- Question: We aimed to determine the incidence of anesthesia-related adverse events and postoperative complications occurring during 1 nongovernmental organization’s (NGO’s) surgical program in Madagascar.
- Findings: The overall incidence of anesthesia-related adverse events and postoperative complications was 2.0% and 9.4%, respectively, which is comparable with data from high-income countries.
- Meaning: An NGO using fully trained staff, resources, and infrastructure comparable to high-income countries can obtain similar complication rates that may help disentangle the influence of staff training and resources from patient factors when investigating why NGO surgery in low-resource settings is commonly associated with poorer outcomes.
Worldwide, 5 billion people lack access to safe surgical and anesthesia care.1 Nongovernmental organizations (NGOs) play an important role in meeting this shortfall in low- and middle-income countries (LMICs).2 However, the quality and safety of NGO-based surgery vary considerably. All-cause mortality after hernia surgery performed by surgical missions in sub-Saharan Africa is up to 20 times higher than in high-income countries (HICs),3 and cleft lip and palate surgical mission organizations reported both a 20-fold higher complication rate4 and poorer functional outcomes.5 Conversely, outcomes after tonsillectomy6 and goiter surgery7 were reported to be comparable to those in HICs. In HICs, higher surgical volumes are associated with better surgical outcomes,8 with a stronger association with “hospital” volume than “surgeon” volume.9 A recent systematic review of the effectiveness of NGO surgical platforms also shows a similar trend with NGOs that undertake larger volumes of surgery achieving better results.10 In general, the more complex the surgery, the more unsatisfactory the NGO’s surgical outcome,10 but little is known about anesthesia outcomes in the NGO context.11 In 2001, Fisher et al11 reported anesthesia outcomes from a single NGO, analyzing over 5000 cases of which over 80% of patients were children with orofacial clefts and reported that the incidence of respiratory complications was 5% intraoperatively and 3.3% in the postanesthesia care unit (PACU), and the incidence of cardiovascular complications was 1.5%.
The safe practice of anesthesia depends on multiple factors, including adequate number of trained staff, reliable infrastructure, use of standard monitoring,12 and the availability of essential drugs. Anesthesia capacity in LMICs is consistently deficient in these areas,13–15 resulting in mortality rates 100–1000 times higher than HICs.16,17 Specific anesthesia provision by NGOs providing surgery in LMICs may overcome the deficits faced by local anesthesia provision, but the quality of anesthesia provided is unclear.
Mercy Ships uses staff, infrastructure, and equipment similar to that of HICs. This allows for the influence of those factors on perioperative adverse events during NGO mission surgery to be disentangled from other influences, such as patient factors. Our goal was to prospectively estimate the incidence of anesthesia-related adverse events and postoperative complications, across a broad range of surgical specialties in adults and children, during a 2-year surgical mission in Madagascar.
The study was approved by the Mercy Ships institutional review board (MS2016-011), and because this was an observational quality improvement study, the need for individual written consent was waived. The article adheres to the applicable Enhancing the QUAlity and Transparency Of health Research (EQUATOR) guidelines (Strengthening the Reporting of Observational Studies in Epidemiology [STROBE] statement).
Mercy Ships is a surgical NGO working in sub-Saharan Africa that undertakes approximately 1200 surgeries per year on board a hospital ship, the “Africa Mercy.” The Africa Mercy has 4 operating rooms for surgery under general (or spinal) anesthesia, a 4-bed PACU and 84 ward beds including 2 intensive care beds. Surgical specialties include maxillofacial, plastics, craniofacial, orthopedics, general, gynecological, and obstetric fistula surgery. Anesthesia is provided by board-certified anesthesiologists (or international equivalent) or certified registered nurse anesthetists (CRNA), using a Paragon anesthesia machine with plenum vaporizer, circle system and full monitoring as defined by international standards.12 In the 4 operating rooms, there is never >1 CRNA present with the remaining rooms run by the board-certified anesthesiologists (or peer equivalent). In addition to the anesthesiologist (or CRNA), every operating room also has a dedicated anesthesia assistant (usually a nurse or operating department practitioner) as is standard practice in the United Kingdom, Australia, and New Zealand. Another anesthesiologist (the Anesthesia Supervisor) is always available as a “float” and a pediatric anesthesiologist is available on the floor for all complex pediatric cases. All volunteer applications are reviewed by an Anesthesia Specialty Consultant and include review of the applicant’s current practice with particular attention to details of pediatric practice, experience in managing difficult airways, and intensive care experience. Before arrival, all volunteers receive information about the equipment and medication available, and copies of relevant guidelines (eg, antibiotic prophylaxis, local anesthetic toxicity) and postoperative orders. On arrival, all volunteers undergo a shipwide safety orientation, host country cultural briefing, and a 2- to 3-hour anesthesia orientation.
There are no standard “recipes” for anesthesia, but typically, propofol is used for induction of anesthesia, isoflurane or sevoflurane for maintenance, and fentanyl or morphine for analgesia.
Postoperative nursing care including PACU, specialized wound care, and outpatient and rehabilitation services are provided by qualified registered nurses.
Mercy ships visits a coastal sub-Saharan Africa country at the invitation of the head of state, typically spending 10 months docked in the principal port city providing surgical, outpatient, and rehabilitation services to the population. The remaining 2 months of the year are spent on routine ship maintenance and maritime inspections.
From October 2014 to June 2015, and August 2015 to June 2016, the Africa Mercy was in Madagascar. As part of an internal quality improvement project and to participate in a proposed American Society of Anesthesiology Anesthesia Quality Institute (AQI)–sponsored NGO Outcomes registry, Mercy Ships decided to prospectively record operating room adverse events occurring intraoperatively and in the PACU. Mid-way through the data collection, before any data were submitted, the AQI terminated the project. Mercy Ships decided to continue collecting anesthesia adverse events as part of our own quality improvement program.
Anesthesia adverse events were defined by the AQI and are shown in Supplemental Digital Content 1, Table 1, http://links.lww.com/AA/C430. Intraoperative adverse events were subdivided into 6 categories: airway, cardiac, medication, regional, neurological, and equipment. PACU adverse events included 4 of the same categories but excluded regional and equipment categories. A paper data collection form (Supplemental Digital Content 2, Appendix 1, http://links.lww.com/AA/C431) was completed after each surgical procedure. The anesthesia provider completed the intraoperative section, and nurse-in-charge of the PACU completed the postoperative section before discharge from the PACU. Missing forms were followed up by the Anesthesia Supervisor and PACU Supervisor both of whom were full-time volunteers who had been working for at least 6 months continuously with Mercy Ships.
Mercy Ships contemporaneously records generic postoperative complications using standard definitions.18,19 Complications recorded include unplanned readmission to hospital, unplanned return to the operating room, unexpected intensive care unit admission, surgical site infection, myocardial infarction, stroke, renal failure, gastrointestinal bleed, deep vein thrombosis, pneumonia, sepsis, urinary catheter–associated urinary tract infection, central venous catheter–associated blood stream infection, coma >24 hours, cardiopulmonary arrest, and death.
All postoperative complications are verified by individual case note review at a monthly Hospital Review Board meeting, chaired by the Deputy Chief Medical Officer. Complications are classified for impact by consensus agreement using the Dindo-Clavien classification20 and recorded in the hospital database, which also includes patient demographics, surgical, and anesthesia details.
Descriptive statistics were used to describe patient demographics, type of surgery, incidence of anesthesia and PACU adverse events, and postoperative complications.
All analyses were performed using statistical analysis software Real Statistics. P values of <.05 were considered significant.
From October 2014 to May 2016, 2607 elective surgeries were performed. Anesthesia adverse event forms were completed in 2146 cases. Repeat operations for surgical complications in the same patient were excluded (Figure). Exclusions and missing patient data accounted for 109 episodes of surgical care leaving 2037 episodes of care for final evaluation.
Patients were managed by a total of 97 different anesthesia providers and 65 different surgeons from 21 different countries. Baseline characteristics of patients, anesthesia, and surgery are shown in Table 1, and the types of surgical interventions are shown in Table 2.
Out of 2037 surgeries, there was a total of 42 (2.0%, confidence interval [CI], 1.4–2.7) anesthesia-related adverse events. Thirty-six (86% CI, 75–96) occurred intraoperatively and 6 (14% CI, 3–25) in PACU giving overall intraoperative and PACU complication rates of 1.8% (CI, 1.2–2.4) and 0.3% (CI, 0.02–0.6), respectively. The details are given in Table 3. The most common intraoperative adverse event, occurring 7 times, was failed regional (spinal) anesthesia; bronchospasm requiring treatment and new arrhythmia requiring unanticipated treatment were the second most common events occurring 5 times each. The high rate (10%) of failure of regional anesthesia may be explained in 6 of 7 cases by the duration of surgery. These were obstetric fistula repairs requiring over 90 minutes of surgery time, and required either conversion to general anesthesia or the addition of intravenous opioids and other sedation medications. The other case of failure of regional anesthesia was a patient anesthetized by a CRNA. The CRNA attempted to administer spinal anesthesia but was unable to locate the subdural space and therefore administered general anesthesia instead.
There were 217 postoperative complications after PACU discharge in 191 unique patients giving a postoperative complication rate of 10.7% (CI, 9.3–12.0) per surgery and 9.4% (CI, 8.1–10.7) per patient (Table 4). The most common postoperative complication was unexpected return to the operating room and the second most common was surgical site infection (39.2%; CI, 37.0–41.3 and 33.2%; CI, 31.1–35.3 of all complications, respectively). Most complications (42.9%; CI, 40.7–45.1) were classified as level II, requiring only simple treatment usually with antibiotics, but over a third (36.4%; CI, 34.2–38.5) required intervention under general anesthesia (level III b). Of the patients experiencing a postoperative complication, 30.1% (59/191; CI, 28.8–32.9) were accounted for by obstetric fistula and 23.6% (45/191; CI, 21.7–25.5) by head and neck surgery. The incidence of complication after obstetric fistula surgery was 17.1% (59/345; CI, 15.4–18.8), and after head and neck surgery 6.4% (45/705; CI, 5.3–7.5).
There was 1 death. A 4-year-old girl undergoing debulking of fibrous dysplasia of the mandible suffered an intraoperative cardiac arrest presumed to be due to venous air embolism. The child weighed 15.6 kg, with no preexisting comorbidities. Intraoperative monitoring and blood analysis shortly before and during the cardiac arrest excluded hypovolemia (normal heart rate, blood pressure, and minimal pulse pressure variation), acute anemia, or electrolyte disturbance as the cause of cardiac arrest. Cardiopulmonary resuscitation was conducted as per American Heart Association Guidelines. Right internal jugular vein catheterization using ultrasound guidance was performed to attempt aspiration of air from the right atrium due to presumed venous air embolism. Return of spontaneous circulation was achieved after 1 hour of resuscitation, and the child was transferred intubated, ventilated, and with inotropic support to the intensive care unit. However, 48 hours later, she was pronounced brainstem dead and invasive support was withdrawn. The cause of death was presumed to be cardiac arrest secondary to venous air embolism because other causes appeared to be excluded and the clinical picture resembled venous air embolism, namely sudden fall in blood pressure and end-tidal carbon dioxide when the child had been hemodynamically stable immediately before the event. The child had been positioned slightly “head up” at the beginning of surgery, as is our standard practice in head and neck surgery, to facilitate venous drainage. Venous air embolism in association with fibrous dysplasia has not previously been reported in the literature. However, massive fibrous dysplasia causing gross facial distortion is rarely, if ever, seen in HICs where most literature on intraoperative complications and cardiac arrest is written.
Across a wide range of surgical interventions and age groups, our results show an overall anesthesia-related adverse event rate of 2.0% and postoperative complication rate of 9.4% and included 1 death.
The anesthesia-related adverse event rate in this study is lower than the 6% reported by Fisher et al11 in the only prior study of NGO anesthesia-related adverse events. When comparing our data with the data by Fisher et al11, it is important to consider that the data by Fisher et al11 were captured in 1998–1999 and studied a population younger and more homogenous (median age 5 years and 80% orofacial clefts) than ours. Eighty-five percent of the cases in the study by Fisher et al11 received halothane, none had end-tidal CO2 monitoring, and most had manual rather than automated blood pressure monitoring and no electrocardiography.11 The use of halothane and differences in monitoring may account for the higher incidence of cardiovascular complications by Fisher et al11 compared with our results (1.5% and 0.5%, respectively). Similarly, the younger median age (5 years compared with 21 years in our study) by Fisher et al11 may account for the higher incidence of respiratory complications compared with our results. Fisher et al11 reported a 3.4-fold increase in relative risk of airway complication in those under 5 years of age; an incidence of 1%–2% for those under 10 years of age, and 0.5% for those over 20 years of age, compared with our overall incidence of 0.9%. Our incidence of PACU adverse events was 0.3% compared with Fisher et al’s11 3.3%. This may be due to differences in staffing levels and monitoring in PACU because we used HIC standards of care in PACU, whereas Fisher et al11 did not. The Mercy Ships PACU is staffed by PACU nurses (who have responsibility only for PACU patients not patients located elsewhere) and a “float” anesthesiologist, and all extubations occur before PACU arrival, possibly contributing to our reported low rate of PACU adverse events comparable with HIC studies.21,22 In common with other HIC studies,23–25 our most frequent intraoperative adverse event category was respiratory, accounting for 46% (16/35) of all intraoperative events, with an overall incidence of 0.8%.
Our study of anesthesia-related adverse events from October 2014 to May 2016 included 1 death giving a mortality rate in our cohort of approximately 1 in 2000 which is higher though not statistically different from the 1 in 6000 tracked by Fisher et al.11 Whitlock et al26 studied AQI data and found a mortality rate (death within 48 hours) of 7 per 100,000 for American Society of Anesthesiologists (ASA) I and II patients. That data, compared with the data by Fisher et al,11 and ours implies that NGO surgery carries higher risk than that in HICs despite our adherence to use of highly trained staff, modern equipment, reliable infrastructure, and HIC standards of care. Reasons for that higher risk in LMICs are unknown, and possible explanations include high incidences of malnutrition and environmental smoke exposure, and excessive pressure to proceed with surgery due to patients’ limited opportunities and extraordinary efforts made to receive surgery. Additionally, even qualified practitioners are dealing with colleagues, equipment, and often a language they are unfamiliar with, which can pose problems even if colleagues are qualified and the equipment is modern.
The postoperative complication rates were highest after obstetric fistula and head and neck surgery with rates of 17.1% and 6.4%, respectively. These rates are comparable with other NGO-based obstetric fistula surgery (11%–17%),27–29 and with HIC head and neck surgery (6%–14%).30,31
A study of over 17,000 surgeries (mainly hernia and cleft palate repairs) by over 114 surgical missions over 2 decades showed an overall mortality of 3.3%3 and complication rates 20 times higher than for similar surgery in HICs.3–5 Exceptions are tonsillectomy6 and goiter surgery7 where results comparable with HIC are reported. The explanation for higher surgical complications in LMICs is unclear and may be related to poorer surgical/anesthesia training, lack of infrastructure and resources, or patient-related factors. Because Mercy Ships uses highly qualified trained staff, advanced monitoring techniques, and a fully resourced infrastructure, it may allow us to some degree, to disentangle the elements of surgical and anesthesia expertise, infrastructure, and resources from patient-related factors. It may also account for our low complication rates (for head and neck and general surgery) compared with other LMIC studies. However, in common with other surgical NGOs using fully qualified staff, the operating room team is made up of people not used to working with each other, language difficulties are frequently encountered, and surgeons and anesthesiologists face emotional pressure to operate on patients who have traveled a long distance in search of care.
This study had a 78% (2037/2607) response rate for completing the adverse events reporting form, despite the presence of at least 1 permanent staff member trying to ensure completion for every case. Self-reporting of adverse events is common practice in most HIC medical institutions, but nonetheless compliance remains low and requires continual motivation and feedback to ensure staff buy-in. In a voluntary setting such as Mercy Ships or other NGO surgical mission, compliance may be even lower as accountability may be perceived to be lower. Self-reporting is prone to underreporting due to the effect of individual anesthesiologists’ judgment as to what events “are worth reporting” especially if dealt with quickly and easily. Good definitions of adverse events can minimize this bias, and the AQI definitions used in our study were of high quality.
This study has a number of limitations. The sample size of 2037 is small to make firm conclusions on the safety of anesthesia practice by NGO surgical missions for rare events such as death. Comparing the incidence of adverse events between HIC and LMICs is also difficult due to lack of standard definitions, barriers to reporting adverse events,32,33 and because most of the anesthesia risk literature focuses on mortality or closed claim analyses where serious injury has occurred,16,26,34–36 rather than a more comprehensive set of adverse events. Mercy Ships uses anesthesia providers trained in HICs, and medication, equipment, and monitoring that would be found in HICs. Therefore, our results may not be translatable to other models of NGO anesthesia care where use of local staff, medication, and equipment might predominate.
Despite these limitations, we believe that the study has a number of strengths. The sample size (2037) and narrow CIs for the primary outcomes (incidence of anesthesia-related adverse events [2.0% CI, 1.4–2.6] and postoperative complications [10.3% CI, 9.3–12.0]) are the major strengths. This report adds to the literature by Fisher et al,11 by presenting data on a wide range of surgical procedures and ages and in the context of current standards such as routine use of sevoflurane, electrocardiography, and noninvasive blood pressure monitoring. Our data also reflect management of LMIC patients while using staffing, infrastructure, and equipment typical in HICs, which has not been previously reported. We believe that this report demonstrates beneficial effects of using HIC resources for practice in LMICs, and hope this report encourages other NGOs to follow similar standards.
The monitoring and standards of anesthesia and PACU care have improved in the 20 years since the study by Fisher et al.11 International standards for the safe practice of anesthesia now exist, including for use in LMICs, and all NGOs should be encouraged to incorporate these into routine practice.12 Fisher et al11 called for widespread monitoring of NGO anesthesia outcomes, and the 2014 ASA AQI NGO Outcomes Registry aimed to do this but failed to gain the necessary support to continue. Given that over 400 surgical NGOs operate globally,37 and, in some countries, more surgery is performed by NGOs than by the government sector,2 monitoring outcomes is increasingly important. Practitioners performing NGO surgery have a duty to ensure NGO surgery, and anesthesia is not just “feel good heroism” but provides quality care of comparable standard to HICs.
In conclusion, this study shows an incidence of anesthesia-related adverse events (2.0%) and postoperative complications (9.4%). As Fisher et al11 did in 2001, we repeat the call for all surgical NGOs to monitor and report anesthesia outcomes and suggest that the ASA AQI NGO anesthesia outcomes registry is relaunched and that surgical NGOs must follow international standards for the safe practice of anesthesia.12
The authors wish to thank Faye Evans, Mark Singleton, and Adrian Gelb for their advice on the content of the data collection form (Supplemental Digital Content 2, Appendix 1, http://links.lww.com/AA/C431) and the definitions of adverse events (Supplemental Digital Content 1, Table 1, http://links.lww.com/AA/C430).
Name: Michelle C. White, MBChB.
Contribution: This author helped conceive the original idea and study design; helped with data acquisition, analysis, and interpretation; and helped review the literature, write the first draft of the manuscript, and approve the final manuscript.
Name: Brian J. Barki, MD.
Contribution: This author helped with data acquisition, and critically appraised and approved the final manuscript.
Name: Stephen A. Lerma, MHS.
Contribution: This author helped with data acquisition, and critically appraised and approved the final manuscript.
Name: Sarah Kate Couch, BA.
Contribution: This author helped with data acquisition, and critically appraised and approved the final manuscript.
Name: Dennis Alcorn, MS.
Contribution: This author helped with data acquisition, analysis, and interpretation; and critically appraised and approved the final manuscript.
Name: Richard G. Gillerman, MD.
Contribution: This author helped conceive the original idea and study design, and critically appraised and approved the final manuscript.
This manuscript was handled by: Angela Enright, MB, FRCPC.
1. Alkire BC, Raykar NP, Shrime MG, et al. Global access to surgical care: a modelling study. Lancet Glob Health. 2015;3:e316–e323.
2. Bolkan HA, Von Schreeb J, Samai MM, et al. Met and unmet needs for surgery in Sierra Leone: a comprehensive, retrospective, countrywide survey from all health care facilities performing operations in 2012. Surgery. 2015:157;992–1001.
3. Poilleux J, Lobry P. Surgical humanitarian missions. An experience over 18 years. Chirurgie. 1991;117:602–606.
4. Maine RG, Hoffman WY, Palacios-Martinez JH, Corlew DS, Gregory GA. Comparison of fistula rates after palatoplasty for international and local surgeons on surgical missions in Ecuador with rates at a craniofacial center in the United States. Plast Reconstr Surg. 2012;129:319e–326e.
5. de Buys Roessingh AS, Dolci M, Zbinden-Trichet C, Bossou R, Meyrat BJ, Hohlfeld J. Success and failure for children born with facial clefts in Africa: a 15-year follow-up. World J Surg. 2012;36:1963–1969.
6. Sykes KJ, Le PT, Sale KA, Nicklaus PJ. A 7-year review of the safety of tonsillectomy during short-term medical mission trips. Otolaryngol Head Neck Surg. 2012;146:752–756.
7. Rumstadt B, Klein B, Kirr H, Kaltenbach N, Homenu W, Schilling D. Thyroid surgery in Burkina Faso, West Africa: experience from a surgical help program. World J Surg. 2008;32:2627–2630.
8. Birkmeyer JD, Siewers AE, Finlayson EV, et al. Hospital volume and surgical mortality in the United States. N Engl J Med. 2002;346:1128–1137.
9. Birkmeyer JD, Stukel TA, Siewers AE, Goodney PP, Wennberg DE, Lucas FL. Surgeon volume and operative mortality in the United States. N Engl J Med. 2003;349:2117–2127.
10. Shrime MG, Sleemi A, Ravilla TD. Charitable platforms in global surgery: a systematic review of their effectiveness, cost-effectiveness, sustainability, and role training. World J Surg. 2015;39:10–20.
11. Fisher QA, Nichols D, Stewart FC, Finley GA, Magee WP Jr, Nelson K. Assessing pediatric anesthesia practices for volunteer medical services abroad. Anesthesiology. 2001;95:1315–1322.
12. Merry AF, Cooper JB, Soyannwo O, Wilson IH, Eichhorn JH. International standards for a safe practice of anesthesia 2010. Can J Anesth. 2010;57:1027–1034.
13. Lebrun DG, Dhar D, Sarkar MI, Imran TM, Kazi SN, McQueen KA. Measuring global surgical disparities: a survey of surgical and anesthesia infrastructure in Bangladesh. World J Surg. 2013;37:24–31.
14. Dubowitz G, Detlefs S, McQueen KA. Global anesthesia workforce crisis: a preliminary survey revealing shortages contributing to undesirable outcomes and unsafe practices. World J Surg. 2010;34:438–444.
15. Hoyler M, Finlayson SR, McClain CD, Meara JG, Hagander L. Shortage of doctors, shortage of data: a review of the global surgery, obstetrics, and anesthesia workforce literature. World J Surg. 2014;38:269–280.
16. Bainbridge D, Martin J, Arango M, Cheng D; Evidence-Based Peri-Operative Clinical Outcomes Research (EPiCOR) Group. Perioperative and anaesthetic-related mortality in developed and developing countries: a systematic review and meta-analysis. Lancet. 2012;380:1075–1081.
17. Ouro-Bang’na Maman AF, Tomta K, Ahouangbévi S, Chobli M. Deaths associated with anaesthesia in Togo, West Africa. Trop Doct. 2005;35:220–222.
18. Khuri SF, Daley J, Henderson W, et al. The National Veterans Administration Surgical Risk Study: risk adjustment for the comparative assessment of the quality of surgical care. J Am Coll Surg. 1995;180:519–531.
19. Centre for Disease Control. Surgical Site Infections 2013. Available at: http://www.cdc.gov
. Accessed May 23, 2018.
20. Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg. 2004;240:205–213.
21. Kluger MT, Bullock MF. Recovery room incidents: a review of 419 reports from the Anaesthetic Incident Monitoring Study (AIMS). Anaesthesia. 2002;57:1060–1066.
22. Van der Walt JH, Webb RK, Osborne GA, Morgan C, Mackay P. The Australian Incident Monitoring Study. Recovery room incidents in the first 2000 incident reports. Anaesth Intensive Care. 1993:21;650–652.
23. Liu EH, Koh KF. A prospective audit of critical incidents in anaesthesia in a university teaching hospital. Ann Acad Med Singapore. 2003;32:814–820.
24. Short TG, O’Regan A, Lew J, Oh TE. Critical incident reporting in an anaesthetic department quality assurance programme. Anaesthesia. 1993;48:3–7.
25. Habre W, Disma N, Virag K, et al.; APRICOT Group of the European Society of Anaesthesiology Clinical Trial Network. Incidence of severe critical events in paediatric anaesthesia (APRICOT): a prospective multicentre observational study in 261 hospitals in Europe. Lancet Respir Med. 2017;5:412–425.
26. Whitlock EL, Feiner JR, Chen LL. Perioperative mortality, 2010 to 2014: a retrospective cohort study using the National Anesthesia Clinical Outcomes Registry. Anesthesiology. 2015:123;1312–1321.
27. Diallo AB, Sy T, Bah MD, et al. Obstetrical vesico-vaginal fistula in Guinea: data analysis of three sites of treatment at Engender Health ONG. Prog Urol. 2016;26:145–151.
28. Gupta NP, Mishra S, Mishra A, Seth A, Anand A. Outcome of repeat supratrigonal obstetric vesicovaginal fistula repair after previous failed repair. Urol Int. 2012;88:259–262.
29. Sjøveian S, Vangen S, Mukwege D, Onsrud M. Surgical outcome of obstetric fistula: a retrospective analysis of 595 patients. Acta Obstet Gynecol Scand. 2011;90:753–760.
30. Boruk M, Chernobilsky B, Rosenfeld RM, Har-El G. Age as a prognostic factor for complications of major head and neck surgery. Arch Otolaryngol Head Neck Surg. 2005;131:605–609.
31. Weber RS, Lewis CM, Eastman SD, et al. Quality and performance indicators in an academic department of head and neck surgery. Arch Otolaryngol Head Neck Surg. 2010;136:1212–1218.
32. Heard GC, Sanderson PM, Thomas RD. Barriers to adverse event and error reporting in anesthesia. Anesth Analg. 2012;114:604–614.
33. Haller G, Courvoisier DS, Anderson H, Myles PS. Clinical factors associated with the non-utilization of an anaesthesia incident reporting system. Br J Anaesth. 2011;107:171–179.
34. Arbous MS, Grobbee DE, van Kleef JW, et al. Mortality associated with anaesthesia: a qualitative analysis to identify risk factors. Anaesthesia. 2001;56:1141–1153.
35. MacRae MG. Closed claims studies in anesthesia: a literature review and implications for practice. AANA J. 2007;75:267–275.
36. Petty WC, Kremer M, Biddle C. A synthesis of the Australian Patient Safety Foundation Anesthesia Incident Monitoring Study, the American Society of Anesthesiologists Closed Claims Project, and the American Association of Nurse Anesthetists Closed Claims Study. AANA J. 2002;70:193–202.
37. Ng-Kamstra JS, Riesel JN, Arya S, et al. Surgical non-governmental organizations: global surgery’s unknown nonprofit sector. World J Surg. 2016;40:1823–1841.