ABSTRACT
Objective To evaluate the effects of acute normovolemic hemodilution (ANH) on hemodynamics and oxygen supply in adult patients undergoing correction of tetralogy of Fallot.Methods Ten consecutive patients,aged 20-59 yr,weighing 41-61 kg,of American Society of Anesthesiologists physical status Ⅲ-Ⅳ,scheduled for elective correction of tetralogy of Fallot,were enrolled in the study.After induction of anesthesia,ANH was performed when hemodynamics was stable and stroke volume variation (SVV) ≤ 10％.Blood was withdrawn from the femoral artery,the blood collected was expected to be 15％ of blood volume,and the shed blood was reinfused after the end of cardiopulmonary bypass.The blood loss was simultaneously replaced with the equal volume of 6％ hydroxyethyl starch.Heart rate,mean arterial pressure,central venous pressure,cardiac output,SVV and peripheral vascular resistance were recorded before ANH and at 5 min after the end of ANH.Blood samples were collected for determination of hemoglobin and blood gas analysis,arterial oxygen saturation,arterial oxygen partial pressure and lactate concentrations were recorded,and oxygen supply was calculated.Results Compared with the baseline before ANH,cardiac output was significantly increased,and peripheral vascular resistance and hemoglobin were decreased after ANH (P＜0.05),and no significant change was found in heart rate,mean arterial pressure,central venous pressure,SVV,arterial oxygen partial pressure,arterial oxygen saturation or oxygen supply after ANH (P＞0.05).Conclusion ANH can increase cardiac output and maintain oxygen supply and hemodynamics stable when used for adult patients undergoing correction of tetralogy of Fallot.
ABSTRACT
Objective To explore the difference between pressure-regulated volume controlled ventilation (PRVCV) and volume controlled ventilation (VCV) during videothoracoscopic bhb excision.Methods Consecutive 20 patients scheduled to undergo videothoracoscopic bleb excision were enrolled into the study.After induction, endotracheal blocker was advanced into endotracheal tube to establish one-lung ventilation,each patient was randomly assigned to receive successively PRVCV and VCV for 20 minutes.Ventilatory variables were kept constantly(tide volume 6 ml/kg, respiratory rate 15 breaths/min and I: E ratio 1: 2).Heart rate,blood pressure,peak airway pressure and blood gas parameters were compared.Results Peak airway pressure was significantly lower with PRVCV than that with VCV [(12.7±3.6 ) cmH_2O(1 cm H_2O =0.098 kPa) vs (18.2±4.3) cm H_2O,P < 0.01].However,there was no significant difference in arterial oxygen tension,arterlal partial pressure of carbon dioxide,heart rate and blood pressure between PRVCV and VCV.Conclusion During one-lung ventilation in videothoracoscopic bleb excision, PRVCV offers lower peak inspiratory airway pressures while maintaining equal oxygenation compared with VCV.
ABSTRACT
Objective To study the effect of endotracheal tube's resistance on the respiratory systolic variation test(RSVT).Methods The RSVT,a test to predict fluid responsiveness was performed in 20 patients.The test consisted of the delivery of three congecutive pressure-controlled breaths with incremental peak inspiratory pressures of 10,20 and 30 cm H2O(1 cm H2O=0.098 kPa).The minimal values of the systolic arterial pressure following each of these three breaths were measured and plotted against their respective airway pressures,producing the RSVT slope.RSVT slope were compared between normal airway resistance and increased resistance circumstances,and the latter was simulated by advancing a Cooperdech bronchial blocker into endotracheal tube.Results Under normal resistance,RSVT slope was(0.39±0.21) volumes were(461.5±95.9),(891.5±149.8)and(1207.5±159.1)ml,when peak inspiratory pressures of 10,20 and 30 cm H2O were dehvered.When bronchial blocker was advanced into endotrecheal tube, (0.27±0.17)mm Hg,cm H2O significantly(P<0.01),and tidal volumes decreased to(434.5±92.8), (796.5±96.6)and(1097.5±68.4)ml(P<0.05 or<0.01).Conclusion Changes in endotraeheal tube's resistance can distort the RSVT slope.