Didier Jacques , Karim Bendjelid , Serge Duperret , Joelle Colling , Vincent Piriou and Jean-Paul Viale. Critical Care 2011, 15:R33doi:10.1186/cc9980. Published: 19 January 2011
Abstract (provisional)
Introduction
The aim of the study was to evaluate dynamic indices of fluid responsiveness in a model of intra-abdominal hypertension.
Methods
Nine mechanically-ventilated pigs underwent an increased intra-abdominal pressure (IAP) by abdominal banding up to 30 mmHg and then a fluid loading (FL) at this IAP. The same protocol was carried out in the same animals made hypovolemic by blood withdrawal. In both volemic conditions, dynamic indices of preload dependence were measured at baseline IAP, at 30 mmHg of IAP, and after FL. Dynamic indices involved respiratory variations in stroke volume (SVV), pulse pressure (PPV), and systolic pressure (SPV, %SPV and [increment]down). Stroke volume (SV) was measured using an ultrasound transit-time flow probe placed around the aortic root. Pigs were considered to be fluid responders if their SV increased by 15% or more with FL. Indices of fluid responsiveness were compared with a Mann-Whitney U test. Then, receiver operating characteristic (ROC) curves were generated for these parameters, allowing determination of the cut-off values by using Youden’s method.
Results
Five animals before blood withdrawal and all animals after blood withdrawal were fluid responders. Before FL, SVV (78 +/- 19 vs 42 +/- 17%), PPV (64 +/- 18 vs 37 +/- 15%), SPV (24 +/- 5 mmHg vs 18 +/- 3 mmHg), %SPV (24 +/- 4% vs 17 +/- 3%) and [increment]down (13 +/- 5 mmHg vs 6 +/- 4 mmHg) were higher in responders than in non responders (P<0.05). Areas under ROC curves were 0.93 (95% confidence interval: 0.80 to 1.06), 0.89 (0.70 to 1.07), 0.90 (0.74 to 1.05), 0.92 (0.78 to 1.06), and 0.86 (0.67 to 1.06), respectively. Threshold values discriminating responders and non responders were 67% for SVV and 41% for PPV.
Conclusions
In intra-abdominal hypertension, respiratory variations in stroke volume and arterial pressure remain indicative of fluid responsiveness, even if threshold values identifying responders and non responders might be higher than during normal intra-abdominal pressure. Further studies are required in humans to determine these thresholds in intra-abdominal hypertension.
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