Department of Anaesthesia and Intensive Care, University Hospital of Trondheim, N-7006 Trondheim, Norway sigurd.fasting@medisin.ntnu.no
Accepted for publication: July 30, 2002
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Abstract |
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Methods. The study is based on a system in which anaesthesia-related data are recorded from all anaesthetic cases on a routine basis. The data include intraoperative problems and their severity. When a problem occurs, the anaesthetist responsible for the case writes a short description of the event on the anaesthetic chart. From all recorded cases of general and regional anaesthesia, we selected cases recorded with anaesthetic equipment/technical problems. These charts were retrieved from departmental archives for analysis.
Results. From 83 154 anaesthetics, we found the frequency of anaesthetic equipment problems to be 0.05% during regional anaesthesia, and 0.23% during general anaesthesia. One-third of problems involved the anaesthesia machine, and in a quarter, human error was involved. No patient died and none suffered any lasting morbidity.
Conclusion. The rate of equipment problems was low, and most often of low severity. Aside from improvements in routines for preoperative equipment checks, no specific strategies for problem reduction could be suggested. The incidence of equipment problems is not a good quality indicator because of the low rate of occurrence. However, recorded equipment problems may be useful for improving quality, by analysing causative factors, and suggesting preventative strategies.
Br J Anaesth 2002; 89: 82531
Keywords: anaesthesia; complications, equipment problems; quality improvement
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Introduction |
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Methods |
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One of the data fields is a check-box for intraoperative problems (Fig. 1), including a list of 22 common anaesthetic problems, and a field for the severity. One of the problems is equipment/technical problems. The anaesthetist responsible for the patient writes a short description of the event and marks the check-box accordingly. If the case was uneventful, this also must be indicated. Other data fields relate to the patient, the operation, type of anaesthetic, and timing of events.
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About 16 500 anaesthetics are given in our hospital each year, and most types of surgery are performed (Trondheim University Hospital, 960 beds, annual admission rate 43 000 patients, in 1999). In Norway, as in the rest of Scandinavia, the physician anaesthetist works in cooperation with a qualified nurse anaesthetist who has 18 months postgraduate education in anaesthesia. The doctor has the medical responsibility. Each morning the nurses do an extensive check of the anaesthesia machine according to departmental procedures. This check includes medical gas supplies, flow-meters, oxygen failure protection, vaporizers, machine/breathing system leakage, machine/breathing system function, ventilator, scavenging, suction and intubation equipment. Between patients a simpler check is performed. One nurse is working full-time to educate all staff on equipment issues, and the department engages two engineers for continuous maintenance and repair of equipment.
The charts recorded with anaesthetic equipment/technical problem were retrieved from our departmental archives. They were sorted according to the type of equipment involved and analysed by the authors according to frequency, severity and contributory factors. We analysed not only cases of true equipment failure where the equipment failed to perform as specified, but also equipment problems where human error, failure to check, or some form of failing humanequipment interface was the most important factor. We did not include problems with surgical equipment or technical problems with anaesthetic or surgical procedures.
For categorical data, we used a 2-test or Fishers exact test as appropriate. We used a
2-test for trend for testing trends in binomial proportions.13 P<0.05 was considered statistically significant.
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Results |
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Types of equipment involved (Table 3)
One-third of the problems (49/157) occurred with the anaesthesia machine, with the most common problem being leakage from, and misconnection of, the breathing system (n=24). Other problems included gas leakage from the vaporizermachine connection (n=7), leakage in the ventilator (n=8), and malfunction of the one-way valve.
The majority of other problems occurred with invasive and non-invasive arterial blood pressure monitoring equipment, and other monitoring equipment. Most of the problems with invasive arterial blood pressure equipment represented low readings from a radial artery cannula compared to the aortic cannula during cardiac surgery. However, measurement errors, drifting, and cable failure also occurred. Non-invasive arterial blood pressure equipment failure was also common, and related to technical failureincluding leaks from the tubing and cuff. Other problems related to malfunction of other monitors, and malfunction of the cardiopulmonary bypass machine during cardiac surgery.
Human error
About one-quarter of the equipment problems (n=40) were considered to be related to human error on the part of the users (Table 5). Twenty-nine of the problems concerned the anaesthesia machine, and of these, 18 were related to inadequate pre-use checks. Most of these errors occurred when the anaesthesia machine was checked between cases, rather than at the start of the day. Contributing factors were last-minute changes because of a change in schedule (change in type of breathing system, ventilator, or type of anaesthesia).
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Discussion |
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Methodology
In all incident reporting, under-reporting is a potential problem. This is related to the added workload from completion of forms, a belief that reporting is of limited value, and fear of consequences of reporting.1417 We believe that the reporting compliance in our study is good. All patients receiving an anaesthetic were followed, and included in the study. The incidents were recorded in a prospective manner, and as information from all cases was included, important events were less likely to be missed. This is in contrast to studies where information is collected only from selected samples of patients.
Our system is designed to add minimal workload, as all recording is done directly on the anaesthetic chart, and no additional form is needed. We are using the data actively in the department, for problem discussions and quality projects, and we have created a non-punitive attitude towards the occurrence of problems.12 All cases are recorded, the recording is obligatory, and both a physician and a nurse are involved in every case. The recording has been part of departmental routine for 15 yr, and definitions and severity assessment are continuously discussed in departmental meetings. Consequently, we believe that the agreement between observers is good. We also believe that the total frequency of problems and the frequency of equipment problems are representative of the occurrence of these problems in our practice, and are a result of routines for checking and maintenance of equipment in the department, and routines for follow-up when problems occur.
Frequency and severity of equipment problems
Four studies have been published representing mandatory reporting, with data recorded from all anaesthetic cases.811 Our results are of the same magnitude as those of Cohen and colleagues8 who found an incidence of 0.10.4% for equipment problems in 27 184 cases of anaesthesia from four different hospitals. In that study, a check-off form was completed for every patient, and 18 types of intraoperative problems were included in the data set. However, severity was not assessed. The frequency of total problems varied from 14.9% to 27.8% amongst the four hospitals.
Three studies have been published from a large German quality assurance project concerning perioperative incidents (both operating room and recovery room).911 Data were collected from all anaesthetics, 63 types of incidents and five levels of severity were defined. The frequency of equipment problems was 0.7% in 18 350 cases,9 0.9% in 26 907 cases,10 and 1.2% in 96 000 cases.11 The frequency of all problems was 23.2%, 27.9% and 22% respectively.911 We found a lower occurrence of total equipment problems and total problems than in the German studies. The cause of this is difficult to discern, as the German studies included the whole perioperative period and the intraoperative problems are not reported separately. In addition, definitions and classifications were different. Finally, there is of course a possibility of differences in problem occurrence, reporting compliance, or both. How ever, the general conclusions from these and our studies are similar, as equipment problems were rare and of low severity, but some had untoward effects on patients, without causing any lasting morbidity. These problems do carry a potential for serious adverse outcome, and preventative measures are important.1 3 7 9 18
Other studies have collected data by voluntary reporting only of problem cases. The overall problem figures are generally lower, as under-reporting is well recognized.16 17 Short and colleagues5 reported a frequency of 0.23% of equipment/breathing system problems in 16 379 anaesthetics, but an overall problem rate of only 0.76%. Spittal and colleagues4 reported a 2% incidence of equipment-related problems in 5056 cases, with an overall problem rate of 6.68%. The case mix, routines for preoperative checking of the anaesthesia machine, and level of maintenance of other equipment, were not specified in these studies.
Type of equipment involved
The anaesthesia machine, including the breathing system, was the most common cause (31%) of equipment problems in our study. This was also the most common cause in the studies by Bothner, Georgieff and Schwilk (30%),11 and Schwilk and colleagues (22%).10 Also, in other incident studies where the denominator is not known,1 46 problems related to the anaesthesia machine were most common, ranging from 52 to 73%.
We found most of the anaesthesia machine problems to be related to the breathing system, as has been found in other studies where this information is supplied.1 46 The breathing system is often reconnected for cleaning and change of system between patients, and this may predispose it to errors, despite the routines for checking the machine at the start of the day.
Non-invasive and invasive arterial pressure measurements were involved in many of the equipment problems. This equipment has many potential problems, and readings may not be correct. This predisposes it to errors, and our findings are a reminder that numbers from invasive and non-invasive automated arterial blood pressure measurement should be constantly evaluated against the patients clinical condition.
Human error
Human error and misuse of equipment have been shown to be more common than true equipment failure.3 5 In our study, human error was the main contributing factor in one-quarter of cases, and most of these involved the anaesthesia machine. The main cause was insufficient checking of the anaesthesia machine before use, especially between cases. This was also shown by Short and colleagues.19 The problems often occurred as a consequence of last-minute modifications, when breathing systems and vaporizers were changed after the checking procedure had been performed.
To reduce the possibility of human error causing equipment problems a three-level approach has been suggested: (i) when possible, equipment should be designed such that the possibility of human error is minimized; (ii) if human error cannot be prevented, systems should be designed to minimize the injury caused by such errors; (iii) if neither of the previous safety approaches is possible, the system should be equipped with monitors and alarms to alert the user of an adverse condition that may be caused by equipment failure or change in the patients condition. This approach is an example of a systems approach to error management, where the working environment of the anaesthetist is optimized to avoid errors.20 21
Continuous quality improvement
We found no change in occurrence of equipment problems during the period of our study, while there was an increasing trend for other problems. However, the low rate of equipment problems limits statistical appraisal, as variation may be the result of chance. The low rate of equipment problems also limits its use as a continuous quality indicator, as changes in occurrence caused by efforts to improve are difficult to separate from natural variation. Therefore, the most suitable analysis of these data may be as sentinel events, where problems are analysed individually, or in groups, to elucidate causative factors and preventative measures, rather than a numerical approach.
The low rate of equipment problems recorded indicates that our routines for use, checking and maintenance of equipment are adequate. However, there is still a potential for serious problems, and strategies to prevent human error should be implemented as this contributed to a quarter of problems. In addition, an improved check between cases may reduce the occurrence of equipment problems with the anaesthesia machine, which was the main cause of problems.
Ideally, follow-up of problems as part of continuous quality improvement efforts should lead to a decreased problem frequency. Short and colleagues19 studied improvements in anaesthetic care resulting from a critical incident reporting programme, but found no change in incidence of problems. However, the programme was considered effective in detecting latent system errors. Changes in the frequency of problems may be explained as a result of quality-related activities in the department, but also changes in reporting compliance, or changing anaesthesia practice may influence the results. A routine-based recording system will give us the possibility of evaluating problem rates, as the total number of anaesthetics is known, but care must be taken when the occurrence is rare.
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Conclusion |
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Acknowledgements |
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References |
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