Table 3.

Hemodynamic responses to FRC_Apnea and RBR_End protocols

	Baseline	Rebreathe	Maneuver
MAP, mmHg
FRCApnea	87 ± 3	89 ± 3	105 ± 9
RBREnd	87 ± 3	88 ± 2	106 ± 11
HR, beats/min
FRCApnea	70 ± 14	68 ± 13	60 ± 9†
RBREnd	68 ± 12	66 ± 13	84 ± 23*
SV, ml
FRCApnea	97 ± 20	90 ± 18	84 ± 18
RBREnd	96 ± 19	91 ± 19	87 ± 23
CO, l/min
FRCApnea	6.6 ± 1.3	6.0 ± 1.0	5.0 ± 0.7*†
RBREnd	6.4 ± 0.9	5.9 ± 0.8	7.0 ± 1.1
TPR, mmHg·l−1·min−1
FRCApnea	13.5 ± 2.3	15.1 ± 2.1	21.6 ± 3.3*†
RBREnd	13.7 ± 1.7	15.2 ± 1.9	15.5 ± 2.1
HbSat, %
FRCApnea	99.5 ± 0.3	97.2 ± 1.5	71.3 ± 6.3*†
RBREnd	99.5 ± 0.4	97.5 ± 1.8	51.9 ± 13.1*
$\mathrm{P}\mathrm{E}{\mathrm{T}}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}$, Torr
FRCApnea	27 ± 6	41 ± 5*	44 ± 4*†
RBREnd	28 ± 6	40 ± 6*	49 ± 6*
$\mathrm{P}\mathrm{E}{\mathrm{T}}_{{\mathrm{O}}_{\mathrm{2}}}$, Torr
FRCApnea	118 ± 5	66 ± 5*	50 ± 5*†
RBREnd	117 ± 7	68 ± 6*	23 ± 5*

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. An effect of time was found for SV whereby the maneuver period was reduced vs. baseline (P < 0.001). An effect of time was found for MAP whereby the rebreathe and maneuver period were greater than baseline (both P < 0.001).

^*P < 0.01, significantly different from baseline.

^†P < 0.01, significantly different from RBR_End.