Intravenous Acetaminophen Reduces Length of Stay Via Mediation of Postoperative Opioid Consumption After Posterior Spinal Fusion in a Pediatric Cohort.

OBJECTIVES: Since approval of intravenous acetaminophen (IV APAP), its use has become quite common without strong positive evidence. Our goal was to determine the effect of IV APAP on length of hospital stay (LOS) via mediation of opioid-related side effects in pediatric patients. MATERIALS AND METHODS: After Institutional Review Board approval, 114 adolescents undergoing posterior spinal fusion were prospectively recruited and managed postoperatively with patient-controlled analgesia and adjuvant therapy. Patients were divided into 2 groups based on the use of IV APAP: control (n=70) and treatment (n=44). Association of IV APAP use with opioid outcomes was analyzed using inverse probability of treatment weighting (IPTW)-adjusted propensity scores to balance the 2 groups for all significant covariates except postoperative opioid consumption. Mediation analysis was carried out for LOS with IV APAP as the independent variable and morphine consumption as the mediator. RESULTS: Oral intake was delayed by ∼1 day (P<0.001) and LOS was 0.6 days longer in the control group (P=0.044). After IPTW, time to oral intake remained significantly longer in the control group (P=0.014). The mediation model with IPTW revealed a significant negative association between IV APAP and morphine consumption (P<0.001), which significantly increased LOS (P<0.003). IV APAP had a significant opioid-sparing effect associated with shorter LOS. DISCUSSION: IV APAP hastens oral intake and is associated with decreased LOS in an adolescent surgery population likely through decreased opioid consumption. Through addition of IV APAP in this population, LOS may be decreased, an important implication in the setting of escalating health care costs.

Fatty acid amide hydrolase-morphine interaction influences ventilatory response to hypercapnia and postoperative opioid outcomes in children.

AIM: Fatty acid amide hydrolase (FAAH) degrades anandamide, an endogenous cannabinoid. We hypothesized that FAAH variants will predict risk of morphine-related adverse outcomes due to opioid-endocannabinoid interactions. PATIENTS & METHODS: In 101 postsurgical adolescents receiving morphine analgesia, we prospectively studied ventilatory response to 5% CO2 (HCVR), respiratory depression (RD) and vomiting. Blood was collected for genotyping and morphine pharmacokinetics. RESULTS: We found significant FAAH-morphine interaction for missense (rs324420) and several regulatory variants, with HCVR (p < 0.0001) and vomiting (p = 0.0339). HCVR was more depressed in patients who developed RD compared with those who did not (p = 0.0034), thus FAAH-HCVR association predicts risk of impending RD from morphine use. CONCLUSION: FAAH genotypes predict risk for morphine-related adverse outcomes.