The Effect Of Different Tidal Volume Mechanical Ventilation On Right Ventricular Function In Patients Undergoing Laparoscopic Colorectal Cancer Surgery By TEE

Objective:To evaluate the effect of different tidal volume mechanical ventilation on colorectal cancer by TEE.Methods:A total of 56 patients undergoing elective laparoscopic radical resection for colorectal cancer from May 2022 to December 2022 were selected.According to the American Society of Anesthesiologists（ASA）classification standard,patients with grade I～III,age range 18～75 years,Body Mass Index（BMI）18～30 kg/㎡,sinus rhythm,no serious respiratory and cardiac diseases were included.The patients were randomly divided into two groups（n=28）,low tidal volume group（L group）and medium tidal volume group（M group）.After entering the room,peripheral venous access was established,ECG,non-invasive blood pressure and oxygen saturation were routinely monitored,and central venous access was established.Under local anesthesia,radial artery puncture was performed and a tube was placed to connect with a pressure sensor to continuously monitor invasive arterial pressure and mean arterial pressure.After induction of general anesthesia,all patients were intubated with mechanical ventilation.According to the expert consensus of lung protective ventilation strategy,all patients were intubated with lung protective ventilation strategy（PEEP 5cm H₂O,Fi O₂ 60%,intermittent lung recruitment）after general anesthesia induction.Group L was ventilated with low tidal volume 5ml/kg,and group M was ventilated with medium tidal volume8ml/kg.Intraoperative anesthesia was maintained with end-tidal carbon dioxide pressure between 35～45mm Hg and BIS values between 40～60.After tracheal intubation,transesophageal echocardiography（TEE）was performed.Pulsed wave Doppler（PW）sampling points were placed in apical four-chamber view,the sampling frame was located at the free wall of tricuspid annulus of right ventricle,the sampling volume was 3.7 mm,and the tracing speed was 100 mm/s.The blood flow spectrum at tricuspid orifice and pulmonary artery was obtained.Respectively marking and measuring the time from the end point of the peak A of the tricuspid valve orifice blood flow frequency spectrum to the start point of the peak S of the next tricuspid valve orifice blood flow frequency spectrum as the right ventricular isovolumic contraction time（IVCT）,the time from the end point of the peak S of the tricuspid valve orifice blood flow frequency spectrum to the start point of the peak E of the next tricuspid valve orifice blood flow frequency spectrum as the right ventricular isovolumic relaxation time（IVRT）and the duration time of the wave Sa of the pulmonary artery blood flow frequency spectrum as the pulmonary artery ejection time（ET）on a graph by using a measuring tool,the right ventricular work index Tei=[isovolumic contraction time（IVCT）+isovolumic relaxation time（IVRT）]/pulmonary ejection time（ET）was calculated.At least 3 consecutive consecutive sinus rhythm cardiac cycles were recorded and averaged.The gender,age,ASA classification,pneumoperitoneum time and operation duration were recorded.Tei index,heart rate（HR）and mean arterial pressure（MAP）were recorded before anesthesia（T₀）,5 minutes after mechanical ventilation（T₁）,immediately after pneumoperitoneum（T₂）,60 minutes after mechanical ventilation（T₃）,closing pneumoperitoneum（T₄）and at the end of operation（T₅）;Blood p H,blood lactate（Lac）,partial pressure of oxygen（Pa O₂）,partial pressure of carbon dioxide（Pa CO₂）and oxygenation index were recorded before anesthesia（T₀）and at the end of operation（T₅）;The levels of serum creatine kinase（CK）,creatine kinase isoenzyme（CK-MB）,lactate dehydrogenase（LDH）and B-type natriuretic peptide（BNP）were recorded before anesthesia（T₀）and 24h after operation（T₆）.Results:1.There were no significant differences in gender,age,ASA classification,height,weight,pneumoperitoneum time and operation duration between the two groups.2.Tei index was significantly lower in group L than in group M at T₂～T₅（P<0.05）.Tei index increased at T₃ compared with T₁ in group L（P<0.05）.Tei index decreased at T₅ in group L compared with that at T₃（P<0.05）.Tei index at T₂ and T₃ in group M was significantly higher than that at T₁（P<0.05）.Tei index at T₄ and T₅in group M was significantly lower than that at T₃（P<0.05）.3.Compared with group M,MAP was significantly lower in group L at T₃（P<0.05）;4.Compared with group M,group L had significantly lower p H and higher Pa CO₂ at T₅ （P<0.05）.Compared with T₀,the p H of L group was lower at T₅（P<0.05）.Lac was higher（P<0.05）;Pa CO₂ was higher（P<0.05）.The Lac index was higher in group M at T₅ than at T₀（P<0.05）.5.Compared with group M,the levels of serum creatine kinase（CK）and lactate dehydrogenase（LDH）were significantly lower in group L after operation 24 h at T₆（P<0.05）.Conclusion:TEE monitoring found that low tidal volume ventilation had less myocardial damage to the right ventricle of patients undergoing laparoscopic radical resection of colorectal cancer,and could effectively prevent the decrease of myocardial function of the right ventricle of patients,reduce the myocardial damage of the right ventricle,provide reference for clinical reasonable setting of tidal volume,and avoid irreversible myocardial damage to patients undergoing laparoscopic radical resection of colorectal cancer.