ABSTRACT
Objective To investigate the effects of different doses of dexmedetomidine on cerebral oxygen saturation and pulmonary shunt fraction in patients undergoing one-lung ventilation (OLV). Methods Sixty ASAⅠ-Ⅱpatients, aged 46-71 years, with body mass index (BMI)18-24 kg/m2 and scheduled for thoracotomy were randomly divided into three groups (n=20 each):high dose dexmedetomidine group (group D1), low dose dexmedetomidine group (group D2) and control group (group C). Dexmedetomidine 1μg/kg was infused in group D1 after anesthesia induction, and then a rate of 0.5μg·kg-1·h-1 was continuously infused. Dexmedetomidine 0.5μg/kg was infused in group D2 after anesthesia induction, and then a rate of 0.3μg · kg-1 · h-1 was continuously infused. Group C was received the equal volume of normal saline. Anesthesia was main?tained with propofol-remifentanil and intermittent iv boluses of rocuronium. Arterial and jugular venous blood samples were collected before anesthesia induction (T0), at 15 min after two-lung ventilation (T1), at 5 min (T2) and 30 min (T3) of OLV for blood gas analysis. Value of Qs/Qt was calculated and SctO2 was recorded at the same time. Results Compared with group C and group D2, Qs/Qt was decreased at T2 in group D1 (P<0.05). Qs/Qt was lower at T3 in group D1 and D2 than that of group C, and which was lower in group D1 than that of group D2 (P<0.05). In group C and group D1 a significant de?crease in SctO2 was observed at T2 and T3 compared to that at T0 and T1 (P<0.05). SctO2 was significantly higher at T2 and T3 in group D2 than that in group C and group D1 (P<0.05). Conclusion Dexmedetomidine given during OLV undergoing thoracotomy can improve oxygenation, decrease pulmonary shunt fraction and reduce the occurrence of low SctO2.
ABSTRACT
Objective To observe the effect of nasal continuous positive airway pressure (nCPAP) and Biphase positive airway pressure (BIPAP) on the oxygen exchange indexes in newborns with mild to moderate neonatal respiratory distress syndrome (NRDS).Methods After infusion of pulmonary suffactant into lung bilaterally,116 cases with mild to moderate NRDS were treated with nCPAP(nCPAP group,n =75) and BIPAP(BIPAP group,n =41) respectively.Oxygen exchange indexes including arterial partial pressure of oxygen [pa (O2)],modified oxygenation index (P/F),alveolar-arterial oxygen tension difference (A-aDO2),respiratory index (RI),artery/alveolar oxygen partial pressure ratio[pa (O2)/pA (O2)] and pulmonary shunt fraction (Qs/Qt) were measured or calculated at 0 (before treatment),2,8 and 24 h after being treated with nCPAP or BIPAP.Results Six different oxygen exchange indexes of Pa (O2),P/F,A-aDO2,RI,pa (O2)/pA(O2) and Qs/Qt in both groups didn't show statistical significance at 0 hour:pa(O2) (kPa) (6.1 ±0.6 vs 6.1 ±0.6,t =0.11,P ＞0.05),P/F(kPa) (15.59 ± 1.45 vs 15.71 ± 1.45,t =1.59,P ＞ 0.05),A-aDO2(kPa)(6.04 ±0.64 vs 6.24 ±0.69,t =1.59,P ＞0.05),RI(6.0 ± 1.0 vs 6.2 ± 1.1,t =1.35,P ＞ 0.05),p,(O2)/pA(O2) (0.24 ±0.02 vs 0.25 ±0.03,t =1.63,P ＞0.05)and Qs/Qt(％)(11.9±1.6 vs 11.6 ± 1.6,t =1.10,P ＞ 0.05).A-aDO2,RI,pa (O2)/pA (O2) and Qs/Qt of BIPAP group had more improvement than those of nCPAP at 2 and 24 h,and oxygen exchange indexes at 2 h of BIPAP group and those of nCPAP group were:A-aDO2 (kPa) (3.83 ±0.49 vs 4.24 ± 0.67,t =18.26,P ＜ 0.05),RI(2.7 ± 0.5 vs 3.3 ±0.7,t =20.59,P ＜ 0.05),p,(O2)/pA(O2) (0.35 ±0.03 vs 0.32 ±0.04,t =15.35,P ＜0.05) and Qs/Qt(％) (8.8 ± 1.6 vs 9.8 ±2.0,t =7.68,P ＜ 0.05) ; 24 h indexes in BIPAP group and the indexes of nCPAP group were:A-aDO2 (kPa) (2.29 ± 1.19 vs 3.07 ± 1.67,t=18.43,P ＜0.05),RI(1.4 ±1.4 vs 2.3 ± 1.6,t=25.02,P ＜0.05),pa(O2)/pA(O2) (0.49 ±0.10 vs 0.42 ±0.11,t =14.96,P ＜0.05) and Qs/Qt(％) (6.5 ±3.0 vs 8.5 ±4.4,t =9.59,P ＜0.05).pa(O2) and P/F of both groups didn't show statistical difference significantly [Pa (O2)(kPa) (12.6 ± 1.0 vs 12.7 ± 1.0,t =3.76,P ＞ 0.05),P/F(28.49 ± 3.17 vs 31.85 ± 2.85,t =3.76.P ＞ 0.05)].Nineteen cases in nCPAP group needed invasive mechanical ventilation,and only 3 cases in BIPAP group underwent the procedure;there was a significant difference (x2 =4.01,P ＜ 0.05).Oxygen exchange indexes in both groups were gradually improved from 2 h,8 h to 24 h,but 22 deteriorated cases showed no improvement,who underwent invasive ventilation.Positive end-expiratory pressure (PEEP) positive airway pressure (EPAP) was (0.42 ± 0.19) kPa in BIPAP group,and (0.56 ± 0.23) kPa in nCPAP group (t =3.45,P ＜ 0.01).Conclusions 1.BIPAP and nCPAP can improve the ability of oxygen exchange in newborns with mild to moderate NRDS,but BIPAP is more effective than nCPAP,which can shorten the possibility of invasive ventilation and reduce the PEEP level.2.p,(O2),P/F,pa (O2)/pA (O2) and RI may be more suitable for evaluating oxygen exchange for neonatal NRDS.