Tiffany C Cox, MD, Ciara R Huntington, MD, Laurel J Blair, MD, Tanushree Prasad, MA, B Todd Heniford, MD, FACS, Vedra A Augenstein, MD, FACS. Carolinas Medical Center

Introduction: Preoperative assessment of patient’s capability to withstand the stress of surgery is necessary. The rarity of IEs for a single institution makes it difficult to investigate the effectiveness of screening strategies. This study stratifies the risk factors associated with IEs in a national registry to better predict their occurrence.

Methods: The National Surgical Quality Improvement Program(NSQIP) database was analyzed to identify all patients who experienced IEs: cardiac arrest requiring cardiopulmonary resuscitation(CA-CPR), on-table myocardial infarction(MI), and unintended intubation(UI). IEs versus no IEs comparison was performed using chi-square, Wilcoxon two-sample test, Analysis of Variance(ANOVA), and logistic regression model for respective variables to identify any preoperative risk factors with statistical impact.

Results: A total of 1,895,433 patients were evaluated between 2005-2012. IEs were identified in 1,043 patients: 353 CA-CPR, 118 MI, and 572 UI. Compared to the 1,894,390 patients without IEs, patients with IEs were older(mean age 63vs56,p<0.001), with elevated preoperative creatinine(1.3vs1.0,p<0.001), and a significant history of smoking(24.6vs9.8 pack years,p<0.001). Only patients with UI had a higher BMI(32.3±9vs30.2±10kg/m2,p<0.001). Comparison of patient demographics and characteristics for categorical variables are detailed below(Table 1). Strong predictors of CA-CPR included history of: cardiac disease, chronic obstructive pulmonary disease(COPD), myocardial infarction, percutaneous coronary intervention(PCI), hypertension, and coagulopathy/anticoagulants; a negative predictive value was seen for patients with independent functional status. MI predictors included: male gender, PCI, hypertension, and renal failure. UI had a statistically significant association with diabetes, alcohol abuse, and COPD. Within the top five billing codes associated with IEs, laparoscopic cholecystectomy and laparoscopic gastric bypass were identified with IE rates of 0.02% and 0.04% respectively. Overall, odds of 30-day mortality for IEs were 92.1(95%CI 73-115) for CA-CPR, 38.8(95%CI 23.8-63.3) for MI, and 8.8(95%CI 5.8-13.2) for UI.

Conclusion: IEs can be devastating. Current screening is not straightforward and predicting those patients at risk based on calculated risk factors could significantly reduce their occurrence. Findings here may be incorporated with current guidelines to improve the accuracy of preoperative screening, calculate risk, and avoid these complications.

Table 1.No Intraoperative Events versus Intraoperative Events, OR(95%CI)
Male genderNS3.5(2.4-5.3)NS
Alcohol AbuseNSNS2(1.4-2.9)
Independent Functional Status0.2(0.1-0.3)NSNS
History of:
Congestive Heart FailureNSNSNS
Myocardial Infarction19(12.7-28.3)NSNS
Renal FailureNS9.6(2.4-38.6)NS

OR= odds ratio, CI=confidence interval, NS=not statistically significant

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