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 Table of Contents  
Year : 2017  |  Volume : 14  |  Issue : 1  |  Page : 18-24

Critical incidents and near misses during anesthesia: A prospective audit

1 Department of Anaesthesia and Intensive Care, Lagos University Teaching Hospital, Lagos, Nigeria
2 Department of Anaesthesia and Intensive Care, College of Medicine, Lagos University Teaching Hospital, University of Lagos, Lagos, Nigeria

Date of Web Publication30-Jan-2017

Correspondence Address:
Pamela Onorame Agbamu
Department of Anaesthesia and Intensive Care, Lagos University Teaching Hospital, PMB 12003, Lagos
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2468-6859.199170

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Background: A critical incident is any preventable mishap associated with the administration of anesthesia and which leads to or could have led to an undesirable patients' outcome. Patients' safety can be improved by learning from reported critical incidents and near misses. Materials and Methods: All perioperative critical incidents (excluding obstetrics) occurring over 5 months were voluntarily documented in a pro forma. Age of patient, urgency of surgery, grade of anesthetist, and patients' outcome was noted. Results: Seventy-three critical incidents were recorded in 42 patients (incidence 6.1% of 1188 procedures) with complete recovery in 88.1% (n = 37) and mortality in 11.9% (n = 5). The highest incidents occurred during elective procedures (71.4%), which were all supervised by consultants, and in patients aged 0–10 years (40.1%). Critical incident categories documented were cardiovascular (41.1%), respiratory (23.25%), vascular access (15.1%), airway/intubation (6.85%), equipment errors (6.85%), difficult/failed regional technique (4.11%), and others (2.74%). The monitors available were: pulse oximetry (100%), precordial stethoscope (90.5%), sphygmomanometer (90.5%), capnography (54.8%), electrocardiogram (31%), and temperature (14.3%). The most probable cause of critical incident was patient factor (38.7%) followed by human error (22.5%). Equipment error, pharmacological factor, and surgical factor accounted for 12.9%. Conclusion: Critical incidents can occur in the hands of the highly skilled and even in the presence of adequate monitoring. Protocols should be put in place to avoid errors. Critical incident reporting must be encouraged to improve patients' safety and reduce morbidity and mortality.

Keywords: Critical incident, critical incident reporting, safety

How to cite this article:
Agbamu PO, Menkiti ID, Ohuoba EI, Desalu I. Critical incidents and near misses during anesthesia: A prospective audit. J Clin Sci 2017;14:18-24

How to cite this URL:
Agbamu PO, Menkiti ID, Ohuoba EI, Desalu I. Critical incidents and near misses during anesthesia: A prospective audit. J Clin Sci [serial online] 2017 [cited 2023 Jun 2];14:18-24. Available from: https://www.jcsjournal.org/text.asp?2017/14/1/18/199170

  Introduction Top

A critical incident in anesthesia is defined as any untoward and preventable mishap associated with the administration of general or regional anesthesia, and which leads to, or could have led to an undesirable patient outcome.[1] A near miss is an event under anesthesia care which has the potential to lead to the substantial negative outcome if left to progress.[2]

Anesthesia-related mortality has been on the decline in the past three decades due to several measures that have been adopted to improve patients' safety.[2] Among these is the review of critical incidents and near misses occurring during anesthesia as well as factors contributing to these incidents. These factors are attributable to the patient, surgery or anesthesia.[3] Anesthesia-related critical incidents may be due to human errors, equipment errors, or pharmacological factors.

To reduce the frequency of these factors and errors, the circumstances that encourage them must be identified and reported. Patients' safety can thus be improved by learning from reported critical incidents.

Our aim was to identify the incidence and potential risk factors leading to critical incidents during anesthesia as well as patients outcome. This will thus encourage voluntary reporting of critical incidents as well as the establishment of protocols to avoid errors.

  Materials and Methods Top

All critical incidents (excluding obstetrics) occurring over a 5-month period from December 2015 to April 2016 at the Lagos University Teaching Hospital, Lagos, Nigeria were prospectively and voluntarily documented in an indigenous critical incident reporting form. We included incidents where the patients encountered harm and “near misses” where the patient did not suffer harm but could have if the problem had not been rapidly resolved.

Before data collection, the audit was explained to all anesthetists at our weekly departmental academic seminar. They were encouraged to record any critical incidents as they occurred in patients subjected to any form of anesthesia (general or regional) each day over a 24-h period. In our department, majority of elective anesthetics are conducted by teams of two or three; a consultant anesthetist and one or two trainees and they completed the forms. They were reassured that no punitive actions would be taken against them. The form was made available in all operating theaters and anesthetists were regularly reminded to record any critical incidents on a voluntary basis.

A critical incident was defined as “any untoward and preventable mishap associated with the administration of general or regional anaesthesia, which leads to, or could have led to an undesirable patient outcome.”[1]

At the end of surgery, the filled forms were collected by the anesthetic technicians and placed in a dedicated file for collection by one of the authors.

The following were recorded in the critical incident reporting form [Appendix 1]:[Additional file 1]

  • Age, sex, and American Society of Anaesthesiologists (ASA) classification of patient, urgency of surgery, time of day of surgery, anesthetic technique, grade of attending anesthetist as well as supervision by consultants
  • Phase of anesthesia in which the critical incident occurred, means of detection of critical incident, and available monitoring
  • Critical incident categories: Airway/intubation, cardiovascular, respiratory, venous access, drug errors, regional, blood transfusion, equipment, power failure and others
  • Probable cause of critical incident which could be:
  • - Human error - equipment error

    - Surgical factor - patient factor

    - Pharmacological factor

  • Patients outcome which could be:
  • Recovery
  • Cardiac arrest with recovery
  • Death.

The following definitions were employed for the respective events:[4]

  • Difficult tracheal intubation - >3 attempts
  • Bradycardia/tachycardia - >20% deviation from baseline pulse rate
  • Hypotension/hypertension - >30% deviation from baseline blood pressure
  • Desaturation – SPO2 <90%
  • Difficult cannulation - >3 attempts
  • Hypothermia – temperature <35°C.

Data obtained was analyzed using SPSS version 20 (SPSS, Chicago, Illinois).

  Results Top

During the 5 month study period, 73 critical incidents were reported in 42 patients. The incidence was 6.1% of 1188 procedures with complete recovery in 88.1% patients (n = 37) and mortality in 11.9% patients (n = 5).

Distribution of critical incidents was 52.4% males and 47.6% females with children 10-year-old or less being the most affected (40.5%). Thirty-two patients (76.2%) belonged to ASA physical Status I and II. Incidents were observed more with elective patients (n = 30, 71.4%, P < 0.05), during the daytime (8 a.m.–4 p.m., P < 0.05), and more frequently in patients who had general anesthesia (n = 36, 85.7%, P < 0.05). All cases were done by senior residents, and 71.4% of the cases were supervised by consultants [Table 1].
Table 1: Demographics

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The majority of the critical incidents occurred during induction of anesthesia (54.8%) followed by maintenance of anesthesia (23.8%), positioning (9.5%), emergence from anesthesia (7.1%) with the least occurring in the postanesthetic care unit (4.8%) [Figure 1]. Means of detection of critical incident was the anesthetist clinical monitoring in 31% of cases, equipment monitoring in 26.2% of cases, a combination of both in 40.5% of cases and in 2.3% of cases by the surgeon. [Figure 2] shows monitoring available during the study. All patients had pulse oximetry; 90.5% had precordial stethoscope and noninvasive blood pressure, 54.8% had end-tidal carbon dioxide, 31% had electrocardiogram whereas 14.1% had their temperature monitored.
Figure 1: Phase of occurrence of critical incident

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Figure 2: Monitoring available

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The analysis of each critical incident category is shown in [Table 2]. The highest incidence of adverse events was observed in the cardiovascular category (41.1%) of which hypotension occurred most frequently. Thirty-eight percent of patients who developed bradycardia were <1 year. Respiratory problems accounted for 23.3% of incidents; 12 cases of desaturation (five cases in the <1 year age group), three cases of bronchospasm and two cases of laryngospasm (1–10 years age group). Eleven incidents (15.1%) involved difficult intravenous cannulation of which 63.6% occurred in the 0–10 years of age group. Airway and intubation problems accounted for 6.8% of incidents with esophageal intubation and accidental extubation being the most common while difficult intubation accounted for one incident (<1 year age group). Equipment category had five events (6.8%); two leaks in the breathing system, one empty vaporizer, one faulty adjustable pressure limiting valve, and one poor light source from laryngoscope and no extra batteries. Events involving regional techniques occurred in 4.1% of incidents. Hypothermia accounted for 2.8% of incidents. There were no drug errors, blood transfusion errors or power failure.
Table 2: Analysis of critical incident categories

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The probable cause of critical incident was patient factor in 38.7%, human error in 22.5%, while pharmacological factor, patient factor, and equipment errors accounted for 12.9% [Figure 3].
Figure 3: Probable cause of critical incident

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Thirty-seven patients had full recovery following the critical incident (88.1%) while five patients died – mortality 11.9%. The causes of cardiac arrest in the mortalities were: hypotension and bradycardia in three patients, hypotension alone in one patient, and bradycardia alone in one patient.

  Discussion Top

An audit is a systematic process whereby medical practice is assessed and improved.[5] An audit on critical incidents and near misses will ensure that policies are generated to prevent reoccurrences following discussions on the critical incident. Different methods of data collection for an audit include morbidity/mortality reports, anecdotal reports, “closed claim” studies, prospective studies, retrospective studies, and peer reviews. Our system of reporting in the audit was prospective which aimed to enable issuance of advice and warnings soon after the occurrence of any incident.

The incidence of critical incident over the 5-month period in our audit was 6.1% of 1188 procedures. This was comparable to the 6.6% of 1717 procedures reported by Desalu and Kushimo in the same institution 10 years ago.[4] Saito et al.[2] reported a much lower incidence compared to ours – 0.84% while Maaløe et al.[6] reported a higher incidence – 12.1%. Varying incidents have however been reported worldwide; <1% to as high as 22%.[4] This may be because interpretation of critical incidents vary from anesthetist to anesthetist as what may be deemed critical to one may be accepted by another as a normal variation. There may also under-reporting of seemingly minor events while some major events go unreported for fear of retribution resulting in low figures.

Mortality associated with anesthesia has been defined as death under, as a result of, or within 24 h of an anesthetic.[7] It has been suggested that anesthesia-related mortality has decreased in the last three decades and in the developed countries ranges between 0.12 and 1.4/10,000 anesthetics.[8] We reported an anesthesia-related mortality of 0.004/1188 anesthetics over a 5-month period which may be equivalent to 0.04/11880 anesthetics. This is far less than what has been reported in the developed world. The patients involved in the audit were however not followed up for 24 h to ascertain whether or not mortalities occurred. Since the period covered for the definition of anesthesia-related mortality is different in both studies, comparison cannot be done. A longer period of audit with at least 10,000 anesthetics will be required in our department as well as patients' follow-up for 24 h for statistical significance on anesthesia-related mortality to be made.

The highest incidents were found during the day time (8–4 p.m.), among elective patients, ASA I and II patients, and in the 0–10 age group. Direct supervision by consultant anesthetists during the routine working hours is partly responsible for better reporting of critical incidents during these hours. Under-reporting during the call duty period (4 p.m.–8 a.m.) is most likely related to poor direct supervision by consultant staff and the desire by trainees to conceal their high rate of critical incidents during this period. In addition, during the hours of 4 p.m.–8 a.m. is when most emergencies present to theatre in our institution. Similar results were observed by Saito et al.[2] as they reported 74.7% of critical incidents occurring in elective patients. Other studies have however shown a higher incidence of critical incidents in emergency surgery compared to elective surgery.[3],[6] Poor optimization of the patients' preoperative status, fatigue in the late hours as well as poor support services may have been responsible for this.

Pediatric anesthesia remains a challenge to the anesthetist because of anatomical and physiological differences compared to the adult. The maximum critical incidents reported in the present study were in the 0–10 years age group some of which were as a result of these anatomical and physiological differences; bradycardia in three patients, hypothermia in one patient, difficult intubation in one patient, and difficult venous access in seven patients.

One of the primary responsibilities of the anesthetist is to act as a guardian of the anesthetized patient during surgery. The ASA has recommended some standards of monitoring for the safe delivery of anesthesia.[9] Standard I is the continuous presence of a qualified anesthetic personnel during any general anesthesia, regional anesthesia or monitored anesthetic care.[9] Standard II is that during all anesthetics the patients oxygenation, ventilation, circulation, and temperature shall be continually evaluated.[9] In the present study, all cases were done by senior residents and 71.4% of the cases were supervised by consultants. Although all patients did not have all compliments of monitoring during delivery of the anesthetic, pulse oximetry was available in all patients. This is in adherence to the 2008 World Health Organization (WHO) global oximetry project which aims to increase safety of anesthesia throughout the world by providing affordable, robust pulse oximetry devices for every operating theater in the developing world that does not have one.[10] The WHO Surgical Safety checklist was developed to decrease errors and adverse events in theatre. It confirms the availability of the pulse oximeter.

The operating theater is a vulnerable site for occurrence of critical incidents. Induction and maintenance phases of anesthesia have been considered as incident-rich phases [11] which was what was observed in our audit.

Critical incidents relating to airway management have been found in 17%–34% of incidents [12],[13] and up to 30% of deaths attributable to anesthesia are associated with inadequate airway management.[14] In our audit, cardiovascular causes were the most frequent critical incidents due to hypotension and bradycardia. This was followed by respiratory incidents of which desaturation was the most common and then difficult venous access. Airway incidents only accounted for 6.85%. Ours is a training center in which efforts are continuously made to ensure consultant supervision of cases. Desalu and Kushimo [4] also reported critical incidents in their audit to be the most common in the cardiovascular system. Airway incidents, however, accounted for 15% of incidents in their audit. The high percentage of consultant supervision in this audit may have influenced the reduced airway incidents compared to theirs as they reported consultant and senior registrar supervision in 40% of cases.[4] In the airway category, two cases of accidental extubation occurred in the 0–10 years age group; during an adenoidectomy in a 3-year-old and palatorrhaphy in an 11 months old. Accidental extubation was detected by the surgeon. These two procedures involve the anesthetist sharing the airway with the surgeon. The anesthetist must thus be extremely vigilant during these procedures to prevent airway complications.

Hypotension in our audit may have resulted from uncorrected dehydration from prolonged fasting which most of our patients subject themselves to before surgery, delay in commencement of surgery and induction agents. The agents in common use in our training center for induction of anesthesia are sodium thiopentone and propofol which are known to cause hypotension worsened in the dehydrated state. It may also have been from inadequately replaced intraoperative fluid and blood loss.

Drug errors are a frequent cause of incidents in anesthesia especially when there is fatigue or when diluting small doses for the pediatric patient. In a review of 1000 critical incidents, James [15] reported drug errors to constitute 7% of critical incidents. Desalu and Kushimo [4] had similar findings. We had no case of drug errors reported during the audit probably because of a greater percentage of consultant supervision. In addition, most of the incidents reported were during the daytime (8 a.m.–4 p.m.) which is the peak working hours in our institution where fatigue will not be expected. We also had no blood transfusion errors as there are established protocols to ensure that blood fulfills the checklist list before it is sent to the operating theater from the blood bank as well as to ensure that blood is checked by two persons. Incessant power supply in a developing country contributes to power failure. Desalu and Kushimo [4] reported power failure to account for 11.4% of incidents. The presence of uninterrupted power supply with the installation of inverters in our operating theaters ensured that there was constant power supply during delivery of surgery and anesthesia.

In spite of adequate monitoring and continuous presence of qualified anesthetic personnel, critical incidents and near misses still occur.[3],[6],[16] This has been associated with errors and factors that can be prevented. These factors are attributable to patient, surgery, and anesthesia.[3] Anesthesia-related critical incidents may be human errors, equipment errors, or pharmacological factor. Studies have continuously reported that human errors are the major causes of anesthesia-related critical incidents.[1],[2],[3] Any system operated by human beings is subject to human error. Errors of judgment, lack of experience and skill, inattention to detail, failure to check, and fatigue have been associated with human errors.[2],[3]

We reported patients' factor as the most common cause of critical incident followed by human error. One limitation of the audit was that the anesthetist(s) involved took the decision as to the probable cause of the critical incident. This should have been analyzed by one or more other anesthetists not involved in the case where the critical incident occurred and not any of the authors. This may have eliminated bias and under-reporting. Individual anesthetists' perception of cause of critical incident may also differ. A dehydrated patient may have had hypotension following induction of anesthesia with propofol. This may have been reported as pharmacological factor or patients' factor when it was an error of judgment in not rehydrating the patient before induction of anesthesia. Other limitations of the study include the short study period and lack of postanesthetic follow-up for 24 h.

The Association of Anaesthetists of Great Britain and Ireland “Checklist of anaesthetic equipment 2012” incorporates a check of self-inflating bag, manufacturers machine check, power supply, gas supplies and suction, breathing system, ventilator, scavenging, monitors and airway equipment, before every case.[17] The equipment errors observed in our audit could have been avoided if the checklist was made available and properly performed.

Saito et al.[2] observed an increase in incidence reporting when the incident reports were not anonymous. Reporting increased despite the fact that the anesthetists' medical council registration numbers were noted on their audit forms. This ensured that the anesthetist could be contacted for further information which helped in educating the department. They emphasized a culture of “blame free” discussions which they suggested will encourage rather than deter incident reporting systems.

  Conclusion Top

Critical incidents can occur in the hands of the highly skilled and even in the presence of adequate monitoring. Protocols and policies should be put in place to avoid errors. Critical incident reporting should be introduced and encouraged in all anesthesia departments in a “blame free culture” to improve patients' safety and reduce morbidity and mortality.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Currie M. A prospective survey of anaesthetic critical events in a teaching hospital. Anaesth Intensive Care 1989;17:403-11.  Back to cited text no. 1
Saito T, Wong ZW, Thinn KK, Poon KH, Liu E. Review of critical incidents in a university department of anaesthesia. Anaesth Intensive Care 2015;43:238-43.  Back to cited text no. 2
Gupta S, Naithani U, Brajesh SK, Pathania VS, Gupta A. Critical incident reporting in anaesthesia: A prospective internal audit. Indian J Anaesth 2009;53:425-33.  Back to cited text no. 3
[PUBMED]  Medknow Journal  
Desalu I, Kushimo OT. An audit of intraoperative critical incidents in anaesthesia. Afr J Anaesth Intens Care 2006;7:4-8.  Back to cited text no. 4
Yentis S, Hirsch N, Smith G. Anaesthesia and Intensive Care A – Z. 4th ed. Edinburgh: Churchill Livingstone; 2009. p. 52.  Back to cited text no. 5
Maaløe R, la Cour M, Hansen A, Hansen EG, Hansen M, Spangsberg NL, et al. Scrutinizing incident reporting in anaesthesia: Why is an incident perceived as critical? Acta Anaesthesiol Scand 2006;50:1005-13.  Back to cited text no. 6
Tiret L, Desmonts JM, Hatton F, Vourc'h G. Complications associated with anaesthesia – A prospective survey in France. Can Anaesth Soc J 1986;33(3 Pt 1):336-44.  Back to cited text no. 7
Braz LG, Módolo NS, do NascimentoPJr., Bruschi BA, Castiglia YM, Ganem EM, et al. Perioperative cardiac arrest: A study of 53,718 anaesthetics over 9 yr from a Brazilian teaching hospital. Br J Anaesth 2006;96:569-75.  Back to cited text no. 8
Morgan GE, Mikhail MS, Murray MJ. Patient monitors. In: Clinical Anaesthesiology. 4th ed. New York: Lange Medical Books; 2006. p. 117-54.  Back to cited text no. 9
Available from: http://www.who.int/patientsafety/events/08/1st_pulse_oximetry_meeting_background_doc.pdf. [Last accessed on 2016 Jul 10].  Back to cited text no. 10
Khan FA, Hoda MQ. A prospective survey of intra-operative critical incidents in a teaching hospital in a developing country. Anaesthesia 2001;56:177-82.  Back to cited text no. 11
Short TG, O'Regan A, Lew J, Oh TE. Critical incident reporting in an anaesthetic department quality assurance programme. Anaesthesia 1993;48:3-7.  Back to cited text no. 12
Russell WJ, Webb RK, Van der Walt JH, Runciman WB. The Australian Incident Monitoring Study. Problems with ventilation: An analysis of 2000 incident reports. Anaesth Intensive Care 1993;21:617-20.  Back to cited text no. 13
Cranshaw J, Cook T. Airway assessment and management. In: Oxford Handbook of Anaesthesia. 3rd ed. Oxford: Oxford University Press; 2012. p. 969-81.  Back to cited text no. 14
James RH. 1000 anaesthetic incidents: Experience to date. Anaesthesia 2003;58:856-63.  Back to cited text no. 15
Lipshutz AK, Caldwell JE, Robinowitz DL, Gropper MA. An analysis of near misses identified by anesthesia providers in the intensive care unit. BMC Anesthesiol 2015;15:93.  Back to cited text no. 16
Association of Anaesthetists of Great Britain and Ireland (AAGBI), Hartle A, Anderson E, Bythell V, Gemmell L, Jones H, et al. Checking anaesthetic equipment 2012: Association of anaesthetists of Great Britain and Ireland. Anaesthesia 2012;67:660-8.  Back to cited text no. 17


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]

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