Table 3:

Examples of Errors of Perception, Comprehension and Projection

Level 1: Perception - What is the information? Key issue: failure to gather information via history, physical exam, diagnostic tests, imaging or monitors, including absence of monitor(s)
Case Type	Case Description	Error Description
Cardiac arrest	35–39 y.o. ASA 3–5 male with history of mental retardation, obesity, hypertension and NIDDM admitted for a urology procedure under GA. Cardiology work-up for difficulty breathing revealed dilated cardiomyopathy, EKG changes, and ejection fraction of 15%. The echo results were not in the records preoperatively. The patient’s family did not relate any cardiac history to the anesthesiologist preoperatively. The patient arrested during surgery, was resuscitated, but arrested again in the ICU and died.	Failure to gather information: preoperative test results not in the records; family did not relay information to anesthesiologist.
Pulmonary aspiration	70–74 y.o. ASA 4 male inpatient with aortic stenosis and regurgitation, post aortic valve replacement, and CHF scheduled for cardiac defibrillator battery replacement. Preoperative evaluation also revealed morbid obesity and a bull neck. On the morning of surgery, the anesthesiologist asked the patient if he had eaten and the patient provided an unclear answer. The anesthesiologist did not query the nurses regarding NPO status. During induction of anesthesia, the patient had emesis consisting of food. The patient’s airway was suctioned and he was intubated, but developed ARDS and eventually died. It was later discovered that the patient had been served breakfast on the day of surgery.	Failure to gather information: Anesthesiologist failed to ascertain NPO status preoperatively.
Inadequate ventilation/oxygenation	50–55 y.o. ASA 3 woman with comorbidities including coronary stents, congestive heart failure, pacemaker, and pulmonary edema 1 month prior for cataract extraction under monitored anesthesia care. The anesthesiologist administered midazolam and fentanyl in the holding area. The patient was then transported unmonitored to the operating room. Upon arrival 2–4 minutes later, she was unresponsive and apneic. She was resuscitated but arrested again two days later and died.	Failure to gather information – absence of monitors: Failure to monitor patient during transport after administering pre-induction drugs.
Inadequate ventilation/oxygenation	70–75 y.o. ASA 3 man for colonoscopy under MAC. Monitors included EKG, FiO2 and ETCO2. The patient was given propofol and O2 delivered by nasal prongs. The anesthesiologist was chatting with the GI physician and not paying attention to the monitors. It was noted that the patient was not breathing. A code was called, LMA inserted, and 100% O2 administered. Saturations could not be obtained as the patient was in asystole. The patient was resuscitated but eventually died. The severity of the encephalopathy suggested a prolonged period of desaturation.	Non-awareness of equipment function: Anesthesiologist was not attentive to the monitors.
Inadequate oxygenation/ventilation	60–65 y.o. morbidly obese ASA 3 man for elective screening colonoscopy under MAC. Numerous comorbidities included COPD requiring O2 at night. The patient was given a small dose of propofol for the procedure and received 3 L/min O2 via nasal cannula. The room was small and the anesthesiologist could not see the monitoring equipment. Severe bradycardia occurred and then the patient arrested. The procedure was aborted, and resuscitation attempts resulted in return of spontaneous circulation after 15 minutes. The patient was admitted to the ICU after he was resuscitated, but his condition continued to decline. Life support was withdrawn twelve days later, and he died shortly thereafter.	Failure to gather information – hidden information: Anesthesiologist could not observe monitoring equipment in small room.
Level 2: Comprehension: What was the diagnosis? Key issue: Failure to understand the significance of information obtained from history, physical exam, diagnostic tests, imaging findings, or monitors. The information was available, but it was not understood or misunderstood.
Case Type	Case Description	Error Description
Hemorrhage	40–44 y.o. ASA 2 woman underwent an elective laparoscopic-assisted vaginal hysterectomy for endometrial cancer under general anesthesia. About an hour into the procedure, the surgeons encountered severe uterine bleeding. The anesthesiologist was aware of this event and treated hypotension with doses of ephedrine 10mg, phenylephrine 100 mcg. The blood pressure fell, the patient developed pulseless electrical activity, and resuscitation was begun. Fluid resuscitation by the anesthesiologist was inadequate and the patient became hypovolemic and acidotic, progressing to ventricular fibrillation. The patient was resuscitated and taken to ICU where she remained hemodynamically unstable and died the following morning. Cause of death on autopsy was hypovolemic shock.	Failure to comprehend the meaning and significance of information: The anesthesiologist perceived hypotension and bleeding but did not correctly comprehend the severity of bleeding resulting in inadequate treatment.
Esophageal intubation	60–65 y.o. ASA 2 woman with history of a difficult intubation was scheduled for partial thyroidectomy under GA. After preoxygenation, GA was induced and the ETT placed. The anesthesiologist documented equal breath sounds bilaterally and negative gastric sounds; ETCO2 was zero, interpreted as monitor malfunction. Over 10 minutes, BP and SpO2 dropped; then the patient became bradycardic progressing to asystole, treated with CPR and atropine/ epinephrine. Twenty minutes after intubation, the patient was extubated and re-intubated, CPR continued, and ETCO2 increased to 38–40. The case was cancelled, and the patient taken to ICU. She was found to have hypoxic brain damage and did not regain consciousness. Review of the vital signs in the monitor after the event showed no ETCO2 and falling SpO2 during the 20 min episode.	Failure to understand monitoring information: Information was available (no ETCO2 on monitor) but was misinterpreted as machine malfunction, leading to failure to diagnosis esophageal intubation.
Tension pneumothorax	45–50 y.o. female for arthroscopic shoulder repair under GA in a free standing ambulatory surgery center. The 3 hour surgery proceeded uneventfully. The patient was not ventilating well at the end of the surgery, so she was taken to the PACU intubated; SPO2 was 99% on admission. The patient’s SPO2 decreased over 15–20 minutes to the low 90’s, and finally to 64% when she arrested. CPR was performed and paramedics were called for transfer to the hospital ER. The patient was noted to have severe subcutaneous air. Bilateral thoracotomies were performed and an x-ray showed her lungs had expanded with significant pneumomediastinum and subcutaneous air. The ETT that was placed was in good position. The patient sustained significant permanent brain damage.	Failure to diagnose: Anesthesiologist did not diagnose patient’s oxygen desaturation postoperatively.
Level 3: Projection: What is likely to occur? Key issue: Failure to forecast future events or scenarios based on a high-level understanding of the situation; failure to forecast potential outcomes based upon a chosen plan; poor planning for future events or poor/absence back-up plan.
Case Type	Case Description	Error Description
Difficult re-intubation	A 40–50 y.o. ASA 2 obese woman underwent septoplasty and endoscopic sinus surgery. The anesthesiologist expected a difficult intubation. When he could not place an ETT via direct laryngoscopy, the anesthesiologist placed a LMA and eventually an ETT. Upon completing the procedure, the patient was extubated, but began to “flail and bite her tongue” and desaturated. The anesthesiologist placed another LMA and the saturation improved. A fiberoptic intubation was performed, but was unsuccessful. The LMA was replaced and a tracheostomy was performed as the patient became hypoxic and bradycardic. The patient transiently responded to atropine and epinephrine, but she eventually became asystolic. Resuscitation efforts were terminated after one hour.	Failure to plan for future events: The anesthesiologist anticipated and managed difficult intubation, but did not have an adequate extubation plan for a patient with a known difficult airway.
Inadequate anesthesia plan	50–55 y.o. ASA 3–5 morbidly obese male suffering from severe aortic stenosis was admitted to the hospital with a-fib and pulmonary congestion. He also had cardiomegaly and elevated ventricular rate above 100. A transthoracic echo showed ventricular dysfunction and moderate aortic insufficiency. Cardiologists wanted to proceed with transesophageal echo with TEE-guided electrical conversion in the hope of converting him to sinus rhythm. The anesthesiologist administered a high dose (100mg) of propofol for sedation. The patient became hypoxic and bradycardic. The anesthesiologist attempted to ventilate with Ambu® bag but was not successful. The patient was intubated, and BP and heart rate returned to normal. The patient suffered anoxic brain injury and was left with permanent neurologic injury.	Poor anesthetic plan for patient with known significant comorbidities including morbid obesity: Anesthesiologist plan for heavy sedation in patient with severe cardiac disease including sedative agent with known BP effects, high sedative dose and failure to anticipate difficult mask ventilation indicates poor planning.
Difficult intubation	25–30 y.o. ASA 3 female with stage IV colon cancer and submental salivary gland abscess which caused difficulty swallowing. A CT scan showed fluid collection at the floor of the mouth. She was taken to the OR for surgery under GA. The patient was induced with 140mg propofol, 220mg succinylcholine, 100mg lidocaine, and 250mcg fentanyl. The anesthesiologist was unable to see the cords with direct laryngoscopy and called for a Glidescope®, which was in another OR. The anesthesiologist was unable to ventilate; SPO2 was 85% and falling. Code was called and CPR begun. The anesthesiologist asked the nurse to bring a cricothyrotomy kit, but it was not readily available. The anesthesiologist proceeded to search for a difficult airway cart; the patient was not being ventilated during this time. Eventually the cricothyrotomy kit was provided and the surgeon performed a tracheostomy. The patient sustained severe brain damage and remained in a persistent vegetative state with need for total custodial care.	Poor plan – absence of backup plan: Anesthesiologist failed to have appropriate difficult airway equipment and plan for induction of GA in patient with airway pathology and potential obstruction.

a-fib = atrial fibrillation; ARDS = acute respiratory distress syndrome; ASA = American Society of Anesthesiologists; BP = blood pressure; COPD = chronic obstructive pulmonary disease; CPR = cardio-pulmonary resuscitation; CT = computed tomography; EKG = electrocardiogram; ER = emergency room; ETCO₂ = end-tidal carbon dioxide; ETT = endotracheal tube; FiO₂ = fraction of inspired oxygen; GA = general anesthesia; GI = gastrointestinal; ICU = intensive care unit; L = liter; LMA = laryngeal mask airway; MAC = monitored anesthesia care; mcg = micrograms; mg = milligrams; min = minute; NIDDM = non-insulin dependent diabetes mellitus; O₂ = oxygen; OR = operating room; PACU = post-anesthesia care unit; SpO₂ = peripheral capillary oxygen saturation; TEE = transesophageal echo; y.o. = year old