Table 1.

Hemodynamic responses to FRC_Apnea and RBR_Matched protocols

	Baseline	Rebreathe	Maneuver
MAP, mmHg
FRCApnea	87 ± 3	89 ± 3	105 ± 9*†
RBRMatched	87 ± 3	88 ± 2	97 ± 6*
HR, beats/min
FRCApnea	70 ± 14	68 ± 13	60 ± 9*†
RBRMatched	68 ± 12	66 ± 13	75 ± 19*
SV, ml
FRCApnea	97 ± 20	90 ± 18	84 ± 18
RBRMatched	96 ± 19	91 ± 19	86 ± 24
CO, l/min
FRCApnea	6.6 ± 1.3	6.0 ± 1.0	5.0 ± 0.7*†
RBRMatched	6.4 ± 0.9	5.9 ± 0.8	6.1 ± 0.9
TPR, mmHg·l−1·min−1
FRCApnea	13.5 ± 2.3	15.1 ± 2.1	21.6 ± 3.3*†
RBRMatched	13.7 ± 1.7	15.2 ± 1.9	16.1 ± 2.8*
HbSat, %
FRCApnea	99.5 ± 0.3	97.2 ± 1.5	71.3 ± 6.3
RBRMatched	99.5 ± 0.4	97.5 ± 1.8	71.3 ± 6.3
$\mathrm{P}\mathrm{E}{\mathrm{T}}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}$, Torr
FRCApnea	27 ± 6	41 ± 5*	44 ± 4*†
RBRMatched	28 ± 6	40 ± 6*	47 ± 5*
$\mathrm{P}\mathrm{E}{\mathrm{T}}_{{\mathrm{O}}_{\mathrm{2}}}$, Torr
FRCApnea	118 ± 5	66 ± 5*	50 ± 5*†
RBRMatched	117 ± 7	68 ± 6*	33 ± 3*

Values are means ± SD. MAP, mean arterial pressure; HR, heart rate; SV, stroke volume; CO, cardiac output; TPR, total peripheral resistance; HbSat, hemoglobin saturation; $\mathrm{P}\mathrm{E}{\mathrm{T}}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}$, end-tidal partial pressure of carbon dioxide; $\mathrm{P}\mathrm{E}{\mathrm{T}}_{{\mathrm{O}}_{\mathrm{2}}}$, end-tidal partial pressure of oxygen. Effects of time were found for SV and HbSat whereby the maneuver periods were reduced vs. baseline (both P ≤ 0.001).

^*P < 0.05, significantly different from baseline.

^†P < 0.05, significantly different from RBR_Matched.