Cutoff Values for Providing the Ideal Intravenous Patient-Controlled Analgesia According to the Intensity of Postoperative Pain-A Retrospective Observational Study.

Keum Young So,Sang Hun Kim

doi:10.3390/medicina57101065

Abstract

Background and Objectives: The cutoff values were analyzed for providing the ideal intravenous patient-controlled analgesia (PCA) that could reduce rescue analgesics or antiemetics requirements, based on the grades of postoperative pain intensity (PPI). Materials and Methods: PCA regimens of 4106 patients were retrospectively analyzed, and they were allocated into three groups with low, moderate, and high PPI grades (groups L, M, and H, respectively) based on numeric rating scores obtained 6 h postoperatively. Opioid and non-opioid analgesic doses were converted into fentanyl-equivalent doses (DOSE-FEN-OP and DOSE-FEN-NONOP, respectively). The primary endpoint was the cutoff values of these parameters. Results: With respect to the PCA settings to reduce rescue analgesic and antiemetic requirements, group L required a background infusion rate (BIR) of 1.75–3 mL/h, bolus volume of 0.5–1.25 mL, and lockout interval of ≤12.5 min. Group M required a BIR of 1.75 mL/h, bolus volume of 0.5–1.75 mL, and lockout interval of ≤5 min. Group H required a BIR of 1.75 mL/h, bolus volume of 0.5 mL, and lockout interval of ≤5 min. In assessments of the analgesic doses to reduce rescue analgesic requirement, the DOSE-FEN-OP was at least 950 μg of fentanyl regardless of group, while the DOSE-FEN-NONOP was ≥250 μg, ≥550 μg, and ≥700 μg for the L, M, and H groups, respectively. In assessments of the analgesic doses to reduce rescue antiemetic requirement, DOSE-FEN-OP was ≤950 μg for groups L and M and ≤850 μg for Group H, while DOSE-FEN-NONOP was ≤50 μg, ≤450 μg, and ≤700 μg for groups L, M, and H, respectively. Conclusion: The ideal PCA for reduction in rescue analgesics or antiemetics can be achieved by adjustment of PCA settings and drug dosages carefully with these cutoff values depending on the expected grades of PPI. Especially, the ideal PCA can be provided by adjusting the lockout interval and bolus volume rather than BIR and by applying smaller bolus doses and shorter lockout intervals with an increasing PPI grade.

Highlights

The three groups showed no significant differences in sex, age, height, weight, body mass index (BMI), Anesthesiologists physical status (ASA PS), and anesthesia duration, and in the prevalence of underlying diseases, smoking, opioid-naïve status, and intraoperative opioid use (Table 1)
For patients with a low expected postoperative pain intensity (PPI), this study showed that a background infusion rate (BIR) of 1.75–3 mL/h, bolus volume of 0.5–1.25 mL, and lockout interval of ≤12.5 min were required for effective analgesia without the need for rescue analgesics and antiemetics (Figure 2)
For the optimal or ideal regimens of patient-controlled analgesia (PCA) depending on PPI, the authors suggest that the adjustment for PCA settings is needed based on a BIR of 1.75 mL/h and bolus volume of 0.5 mL regardless of expected PPI and the lockout interval among PCA setting is needed to adjust within 12.5 min for cases with a low expected PPI, and within 5 min for those with a moderate or high expected PPI

Summary

Introduction

Situation, patients commonly require rescue analgesics or antiemetics for controlling these adverse events. Fentanyl has been popularly adopted as a more appropriate and suitable opioid than morphine for intravenous PCA due to its more rapid onset and shorter duration of action, fewer opioid-related adverse events, and higher satisfaction score than morphine [1,4,5]. BIR-EME was significantly different among groups (p = 0.014) and was lower in group H than in group L (p = 0.020, Table 4). Requirement for Rescue Analgesics and Antiemetics during Intravenous PCA. The requirement for rescue analgesics was significantly different among the three groups (p < 0.001) and was the highest in group H (26.6%), followed by group M (20%). Rescue antiemetic requirement was not significantly different among the three groups.

Methods

Results

Discussion

Conclusion