Table 3.

Cardiorespiratory and sympathetic responses during modified Oxford test

	Baseline	Nitroprusside	Phenylephrine
Heart rate, beats/min	58 ± 2	73 ± 4*†	61 ± 3
Systolic blood pressure, mmHg	138 ± 4	130 ± 4*†	139 ± 5
Diastolic blood pressure, mmHg	75 ± 3	65 ± 3*†	75 ± 3
Mean blood pressure, mmHg	96 ± 3	86 ± 3*†	95 ± 3
Respiratory rate, breaths/min	13 ± 1	12 ± 1	12 ± 1
Tidal volume, l/breath	0.58 ± 0.10	0.77 ± 0.07	0.98 ± 0.17*
Minute ventilation, ml/min	7.1 ± 1.0	8.9 ± 1.1	11.5 ± 2.1*
Burst frequency, bursts/min	21 ± 1	36 ± 2*†	22 ± 4
Burst incidence, bursts/100 heartbeats	37 ± 4	53 ± 4*†	37 ± 7
Mean burst area, AU/min	1.1 ± 0.2	2.1 ± 0.2*†	1.2 ± 0.2
Action potential frequency, APs/min	222 ± 36	454 ± 71*†	254 ± 74
Action potential incidence, APs/burst	10.3 ± 1.2	12.2 ± 1.8	10.7 ± 1.6
Action potential incidence, APs/100 heartbeats	398 ± 75	678 ± 120*	431 ± 127
Mean cluster incidence, clusters/burst	5.3 ± 0.6	5.4 ± 0.6	5.0 ± 0.5
Max cluster incidence, clusters/burst	9.8 ± 0.8	10.0 ± 0.9	10.3 ± 1.0
Max cluster number	10.7 ± 1.2	11.3 ± 1.2	10.6 ± 1.2

Data are means ± SE from n = 9. Data were analyzed with a 1-way repeated-measures ANOVA. Normality was assessed with the Shapiro-Wilk test. If not normally distributed, a Friedman repeated-measures ANOVA on ranks was conducted (heart rate). Pairwise comparisons were done with the Holm-Sidak method.

^*P < 0.05 vs. baseline.

^†P < 0.05 vs. phenylephrine.