Can a central blood volume deficit be detected by systolic pressure variation during spontaneous breathing?

• Background: Whether during spontaneous breathing arterial pressure variations (APV) can detect a volume deficit is not established. We hypothesized that amplification of intra-thoracic pressure oscillations by breathing through resistors would enhance APV to allow identification of a reduced cardiac output (CO). This study tested that hypothesis in healthy volunteers exposed to central hypovolemia by head-up tilt. Methods: Thirteen healthy volunteers were exposed to central hypovolemia by 45 degrees head-up tilt while breathing through a facemask with 7.5 cmH(2)O inspiratory and/or expiratory resistors. A brachial arterial catheter was used to measure blood pressure and thus systolic pressure variation (SPV), pulse pressure variation and stroke volume variation. Pulse contour analysis determined stroke volume (SV) and CO and we evaluated whether APV could detect a 10 % decrease in CO. Results: During head-up tilt SV decreased form 91 (+/- 46) to 55 (+/- 24) mL (mean +/- SD) and CO from 5.8 (+/- 2.9) to 4.0 (+/- 1.8) L/min (p < 0.05), while heart rate increased (65 (+/- 11) to 75 (+/- 13) bpm; P < 0.05). Systolic pressure decreased from 127 (+/- 14) to 121 (+/- 13) mmHg during head-up tilt, while SPV tended to increase (from 21 (+/- 15)% to 30 (+/- 13) %). Yet during head-up tilt, a SPV >= 37 % predicted a decrease in CO >= 10 % with a sensitivity and specificity of 78 % and 100 %, respectively. Conclusion: In spontaneously breathing healthy volunteers combined inspiratory and expiratory resistors enhance SPV during head-up tilted induced central hypovolemia and allow identifying a 10 % reduction in CO. Applying inspiratory and expiratory resistors might detect a fluid deficit in spontaneously breathing patients.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Anestesi och intensivvård (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Anesthesiology and Intensive Care (hsv//eng)

Nyckelord

Fluid responsiveness

Spontaneous breathing

Head-up tilt

Pulse pressure variation

Stroke volume variation

Systolic pressure variation

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