Table 2.
Pulmonary vascular responses to hypoxia: parameter values (mean ±s.e.m.) for the model of the pulmonary vascular response to acute hypoxia for the trimetaphan and control protocols before and after an 8 h period of sustained hypoxic exposure
| Protocol/factor | GΔP (mmHg %−1) | ΔP100 (mmHg) | TΔP (min) |
|---|---|---|---|
| AM measurements – before sustained hypoxia | |||
| Control 1 | 0.50 ± 0.06 | 18.9 ± 1.5 | 2.41 ± 0.41 |
| Trimetaphan | 0.41 ± 0.04 | 17.4 ± 1.2 | 3.06 ± 0.32 |
| Control 2 | 0.58 ± 0.06 | 17.9 ± 1.2 | 3.24 ± 0.20 |
| PM measurements – after sustained hypoxia | |||
| Control 1 | 0.95 ± 0.10 | 22.2 ± 1.8 | 3.90 ± 0.64 |
| Trimetaphan | 0.68 ± 0.07 | 21.2 ± 1.6 | 2.91 ± 0.35 |
| Control 2 | 0.82 ± 0.04 | 22.1 ± 1.4 | 3.61 ± 0.40 |
| Statistical analysis – ANOVA | |||
| Time (before/after sustained hypoxia) | < 0.001 | < 0.001 | — |
| Protocol (C1, C2 versus T) | < 0.02 | < 0.05 | — |
| Interactive term | — | — | < 0.05 |
GΔP is the sensitivity of maximum pressure difference across tricuspid valve during systole (ΔPmax) to a decrease in saturation; ΔP100 is the steady-state value for ΔPmax in the absence of hypoxia (i.e. when saturation is 100%); TΔP is the time constant for the response; AM, morning; PM, afternoon. ANOVA conducted on the parameter values with fixed factors Time (before/after sustained hypoxia) and Protocol (control protocols (Protocols C1, C2) versus Protocol T). Statistical significance was accepted at P < 0.05.