Esophageal intubation was a major source of anesthesia patient death and brain damage as well as a major source of liability in the 1980s.1 Esophageal intubation accounted for 6% of all closed anesthesia malpractice claims and 18% of those associated with adverse respiratory events in the earliest closed claims analysis.1 Nearly all (98%) of those claims resulted in death or brain damage, and most (82%) resulted in malpractice claim payments, with average payments significantly higher than nonrespiratory claims. In 1991, identification of CO2 in the expired gas to verify correct position of the endotracheal tube became an American Society of Anesthesiologists standard of basic anesthetic monitoring for general anesthesia.2 This study aims to identify factors associated with delayed detection of esophageal intubation in anesthesia malpractice claims after this change in monitoring standards.
After IRB approval, we analyzed the trends in delayed detection of esophageal intubation from 1970 to 2013. We analyzed in detail the 45 claims for delayed detection of esophageal intubation that occurred in 1995 or later in the Anesthesia Closed Claims Project Database of 10,811 claims.3,4 Personnel performing the intubation, location, and factors associated with delayed detection were abstracted from claim narratives. Payment data were adjusted to 2015 dollar values using the Consumer Price Index, with median and interquartile range reported. Esophageal intubations between groups were compared by Fisher exact test for proportions and Mann-Whitney U test for payment amount, with P < .05 for statistical significance. Confidence intervals for proportions were calculated according to Fleiss.5
Delayed detection of esophageal intubation declined as a proportion of anesthesia malpractice claims from approximately 3% to 8% of claims per year before 1990 to 1% to 2% per year in 1990 and later (Figure). There were a total of 45 cases that occurred in the year 1995 or later, with 31 (69%) occurring in the year 2000 or later.
Half (49%) of these 45 cases occurred during anesthesia care in surgical locations in an operating room (OR; 40%) or a nonoperating room anesthesia (NORA) location (9%). The other most common locations were the intensive care unit (20%), resuscitation in the cardiac catheterization laboratory (cath lab) (11%), and reintubation or resuscitation in the postanesthesia care unit (9%). The remainder occurred in emergency room and ward (4% each) or outside the hospital (2%). Purely elective cases accounted for 29% and resuscitation for 38%.
Of the 45 claims for delayed detection of esophageal intubation, 29 (64%) of the intubations were performed by an anesthesiologist and 13 by other health care providers (3 were unspecified, but most likely not by an anesthesiologist). Among the 29 esophageal intubations by anesthesiologists, 13 were detected by an anesthesiologist, 5 by another (nonanesthesiologist) physician, and 4 were not diagnosed until autopsy. Among the 16 claims where the esophagus was intubated by a nonanesthesiologist, 9 were detected by an anesthesiologist, 2 were detected by another type of physician, and 2 were not diagnosed until autopsy. In total, 76% of esophageal intubations were recognized during resuscitation and 13% were not detected until autopsy.
Among the 28 cases in which there was information on the method used to erroneously confirm proper endotracheal tube placement, 15 used 1 technique, while 11 used 2 techniques and 2 used 3 techniques. The most common technique used to confirm endotracheal tube placement was auscultation of breath sounds (21 cases, 46% of 45 total cases). Other common techniques were colorimetric CO2 detection devices (n = 8, 18%), capnography (n = 6, 13%), visualization of the larynx (n = 5, 11%), and condensation in the endotracheal tube (n = 3, 7%).
CO2 monitoring issues were factors in delayed detection in 3 quarters of claims (73%). The most common CO2 monitoring issues were not using or ignoring end-tidal CO2 (etco2; Table). In 10 of the 12 cases in which a CO2 monitoring device was not used, it was not clear that a CO2 monitoring device was available. Among the 9 cases where etco2 readings were ignored, overconfidence in endotracheal tube placement was sometimes observed (Table). In 7 cases, CO2 readings were misinterpreted, and in 6 cases, there was equivocal color change of the colorimetric CO2 device. Confirmation bias was a factor in some of these cases. For example, in 1 case a positive CO2 waveform was seen for a short period of time, leading the team to think the endotracheal tube was correctly placed, but the trace then disappeared. In another case, the CO2 device was in the process of calibrating, so the team observed an erroneous positive reading. In one case of equivocal color change, the endotracheal tube was removed and replaced, with multiple opinions sought to confirm placement.
In one-third of cases (33%), late detection was associated with confusion over differential diagnosis, most often bronchospasm (Table).These cases often exemplified fixation errors, with focus on treating a comorbidity rather than questioning endotracheal tube placement.
Cardiac arrest (presumably with lack of cardiac output) contributed to delayed detection in 13% of esophageal intubation claims (Table). Communication problems occurred in 27% of esophageal intubations and were more common when the anesthesiologist was called to help in a nonanesthesia location (43%) than during anesthesia care in the OR/NORA (9%, P = .017).
Nearly all esophageal intubations with delayed detection resulted in patient death or severe brain damage (96%). Most (67%) resulted in payment made on behalf of the anesthesiologist, with median payment of $665,000 (interquartile range $236,000 to $1,213,500). Payment on behalf of the anesthesiologist was more common when the anesthesiologist had performed the intubation (86% paid) than when performed by others (50% paid, P = .041), but the payment amount did not differ between groups.
Although advanced anesthetic monitoring has been a standard of care for confirmation of endotracheal tube placement during general anesthesia since 1991, CO2 detection issues contributed to persistence of delayed detection of esophageal intubation in these malpractice claims for events that occurred well after adoption of these standards (1995 or later, with most occurring in the 2000s). Half of these cases (49%, 95% confidence interval 34%–64%) arose in the OR or another procedural (NORA) location, where CO2 detection equipment should have been readily available. Although malpractice claims data are limited by retrospective nonrandom sampling, bias toward severe outcomes, and lack of a denominator for risk estimation, valuable information on relatively rare adverse events can be gained.4 This study found that errors in differential diagnosis and communication problems also contributed to delayed detection (Table). Three cognitive factors contributing to delayed detection of esophageal intubation were observed in this case series: fixation error, confirmation bias, and overconfidence.6 Fixation error is a focus on a single issue at the expense of all others, such as seen in case example 5 where the team focused on bronchospasm and failed to consider esophageal intubation (Table). Confirmation bias involves focus on information that supports a working diagnosis while ignoring conflicting information. Diagnostic methods such as auscultation of breath sounds used in conjunction with CO2 detection may have contributed to confirmation bias. Air flowing through a tube in the esophagus, especially with the faster gas flows and higher tidal volumes during mechanical ventilation, may be misinterpreted as breath sounds in the lungs on auscultation.7 Vesicular breath sounds may be transmitted to the epigastric area in patients with thin or small body habitus, rendering epigastric auscultation unreliable for detection of esophageal intubation.7 Confirmation bias was also observed when colorimetric CO2 detection devices showed equivocal color change, such as that illustrated by case 3 (Table), with the team preferring to accept a working diagnosis of correct endotracheal tube placement in the face of ambiguous or potentially conflicting information. Overconfidence with inaccurate self-assessment results in misplaced certainty about diagnoses. In cases 1 and 7, overconfidence was exhibited when the intubating physician refused to allow another physician to check endotracheal tube placement, even in the absence of CO2. Training and education, workplace strategies, forcing functions to prevent confirmation bias and fixation errors, remedy of overconfidence,8 and improvement of anesthesiologists’ nontechnical skills9 have the potential to reduce catastrophic patient injury from esophageal intubation. Training can prevent future errors, while workplace strategies and forcing functions can catch errors in the present time.8 Education about cognitive errors, including “consider the opposite” procedures, can reduce confirmation bias and fixation errors.8 Workplace strategies to address overconfidence include group decision strategies as a norm in complex situations.8 Forcing functions to catch errors include standing rules that require ruling out “must-not-miss” diagnoses, ROWS (Rule Out Worst-Case Scenario), and “consider the opposite.”8 However, prevention of error through such strategies is entirely theoretical because the strategies have not been tested in the complex, high-stakes, real-world environment. Application of these strategies during critical events under conditions of time pressure and uncertainty is fraught with difficulty. Hence, the magnitude of potential improvement in detection of esophageal intubation is impossible to predict. The occurrence of delayed detection related to lack of etco2 monitoring devices, especially outside of the OR, suggests that availability of etco2 monitoring devices in all locations where intubation might occur has additional potential to address the continued occurrence of catastrophic injury resulting from delayed detection of esophageal intubation.
The authors acknowledge the closed claims reviewers from the American Society of Anesthesiologists and participation of the following liability insurance companies who have given permission to be acknowledged: Anesthesia Service Medical Group, Inc, San Diego, CA; COPIC Insurance Company, Denver, CO; ISMIE Mutual Insurance Company, Chicago, IL; MAG Mutual Insurance Company, Atlanta, GA; Medical Liability Mutual Insurance Company, New York, NY; Midwest Medical Insurance Company, Minneapolis, MN; NORCAL Mutual Insurance Company, San Francisco, CA; Physicians Insurance A Mutual Company, Seattle, WA; Preferred Physicians Medical Risk Retention Group, Overland Park, KS; Risk Management Foundation, Cambridge, MA; State Volunteer Mutual Insurance Company, Brentwood, TN; The Doctors’ Company, Napa, CA; The University of Texas System, Austin, TX.
Name: Marzieh R. Honardar, MD.
Contribution: This author helped analyze the data, write and edit the manuscript, and review the literature.
Name: Karen L. Posner, PhD.
Contribution: This author helped design the study, analyze and manage the data, write and edit the manuscript, and review the literature.
Name: Karen B. Domino, MD, MPH.
Contribution: This author helped design the study, analyze the data, and write and edit the manuscript.
This manuscript was handled by: Avery Tung, MD, FCCM.