Research Article
Respiratory Variations in Pulse Pressure Reflect Central Hypovolemia during Noninvasive Positive Pressure Ventilation
Table 2
Data from the generalized mixed model analyses showing effect estimates of LBNP and NPPV separately and in combination (LBNP * NPPV).
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Estimates of LBNP-effects and LBNP * NPPV-effects are given as changes per 20 mmHg change in LBNP (−20, −40, −60, and −80 mmHg). Estimates of NPPV-effects are constant and independent of LBNP-level. There are separate statistically significant effects of both LBNP and NPPV on SV. This means that LBNP led to a decrease in SV both during spontaneous breathing and NPPV, and NPPV led to a decrease in SV both during normo- and hypovolemia. In contrast, the effect of NPPV on ΔPP is due to a significant interaction between LBNP and NPPV (LBNP * NPPV), which means that NPPV only affected ΔPP significantly during hypovolemia. PI is significantly affected by LBNP alone. LBNP: lower body negative pressure; NPPV: noninvasive positive pressure ventilation; LBNP * NPPV: interaction between LBNP and NPPV; ΔPP: pulse pressure variation; ΔPOP: photoplethysmographic waveform amplitude variation; PVI: pleth variability index; PI: perfusion index; SV: stroke volume; HR: heart rate; MAP: mean arterial pressure; PP: pulse pressure; #: statistically significant. |