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Introduction
Anesthesia equipment is important for the safe conduct of anesthesia, but equipment malfunction may occur and also contribute to morbidity and mortality.1-3 The anesthesia machine, which is one part of the inhaled anesthetic delivery system, has most often been involved in equipment-related morbidity during general anesthesia1,4-7 and this has led to recommend and extensive use of preoperative checklists. Previous studies have shown that the incidence of anesthesia equipment problems vary from 0.2 to 2.1%. However, study design, method of problem reporting, and problem classification have varied. In addition, routines for the preoperative checking of the inhaled anesthetic delivery system has not been specified.4,5,8-11 In recent studies, although specific preoperative checking of the inhaled anesthetic delivery system was established, the equipment problems were still reported.12,13 Those studies have shown that anesthesia machine including the breathing system, are the most common cause of equipment problems during general anesthesia.1,4-6,10-12 Human error and misuse of equipment, however, have to be more common than true equipment failure.3,5,12 The main cause is insufficient checking before use, especially between cases.12,14
At Srinagarind Hospital, as a university hospital, from the early past decade, the anesthesia providers (anesthesiologists and nurse anesthetists) of the Department of Anesthesiology, simply checked the inhaled anesthetic delivery system and other equipment before anesthetizing the patients. There were no guideline or checklists for checking equipment before use and no recording system for anesthesia-related problems. The incidence of equipment problems were presented and passively recorded in the morbidity & mortality conference only. Nowadays, according to the Hospital Accreditation program, we have established a recording system for anesthesia-related problems, including inhaled anesthetic delivery system problems and a systematic guideline and checklists especially for checking the inhaled anesthetic delivery system before use since 2002. We have created a non-punitive attitude towards the occurrence of problems. All cases were recorded, the recording is obligatory and both an anesthetist and a nurse anesthetist were involved in every case. We have used the data actively in the department for problem discussions and risk management (quality control). However, the incidence, severity and causes of, especially in, inhaled anesthetic delivery system problems in our hospital have not been reported.
We conducted this study in order to identify the exact incidence, severity and causes of inhaled anesthetic delivery system problems that we are interested. We would like to study and analyze these data in prospective manner and find out for more preventive strategies that may help us to improve the quality of service.
Methods
This is a prospective, descriptive study, settings at Srinagarind Hospital, Faculty of Medicine, Khon Kaen University. The protocol was approved by Ethical Committee, Khon Kaen University before the study began. Patients underwent surgery under general anesthesia in a year of 2005, were informed and written informed consent in part of the way of anesthesia routines. All of them were recorded on the anesthetic charts on a routine basis. When inhaled delivery system problems occurred, the anesthesia provider responsible for the cases wrote a short description of the event on the Remark Field of the anesthetic charts and reported to the authors to complete the details in the incident form for analysis.
The problem was graded according to severity. Severity Grade 1 is a trivial problem and no any adverse effect, Grade 2 is a moderately difficult problem with some effects on the patient, but of a low severity and complete recovery. Grade 3 is a serious situation that causes a serious deterioration in the patient state. Grade 4 is a problem associated with a fatal outcome.12
About 9,000 general and 2,000 regional anesthetics are given in our hospital each year, and most types of surgery were performed. In our hospital, the anesthesiologist works in cooperation with a qualified nurse anesthetist who has 12 months postgraduate education in anesthesia. Each morning, the nurses did an extensive check of the inhaled anesthetic delivery system and monitoring system according to departmental procedures. This check includes medical gas supplies, flowmeters, oxygen failure protection, vaporizers, machine/breathing system leakage, machine/breathing system function, ventilator, scavenging system, suction, intubation equipment and related monitors. During the study period, all patients were monitored with blood pressure monitor, EKG monitor, pulse oximeter and capnometer. One doctor and three nurses worked as a team to educate all staff on equipment issues, and the department engaged some companies for continuous maintenance or calibration every 6 months.
The incident forms were sorted according to components of the inhaled anesthetic delivery system involved and analyzed by the authors according to frequency, severity and causes. We used the descriptive statistics and presented as number and percentage.
Results
We anesthetized and recorded 8,904 general anesthetic patients in 2005. The age, gender, ASA class, operative condition, type of surgery and duration of anesthesia were presented in Table 1.
Incidence and severity of inhaled anesthetic delivery system problems
As presented in Table 2, inhaled anesthetic delivery system problems were 0.18% (n=16) in 8,904 cases of all general anesthetics. Most problems (n=11) were trivial (Severity Grade 1). About one-third (n=5) were intermediate (Severity Grade 2) and affected the patients to some degree. Hypoxemia was the most frequent effect on patients (n=4) but no patient suffered any lasting morbidity or needed prolonged postoperative care (Table 3).
Involved components of inhaled anesthetic delivery system problems (Table 2)
We found that 37.5% (6/16) of the problems occurred during the use of ventilator. The most common problem related to the ventilator was periodic non-function from electronic control unit malfunction (n=5), and inadequate tidal volume from using pediatric bellow in adult patient (n=1). Other problems included electric power supply failure of anesthesia machine (n=2), gas leakage from loose connection and disconnection of breathing circuit (n=2), leakage from the canister of CO2 absorber (n=2), leakage from the vaporizer-machine connection (n=1), leakage from the torn breathing bag (n=1), no connection of gas supplies (n=1), and malfunction of the unidirectional valve (n=1).
Human error
A half of the problems (8/16) were considered to be related to human error on the part of the users (Table 4). The problems concerned the breathing circuit (n=2), CO2 absorber canister (n=2), gas supply (n=1), vaporizer (n=1), breathing bag (n=1) and ventilator (n=1). All of them were related to inadequate pre-use checks. Most of these errors occurred when the equipment was checked between cases, rather than at the start of the day. Contributing factors were a change of equipment, such as changes in type of breathing system, vaporizer, bellow of ventilator, type of anesthesia or change of exhausted CO2 absorber between cases.
Table 1 Patient characteristics
|
Characteristics |
N (8,904) |
% |
|
Age : 0-30 days |
106 |
1.19 |
|
>1-12 months |
397 |
4.46 |
|
>1-6 yr |
755 |
8.48 |
|
>6-12 yr |
633 |
7.11 |
|
>12-65 yr |
6,086 |
68.35 |
|
>65 yr |
927 |
10.41 |
|
Gender : Male |
4,222 |
47.42 |
|
Female |
4,682 |
52.58 |
|
ASA class : I |
3,605 |
40.49 |
|
II |
3,741 |
42.01 |
|
III |
1,263 |
14.18 |
|
IV |
250 |
2.81 |
|
V |
45 |
0.51 |
|
Operative condition : Elective |
7,004 |
78.66 |
|
Emergency |
1,900 |
21.34 |
|
Type of surgery: Cardio-vascular-thoracic surgery |
815 |
9.15 |
|
Ear nose throat surgery |
1,289 |
14.48 |
|
Eye surgery |
391 |
4.39 |
|
General surgery |
2,370 |
26.62 |
|
Neurosurgery |
435 |
4.85 |
|
OB/GYN surgery |
1,158 |
13.01 |
|
Orthopedic surgery |
1,233 |
13.85 |
|
Pediatric surgery |
423 |
4.75 |
|
Others |
220 |
2.47 |
|
Duration of anesthesia : < 1 hr |
1,855 |
20.83 |
|
1-2 hr |
3,170 |
35.60 |
|
> 2 hr |
3,879 |
43.56 |
Table 2 Involved components of inhaled anaesthetic delivery system and severity of problem
|
Part involved |
Severity |
Total problems
(n) |
|
Grade 1 |
Grade 2 |
Grade 3 |
Grade 4 |
|
Ventilator |
5 |
1 |
|
|
6 |
|
Anesthesia machine |
|
|
|
|
|
|
- Power supply |
2 |
|
|
|
2 |
|
Breathing circuit |
1 |
1 |
|
|
2 |
|
CO2 absorber |
1 |
1 |
|
|
2 |
|
Gas supply |
1 |
|
|
|
1 |
|
Vaporizer |
|
1 |
|
|
1 |
|
Unidirectional valve |
1 |
|
|
|
1 |
|
Breathing bag |
|
1 |
|
|
1 |
|
Total |
11 |
5 |
|
|
16 |
Table 3 Untoward effects on the patient caused by inhaled anesthetic delivery system problems (Severity Grade > 2)
|
Equipment involved |
Problems |
Effect on patients |
n |
|
Vaporizer |
Leakage from the vaporizer-machine connection |
Severe Hypoxemia (SpO2 55%)
|
1
|
|
Breathing circuit |
Leakage from inspiratory unidirectional valve-circuit connection |
Mild Hypoxemia (SpO2 92%)
|
1
|
|
CO2 absorber |
Leakage from CO2 canister |
Severe Hypoxemia (SpO2 67%) |
1 |
|
Breathing bag |
Leakage from breathing bag |
Mild Hypoxemia (SpO2 90%) |
1 |
|
Ventilator |
Pediatric bellow in adult |
Hypercarbia (PaCO2 65 mmHg) |
1 |
|
Total |
|
|
5 |
Table 4 Human error contributing to inhaled anaesthetic delivery system problems
|
Equipment involved |
Problems |
n |
|
Breathing circuit |
Leakage from breathing circuit: |
|
|
|
- Loose connection between unidirectional valve and inspiratory limb of circle circuit |
1 |
|
|
- Disconnection between unidirectional valve and inspiratory limb of circle circuit |
1 |
|
CO2 absorber |
Leakage from CO2 absorber canister |
|
|
|
- After soda lime change over |
1 |
|
|
- Canister broke from crashing during adjustment the operative table |
1 |
|
Gas supply |
No connection of gas supplies |
1 |
|
Vaporizer |
Leakage from the vaporizer-machine connection after change over |
1 |
|
Breathing bag |
Torn breathing bag |
1 |
|
Ventilator |
Inadequate tidal volume because pediatric bellow was used in adult |
1 |
|
Total |
|
8 |
Discussion
From prospectively recorded problems in 8,904 cases of general anesthesia, we found inhaled anesthetic delivery system problems to be rare and low in severity. Human errors are important factors, in addition to pure equipment failure. The low incidence limits its usefulness as a numerical quality indicator. However, analysis of patterns and causes of these problems can be a useful part of a quality assurance program in our department.
Methodology
From the previous studies about incident reporting, under-reporting is a potential problem. This is related to the added workload from completion of forms, a belief that reporting has limited value, and fear of consequences of reporting.15-18 But in our study, we belief that the reporting compliance was good, because our study is designed to add minimal workload. In addition, we have a non-punitive attitude of problems and all general anesthetic patients were followed and included in the study. The incidents are recorded in a prospective manner and important events are less likely to be missed.
Incidence and severity of inhaled anesthetic delivery system problems
The anesthesia machine, which is one part of the inhaled anesthetic delivery system, has most often been involved in equipment-related morbidity during general anesthesia1,4-7 and this has led to recommend and extensive use of preoperative checklists. Five studies have been published representing mandatory reporting, with data recorded from all anesthetic cases.8-11 The incidence of equipment problems were 0.1-0.4% in 27,184 cases,8 0.7% in 18,350 cases,9 0.9% in 26,907 cases,10 1.2% in 96,000 cases11 and 0.2% in 10,607 cases.13 However, study design, method of problem reporting, and problem classification varied, and routines for the preoperative checking of inhaled anesthetic delivery system were not specified.
From the study of Fasting and Gisvold,12 they have studied about equipment problems recorded from 83,154 cases in 1996-2000, in the University Hospital of Trondheim, Norway, where has already instituted a system for the recording of anesthetic-related data and established a specific preoperative checking of inhaled anesthetic delivery system during general anesthesia, which has the settings similar to our hospital. The incidence of equipment problems of all anesthetic cases was 0.19% (0.05% of regional anesthetics (n=20,564) and 0.23% of general anesthetics (n=62,590). These problems from anesthesia machine including the breathing system, were the most common cause of equipment problems during general anesthesia (31.21% of equipment problems and 0.08% of general anesthetics). Most problems (92.28%) were trivial (Severity Grade 1) and 2.72% were intermediate in severity (Severity Grade 2) and affected the patients to some degree but no patient suffered any lasting morbidity or needed prolonged postoperative care. In our study, we found that the incidence in general anesthetic cases was low (0.18%) and most problems (68.75%) were trivial and 31.25% were intermediate severity and slightly affected the patients, as similar as the study of Fasting and Gisvold. The low rate and severity of the incidents in our study may result from improvement in routines for preoperative equipment checks, regular equipment calibration and good monitoring system in our hospital.
Involved components of the inhaled anesthetic delivery system problems
We found that the anesthetic ventilator was the most common cause (37.5%) of inhaled anesthetic delivery system problems in our hospital. All were electronic-controlled system. The main problems are periodic non-function from electronic control unit malfunction. These ventilators were often used heavily for a long time per day for many years and this might predispose it to errors, despited the routines for checking them at start of the day and continuous maintenance or calibration them every 6 months. It was different from other studies, in which the anesthesia machine including the breathing system, was the most common cause of equipment problems.1,4-6,10-12
Human error
Human error and misuse of equipment have been shown to be more common than true equipment failure.3,5,12 In our study, human error was the main contributing factor in a half of cases, and these involved many components of the inhaled anesthetic delivery system. The main cause was insufficient checking of it before use, especially between cases. This was also shown by previous studies.12,14
To reduce the possibility of human error causing equipment problems, a three-level approach has been suggested: (a) when possible, equipment should be designed such that the possibility of human error is minimized; (b) if human error cannot be prevented, systems should be designed to minimize the injury caused by such errors; (c) 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.19,20
Continuous quality improvement
The low rate of the inhaled anesthetic delivery system problems limits our results to be used as a continuous numerical quality indicator, as changes in occurrence caused by efforts to improve are difficult to separate from natural variation. The low rate of these problems recorded also indicates that our routines for maintenance and checking before use of equipment are quite adequate. However, there is still a potential for serious problems. Therefore, strategies to prevent human error should be implemented as this contributed to a half of problems. In addition, an improved check between cases may reduce the occurrence of equipment problems with the inhaled anesthetic delivery system.
A routine-based recording system will give us the possibility of evaluating problem rates, as the total number of anesthetics is known, but closely surveillance must be taken if the occurrence is rare.
Conclusion
In our checking and maintenance routines, we found the inhaled anesthetic delivery system to cause few problems, the incidence related to number of cases was 0.18%. Human factors were important causes of problems, and the ventilator problems were most often involved. Although we recorded no morbidity from these problems in 8,904 cases, both this and other studies have indicated that a potential for equipmentrelated morbidity exists. The type of data retrieved from our analysis provides valuable information for departmental quality improvement projects.
Acknowledgements
The study is supported with grants from the Faculty of Medicine, Khon Kaen University.
References
1. Cooper JB, Newbower RS, Kitz RJ. An analysis of major errors and equipment failure in anesthesia management: considerations for prevention and detection. Anesthesiology 1984; 60: 34-42.
2. Gilron I. Anaesthesia equipment safety in Canada: the role of government regulation. Can J Anaesth 1993; 40: 987-92.
3. Caplan RA, Vistica MF, Posner KL, Cheney FW. Adverse anesthetic outcomes arising from gas delivery equipment: a closed claim analysis. Anesthesiology 1997; 87: 741-8.
4. Spittal MJ, Findlay GP, Spencer I. A prospective analysis of critical incidents attributable to anaesthesia. Int J Qual Health Care 1995; 7: 363-71.
5. Short TG, ORegan A, Lew J, Oh TE. Critical incident reporting in an anaesthetic department quality assurance programme. Anaesthesia 1993; 48: 3-7.
6. Webb RK, Russel WJ, Klepper I, Runciman WB. The Australian Incident Monitoring Study. Equipment failure: an analysis of 2000 incident reports. Anaesth Intens Care 1993; 21: 673-7.
7. Bothner U, Georgieff M, Schwilk B. The impact of minor perioperative anesthesia-related incidents, events, and complications on post-anesthesia care unit utilization. Anesth Analg 1999; 89: 506-13.
8. Cohen MM, Duncan PG, Pope WD, Biehl D, Tweed WA, MacWilliam L, et al. The Canadian four-centre study of anaesthetic outcomes: II. Can outcomes be used to assess the quality of anaesthesia care? Can J Anaesth 1992; 39: 430-9.
9. Schwilk B, Muche R, Bothner U, Goertz A, Friesdorf W, Georgieff M. Quality control in anesthesiology. Results of a prospective study following the recommendations of the German Society of Anesthesiology and Intensive Care. Anaesthesist 1995; 44: 242-9.
10. Schwilk B, Muche R, Treiber H, Brinkmann A, Georgieff M, Bothner U. A cross-validated multifactorial index of perioperative risks in adults undergoing anaesthesia for non-cardiac surgery. Analysis of perioperative events in 26 907 anaesthetic procedures. J Clin Monit Comput 1998; 14: 283-94.
11. Bothner U, Georgieff M, Schwilk B. Building a large-scale perioperative anaesthesia outcome-tracking database: methodology, implementation, and experiences from one provider within the German quality project. Br J Anaesth 2000; 85: 271-80.
12. Fasting S, Gisvold SE. Equipment problems during anaesthesia are they a quality problem? Br J Anaesth 2002; 89: 825-31.
13. Boonmak P, Boonmak S, Sathitkarnmanee T, Chua-In W, Nonlhaopol D, Thananun M. Surveillance of anesthetic related complications at Srinagarind Hospital, Khon Kaen University, Thailand. J Med Assoc Thai 2005; 88: 613-22.
14. Short TG, ORegan A, Jayasuriya JP, Rowbottom M, Buckley TA, Oh TE. Improvements in anaesthetic care resulting from a critical incident reporting programme. Anaesthesia 1996; 51: 615-21.
15. Sanborn KV, Castro J, Kuroda M, Thys DM. Detection of intraoperative incidents by electronic scanning of computerized anesthesia record. Comparison with voluntary reporting. Anesthesiology 1996; 85: 977-87.
16. Cooper JB. Is voluntary reporting of critical events effective for quality assurance? Anesthesiology 1996; 85: 961-4.
17. Cullen DJ, Bates DW, Small SD, Cooper JB, Nameskal AR, Leape LL. The incident reporting system does not detect adverse drug events: a problem for quality improvement. Jt Comm J Qual Improv 1995; 21: 541-8.
18. Jayasuriya JP, Anandaciva S. Compliance with an incident report scheme in anaesthesia. Anaesthesia 1996; 50: 846-9.
19. Leape LL. Error in Medicine. JAMA 1994; 272: 1851-7.
20. Schreiber PJ. Con: there is nothing wrong with old anesthesia machines and equipment. J Clin Monit 1996; 12: 39-41.
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