Opioid free multimodal analgesia versus opioid based analgesia in bariatric surgery outcome

INTRODUCTION

Multimodal mechanisms of action by different agents minimize doses of individual drugs resulting in less the side effects and affects different pain pathways in the nervous systems^1,2. This result in good quality general anesthesia, enhances outcomes, and saves doses of opioid especially after surgery. This association can combine sodium channel blockers, NMDA antagonists, anti-inflammatory drugs and alpha-2 agonists³. Lignocaine is sodium channel blocker, with analgesic, anti-inflammatory, and anti-arrhythmic effects. Intravenous infusion of lidocaine reduces  intraoperative  anesthetics  consumption,  postoperative analgesic usage, pain score and length

of hospital stay. Low to moderate plasma levels of lidocaine are associated with vasoconstriction, therefore blood pressure monitoring is essential during lidocaine infusion and anti-hypertensive agents should be available^{4, 5}. Magnesium sulphate (NMDA) receptor antagonist non competitively, with an anticonvulsant, anti-inflammatory and muscle relaxant effects. Consequently, it has an opioid sparing effect and reduce postoperative pain scores ⁶.

We aimed evaluation of the OFA & TE technique in pathway of ERAS and comparison of patient hemodynamic (MABP) through operation, recovery room and up to 24-hours postoperative. In addition to assessing total opioid requirements postoperatively, pain scores using the visual analogue scale (VAS) Postoperatively, and length of stay in the unit of anesthesia post care (PACU) and in hospital. Moreover, increased patient satisfaction and reduced complications such as hypoxia, nausea, vomiting and shivering during different phases of operations pre, intra, and postoperative with balanced general anesthesia.

PATIENTS AND METHODS

The study protocol was approved by the Ethics Committee of Al-Zahra hospital and informed written consent was obtained. The study recruited 60 patients ASA I, II, aged between 20-50 years, underwent bariatric surgery under their ERAS pathway. 30 patients who received OFA with thoracic epidural (OFA & TE; n=30) and 30 patients received traditional BGA regimen (BGA; n=30). In both groups standard monitors were applied (pulse oximetry, ECG, NIBP, and capnogram). 2 hours before the procedure clear liquids was allowed. Wide pore canula 18 gauge inserted, and Patients received midazolam IV 0.05 mg/kg as premedication, fluid solution as Ringer’s lactate infused at rate 8 –12 ml/kg/hr. In Group OFA &TE while the patient was seated or on the lateral position after sterilization linear transducer was placed in a horizontal manner at the T5 spinous process corresponding to T4 transverse process. Three muscles were identified superior to the hyper echoic transverse process trapezius (uppermost), rhomboids major (middle), and erector spinae (lowest). Site of insertion, skin to epidural space distance, and direction were identified and marked before insertion of 18 Gauge Touhi needle (prefix epidural Catheter set, b Braun) (Figure 1), then a single injection with 20 ml Bupivacaine 0.25 % (0.25% BUPIVACAINE HClinj, USP HOSPIRA INC USA) was injected after negative aspiration. Then anesthesia pre-induction while providing 100% oxygen mask (8L/min) by 0.2 mcg/kg precedex, ketamine 0.25 mg/kg, xylocaine 1 mg/kg, esmolol 150 mcg/kg, 0.1 mg/kg dexamethasone, paracetamol 1g and magnesium sulfate 1 g, titrating all drugs as intravenous boluses. Then 1 to 1.5 mg/kg propofol titrated till sleep dose, 0.5 mg/kg atracurium thereafter inserted into an appropriately sized endotracheal tube (ETT). After intubation anesthesia maintained by the inhalational anesthetic agents, sevoflurane halved to (1/2 MAC) a bispectral target index of 55. Premixed IV infusion dexmedetomidine 0.1–2 ug/kg/h, lidocaine 1 mg/kg/h, 0.2 mg/kg/h ketamine esmolol 5–10 mcg/kg/min, and magnesium sulfate10 mg/kg/h. Mechanical ventilation was performed with oxygen 50% FiO₂ mixing air, tidal volume (TV) 4–10 ml/kg and RR 9–16 C/m to end-tidal CO₂ (30–35 mm).patients controlled analgesia (PCA) with a bottle filled by 0.2 mcg/kg precedex, ketamine 0.25 mg/kg, xylocaine 1 mg/kg, esmolol 150 mcg/kg, 0.1 mg/kg dexamethasone, paracetamol 1g and magnesium sulfate 1 g, titrating all drugs as intravenous infusion rate 6-hour limits, 5ml boluses as demand dose, and lock out interval 15 min to control post operative pain.

 Balanced opioid based general anesthesia (BGA) group for induction of anesthetized patients received 1-2 ug/kg fentanyl, titrated propofol 1.5–2 mg/kg, 0.5 mg/kg atracurium for intubation. After endotracheal intubation 1–2 ug/kg boluses of fentanyl were given up to 2 mg total, MAC inhalational anesthetic with sevoflurane to maintain anesthesia. Mechanical ventilation with a volume of 4–10 ml/kg and RR 9–15C/min, with FiO₂ 50% oxygen: air to achieve ETCO₂ = 30–35 mm. PCA used with 200 ug fentanyl, paracetamol 1gm as intravenous infusion rate 4hour limits, 5ml boluses as demand dose, and lock out interval 20 min to control post operative pain.

Fig 1: Ultra sonic guided thoracic epidural block.

Statistical analysis

Recorded data were analyzed using the statistical package for the social sciences, AS (SPSS Inc., Chicago, Illinois, USA) version 20.0. Qualitative data were expressed as percentage and frequency. Quantitative data were expressed as mean± SD. A 95% the confidence interval was set and 5% the margin of error was accepted. Therefore, up to p- value was considered significant as follows: up to P value 0.05 considered significant, up to P- value 0.001 was considered highly significant, and more than P- value 0.05 insignificant.

RESULTS

The demographic data including BMI, ASA status, and duration of surgery were compared among two groups statistically non-significant and p value (𝑃>0.05) show (Table 1). There were no significant differences between the hemodynamic MABP, during operation, PACU and 24 hours postoperative at p value of (𝑃>0.05) as shown in (Figure 2).

Fig 2: Hemodynamic (MABP) during operation, PACU and 24 hours postoperative in two groups (*P > 0.05: NS).

With regard to postoperative pain using VAS score, a statistically significant decrease was observing in (OFA & TE) group than the (BGA) group at p value of (P<0.005) as demonstrated in table (2). A significant reduction in total requirement of Opioid postoperatively in PACU in OFA & TE group was (5.28 ± 1.7), whereas it was (24.86 ± 5.5) in BAG and (p value < 0.001). In ward, there was also a significant difference regarding consumption of Opioid in group the OFA & TE (6.43±2.68) compared to BGA (23.68±4.6) and (p value< 0.001) as shown in table (3). Regarding patient satisfaction, more patients were not satisfied in the BGA group 11 (36.7%) compared to OFA & TE 4 (13.3%), while more patient partially satisfied in OFA &TE 10 (33.3%) compared to BGA group 8 (26.7%) at p-value 0.779 (p < 0.05). More patients 18(60%) were highly satisfied in the OFA &TE than the BGA group 9(30%) (p=0.037) as shown in table (4). With respect to postoperative complications in the PACU, regarding hypoxia there is no significant difference in OFA & TE (12%) and (15%) in BGA, there is no significant difference between two groups concerning to vomiting and nausea no patients in OFA & TE group compared with 18% and 12% respectively in BGA group and (p- value < 0.001). Finally, with regard to shivering there was a significant difference (15%) in OFA &TE group and 60% in BGA at (p- value < 0.05) as show (table 5).

Table 1: Demographic data of the two of studied groups.

Table 2: The visual analogue scale (VAS), significant (p < 0.05).

Table 3: Postoperative opioid consumption (*p < 0.001, Highly Statistically significant).

Table 4: Comparison Patients satisfaction in the two groups (*p < 0.05 significant).

Table 5: Postoperative complication (*P< 0.05, significant; **p <0.001, highly significant.