Effects of the lateral positioning plus jackknife positioning on difference of partial pressure of carbon dioxide in artery and end-tidal pressure of carbon dioxide

Abstract

Objective To observe the effects of lateral position plus jacknife position on difference of partial pressure of carbon dioxide in artery and end-tidal pressure of carbon dioxide[P(a-ET）CO2].Methods Thirty-six patients undergoing elective surgery under total intravenous anesthesia were involved.Patients were divided into two groups (n=18):control group (group C) and experimental group (group L).Patients undergoing abdominal surgery were at supine position in group C.Patients undergoing nephrectomy,ureterolithotomy surgery or adrenal cyst resection were at lateral position plus jacknife position.Patients were endotracheal intubation and mechanical ventilation,respiratory rate was 15 rpm,inspiratory/expiratory ratio was 1∶1.5.End-tidal pressure of carbon dioxide(PETCO2) was stable between 30 mmHg-35 mmHg (1 mm Hg=0.133 kPa).Blood gas analysis was done at 15 (T1),35 min (T2) and PETCO2 was stable (T0)(the fluctuation was less than 1 mmHg).The ventilator parameters were not been constant during T0-T2 At T1,patients' position were changed from supine position to lateral position plus jacknife position in group L,and patients' position remained supine position in group C.Intraoperative monitoring consisted of electrocardiogram,invasive arterial pressure,heart rate,pulse oxygen saturation,tidal volume,minute ventilation,peak of airway pressure,end-tidal pressure of carbon dioxide(PETCO2),and so on.Results PETCO2,partial pressure of carbon dioxide in artery(PaCO2) and P(a-ET)CO2 were respectively (28.4±2.3),(35.7±3.3),(7.2±3.0) mmHg at T2 in group L.In group L,those items were(32.2± 1.8),(34.2±2.0),(2.6±2.8) mmHg at T1 respectively(P＜O.05).P(a-ET)CO2 were(2.6±2.5) and (3.1 ±1.5) mmHg at T1 and T2 respectively in group C.Compared with group L,P (aET)CO2 were significantly lower (P＜0.05).Conclusions P (a-ET)CO2 was significantly increases at lateral position plus jacknife position.So the ventilator parameters should be adjusted according PETCO2. Key words: Lateral position; Jackknife position; End-tidal pressure of carbon dioxide ; Hemodynamics; Blood gas analysis