Considerations for the Perioperative Care of Elderly and Frail Patients.

The number of elderly patients undergoing anesthesia is increasing. At the same time aging is associated with decreased functional reserve of all major organ systems and an increase in comorbid conditions, requiring a comprehensive perioperative evaluation to minimize morbidity and mortality. The preoperative assessment should focus on the risk/benefit analysis vis-à-vis the proposed intervention, allowing the practitioner to adapt surgical and anesthetic care, as well optimize health and functional status. In addition to the usual evaluation for cardiac and pulmonary risk, the preoperative assessment in the older patient should also address the risk of postoperative cognitive dysfunction and delirium. 'Do-not-resuscitate' orders must be clarified with the patients or substitute decision maker. Studies have not been able to clearly show the superiority of one anesthetic approach for the geriatric patient, although there are probably advantages to using regional anesthetic techniques. Overall the patient's preoperative functional status along with the proposed intervention is the primary determinants of the patient's long term functional outcome and wellbeing. The elderly patient may be at his most vulnerable during the postoperative phase, and a relatively high frequency of adverse events in the elderly, including respiratory insufficiency, myocardial and cerebrovascular ischemia, renal failure, infectious complications as well as delirium and postoperative cognitive dysfunction have been observed. Perioperative interventions should target modifiable risk factors and the avoidance of even minor complications with an ultimate goal of improving long-term outcome.

The validity of performance assessments using simulation.

BACKGROUND: The authors wished to determine whether a simulator-based evaluation technique assessing clinical performance could demonstrate construct validity and determine the subjects' perception of realism of the evaluation process. METHODS: Research ethics board approval and informed consent were obtained. Subjects were 33 university-based anesthesiologists, 46 community-based anesthesiologists, 23 final-year anesthesiology residents, and 37 final-year medical students. The simulation involved patient evaluation, induction, and maintenance of anesthesia. Each problem was scored as follows: no response to the problem, score = 0; compensating intervention, score = 1; and corrective treatment, score = 2. Examples of problems included atelectasis, coronary ischemia, and hypothermia. After the simulation, participants rated the realism of their experience on a 10-point visual analog scale (VAS). RESULTS: After testing for internal consistency, a seven-item scenario remained. The mean proportion scoring correct answers (out of 7) for each group was as follows: university-based anesthesiologists = 0.53, community-based anesthesiologists = 0.38, residents = 0.54, and medical students = 0.15. The overall group differences were significant (P < 0.0001). The overall realism VAS score was 7.8. There was no relation between the simulator score and the realism VAS (R = -0.07, P = 0.41). CONCLUSIONS: The simulation-based evaluation method was able to discriminate between practice categories, demonstrating construct validity. Subjects rated the realism of the test scenario highly, suggesting that familiarity or comfort with the simulation environment had little or no effect on performance.

Testing internal consistency and construct validity during evaluation of performance in a patient simulator.

UNLABELLED: The primary goal of this study was to test the items in a rating system developed to evaluate anesthesiologists' performance in a simulated patient environment. A secondary goal was to determine whether the test scores could discriminate between resident and staff anesthesiologists. Two 5-item clinical scenarios included patient evaluation and induction and maintenance of anesthesia. Rating scales were no response to the problem (score = 0), compensating intervention (score = 1), and corrective treatment (score = 2). Internal consistency was estimated using Cronbach's coefficient alpha. Scores between groups were compared using the Cochran-Mantel-Haenszel test. Subjects consisted of 8 anesthesiology residents and 17 university clinical faculty. The Cronbach's coefficient alpha was 0.27 for Scenario A and 0.28 for Scenario B. Two items in each scenario markedly decreased internal consistency. When these four items were eliminated, Cronbach's coefficient alpha for the remaining six items was 0.66. Faculty anesthesiologists scored higher than residents on all six items (P < 0.001). A patient simulator-based evaluation process with acceptable reliability was developed. IMPLICATIONS: The reliability of anesthesia clinical performance in a patient simulation environment was assessed in this study. Of 10 items, 4 were poor in the evaluation process. When these items were removed, the reliability of the instrument improved to a level consistent with other studies. Because faculty scored higher than resident anesthesiologists, the instrument also showed discriminant validity.

Cardiac arrest in the OR: how are our ACLS skills?

PURPOSE: While advanced cardiac life support (ACLS) training is widely available, it is not mandatory for all anaesthetists. We hypothesised that adherence to ACLS guidelines during resuscitation of ventricular fibrillation (VFib) as assessed in a simulator environment would be poor by anaesthetists not trained in ACLS compared with those who had received training. METHODS: With approval by the ethics review board, 89 subjects participated in the study. The simulation system consisted of a computer controlled mannequin with lifelike qualities set in a mock operating room. Each subject was given a test scenario that contained several standard anaesthetic problems. A VFib cardiac arrest occurred after approximately one hour into the simulation. A perfect score (score = A) defined complete compliance with the ACLS guidelines, whereas minor deviations (score = B) included changes in energy levels, drug doses or treatment order. The failure to discontinue the anaesthetic, defibrillate or administer epinephrine were considered major deviations (score = C). RESULTS: Eight subjects followed the ACLS guidelines (9%, score = A), while 27 subjects showed minor (30%, score = B) and 54 subjects major deviations (61%, score = C). Sixty-two of the 89 participants (70%) had taken the ACLS course and achieved higher scores than did anaesthetists without such training (P < 0.05). Forty-two participants (47%) did not discontinue the anaesthetic, 10 (11%) never gave epinephrine and 5 (6%) never used the defibrillator. CONCLUSION: Adherence to ACLS guidelines was poor. A greater proportion of subjects without previous ACLS training had deviations from protocol than did subjects who had received training. We need to consider ways to ensure that anaesthetists obtain and retain resuscitation skills according to ACLS guidelines.

The cost for construction and operation of a simulation centre.

PURPOSE: Lack of financial information results in planning difficulties and may delay the introduction of simulator based education. We collected data from an existing simulation centre and describe a construction and operating budget to facilitate planning and construction for interested institutions. METHODS: After obtaining approval from the managing board, the plans and financial statements of the Canadian Simulation Centre, Sunnybrook Health Science Centre, University of Toronto were reviewed from the period from July 1994 through June 1996. Costs were calculated from the financial reports and separated into construction and operation phases. A list of the ongoing educational and research activities was compiled. RESULTS: All dollar figures are expressed in 1996 Canadian Dollars. The planning and construction took place from July 1994 through June 1995. Construction costs for the simulation centre totalled $665,000, of which 85% was related to capital equipment purchases and 15% for salary support. The net costs of ongoing education and research activities (3.35 days/week) were $167,250 from July 1995 through June 1996. About 65% of this consisted of salary support and was absorbed by the existing educational resources of the University of Toronto Department of Anaesthesia. CONCLUSION: Substantial resources are required for the construction of a simulation centre ($665,000) primarily use of capital equipment purchases. However, there is also a considerable operating cost per year ($167,250) which consists mostly of salary support.

Testing the raters: inter-rater reliability of standardized anaesthesia simulator performance.

PURPOSE: Assessment of physician performance has been a subjective process. An anaesthesia simulator could be used for a more structured and standardized evaluation but its reliability for this purpose is not known. We sought to determine if observers witnessing the same event in an anaesthesia simulator would agree on their rating of anaesthetist performance. METHODS: The study had the approval of the research ethics board. Two one-hour clinical scenarios were developed, each containing five anaesthetic problems. For each problem, a rating scale defined the appropriate score (no response to the situation: score = 0; compensating intervention defined as physiological correction: score = 1; corrective treatment: defined as definitive therapy score = 2). Video tape recordings, for assessment of inter-rater reliability, were generated through role-playing with recording of the two scenarios three times each resulting in a total of 30 events to be evaluated. Two clinical anaesthetists, uninvolved in the development of the study and the clinical scenarios, reviewed and scored each of the 30 problems independently. The scores produced by the two observers were compared using the kappa statistic of agreement. RESULTS: The raters were in complete agreement on 29 of the 30 items. There was excellent inter-rater reliability (= 0.96, P < 0.001). CONCLUSIONS: The use of videotapes allowed the scenarios to be scored by reproducing the same event for each observer. There was excellent inter-rater agreement within the confines of the study. Rating of video recordings of anaesthetist performance in a simulation setting can be used for scoring of performance. The validity of the scenarios and the scoring system for assessing clinician performance have yet to be determined.

Anaesthesia crisis resource management training: an intimidating concept, a rewarding experience.

PURPOSE: This two-part study was performed to identify and address anaesthetists' concerns regarding anaesthesia simulation and to evaluate the response of practitioners to simulation-based Anaesthesia Crisis Resource Management Training (ACRM). METHODS: First, 150 survey questionnaires were distributed to participants of the Anaesthesia Practice '94 meeting in Toronto and to staff and resident anaesthetists at the Sunnybrook Health Science Centre. In the second part of the study, 35 anaesthetists from the Toronto area who participated in Anaesthesia Crisis Resource Management (ACRM) workshops at the Canadian Simulation Centre completed an anonymous exit evaluation questionnaire. RESULTS: Among staff anaesthetists (n = 42), 19% of the surveyed respondents had never heard about anaesthesia simulation, whereas all residents (n = 17) had heard of, or seen an anaesthesia simulator. Horizontal numerical scale ratings (from 1-10, with 10 being extremely supportive) indicated support for the purchase of a simulator (8.3 +/- 2.0 for staff, 9.2 +/- 1.1 for residents). Staff and residents anticipated substantial anxiety while training with a simulator (6.8 +/- 2.4 and 7.6 +/- 1.4 respectively, with 10 indicating extreme anxiety). Participants in the ACRM workshops at the Canadian Simulation Centre enjoyed the course (1.2 +/- 0.6, on a scale form 1 through 5, with 1 indicating total support and 5 representing no support), felt that it would be beneficial to most anaesthetists (1.2 +/- 0.5) and should be taken, on average, every 18 mo. CONCLUSIONS: Even though the majority of respondents have not been exposed to anaesthesia simulators, they appear to support their use in education strongly. Whereas substantial anxiety could delay the introduction of simulation based education, participants of ACRM workshops enjoy the courses and perceive them as very educational.

In vivo lipopolysaccharide pretreatment inhibits cGMP release from the isolated-perfused rat lung.

Administration of bacterial lipopolysaccharide (LPS) to rats stimulates synthesis of nitric oxide (NO), a free radical molecule that activates soluble guanylate cyclase, thereby increasing intracellular guanosine 3',5'-cyclic monophosphate (cGMP) concentration and inducing systemic vasodilatation. To investigate the effect of endotoxemia on the pulmonary NO/cGMP signal transduction system, we measured the release of cGMP by isolated-perfused lungs of rats that received an intraperitoneal injection of LPS (1 mg/kg) or saline 2 days earlier. Over 90 min, 1.4 +/- 0.78 and 0.079 +/- 0.016 nmol cGMP accumulated in pulmonary perfusates of saline- and LPS-treated rats, respectively (P < 0.05). Despite addition to the perfusate of Zaprinast, superoxide dismutase, or A23187, markedly less cGMP was released from the lungs of rats exposed to LPS than from the lungs of control rats. In contrast, after ventilation with 100 parts per million NO gas, cGMP accumulating in the perfusate of the lungs of both groups of rats was markedly increased, and the quantity of cGMP released from the lungs of LPS-treated rats was similar to that released by control rat lungs (2.8 +/- 0.57 vs. 3.3 +/- 0.88 nmol, P = NS). With the use of immunoblot techniques, equal concentrations of constitutive endothelial NO synthase were detected in the lungs of rats treated with saline or LPS. These results demonstrate that the NO/cGMP signal transduction system is abnormal in the lungs of rats exposed to LPS, at least in part, at the level of endothelial NO synthase activation.

Inhaled nitric oxide does not alter endotoxin-induced nitric oxide synthase activity during rat lung perfusion.

Nitric oxide (NO) has been demonstrated to decrease its own synthesis in tissue preparations. We tested the hypothesis that endogenous NO synthesis induced by lipopolysaccharides (LPS) would be decreased by exogenous NO during isolated lung perfusion. Rats were pretreated with either saline or LPS 48 h before lung harvest. Endogenous NO synthase activity was measured as conversion of L-[14C]-arginine to L-[14C]citrulline during 90 min of perfusion. NO (100 ppm) was added to the ventilating gas during perfusion of lungs from one group of control or LPS-treated rats. A second group of control or LPS-treated rats was exposed chronically to 100 ppm NO for the 48 h before lung harvest, in addition to receiving 100 ppm NO added to the ventilating gas during lung perfusion. We conclude that conversion of L-[14C]arginine to L-[14C]citrulline was minimal in control lungs and increased in response to LPS pretreatment. NO added to the ventilating gas for the 90 min of ex vivo perfusion did not alter the rate of L-[14C]citrulline production. In vivo exposure to 100 ppm NO for 48 h did not alter the induction of inducible NO synthase activity as measured during ex vivo lung perfusion. This indicates that inhaled NO does not exert negative-feedback inhibition on inducible NO synthase in the ex vivo rat lung.

Platelet factor 4 injection produces acute pulmonary hypertension in the awake lamb.

BACKGROUND: Reversal of heparin anticoagulation by intravenous protamine sulfate consistently produces acute pulmonary vasoconstriction mediated by the release of thromboxane in the awake lamb. Recently, recombinant platelet factor 4 (rPF4) has been cloned, expressed in Escherichia coli, and infused to reverse heparin anticoagulation in the rat, without producing adverse hemodynamic or pulmonary morphologic effects. The authors sought to learn whether intravenous administration of PF4 is devoid of side effects in the pulmonary circulation of lambs. METHODS: The authors evaluated the hemodynamic response and plasma release rates of thromboxane during intravenous challenges with heparin-rPF4 (n = 2), rPF-free carrier (n = 5), rPF4 (n = 5), rPF4 after indomethacin (n = 5), protamine (n = 5) and heparin-protamine (n = 5) in 17 awake, hemodynamically monitored lambs. Each lamb underwent up to three random challenges with a 2-h recovery period between each challenge. RESULTS: In two lambs, systemic anticoagulation with heparin followed by reversal of anticoagulation with an intravenous bolus of rPF4 (4 mg/kg) led to acute pulmonary vasoconstriction and hypertension with the release of thromboxane (peak pulmonary artery pressure [Ppa] 40 and 33 mmHg and peak plasma thromboxane B2 50 and 30 ng/ml, respectively). Intravenous administration of rPF4 (1.5 mg/kg) alone increased the Ppa from 17.2 +/- 0.7 mmHg (mean +/- SEM) at baseline to 31.2 +/- 2 mmHg at 1 min (n = 5, P < 0.05). This was associated with an increase of plasma thromboxane B2 from 0.06 +/- 0.02 to 3.96 +/- 1.21 ng/ml. Acute pulmonary vasoconstriction lasted approximately 5 min and was completely prevented by pre-treatment with oral indomethacin (10 mg/kg). Intravenous bolus administration of rPF4 carrier (n = 5) or protamine (2 mg/kg) alone (n = 5) did not induce pulmonary hypertension or the release of thromboxane. In five lambs, intravenous heparin (200 U/kg) followed by protamine (2 mg/kg) consistently produced acute pulmonary vasoconstriction and hypertension. CONCLUSIONS: Intravenous injection of human rPF4 into the awake lamb produces acute pulmonary vasoconstriction and hypertension associated with thromboxane release into circulating blood. The effects of rPF4 on the pulmonary vasculature should be evaluated in primates before rPF4 is substituted for protamine in reversing heparin anticoagulation in humans.