Scrutinizing incident reporting in anaesthesia: why is an incident perceived as critical?

BACKGROUND: The purpose of the present study was to measure the incidence and type of incidents that occurred in relation to anaesthesia and surgery during a 1-year period in six Danish hospitals. Furthermore, we wanted to identify risk factors for incidents, as well as risk factors for incidents being deemed critical. METHODS: A four-page questionnaire describing patient data, type of anaesthesia and surgery, and occurrence of incidents was filled in for all anaesthesias in the period, and subsequently processed. The incident reporting form incorporated 59 predefined adverse events. The occurrence of one or more of these events described the incident. When the reporting anaesthetist deemed that an incident had harmed the patient, that incident was defined as critical. RESULTS: A total of 64,312 anaesthesias were reported, and in 7754 of them one or more incidents occurred. A total of 8510 incidents occurred, 4077 of them were solely related to the anaesthetic procedure, 3702 described events related to physiological alterations in the patient (physiological incidents). Three hundred and twenty-three of the incidents were deemed critical. High ASA score, high age, abdominal surgery, urgent surgery, and complex anaesthetic procedure were significant risk factors for physiological incidents and critical incidents. We could not identify a simple subset of adverse events that could adequately be used to describe the critical incidents. However, complex incidents, i.e. incidents involving more than one adverse event, were more likely to be deemed critical than simple incidents. CONCLUSION: The incidence of incidents was 12.1%, and the incidence of critical incidents was 0.5%. Incidents were more likely to be deemed critical in patients with an ASA score of III and above undergoing urgent surgery.

ICP is lower during propofol anaesthesia compared to isoflurane and sevoflurane.

OBJECTIVES: Propofol is a cerebral vasoconstrictor while inhalation anaesthetics like isoflurane and sevoflurane act as cerebral vasodilators in both animal and human studies. This difference of action upon cerebral vessels might implicate a lower ICP during propofol anaesthesia. Cerebral metabolism is decreased by all three anaesthetics. In a prospective, randomised multicenter study ICP was compared during anaesthesia with propofol, isoflurane and sevoflurane. METHODS: 117 patients subjected to elective craniotomy for supratentorial tumour. Propofol: N = 41; isoflurane: N = 38; sevoflurane: N = 38. Nitrous oxide was omitted and all anaesthetics were supplemented with a continuous infusion of fentanyl. ICP was measured subdurally after removal of the bone flap. MABP, CPP, PCO2, AVDO2, rectal temperature, tumour size and midline shift were registered too. STATISTICS: Kruskal-Wallis Variance on Ranks. All values in medians with range. P < 0.05 was considered significant. RESULTS: ICP (mmHg): propofol 7 (-1-20), isoflurane 12 (1-29), sevoflurane 11 (2-32). ICP was significantly lower in the propofol group compared to the isofluane and sevoflurane groups. CPP (mmHg): propofol 80 (45-104), isoflurane 60 (32-84), sevoflurane 63 (44-77). CPP was significantly higher in the propofol group compared to the isoflurane and sevoflurane groups. AVDO2 (mmol/l): propofol 3.1 (0.9-5.1), isoflurane 2.5 (1.1-4.5), sevoflurane 2.6 (0.8-4.1). AVDO2 was significantly higher in the propofol group compared to the isoflurane and sevoflurane groups. No significant differences in PCO2, rectal temperature, tumour size and midline shift were found. CONCLUSIONS: Subdural ICP is significantly lower during propofol anaesthesia compared to isoflurane and sevoflurane anaesthesia. CPP and AVDO2 are significantly higher during propofol anaesthesia compared to isoflurane and sevoflurane anaesthesia.

Subdural monitoring of ICP during craniotomy: thresholds of cerebral swelling/herniation.

It is possible to define thresholds for cerebral swelling or herniation during craniotomy. In 178 patients subjected to craniotomy for space occupying processes subdural ICP was measured before opening of dura. The subdural ICP was correlated to the degree of cerebral swelling or herniation after opening of dura. At subdural ICP < 7 mm Hg cerebral swelling/herniation after opening of dura rarely occurs, while at ICP > or = 10 mm Hg cerebral swelling/herniation occurs with high probability. These ICP thresholds are independent of the pathophysiology (SAH, cerebral tumor), the anaesthetic agent (isoflurane, propofol) and the PaCO2 level (< or = 4.0 kPa, > 4.0 kPa). Generally, a good correlation between the tactile estimation of dural tension and the tendency to cerebral swelling or herniation after opening of dura was found. However, in 8.5% the surgeons were unable to predict swelling/herniation.

ICP during anaesthesia with sevoflurane: a dose-response study. Effect of hypocapnia.

In patients with a supratentorial cerebral tumor, an increase in sevoflurane concentration from 1.5% (0.7 MAC) to 2.5% (1.3 MAC) did not change the intracranial pressure (ICP) significantly (12 to 14 mm Hg (medians)). However, a significant increase in cerebral blood flow (CBF) from 29 to 39 ml/100 g/min (medians) was disclosed. During administration of sevoflurane 1.5% and 2.5%, a significant decrease in ICP (3.5 and 3.0 mm Hg (median) respectively) was found when PaCO2 was decreased by 0.8 kPa.

Effects of sevoflurane on intracranial pressure, cerebral blood flow and cerebral metabolism. A dose-response study in patients subjected to craniotomy for cerebral tumours.

BACKGROUND: Studies concerning the cerebrovascular effects of sevoflurane in patients with space-occupying lesions are few. This study was carried out as a dose-response study comparing the effects of increasing sevoflurane concentration (1.5% (0.7 MAC) to 2.5% (1.3 MAC)) on cerebral blood flow (CBF), intracranial pressure (ICP), cerebrovascular resistance (CVR), metabolic rate of oxygen (CMRO2) and CO2-reactivity in patients subjected to craniotomy for supratentorial brain tumours. METHODS: Anaesthesia was induced with propofol/fentanyl/atracurium and maintained with 1.5% sevoflurane in air/oxygen at normocapnia. Blood pressure was maintained constant by ephedrine. In group 1 (n = 10), the patients received continuously 1.5% sevoflurane. Subdural ICP, CBF and CMRO2 were measured twice at 30-min intervals. In group 2 (n = 10), sevoflurane concentration was increased from 1.5% to 2.5% after CBF1. CBF2 was measured after 20 min during 2.5% sevoflurane. Finally, CO2-reactivity was studied in both groups. RESULTS: In group 1, no time-dependent alterations in CBF, CVR, ICP and CMRO2 were found. In group 2, an increase in sevoflurane from 1.5% to 2.5% resulted in an increase in CBF from 29 +/- 10 to 34 +/- 12 ml 100 g-1 min-1 and a decrease in CVR from 2.7 +/- 0.9 to 2.3 +/- 1.2 mmHg ml-1 min 100 g (P < 0.05), while ICP and CMRO2 were unchanged. CO2-reactivity was maintained at 1.5% and 2.5% sevoflurane. CONCLUSION: Sevoflurane is a cerebral vasodilator in patients with cerebral tumours. Sevoflurane increases CBF and decreases CVR in a dose-dependent manner. CO2-reactivity is preserved during 1.5% and 2.5% sevoflurane.

[Data and quality assurance tools from a new cardiac center in Denmark]. / Data samt kvalitetsstyringsredskab fra et nyt hjertecenter i Danmark.

Open heart surgery was established at Aalborg Hospital in 1992. In the time period March to December 1992 cardiac anaesthesia was administered in 98 operations utilizing extracorporeal circulation and cardiopulmonary bypass. Mortality in coronary artery surgery was 1.6%. All patients were prospectively registered using a new dataform allowing registration of 228 patients related variables concerning preoperative status, course of anaesthesia and perfusion, surgery and postoperative intensive care. Quality assurance in cardiac surgery requires risk factor analysis, and registration of numerous data is a necessary tool. The software for our database system has been developed and programmed using the database programme dBASE IV from the Ashton/Tate Corporation.

[Cardiac events after myocardial infarction treated with streptokinase. The prognostic value of symptom-limited ECG on day 7]. / Kardiale begivenheder efter streptokinasebehandlet myokardieinfarkt. Den prognostiske voerdi af symptomlimiteret arbejds-ekg på syvendedagen.

One hundred and forty-seven consecutive patients admitted with suspected acute myocardial infarction (AMI) were treated with streptokinase. On day 7 after AMI 107 patients performed a symptom-limited exercise test (bicycle ergometer). Thirty-four of the tested patients developed at least one cardiac event (reinfarction, cardiac death, decided myocardial revascularization) during follow-up (30 months). Exercise induced ST-depression was more frequent among patients with cardiac events than among those without cardiac events (chi 2-test, p < 0.05). With multiple logistic regression analysis (BMPD) the following variables were found to have independent prognostic value for the development of new cardiac events: low maximal heart-rate during the exercise test, long duration of acute symptoms before streptokinase treatment and male sex. Exercise-induced ST-depression had no prognostic value in the BMPD-analysis. Exercise testing can be carried out with safety and supplies prognostic information concerning future cardiac events in patients with streptokinase-treated AMI.

[The accuracy and reproducibility of clinical examination of adenoma of the thyroid--corrected for randomness with iota and kappa]. / Rigtighed og reproducerbarhed ved klinisk undersøgelse for adenomer i glandula thyreoidea--korrigeret for tilfaeldighed med "iota" og "kappa".

The aim of this study was to evaluate the reliability (accuracy and observer variability) of the clinical examination of the thyroid gland for adenomatous changes. All patients (n = 105) admitted for scintigraphic examination of the thyroid gland were examined by three observers and the thyroid scintigraphy was performed. The study population consisted of the patients (n = 84), where the result of the scintigraphic examination could be classified as either "normal" (n = 24), "solitary adenoma" (n = 32) or "nodular goitre" (n = 28), with scintigraphy used as golden standard. The accuracy was evaluated using each observer's sensitivity, specificity and total agreement with the golden standard for each diagnosis and the observer variability by the overall agreement between each pair of observers. After random agreement was eliminated by calculation of iota and kappa, the results showed a fair reliability of the clinical diagnoses "normal" and "solitary adenoma" (iota between 0.20 and 0.62; kappa between 0.33 and 0.46), but poor reliability for "nodular goitre", (iota between 0.00 and 0.50, kappa between 0.00 og 0.46). Calculation of the newly introduced iota is discussed in the appendix.

An evaluation of the accuracy of clinical diagnosis at admission in a population with epidemic meningococcal disease.

The accuracy (sensitivity and positive predictive value) of the clinical diagnosis given by the general practitioner before admission to hospital was evaluated retrospectively in a population with epidemic meningococcal disease. The study population consisted of approximately 32,000 subjects. In a 12-year period, 344 patients were discharged from hospital with CNS infections, 274 of whom were admitted with a diagnosis suspecting a CNS infection. A further 401 patients were admitted with suspicion for, but discharged without a CNS infection. Overall, the sensitivity was 79.7% and the positive predictive value was 40.6%. There were no significant changes in the accuracy during the study. The sensitivity differed significantly between the age groups (P less than 0.001) and was lowest among the adults (15+ years, 67.9%) and the 0-2-year-old children (72.7%). Also among the 0-2 year-olds, the positive predictive value was low (34.1%) and not significant, indicating that it was more difficult to obtain the correct clinical diagnosis in this group.