Monitored Anesthesia Care- Injury and Liability

The common belief is that monitored anesthesia care and sedation for procedures are not usually associated with morbidity, and mortality.  This notion occasionally results in providing sedation for procedures without ensuring adequate monitoring. The findings of closed claims analysis of American Society of Anesthesiologists (ASA) are contradicts this common belief.  Serious cardiorespiratory depressions and deaths have been reported after sedation for therapeutic and diagnostic procedures in both adults and children.1,2  In addition to inadequate monitoring,several factors such as medication errors, and poly pharmacy of sedation drugs have contributed to substantial morbidity during sedation procedures.3 Bhananker et al, used ASA Closed Claims Database case analysis to determine the outcomes after monitored anesthesia procedures, or sedation procedures (MAC).4 

 The ASA Closed Claims Project is a structured evaluation of adverse anesthetic outcomes obtained from the closed claims files of 35 US professional liability insurance companies. Claims of dental damage are not included in the database. A closed claim file is reviewed by a practicing anesthesiologist to determine various factors from every source of information pertaining to the case including the cost of settlement or jury award. Bhanaker et al reviewed all theses ASA closed claims from 1990 to 2002 for the study.4 Contributing role of sedation to adverse outcome is reviewed by three authors. Claims were classified as associated with MAC (MAC claims), associated with general anesthesia (GA claims) or associated with regional anesthesia (RA claims).  Of 1952 claims for surgical anesthesia in the analysis, 121 claims (6%) were associated with MAC, 1519 (78%) were associated with GA and 312 (16%) were associated with RA claims. A noteworthy finding in this study was MAC claims involved a higher proportion of patients aged older than 70 yr as compared with GA claims, and a higher proportion of ASA physical status III-V as compared with GA and RA claims.

The authors determined that the severity of injury for MAC claims was similar to that of GA claims, with similar proportion of death and permanent brain damage, Deaths and permanent brain damage were more common (P<0.01) and temporary injuries were less common in MAC claims compared with RA claims. (P<0.01) (27% deaths and 10* brain damage).

 A respiratory damaging event led to an adverse outcome in similar proportions of MAC and GA claims but significantly smaller proportion of RA claims (P<0.025). Median payment made for MAC cases was 159,000 vs 140,000 for GA cases. The payment was done in 57% of MAC cases and 52% of GA cases. Respiratory depression due an absolute or relative overdose of sedative-hypnotic-analgesic agents was responsible for 25 MAC-related claims (21%). Six claims (24%) related to sedation occurred during MAC for endoscopy procedures.  Propofol was used in half of the cases, either alone or in combination with benzodiazipine and/or an opioid.  Death or brain damage resulted in most of the claims related to oversedation. Although most had pulse oximetry for monitoring oxygenation and 20% had both pulse oximetry and capnography in use the time of the event. 80% of the cases did not have capnogaphy.  In nearly half of the claims where death or brain damage occurred, it was judged that these injuries could have been prevented by additional, or better monitoring. Among others, inattention to monitors was also a primary cause of injury. 44% of the cases were preventable if better monitoring was used. 20% of the cases, capnography could have prevented death or brain injury. 

 Interpretation of these findings by Bhavani Shankar Kodali MD

The line between general anesthesia and conscious sedation is extremely thin and patients drift between the them. Most of the sedation drugs are potent respiratory and cardiac function. Once noxious stimuli decrease in intensity during the procedure, the respiratory depression becomes profound. Patients behave differently to same drug and dosage. It is mandatory that ventilatory status should be monitored during sedation, or MAC. Capnography offers an easy method of monitoring ventilation as explained in the other sections of capnography website (www.capnography.com). Apnea lasting more than 20 seconds or more is common occurrence during sedation and not easily detected by the providers. Capnography offers a distinct pathway to detect apnea, or respiratory obstruction.  A change in end-tidal carbon dioxide should prompt the provider to have a closer look at the patient and not wait until the manifestation of hypoxia.  Capnography is also useful when the environment where the procedure is being done is dark.  Continuous monitoring and vigilance are the essential components of safety. 


1.    Arrowsmith JB, Gerstman BB, Fleischer DE, Benjamin SB: Results from the American Society for Gastrointestinal Endoscopy/U.S. Food and Drug Administration collaborative study on complication rates and drug use during gastrointestinal endoscopy. Gastrointest Endosc 1991; 37:421–7.

2.    Cote CJ, Notterman DA, Karl HW, Weinberg JA, McCloskey C: Adverse sedation events in pediatrics: A critical incident analysis of contributing factors. Pediatrics 2000; 105:805–14.

3.    Cote CJ, Karl HW, Notterman DA, Weinberg JA, McCloskey C: Adverse sedation events in pediatrics: Analysis of medications used for sedation. Pediatrics 2000; 106:633–44.


4.    Bhanaker, SM, Posner KL, Cheney, FW, Caplan RA, Lee LA, Domino KB. Injury and liability associated with monitored anesthesia care: A closed Claims Analysis. Anesthesiology 2006;104;228-234.