Efficacy of low opioid anaesthesia protocol in a high volume centre for bariatric surgery

Ene A1, Badescu R1, Constantin G1, Fodor A1, Godoroja D1
1Department of Anaesthesia and Intensive Care, Ponderas Academic Hospital Bucharest, Romania

Background and Aim 

In morbidly obese patients, anaesthesiologists are recommended to use an obstructive sleep apnoea safe anaesthetic technique (minimising opioids). 
The primary goal of the study was to assess the efficacy of  using  a low opioid protocol for general anaesthesia in bariatric surgery.

Method 

After local ethics committee approval, in February 2016  we introduced a protocol of low opioid general anaesthesia for obese patients  undergoing laparoscopic bariatric operations (sleeve gastrectomy  and gastric bypass). The protocol was used by all anaesthetists and was based on using low dose of fentanyl ( 100 mcg), adjuvants(ketamine, magnesium sulphate, lidocaine) and opioid free analgesics ( Table1).No intravenous morphine was administered at the end of the procedure. All patients received a protocolised opioid free multimodal postoperative analgesia and intravenous morphine only if the  visual analogue score (VAS) was higher than 5. Cumulative opioid ( iv mg morphine) consumption for 24 hours  and pain severity scores (VAS) at rest and movement (cough) were recorded at 1, 4, 12, and 24 h postoperatively.

Results.

Between February 2016 and August 2017 in Ponderas Academic Hospital, 1227 patients were operated on for bariatric procedures. The descriptive statistical data showed that 70,18% were women and 29,82% men with a mean age of  40.63 (±12.03 SD) and the median BMI(kg/sqm) of 39,7(IQR-9,30). 247( 20,13% ) patients presented moderate –severe obstructive sleep apnoea and received CPAP treatment. Out of 1227 patients only 361 (29,43 %) received intravenous morphine in the first 24 hours after operation at a VAS higher than 5. The median of cumulative consumption of morphine at 24 h (mg morphine) in the morphine group was 6.00 (IQR 2.00). The pain scores at rest and with movement during all measured intervals were significantly low.

Vas 1h - Mean (±SD)	3.70 (±1.92)
Vas 4h - Mean (±SD)	2.60 (±0.96)
Vas 12h - Mean (±SD)	1.50 (±0.97)
Vas 24h - Mean (±SD)	1.20 (±0.63)

Women were more susceptible to the pain with increased consumption of morphine. In the CPAP group of patients the morphine used was statistic significantly lower (p<0.00001). Only 14 % of the patients with moderate-severe OSA  needed morphine comparing with 33 % of the patients without OSA.

Conclusion

The low opioid anesthesia  protocol in bariatric patients proved to be safe and feasible.


TABLE 1- Protocol of low opioid anaesthesia

Induction			Maintainance		
Magnesium sulphate	40mg/LBW in 	15 min prior	Sevoflurane	1-1,5 MAC	
Lidocaine	1,5 mg/LBW	15 min prior	Lidocaine	1mg/kg/h	
Diclophenac	150 mg	15 min prior	Magnesium sulphate	10mg/kg LBW/h	
Dexamethasone	8 mg	iv	Betaloc	1-5 mg Iv/ if needed	
Ketamine	20mg	iv			
Fentanyl	100ug           15 min before Extubation		
Propofol	2,5-3 mg/kg LBW	iv	Paracetamol	2g iv	
Muscular relaxant Rocuronium			Nefopam 	20 mg iv	
			Tramadol 	100 mg iv	



04 / Efficacy of low opioid anaesthesia protocol in a high volume centre for bariatric surgery