper gastrointestinal laparoscopic surgery were randomized to have insufflation achieved by using either helium (n = 8) or CO2 (n = 10) gas. Intraperitoneal pH was monitored continuously during surgery, and peritoneal macrophage function was determined by harvesting peritoneal macrophages at 5 min and 30 min after commencing laparoscopy, and then assessing their ability to produce tumour necrosis factor-alpha (TNF-alpha), and their phagocytic function.Carbon dioxide laparoscopy was associated with a lower intraperitoneal pH at the commencement of laparoscopy, although this difference disappeared as surgery progressed. The production of TNF-alpha was better preserved by CO2 laparoscopy, but the insufflation gas used did not affect macrophage phagocytosis. Patients undergoing helium laparoscopy required less postoperative analgesia.The choice of insufflation gas can affect intraperitoneal macrophage function in the clinical setting, and possibly acid-base balance. The present study suggested no immunological advantages for the clinical use of helium as an insufflation gas. The outcomes of the present study, however, are different to those obtained from previous laboratory studies and further research is needed to confirm this outcome.

Theoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial haemoglobin oxygen saturation (SaO 2 ) should improve as the venous oxygen extraction per ml of blood decreases. To test this hypothesis, eight pigs were subjected to one-lung ventilation and adrenaline and isoprenaline infusions used to increase the cardiac output. The mixed venous oxygen, shunt fraction and oxygen consumption were measured. With both adrenaline and isoprenaline, although there was a small rise in mixed venous oxygen content, there was a fall in SaO 2. With adrenaline, the mean shunt rose from 48% to 65%, the mean oxygen consumption rose from 126 ml/min to 134 ml/min and the mean SaO 2 fell from 86.9% to 82.5%. With isoprenaline, the mean shunt rose from 45% to 59%, the mean oxygen consumption rose from 121 ml/min to 137 ml/min and the mean SaO 2 fell from 89.5% to 84.7%. It is concluded that potential improvement in SaO 2, which might occur from a catecholamine-induced increase in mixed venous oxygen content during one-lung ventilation, is more than offset by increased shunting and oxygen consumption which reduce SaO 2.

It has been suggested that the appropriate length of insertion for double-lumen tubes can be estimated by external measurement. This study examined the accuracy of external measurement in estimating the actual length of insertion required in 130 patients. It also examined the relationship between the length inserted and the patient's height in 126 patients and their weight in 125 patients. Although there was a fair correlation between the measured external length and the final inserted length (r=0.61), the 95% confidence intervals of slope and intercept allowed a large variation and the prediction was too wide to be clinically useful. Height was reasonably well correlated with the final length (r=0.51) but an equally wide 95% confidence interval rendered it of little clinical value. There was no correlation between weight and final tube length. It is concluded that external measurement alone is not adequate to predict a clinically acceptable position of the double-lumen tube.

Two hundred and six standard PA chest X-rays were measured. The mean diameter of the left main bronchus (LMB) was 12.6±1.9 mm. The mean diameter of the 92 male LMB was 13.0±2.6, and for females 11.8±1.6. These data correspond closely to that reported by others. The correlation between the diameter of the LMB and that of the trachea was 0.74 but was not precise enough to be useful as an estimate for clinical use. Similarly there was good correlation between the diameter of the right main bronchus and that of the left (r=0.75) but not precise enough to be clinically useful. In contrast to previous claims, only direct measurement of the left main bronchus has sufficient precision to define the appropriate size of left double-lumen tube to be selected for lung separation.

Glomerulopathic light chains (LCs) are associated with two distinct mesangiopathies: AL (light-chain-related) amyloidosis and light-chain deposition disease (LCDD) with immunomorphologic features that are well documented in the literature. Even though both conditions are caused by monoclonal LCs, these entities differ dramatically in their morphologic expressions. In AL amyloidosis the mesangial matrix is replaced by amyloid fibrils, while in LCDD the matrix increases as a consequence of deposition of excess extracellular matrix (ECM). The immunomorphologic mesangial alterations observed in biopsy material are closely reproduced in vitro when mesangial cells grown on an artificial matrix are incubated with monoclonal light chains obtained from the urine of patients with either condition. This article summarizes previously reported data, reports new findings, and focuses on integrating all the available information on the subject. When mesangial cells are incubated with LCDD-LCs, production of ECM proteins (collagen IV, laminin, fibronectin, and tenascin) is increased, with maximum effect at 72 hours post LC treatment. A concomitant decrease in collagenase IV activity further accentuates the accumulation of mesangial matrix. These effects are mediated through transforming growth factor-beta (TGF-beta) activation. In contrast, when mesangial cells are incubated with Am-LCs, a decrease in ECM protein production and a stimulatory effect on collagenase IV is observed, which results in matrix degradation and facilitates amyloid deposition. The decreased TGF-beta documented in the literature in this setting precludes adequate matrix repair. These findings substantiate the morphologic alterations observed in renal biopsy specimens and in the in vitro model. Using this in vitro model, it is then possible to delineate the LC interactions with putative receptors at the mesangial cell surface that regulate mesangial cell pathobiologic responses and mesangial matrix homeostasis.

Although the preoperative use of alpha-receptor antagonist drugs is generally accepted for patients with phaeo-chromocytoma, evidence on the most appropriate treatment and its timing is scarce. In this retrospective study, the effectiveness of the preoperative preparation of fourteen patients who required surgical excision of a phaeochromocytoma was examined in the light of their operative stability. A simple score was developed of blood pressure stability by scoring the need for additional antihypertensive agents intraoperatively before, and blood pressure support after, tumour removal. A higher score indicated greater instability. Twelve patients received phenoxybenzamine and their stability was superior to the two patients treated with labetalol and with prazosin. There was no correlation between the duration of treatment with phenoxybenzamine and the operative stability (r=0.18 P=0.55 Spearman). The five patients who were treated with phenoxybenzamine for longer than 10 days did not have better perioperative blood pressure stability than the five patients who had treatment for less than a week. Predictive factors for intra-operative blood pressure stability were also sought. The degree of postural hypotension after treatment with phenoxybenzamine did not predict operative stability (r=-0.31, P=0.33 Spearman). However, the peak total catecholamine level found during surgery correlated quite well with more operative instability (r=0.65, P=0.031, Spearman), suggesting that patients with phaeochromocytomas with high production of catecholamines are more likely to show cardiovascular instability.

Mitochondrial manganese-containing SOD (MnSOD) is located at the primary site of O2 metabolism, and its expression may be regulated by changes in O2 level. We hypothesized that lung MnSOD expression and promoter activity would decrease in response to hypoxia. We tested effects of hypoxia (10% O2 at sea level for 7 days) on chloramphenicol acetyltransferase (CAT) reporter and MnSOD gene expression in transgenic mice. The transgene consisted of a 3.3-kb portion of the rat MnSOD gene 5' flanking region coupled to a CAT reporter gene. Lung MnSOD activity in male (but not female) mice decreased significantly after hypoxia exposure. The decrease in MnSOD enzymatic activity in male mice was specific. Neither total SOD nor glucose-6-phosphate dehydrogenase (G-6-PDH) activity decreased significantly in hypoxia. CAT protein expression decreased in transgenic males exposed to hypoxia, while CAT protein expression in hypoxic transgenic females remained comparable with controls. The mRNA for both the native MnSOD and the MnSOD-CAT reporter genes remained constant after hypoxia, as did CuZnSOD and G-6-PDH mRNAs.

Although the mortality for coronary artery bypass graft surgery has declined, some categories of patients are still recognized as being at greater risk. Because the mortality, even for most patients with risk factors, is less than 10%, evaluating this risk and any improvement arising from changing techniques requires thousands of cases. The need for these large patient numbers makes the evaluation of changes difficult. Even when other risk factors are accounted for in the mortality estimate, the patient's age remains an important factor, although there is no obvious reason why this should be so. Similarly, female sex is well recognized as a risk factor. However, the tendency for women to have a smaller body surface area and corresponding smaller arterial diameters may be the explanation. Perfusion time appears to have a strong influence on mortality after it exceeds about 90 minutes, and a similar influence on myocardial infarction also appears to be present. The increased risk of myocardial infarction with unstable angina may relate to disruption of the normal endothelial vasodilatation caused by nitric oxide.

Abdominal ultrasonographic screening for cancer was performed in 6,001 Hiroshima and Nagasaki A-bomb exposed and comparison subjects, all members of the Adult Health Study of the Radiation Effects Research Foundation, formerly the Atomic Bomb Casualty Commission. This study yielded 20 cancers, including 7 hepatocellular, 3 gastric, 3 renal and 2 urinary bladder cancers; one cancer each of the ovary, pancreas, colon and ureter; and one cancer metastatic to the liver, whose primary was unknown. Seventeen of these 20 subjects manifested no symptoms or signs of their disease. A variety of additional tumors, unproven and probably benign, including uterine myomata, and other abnormalities were also detected. Abdominal ultrasonographic screening greatly assisted in the detection of cancers, most of which neither the patients nor their physicians were aware. In this screened fixed population sample the cancer detection rate was 0.33%, exceeding any such rates previously reported in the medical literature.

The role of monitors in patients undergoing general anaesthesia was studied by analysing the first 2000 incidents reported to the Australian Incident Monitoring Study; 1256 (63%) were considered applicable to this study. In 52% of these a monitor detected the incident first; oximetry (27%) and capnography (24%) detected over half of the monitor detected incidents, the electrocardiograph 19%, blood pressure monitors 12%, a low pressure (circuit) alarm 8%, and the oxygen analyser 4%. Of the other monitors used, 5 first detected 1-2% of incidents, and the remaining 8 less than 0.5% each. The oximeter would have detected over 40% of the monitor detected incidents had its more informative modulated pulse tone always been relied upon instead of the "bleep" of the ECG. A theoretical analysis was then carried out to determine which of an array of 17 monitors would reliably have detected each incident had each monitor been used on its own and had the incident been allowed to evolve. To facilitate "scoring" of monitors, the incidents were categorized empirically into 60 clinical situations; 40% of applicable incidents were accounted for by only 5 clinical situations, 60% by 10 and nearly 80% by 20. 98% were accounted for by the 60 situations. A pulse oximeter, used on its own, would theoretically have detected 82% of applicable incidents (nearly 60% before any potential for organ damage). These figures for capnography are 55% and 43% and for oximetry and capnography combined are 88% and 65%, respectively. With the addition of blood pressure monitoring these become 93% and 65%, and of an oxygen analyser, 95 and 67%. Other monitors, including the ECG, each increase the yield by by less than 0.5%. The international monitoring recommendations and those of the Australian and New Zealand College of Anaesthetists are thoroughly vindicated by the patterns revealed in this study. The priority sequence of monitor acquisition for those with limited resources should be stethoscope, sphygmomanometer, oxygen analyser if nitrous oxide is to be used, pulse oximeter, capnograph, high pressure alarm, and, if patients are to be mechanically ventilated, a low pressure alarm (or spirometer with alarm); an ECG, a defibrillator, a spirometer and a thermometer should be available.

The Australian Patient Safety Foundation was formed in 1987; it was decided to set up and co-ordinate the Australian Incident Monitoring Study as a function of this Foundation; 90 hospitals and practices joined the study. Participating anaesthetists were invited to report, on an anonymous and voluntary basis, any unintended incident which reduced, or could have reduced, the safety margin for a patient. Any incident could be reported, not only those which were deemed “preventable” or were thought to involve human error. The Mark I AIMS form was developed which incorporated features and concepts from several other studies. All the incidents in this symposium were reported using this form, which contains general instructions to the reporter, key words and space for a narrative of the incident, structured sections for what happened (with subsections for circuitry incidents, circuitry involved, equipment involved, pharmacological incidents and airway incidents), why it happened (with subsections for factors contributing to the incident, factors minimising the incident and suggested corrective strategies), the type of anaesthesia and procedure, monitors in use, when and where the incident happened, the experience of the personnel involved, patient age and a classification of patient outcome. Enrolment, reporting and data-handling procedures are described. Data on patient outcome are presented; this is correlated with the stages at which the incident occurred and with the ASA status of the patients. The locations at which the incidents occurred and the types of procedures, the sets of incidents analysed in detail and a breakdown of the incidents due to drugs are also presented. The pattern and relative frequencies of the various categories of incidents are similar to those in “closed-claims” studies, suggesting that AIMS should provide information of relevance to those wishing to develop strategies to reduce the incidence and/or impact of incidents and accidents.

Human error is a pervasive and normal part of everyday life and is of interest to the anaesthetist because errors may lead to accidents. Definitions of, and the relationships between, errors, incidents and accidents are provided as the basis to this introduction to the psychology of human error in the context of the work of the anaesthetist. Examples are drawn from the Australian Incident Monitoring Study (AIMS). An argument is put forward for the use of contemporaneous incident reporting (eliciting relevant contextual information as well as details of use to cognitive psychologists), rather than the use of accident investigation after the event (with the inherent problems of scant information, altered perception and outcome bias). A classification of errors is provided. "Active" errors may be classified into knowledge-based, rule-based, skill-based and technical errors. Different strategies are required for the prevention of each type and it may now be useful to place more emphasis in anaesthetic practice on categories to which little attention has been directed in the past. "Latent" errors make an enormous contribution to problems in anaesthesia and several categories are discussed (e.g. environment, physiological state, equipment, work practices, personnel training, social and cultural factors). An approach is provided for the prevention and management of errors, incidents and accidents which allows clinical problems to be categorized, the relative importance of various contributing factors to be established, and appropriate preventative strategies to be devised and implemented on the basis of priorities determined from the AIMS data. Accidents cannot be abolished; however, an understanding of the factors underlying them can lead to the rational direction of resources and effort to prevent them and minimise their effects.