Effects of depth of neuromuscular block on postoperative pain during laparoscopic gastrectomy: A randomised controlled trial.

BACKGROUND: Evidence on whether the use of deep neuromuscular block (NMB) influences postoperative pain after laparoscopic surgery is limited, and existing studies have shown conflicting results. We studied the effect of the depth of NMB during laparoscopic gastrectomy on postoperative pain. OBJECTIVE: The aim of this study was to evaluate the effect of depth of NMB during laparoscopic gastrectomy on postoperative pain by allocating patients randomly to either deep or moderate NMB with a standard-pressure pneumoperitoneum. DESIGN: A randomised, controlled, double-blind study. SETTING: A university-affiliated hospital. PARTICIPANTS: One hundred patients. INTERVENTIONS: Patients were allocated randomly to receive either deep (posttetanic count 1 to 2) or moderate (train-of-four count 1 to 2) levels of NMB. Following surgery, the patients were asked to rate their pain every 10 min using a visual analogue scale (VAS) (0 = no pain, 10 = most severe pain) in the postanaesthesia care unit (PACU). Patients received intravenous oxycodone, 2 mg every 10 min, until the pain intensity (VAS) had decreased to less than 3 at rest and less than 5 on wound compression, at which point the minimum effective analgesia dose (MEAD) of oxycodone was determined. MAIN OUTCOME MEASURES: The primary endpoint was the MEAD of oxycodone. Secondary endpoints included area under the curve of VAS for wound pain, VAS scores for wound and shoulder pain at 6 and 24 h after the end of surgery, rescue analgesics, a five-point surgical rating scale, Rhodes index of nausea vomiting retching at 6 and 24 h after the end of surgery and duration of pneumoperitoneum. RESULTS: The median value for the MEAD of oxycodone was 8 mg in both groups. Area under the curves of VAS over time were similar in both groups. Variables associated with postoperative pain including mean VAS at PACU and frequency of rescue analgesics in the ward did not differ significantly between the two groups. The duration of pneumoperitoneum was a significant variable in determining the MEAD of oxycodone (linear regression, R = 0.07, P = 0.008). The number of patients who reached the acceptable surgical score was not significantly different between the two groups. However, the moderate NMB group did have a significantly higher proportion of cases that required additional muscle relaxants (P < 0.001). CONCLUSION: Deep, compared with moderate, NMB did not significantly reduce the MEAD of oxycodone administered in the PACU. The duration of pneumoperitoneum was positively correlated with the MEAD. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03266419.

Quantitative analysis of the effect of end-tidal carbon dioxide on regional cerebral oxygen saturation in patients undergoing carotid endarterectomy under general anaesthesia.

AIMS: Regional cerebral oxygen saturation (rSO2 ) is currently the most used measure in clinical practice to monitor cerebral ischaemia in patients undergoing carotid endarterectomy (CEA). Although end-tidal carbon dioxide (PET CO2 ) is known as a factor that influences rSO2 , the relationship between PET CO2 and rSO2 has not been quantitatively evaluated in patients with severe arteriosclerosis. This study aimed to evaluate the effect of PET CO2 on rSO2 in patients undergoing CEA under general anaesthesia. METHODS: The intervention to change PET CO2 was conducted between skin incision and clamping of the carotid artery. The rSO2 values were observed by changing PET CO2 in the range of 25-45 mmHg. The PET CO2 -rSO2 relationship was characterized by population analysis using a turnover model. RESULTS: In total, 1651 rSO2 data points from 30 patients were used to determine the pharmacodynamic characteristics. Hypertension (HTN) and systolic blood pressure (SBP) were significant covariates on the slope factor in the stimulatory effect of PET CO2 on rSO2 and fractional turnover rate constant (kout ), respectively. The estimates of the parameters were kout (min-1 ): 3.59 for SBP <90 mmHg and 0.491 for SBP ≥90 mmHg, slope: 0.00321 for patients with HTN and 0.00664 for patients without HTN. CONCLUSION: The presence of HTNattenuates the response of rSO2 after a change in PET CO2 . When cerebral blood flow is in a state of decline caused by a decrease in SBP to <90 mmHg, the response of rSO2 to PET CO2 is increased. It is advisable to maintain SBP >90 mmHg in patients with HTNduring CEA.