ABSTRACT
Objective To evaluate the accuracy of an expiratory resistance device assisting pulse pressure variation (PPV) in predicting volume responsiveness in the spontaneously breathing patients.Methods Forty spontaneously breathing patients of both sexes,aged 22-61 yr,weighing 51-73 kg,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,undergoing elective operation,were enrolled.Before induction of anesthesia,mean arterial pressure (MAP),heart rate (HR),central venous pressure (CVP),cardiac index (CI) and pulse pressure variation (PPVB) were recorded after haemodynamics were stable.Then the expiratory resistance device was used,and MAP,HR,CVP,CI,and PPVA were recorded.The device was then removed.Volume expansion was carried out.6％ hydroxyethyl starch 130/0.4 6 ml/kg was infused over 10 min.MAP,HR,CVP,CI and PPVB were recorded within 3 min after volume expansion.The device was used again,and 1 min later MAP,HR,CVP,CI and PPVA were recorded.The device was then removed.The patients were divided into 2 groups according the percentage of increase in CI after volume expansion (△ CI):△ CI≥ 15％ considered to be a positive response group (group P),and ACI＜15％ considered to be a negative response group (group N).A receiver-operating characteristic (ROC) curve for PPV was plotted.According to the ROC curve,the diagnostic threshold,sensitivity,specificity,area under the curve,and 95％ confidence interval of the expiratory resistance device assisting PPV in predicting volume responsiveness were determined.Results The area under the curve (95％ confidence interval) of PPVA was 0.880 (0.70-0.98),the diagnostic threshold was 13.5％,and the sensitivity and specificity in determining volume responsiveness were 87％ and 88％,respectively.Compared with the value before administration of the loading dose,the CVP and CI were significantly increased,and PPVB and PPVA were decreased after volume expansion in group P,and the CVP and CI were significantly increased after volume expansion in group N (P＜0.05).Compared with group P,the PPVA was significantly decreased before volume expansion,and the CI was increased after volume expansion in group N (P＜0.05).Conclusion The expiratory resistance device can assist PPV in predicting volume responsiveness in the spontaneously breathing patients.
ABSTRACT
Objective To evaluate the efficacy of ultrasound for placement of laryngeal mask airway (LMA) in comparison with fiberoptic bronchoscope in adult patients.Methods Fifty-eight ASA physical status Ⅰ or Ⅱ patients,aged 18-57 yr,weighing 50-70 kg,with body mass index 20-30 kg/m2,scheduled for gynecological operation under general anesthesia,underwent standard general anesthetic technique with 4 # LMA-ClassicTM.After clinical assessment of correct placement of LMA,the position of the LMA was confirmed by transverse neck ultrasound,and reconfirmed using fiberoptic bronchoscopy.The peak airway pressure and oropharyngeal leak pressure were recorded.Results When the outcome of clinical assessment of correct placement of LMA was considered as satisfactory,the rate of ideal anatomic placement assessed by ultrasound evaluation was 69 %,and the rate of ideal anatomic placement assessed by fiberoptic bronchoscopy was 59 %,and it showed that there was no significant difference in detecting the ideal placement of the LMA (P ＞ 0.05).The oropharyngeal leak pressure was significantly higher when ultrasound was used for confirmation of the correct placement of LMA than that when fiberoptic bronchoscope was used (P ＜ 0.05).Conclusion Ultrasound provides better efficacy for placement of LMA in indicating sealing of LMA than fiberoptic bronchoscope and is helpful in improving ventilation conditions in adult patients.