Arterial pressure changes during the Valsalva maneuver to predict fluid responsiveness in spontaneously breathing patients

Introduction

Although superiority of dynamic parameters compared with static values of preload is widely accepted, predicting fluid responsiveness in spontaneously breathing patients is still a challenging problem. A sudden increase in intrathoracic pressure during the Valsalva maneuver transiently impairs venous return and, only in preload-dependent patients, decreases the stroke volume and arterial pulse pressure (PP). We designed this study to assess the predictive value of arterial pressure response to a Valsalva maneuver for fluid responsiveness in spontaneously breathing patients.

Methods

In 27 spontaneously breathing patients, the Valsalva maneuver, consisting of a forced expiration through a closed mouthpiece, was performed. Patients were encouraged to maintain a constant pressure of 30 cmH₂O for 10 seconds. The Valsalva pulse pressure variation (ΔVPP) was defined using the maximum PP at the beginning of the strain (PP_max) and the minimum PP (PP_min) according to the known formula: ΔVPP (%) = (PP_max - PP_min)/[(PP_max + PP_min)/2]. A first set of measurements was obtained at baseline and immediately after the Valsalva maneuver was performed. Cardiac output (FloTrac/Vigileo™), central venous pressure, invasive arterial pressure and respiratory pressure were continuously recorded during the whole strain time. After volume expansion, new measurements were obtained and the Valsalva maneuver was performed again post infusion.

Results

The volume expansion-induced increase in the stroke volume index was ≥ 15% in 10 patients (responders) and <15% in 17 patients (nonresponders). The baseline ΔVPP was higher and decreased more after volume expansion in responders (P < 0.0001). The baseline ΔVPP and ΔVPP increase after volume expansion were statistically correlated with changes in the stroke volume index (r = 0.83 and r = 0.74, P < 0.0001, respectively). The baseline ΔVPP accurately predicted changes induced by volume expansion with a sensibility of 90% and a specificity of 94%. The area under the ROC curve for ΔVPP was 0.96 (95% CI = 0.81–0.99, P = 0.0001), with a best cutoff value of 50%.

Conclusion

Arterial pressure variations induced by a Valsalva maneuver reliably predict fluid responsiveness in spontaneously breathing patients.