Longer NPO intervals are causal in eHLOS following laparoscopic bariatric surgery

Vaughn E Nossaman, MD, MS, MS¹, William S Richardson III, MD², James B Wooldridge Jr., MD², Bobby D Nossaman, MD². ¹Nassau University Medical Center, ²Ochsner Medical Center

Introduction: Recent studies in bariatric surgery have demonstrated a statistically significant dose-response association of increasing intravenous hydration (ml/kg/hr) progressively decreasing the incidence of extended hospital length of stay (eHLOS) (Fig. 1) [1]. However, attainment of a recommended ‘liberal’ intravenous fluid hydration strategy during these procedures with median surgical times of 1.0 [0.9-1.1] hrs is difficult [1]. A post-hoc analysis of the duration of nil per os (NPO) revealed a statistically significant dose-response association on the incidence of eHLOS [1]; with the lowest projected incidence within the 2-5 hr NPO interval (10-12%, Fig. 2). As NPO is associated with a state of compensatory dehydration [2], the primary purpose of this study was to examine the role of a shorter NPO interval (≥2 hrs) on the incidence of eHLOS and to establish causality between these variables.

Methods: Following IRB approval and established fasting guidelines for adult patients, 168 consecutive bariatric surgeries were analyzed following institution of a revised oral water ad libitum policy on the incidence of eHLOS when compared to the prior data set [1]. Categorical variables were presented as percentages with differences between the groups assessed using Chi-square or Fisher exact tests. Continuous variables with skewed distributions were presented as median and 25-75% interquartile range [IQR] with differences between groups assessed by the Wilcoxon rank-sum test.

Results: There were no perioperative pulmonary aspirations or gastrointestinal complications. There were significant differences in the incidences of histories of anemia, GERD, previous PCI/PTCA, and preoperative albumin levels between the types of previously reported demographic, comorbidities, or preoperative laboratory values observed between the two groups (Table 1). Following reduction of the NPO interval to ≥2 hrs, a significant decrease in the incidence of eHLOS from 23.8% in the ≥8 hr interval patient group (Fig. 2) to 14.3% was observed in the 2-5 hr NPO interval patient group (54 patients) (Fig. 3). Comparison of the projected eHLOS incidence line for the NPO interval between 2-5 hrs in figure 2 is confirmed by the data populated for this interval in figure 3, suggesting a true dose-response relationship exists that supports causality.

Conclusions: These results suggest that allowing bariatric patients access to ad libitum water for up to 2 hrs prior to surgery decreased the incidence of eHLOS without apparent gastrointestinal or pulmonary complications. Causality is supported by a predicted and confirmed dose-response relationship between duration of NPO and eHLOS.