Crisis management during anaesthesia: awareness and anaesthesia.

BACKGROUND: Patient awareness during general anaesthesia has considerable potential for severe emotional distress in the patient as well as professional, personal, and financial consequences for the anaesthetist. OBJECTIVES: To examine the role of a previously described core algorithm "COVER ABCD-A SWIFT CHECK", supplemented by a specific sub-algorithm for awareness, in the detection and management of potential awareness in association with general anaesthesia. METHOD: The potential performance of this structured approach for each of the relevant incidents among the first 4000 reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual management as reported by the anaesthetists involved. RESULTS: Of the first 4000 reports received by AIMS, there were 21 incidents of patient awareness under general anaesthesia, and 20 of patients being paralysed while awake from "syringe swaps" before induction of anaesthesia. In 12 of the 21 reports there was an obvious cause, most commonly a low concentration of volatile agent (8 of 12 reports). The AIMS "core" crisis management algorithm would have detected the cause of awareness in all of these cases. In nine reports the course of anaesthesia appeared unremarkable, and in these the algorithm would not have been expected to detect or prevent awareness. Volatile agent monitoring would have prevented some cases of awareness, as would bispectral index electroencephalographic (BIS) monitoring. The role of BIS monitoring is still contentious, but it should be considered for high risk patients. CONCLUSION: Awareness should be minimised by thorough checking of equipment, particularly vaporisers, and frequent application of a structured scanning routine. Awareness may occur during crisis management and aftermath protocols should include patient follow up to detect and manage awareness when it occurs.

Trauma: development of a sub-algorithm.

BACKGROUND: Anaesthetists are regularly involved in the management of patients who have suffered trauma. Acute physiological derangements can occur at any time after the original injury, with life threatening sequelae. These problems may be complex in nature and evolve rapidly, often with an obscure aetiology, so a systematic approach to them is essential. OBJECTIVES: To examine the role of a previously described core algorithm "COVER ABCD-A SWIFT CHECK" supplemented by a specific sub-algorithm for trauma, in the management of anaesthesia involving trauma cases. METHODS: The potential performance of a structured approach for each of the trauma incidents among the first 4000 incidents reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual performance as reported by the anaesthetists involved. RESULTS: There were 38 relevant reports relating to trauma in the first 4000 reports to AIMS. In 39% of these there was "emergency corner cutting", although in the majority the urgency was thought to have been more perceived than real. The previously described "core" crisis management algorithm for crises during general anaesthesia was an effective means of discovering (82%), diagnosing (68%), and correcting (66%) the majority of trauma incidents. However a sub-algorithm specific for the traumatised patient was required for unusual, obscure, or complex presentations. CONCLUSION: Although the small numbers preclude validation of the sub-algorithm, it would have successfully managed all the trauma cases reported to AIMS.

Crisis management during anaesthesia: sepsis.

BACKGROUND: Anaesthesia with concurrent sepsis is risky, and involves consideration of possible organ dysfunctions-respiratory, cardiovascular, renal, and haematological--as well as ensuring that appropriate antibiotics are given after taking the necessary microbiological specimens. Because prompt attention needs to be paid to so many body systems, the place for a structured approach during anaesthesia for a septic patient was assessed. OBJECTIVES: To examine the role of a previously described core algorithm "COVER ABCD-A SWIFT CHECK", supplemented by a specific sub-algorithm for sepsis, in the management of sepsis occurring in association with anaesthesia. METHODS: The potential performance of this structured approach for each of the relevant incidents among the first 4000 reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual management as reported by the anaesthetists involved. RESULTS: Sepsis was identified as the primary problem in 13 of the first 4000 reports (<1%) to AIMS. The incidents reported generally occurred in sick patients; 70% were ASA status III or worse. The COVER ABCD algorithm provided a diagnosis and corrective manoeuvre in only 15% (2/13) of reported incidents, and the sepsis sub-algorithm provided adequate therapeutic strategies in a further 38% (5/13) of the incidents. Eight cases required the use of additional sub-algorithms for desaturation (30%), cardiac arrest (15%), hypotension (8%), and aspiration (8%). CONCLUSION: Sepsis involves a serious physiological stress upon multiple organ systems. The use of a structured approach involving a core algorithm and additional sub-algorithms as required provides a series of checklists that can successfully deal with the complex multiple and interrelating problems that these patients present.

Monitored patient-controlled sedation: practical technique or academic research tool?

Monitored patient-controlled sedation (MPCS) is a technique that allows patients to administer intravenous sedatives, under the supervision of an anaesthetist, to achieve a level of conscious sedation that meets their individual requirements. Experience to date has shown that this technique is effective and highly acceptable to patients. Propofol is an appropriate choice of agent for MPCS. Criteria for such agents include short arm-brain circulation time, which results in a rapid and clearly defined onset of action. The MPCS technique offers a number of benefits to the patient and the theatre staff.

Laparoscopic cholecystectomy as a day surgery procedure.

Outcome is presented for 40 consecutive laparoscopic cholecystectomies performed in a public teaching hospital day surgery unit. The unanticipated hospital admission rate on the day of surgery was 17.5% (seven patients) and the majority of these (12.5%; five patients) were due to surgery-related considerations. Two other admissions were due to nausea and vomiting. One patient was admitted to hospital on the second postoperative day with nausea and vomiting. Procedure duration for the day cases averaged 98 minutes (SD25; range 60-167). Recovery room times before discharge averaged 272 minutes (SD 58; range 125-365). Each day surgery patient averaged 3.3 postoperative home visits from community nurses. Most patients (94%) mobilized at home by the second postoperative day and 85% resumed normal activities of daily living by two weeks. At follow-up, 25 patients (76%) stated they were happy to spend the first night at home, but seven (21%) would have preferred to remain in hospital for the first postoperative night. Laparoscopic cholecystectomy can be performed successfully as a day-case procedure, but long operating and recovery room times and potentially high admission rates suggest that these factors should be considered in cost equations for day-case management of this procedure.

The relationship between clinical effect and concentrations of temazepam in plasma and cerebrospinal fluid.

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.

Outcome from day-case knee arthroscopy in a major teaching hospital.

Outcome is presented for 465 knee arthroscopies performed under general anesthesia in a public teaching hospital day surgery unit. The unanticipated hospital admission rate on the day of surgery was 1.07%. There were 11 (2.37%) major complications in the combined perioperative and postdischarge periods (up to 4 weeks postdischarge). Surgery-related complications (incidence 1.08%) were more frequent than complications of anesthesia (0.65%). Four patients (0.86%) had delayed complications after discharge that required hospital readmission. Stepwise polychotomous logistic regression showed that these complications were not significantly related to patient age, sex, American Society of Anesthesiologists (ASA) status or type of surgery. Mean recovery times required for patients to sit out of bed and to be ready for discharge were 61 +/- 37 and 142 +/- 52 min, respectively. Both postoperative pain and postoperative nausea and vomiting, present in 76% and 11.5% of patients, respectively, significantly delayed patient recovery, with longer delays associated with nausea and vomiting. Times required for patients to be ready for discharge were not correlated to either patient age (r = 0.07; p = 0.15) or duration of procedure (r = 0.07; p = 0.13). At early follow-up, 4.7% and 2.5% of patients had presented to hospital accident and emergency departments and local family doctors, respectively, usually for minor problems. Ninety-nine percent of all patients were happy with the ambulatory surgery service. With careful patient assessment and selection, day-case knee arthroscopy in a teaching hospital can provide satisfactory outcome.

Intra-operative patient-controlled sedation and patient attitude to control. A crossover comparison of patient preference for patient-controlled propofol and propofol by continuous infusion.

Intra-operative patient controlled sedation with propofol (bolus dose 18 mg over 5.4 s; lockout period 1 min) has been compared to continuous propofol infusion (3.6 mg.kg-1.h-1) in a randomised crossover study of 38 ASA 1 or 2 day surgery patients undergoing two-stage bilateral extraction of third molar teeth under local anaesthesia (76 procedures). Mean (SD) propofol used (mg.kg-1) was less with patient-controlled sedation (2.39 (1.28) than with the infusion (2.58 (0.84)) but the difference was not statistically significant. There were only minor differences between the methods in postoperative recovery of cognitive function and no differences for patient cooperation and surgeon's satisfaction with sedation. Patient-controlled sedation was preferred by 19 patients, continuous infusion by 10, with nine indifferent. Preferences, expressed as mild, moderate or strong, were significantly stronger for patient-controlled sedation (p < 0.05). Sedation was no deeper than eyelid closure with response to command in all 76 procedures. This level was reached in all 38 infusion cases but in only 26 cases with patient-controlled sedation, where 12 patients remained less sedated (p < 0.01). Patient-controlled sedation with propofol provided safe sedation and was strongly preferred over the infusion by a large proportion of patients.

Outcome after day-care surgery in a major teaching hospital.

Outcome has been measured for 6000 consecutive procedures in a major public teaching hospital day surgery unit. The unanticipated hospital admission rate was 1.34% and surgery-related admissions (0.95%) exceeded those related to anaesthesia (0.13%). Perioperative complications related to surgery (1:105) were more frequent than those related to anaesthesia (1:176) and pre-existing medical problems (1:500). Anaesthesia-related complications were more frequent with general anaesthesia (1:114) than with local anaesthesia plus sedation (1:780) or regional anaesthesia (1:180). Recovery times after general anaesthesia were longer than after other anaesthetic techniques but did not correlate with patient age (r = 0.04; P = 0.02) and only weakly correlated with procedure duration (r = 0.21; P < 0.01). At early follow-up, 4.0% of patients had presented to a local medical practitioner and 3.1% to a hospital accident and emergency service, usually for minor problems. Take home analgesia was adequate for 95% of patients and 98.9% were happy with the day surgery service. Day surgery in a teaching hospital can provide satisfactory outcome, with low complication rates, high patient acceptance and low community support requirements after patient discharge.

The Australian Incident Monitoring Study. Recovery room incidents in the first 2000 incident reports.

Of the first 2000 incidents reported to the Australian Incident Monitoring Study 120 (6%) occurred in the recovery room after general, regional or local anaesthesia. Over two thirds (69%) of these involved the respiratory system, 19% were cardiovascular, 3% involved the central nervous system and 9% were miscellaneous in nature. These recovery room incidents were associated with significantly more adverse outcomes (56%) than incidents in the operating theatre (24%). The types and relative frequencies of these recovery room incidents were similar to those of serious recovery complications in a recent analysis of closed malpractice claims; this suggests that incident monitoring may be useful in the study and prevention of recovery room complications. Over three quarters (77%) of all recovery incidents (and 88% of respiratory incidents) were detected clinically; the remainder were first detected by a monitor. A theoretical analysis showed that over 95% of respiratory events, had they been allowed to evolve, would have been detected by pulse oximetry before organ damage occurred, emphasising the potential importance of pulse oximetry in reducing adverse outcome from any complication in the recovery ward which might be "missed" by clinical observation. The findings of this study underline the importance of having an adequate number of trained recovery nursing staff supported by the availability of a pulse oximeter for each patient at least until the return of protective reflexes and the ability to maintain adequate arterial saturation has been established.

The Australian Incident Monitoring Study. Patient awareness during anaesthesia: an analysis of 2000 incident reports.

Amongst the first 2000 incidents reported to the Australian Incident Monitoring Study were 16 cases in which patient recall of perioperative events was consistent with awareness. Awareness that occurred in 3 of 10 cases during anaesthesia was attributed to low concentrations of volatile anaesthetic agent; the conduct of anaesthesia appeared to be unremarkable in the other 7. The remaining 6 cases involved the inadvertent paralysis of patients prior to induction of anaesthesia, most commonly by "syringe swap" when suxamethonium was given instead of fentanyl. Some of these patients were significantly distressed. These preliminary findings suggest that incident monitoring should be useful in the study of awareness associated with anaesthesia and the development of strategies to prevent it.

The determination of absorption coefficients for measurement of carboxy-hemoglobin, oxy-hemoglobin, reduced hemoglobin, and met-hemoglobin in sheep using the IL482 CO-Oximeter.

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)

Outcomes after same-day oral surgery: a review of 1,180 cases at a major teaching hospital.

Outcome was measured from data collected on 1,180 consecutive ambulatory oral surgery patients, two thirds of whom were treated under general anesthesia and the remainder who were treated under local anesthesia supplemented with intravenous sedation. Three patients (0.25%) required admission on the day of surgery; all had undergone general anesthesia. The surgery-related complication rate in the general anesthesia group (1:132) was similar to that for local anesthesia and sedation (1:128). However, anesthesia-related complications had an incidence of 1:99 in the general anesthesia group, but were absent in those receiving local anesthesia and sedation. Eight patients (0.7%) required hospital readmission after being discharged, mostly because of complications of surgery. The incidence of postoperative nausea and vomiting in the recovery room after local anesthesia and sedation (6%) was less than after general anesthesia (14%) (P < .01) Average recovery times to sitting out of bed and being ready for discharge were less after local anesthesia and sedation (38 +/- 15 minutes and 120 +/- 39 minutes, respectively) than after general anesthesia (61 +/- 50 minutes and 141 +/- 62 minutes). At the time of follow-up during the first few postoperative days, 7% of patients had gone to a family doctor and 4% to hospital accident and emergency departments, usually for minor problems. Paracetamol 500 mg plus codeine phosphate 30 mg was effective in 97% of cases when provided as a take-home analgesic. Ninety-nine percent of patients were satisfied with their management.

Assessment and selection of patients for day surgery in a public hospital.

OBJECTIVE: To describe methods used for adult patient assessment and selection for day case surgery at a major Australian teaching hospital. DESIGN: A prospective analysis of assessment data and information from the unit's computerised database. PATIENTS AND SETTING: Five thousand day patients consecutively admitted to the Day Surgical Unit, Royal Adelaide Hospital. MAIN OUTCOME MEASURES: The proportion of patients assessed only by trained nursing assessment staff was determined and compared with that for patients requiring additional anaesthetic assessment before surgery. The percentage of patients requiring preoperative investigations was established. Unanticipated hospital admission rates were calculated for surgical, anaesthesia-related and social reasons. RESULTS: After initial screening by a trained assessment nurse, 46% of patients required additional review by an anaesthetist before the day of surgery. The remaining 54% were assessed by an anaesthetist on the day of surgery. Preoperative investigations were ordered by anaesthetists in 8.5% of all day patients. The assessment methods outlined resulted in a 1.28% rate of unanticipated hospital admissions. This admission rate was mostly caused by complications of surgery (0.94%). Only 0.12% of patients were admitted for anaesthesia-related reasons and 0.14% were admitted for social reasons. CONCLUSIONS: This cost-effective system allows suitable patients and procedures to be identified, with a satisfactory unanticipated hospital admission rate. Satisfactory assessment also results in short preoperative waiting periods, fewer cancellations, reduced postoperative problems and more satisfied patients. The development of an efficient assessment system is aided by the use of a dedicated day surgery area with experienced nursing staff, the use of a comprehensive patient questionnaire and coordination by experienced day surgery anaesthetists.

Double-blind comparison of patient recovery after induction with propofol or thiopentone for day-case relaxant general anaesthesia.

Postoperative recovery after induction with either propofol or thiopentone has been compared in forty ASA I unpremedicated day surgery patients undergoing surgical extraction of third molar teeth under relaxant general anaesthesia. Mean recovery times in the propofol group, required for patients to sit out of bed (44.8 minutes; SD 18.6) and meet discharge criteria (113.1 minutes; SD 34.5) were significantly (P less than 0.05) shorter than those in the thiopentone group (59.7 minutes; SD 21.4 and 133.5 minutes; SD 34.5). Fewer patients in the propofol group were treated in the recovery room for nausea and vomiting and the incidence of mild nausea not requiring treatment was less in the propofol group, but these differences were not statistically significant. Postoperative mental performance, measured by the FAST index, a new test of mental speed, was reduced on average by 1.7% of preoperative levels, during the recovery period tested, with no significant difference between the groups.

Intra-operative patient-controlled sedation. Comparison of patient-controlled propofol with patient-controlled midazolam.

Propofol and midazolam were compared for intra-operative patient-controlled sedation in 40 ASA 1 day patients undergoing surgical extraction of third molar teeth under local anaesthesia. All patients initially received 0.7 micrograms.kg-1 fentanyl. Patients in the propofol group self-administered 20 mg (2 ml over 6 s) bolus doses of propofol; successful demands averaged 8.0 (SD 4.4) and unsuccessful demands (during the 1 min lockout period) 2.8 (SD 4.1). The midazolam group self-administered 0.5 mg (2 ml over 6 s) bolus doses and averaged 14.0 (SD 6.3) and 17.6 (SD 19.8) successful and unsuccessful demands respectively. Postoperative memory, measured with delayed free recall, and postoperative mental performance, measured with the frequency accrual speed test index, were both significantly less impaired in the propofol group. Although there was no significant difference in patient satisfaction, measured postoperatively, propofol was judged the more suitable agent for patient-controlled sedation, because of its more rapid response to fluctuating intra-operative requirements, superior recovery characteristics and beneficial effect on mood.

The relationship between the concentration of temazepam in cerebrospinal fluid and sedation in man.

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 = 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, other factors, possibly the receptor population or their responsiveness, are also important contributors.

Intra-operative patient-controlled sedation. Comparison of patient-controlled propofol with anaesthetist-administered midazolam and fentanyl.

The quality of sedation and postoperative recovery have been assessed for intra-operative sedation provided by either patient-controlled sedation with propofol or a standard method using divided doses of midazolam and fentanyl, in 40 ASA 1 day surgery patients undergoing extraction of third molar teeth under local analgesia. Patient-controlled sedation with propofol produced sedation no deeper than full eyelid closure with prompt response to verbal command, but deeper levels were seen in three patients in the midazolam and fentanyl group. Patient satisfaction was higher in the patient-controlled sedation propofol group for both subjective intra-operative feelings (p less than 0.01) and willingness to have the procedure again in the same manner (p less than 0.05). Amnesia was more limited to intra-operative events (rather than extending into the postoperative period) in the patient-controlled sedation propofol group (p less than 0.05). Drug dose was correlated with duration of procedure and surgical difficulty in the patient-controlled sedation propofol group but not in the midazolam and fentanyl group. Postoperative testing included a new computerised test, the FAST index, which indicated a dose-dependent reduction in cognitive function in the midazolam and fentanyl group, which persisted until the time of discharge. Changes in cognitive function in the patient-controlled sedation propofol group in the same postoperative interval were significantly less and not related to propofol dose.

Fluid uptake in laser endometrial ablation.

Fluid uptake was measured from accurate preoperative and postoperative patient weights for 25 consecutive patients undergoing Nd:YAG laser endometrial ablation under general anaesthesia. One patient had a uterine perforation with 5.1 litres of fluid deposited in the peritoneal cavity. In the remaining 24 cases, maximum fluid uptake was 5.1 litres, three patients absorbed more than four litres and eight absorbed more than two litres. In those same 24 patients, the mean fluid uptake was 1.5 litres (SD 1.6) and six patients without tubal ligation had a higher mean uptake (2.2 litres, SD 1.7) than the eighteen with surgically occluded Fallopian tubes (1.3 litres, SD 1.4) but the difference was not statistically significant. Fluid uptake has the potential to cause significant morbidity in this procedure. Both procedure duration and volume of uterine irrigation fluid were poor predictors of fluid gain. Observation of the ongoing volume deficit between infused and collected fluid provided intraoperative monitoring of fluid gain that prevented complications from fluid overload in healthy patients. However, this method of monitoring fluid uptake may be insufficient to prevent either complications from glycine absorption, if glycine is used for irrigation, or fluid overload in patients with cardiac disease.