Effects Of Intraoperative Ventilation Strategies And Fluid Therapies On Respiratory Function During Laparoscopic Surgery

ObjectivesThe study aims to observe the effects of intraoperative ventilation strategies and fluid therapies on the respiratory function in patients undergoing laparoscopic colorectal surgery, and analyze the effects of these treatments on patients'oxygennation and postoperative rehabilitation.MethodsPatient selection and grouping:60 patients undergoing elective laparoscopic colorectal surgery under general anaesthesia were given written informed consents to participate in this randomized controlled study. They were randomly divided into two groups-Group RM and Group C, each with 30 patients. Group RM underwent lung recruitment maneuver (RM) ventilation strategy with Tidal Volume (VT):6 ml/kg, Respiratory Rate (RR):20 breaths per minute, and I:E=1:2, with intermittent intraoperative lung recruitment maneuvers (see the ventilation treatment mentioned below). Group C underwent conventional intermittent positive-pressure ventilation (IPPV) strategy, with VT:10 ml/kg, RR:10 breaths per minute, and I:E= 1:2. All the patients received the loading fluid infusion with Lactated Ringer's Solution (LRS,10 ml/kg) before the incision. The patients were infused with LRS (Group A:5 ml·kg-1·h-1 and Group B:10 ml·kg-1·h-1 respectively) throughout the intraoperative periods.Anesthesia:MBP (Mean Blood Pressure), CVP (Central Venous Pressure), HR (Heart Rate), ECG (electrocardiogram), PETCO2 (end-tidal partial pressure of carbon dioxide) and SpO2 (Pulse Oxygen Saturation) were monitored. Anesthesia were induced by the propofol, fentanyl, and cisatracurium, and maintained by the continuous infusion of propofol and cisatracurium, and fentanyl intermittently. Mechanical ventilation (Drager-FabiusGS, Ventilator, GERMANY) was initiated immediately after the intubation.Ventilation Treatment:After the CO2 was insufflated for pneumoperitoneum, Group RM patients received lung recruitment maneuvers every 30 minutes. The lung recruitments were achieved by the sequential increment of PEEP in three steps:from 0 to 5 cm H2O (for 10 breaths), at 10 cm H2O (for 10 breaths), and at 20 cm H2O PEEP (for 20 breaths). Afterward the levels of PEEP were maintained at 0 cm H2O during the rest of the operation. Group C patients received IPPV.Observed parameters:HR, SBP, DBP, MBP, CVP, SPO2 and PETCO2 were recorded at the following time points:pre-anesthesia (T1), induction (T2), intubation (T3), pre-incision (T4),30 minutes after incision (T5),60 minutes after incision (T6),90 minutes after incision (T7),120 minutes after incision (T8), at termination of pneumoperitoneum (T9) and the end of the operation (T10). Compl (ml/cmH2O) and Pplat (cmH2O) were measured by the non-invasive monitor (MINDRAYTM BeneViewT8); the data of the arterial blood were collected at T4 and T8 for the blood-gas analysis. The blood routine, clotting time and liver and renal functions were tested respectively one day before and after the surgery. The surgery duration, total narcotic consumption, dosage of drugs administrated during the surgical procedure, blood transfusion, blood loss, urine output, and the overall volume and types of dosage used within 24 hours after surgeries were recorded. Any adverse reactions such as hypotension, abdominal distension, slow wound healing, nausea and vomiting, gastrointestinal recovery time and hospitalization time were observed.Statistical analysis:The analysis was performed using the statistical analysis software, SPSS 13.0. Quantitative data were expressed as means±standard deviations. Within the same group of patients, the paired samples t-test was conducted. Between different groups of patients, the independent t-test or the analysis of variance was performed. The Comp, Pplat, PaO2 and PaCO2 were analyzed by multivariate ANOVA, while the HR, MBP, CVP and PETCO2 were analyzed by factorial design ANOVA for repeated measures. The data of two groups were measured with LSD. The categorical data were analyzed with the chi-square test. P<0.05 represented the statistical significance.Results1. Of all the patients, there was no significant difference between the 4 sub-groups in age, weight, height, body mass index, sex ratio, Anesthetics, the volume of blood transfusion, blood loss and urine (P> 0.05)2. There was no significant difference in Comp, Pplat, PaO2,between the two methods of fluid therapies, but there were significant differences in Comp with the two ventilation strategies (P< 0.05).There were significant differences of Comp at each time during pneumoperitoneum than T4 in Group RM and Group C (P< 0.01). Comp in Group RM was higher at T9 than T4 (P< 0.01). In contrast, Comp in Group C was lower at T9 than T4 (P< 0.01). Comp in Group RM compared to Group C, increased obviously from T4 to T8 and T9, (P< 0.01). Group C revealed obvious increasing of Pplat at T9 than T4 (P< 0.01). Group RM didn't have significantly different variables of Pplat (P> 0.05) while Group C patients had higher Pplat variables compared with Group RM since T9 to T4 (P< 0.05). Group RM patients revealed obvious increasing in PaO2 at T8 than T4 (P< 0.01), but Group C patients had an obvious decrease in PaO2 at T9 than T4 (P< 0.01).3. With both ventilation strategies, Group RM and Group C both had higher PaCO2 at T8 than at T4 (P< 0.01). Group RM had more significant increasing than Group C (P<0.01) With the two fluid therapies, both Group A and Group B were higher in PaCO2 at T8 than at T4 (P<0.01). Group B had more significant increasing than Group A (P<0.01)4. As to HR, MBP, CVP, PETCO2 at different stages, there were significant differences in Group RM and in Group C (P< 0.05), but no significant difference between Group RM and Group C (P> 0.05). In both groups, HR at T2 after anaesthesia was decreased, increased slightly at T3 after intubation, returned back to post-anesthesia induction level at T4, and maintained the same level lower than that before anaesthesia until end-operation.MBP in both groups decreased at T2 after anesthesia induction, raised at T3 after intubation, increased after pneumoperitoneum induction and maintained the higest level for 30 min, and it decreased to post-anesthesia induction level, maintained the same level until end-operation.CVP in both groups decreased at T2 after anesthesia induction, increased slightly at T3 after intubation, maintained higher at T5 than T3, and stayed a little higher than before anesthesia at T9.PETC02 in both groups increased from T5, went back to post intubation level at T9. PETCO2 displayed a more significant increasing in Group RM than in Group C after pneumoperitoneum, and returned to the level at T4. 5. As for all four sub-groups after surgeries, WBC and NE% were all higher than pre-operation levels, and there were significant differences in each sub-group (P< 0.05). Hb was lower than pre-operation level for all the sub-groups except for Group CB (P< 0.05). PLT declined significantly after surgeries in Group RMB and Group CB (P<0.01). There were no significant differences in variables of different groups (P> 0.05). The sodium, chlorine, Creatinine and Urea nitrogen levels postoperation in blood, were stable and there was no significant difference between the four groups (P> 0.05). In each group, post-operation PT and INR were both longer than pre-operation, while AT was lower than pre-operation (P< 0.05). APTT in Group RMA was significantly different than that of pre-operation. PT and INR in Group CB were significantly different from pre-opertion (P< 0.05). Coagulation indicators in the four groups were not significantly different (P> 0.05).6. The postoperative nausea and vomiting, abdominal distension, abdominal infection, and hypotension in four groups were not significantly different (P> 0.05).The defecation and hospitalization of patients were not significantly different in four groups (P> 0.05). It took longer to draw the tube from and feed in Group CA, which was significantly different from the other groups (P< 0.05).Conclusions1. The ventilation strategy of lung recruitment maneuver (RM) with a low tidal volume applied to patients undergoing laparoscopic colorectal surgeries under general anesthesia was conducive to increase Comp, reduce Pplat, increase oxygenation, and might protect patients'respiratory function.2. Either fluid therapy or fluid therapy interacting with ventilation strategies barely has effect on Comp, Pplat, and oxygenation.3. Comparing the two fluid therapies in a laparoscopic colorectal surgery, a 5ml·kg-1·h-1 or a 10ml·kg-1·h-1 speed infusion, after a loading infusion of LRS (10ml/kg), can both effectively maintain a stable circulation during surgeries, and there was no significant effect on postoperative rehabilitation.