Effects Of Pupillary Monitoring On Remifentanil Consumption During General Anesthesia And Postoperative Recovery Quality

ObjectiveRifentanil is a widely used analgesic during perioperative period,with the advantages of rapid onset of action,rapid metabolism and strong analgesic effect.It can cause certain adverse effects on patients if used improperly.Therefore,it is important to assess the appropriate dosage of remifentanil and detect changes in patients’ pain levels timely by use sensitive and reliable pain monitoring methods.Pupillary indicators can be used to reflect the depth of anesthesia,the level of analgesia and pain,the function of the nervous system and prognostic situation.The pupillary reflex is regulated by both the sympathetic and parasympathetic nervous systems.While traditional monitoring tools cannot quantify the specific values of various changes in the pupil and is sometimes limited to the presence or absence of reflexes.Infrared pupillometry provides more accurate measurements of pupillary indicators and has a wider range of applications.In this study,we used infrared pupillometry to measure pupillary changes in patients during the perioperative period,to investigate the significance of pupil monitoring on remifentanil consumption during general anesthesia and postoperative recovery,and to explore sensitive indicators for monitoring postoperative pain changes.MethodsEighty-four patients undergoing elective laparoscopic uterine surgery from November 2020 to June 2021,aged 18～65 years,with body mass index(BMI)of 18.5～29.9 kg/m2 and American society of anesthesiologists(ASA)classification Ⅰor Ⅱ.Patients were divided into two groups using the random number table method:pupillary monitoring group(Group P)and routine monitoring group(Group C).The intraoperative mean artery pressure(MAP)and heart rate(HR)fluctuations were maintained below 20%of the basic values in both groups.In Group P,the pupillary dilation reflex was used to guide the dosage of intraoperative remifentanil infusion.If the pupil diameter was 30%larger than the baseline or the pupillary dilation reflex amplitude was greater than 15%,the speed of remifentanil pump was increased by 0.6 μg·kg-1·h-1;if the increase in pupil diameter was less than 30%or its decrease was less than 5%relative to the baseline,no changes were made to remifentanil pump;if pupil diameter decrease was more than 5%relative to the baseline,the speed of remifentanil consumption was reduced by 0.6 μg·kg-1·h-1.The intraoperative remifentanil dosage was adjusted by an experienced anesthesiologist in Group C according to changes in patients’hemodynamics.The following indicators were recorded:(1)Demographic data:age,BMI,ASA classification,duration of surgery,fluid intake and output,remifentanil and propofol dosage;(2)Pain levels were assessed at the time of extubation(Ti),10 min(T2),20 min(T3)and 30 min(T4)after extubation using numerical rating scale(NRS),MAP and HR,and the occurrence of complications related to anesthesia(nausea and vomiting,bradycardia,dizziness,respiratory depression,etc)from the end of the procedure until discharge from the postanesthesia care unit(PACU);(3)Pupillary light reflex measurements were performed in Group P.The parameters of pupillary light reflex(maximum diameter Init,minimum diameter End,percent variable Delta,latency of contraction LAT,contraction velocity ACV and maximum contraction velocity MCV)were recorded at the time of T1,T2,T3,T4;(4)The rate of change of pupillary and circulatory indexes was calculated for patients in Group P after extubation.Δ=(maximum value-minimum value)/mean value×100%(5)Binary logistic regression was applied to determine the indicators that were significant for pain changes and then the receiver operating characteristic curve(ROC)was plotted,and the area undercurve(AUC)was calculated to analyze the accuracy of pupillary light reflex indicators,MAP and HR for predicting pain changes.Results(1)The two groups did not significantly differ in terms of demographics,including age,BMI,and ASA classification,and operation time,fluid intake and output,and propofol total use(P>0.05);(2)The intraoperative consumption of remifentanil was significantly lower in Group P than in Group C(P<0.05);(3)The NRS score was significantly lower in Group P than in Group C(P<0.05)at T1,T2,T3,while did not differ significantly between the two groups at T4(P>0.05).The peak value of NRS score within 30 minutes after extubation was significantly lower in Group P than in Group C(P>0.05);(4)There was no statistically significant difference in MAP and HR between the two groups immediately after extubation,10 min,20 min and 30 min after extubation(P>0.05);(5)The removal time of endotracheal tube was significantly shorter and the incidence of nausea,vomiting,and respiratory depression was significantly lower in Group P than in Group C(P<0.05).The incidence of bradycardia and dizziness did not significantly differ between the two groups(P>0.05);(6)ΔHR and ΔMAP had no value in judging the change of NRS score.The areas under the curves of ΔInit,ΔACV,and ΔMCV were 0.775(95%CI,0.582～0.968),0.734(95%CI,0.537～0.930),and 0.822(95%Cl,0.648～0.997),respectively.When the cutoff value of Δ Init was 0.21,the sensitivity and specificity were 92.3%and 23.1%,respectively.When the cutoff value of ΔACV was-1.3,the sensitivity and specificity were 92.3%and 18.3%,respectively.In addition,when the cutoff value of ΔMCV was-1.0,the sensitivity and specificity were 84.6%and 17.7%,respectively.ConclusionCompared with traditional hemodynamics monitoring,intraoperative pupillary dilation reflex monitoring can more accurately guide the use of intraoperative remifentanil and improve the quality of postoperative recovery.Postoperative pupillary light reflex monitoring can identify postoperative pain changes more sensitively.