Pulmonary Vascular Hemodynamics in Chronic Lung Disease Patients: Pulmonary Function and Gas Exchange

Since the groups were selected on the basis of NOD, mean sleep and nadir Sa02 for the NOD group was predictably lower than that for the non-NOD group (Table 3). Total sleep time was slightly lower in the NOD group. Mean time in bed, total REM, and NREM sleep time were not different between groups. The NOD subjects spent 27.3 percent of sleep at a SaOz between 85 to 90 percent while the non-NOD subjects spent only 1.4 percent of the night at this level.

Supine, Resting, Pulmonary Hemodynamics and Systemic Blood Pressure
Breathing room air (Table 4; Fig 1, points labeled 0.21), the systolic and mean Ppa and PVR were significantly higher in the NOD group while diastolic Ppa, Pew, and CO did not differ. Supine systolic, diastolic, and mean systemic artery pressures were higher in the NOD group. During hypoxic challenge (Table 4; Fig 1, points labeled 0.13), all pulmonary hemodynamics including Ppa, Pew, PVR, and CO showed significant increases from room air measurements for both groups. Mean Ppa for NOD subjects increased 29 percent above baseline air mesurements and 34 percent for non-NOD subjects. While mean systemic pressure increased during hypoxic challenge in the NOD group (98.4 vs 107.1 mm Hg; p<0.001), this variable did not change in non-NOD subjects (Fig 1, midright panel).
During hyperoxic challenge (Table 4; Fig 1, points labeled 1.0), hemodynamics in both groups returned to values equal to or slightly lower than those breathing room air. The mean hyperoxic Ppa did not vary from room air for control subjects but was slightly lower than room air for NOD subjects (23.3 vs 22.1 mm Hg, p<0.005). Hyperoxic PVR returned to baseline supine room air values in the non-NOD group, but to slightly lower levels in NOD subjects.
The correlation coefficients between daytime PaOz vs Ppa and PVR were — 0.16 and – 0.49, respectively. Correlations between mean (1) nocturnal Sa02, (2) nadir nocturnal Sa02, and (3) percentage of sleep spent at Sa02^89 percent vs Ppa and PVR were -0.23, -0.41, 0.20 and -0.32, -0.25, 0.17, respectively.
Table 3—Parameters of Sleep and Sleep Oxygen Saturation

Group 1 (NOD) N = 36 Group 2 (Non-NOD) N = 13
Mean SD Mean SD P
Time in bed, min 365 73.5 376 64.5 NS
Total sleep time, min 250 74.5 300 85.0 NS
Total REM time, min 39.5 22.9 46.1 24.6 NS
Total NREM time, min 210 67.5 255 72 NS
Mean sleep SaO„ % 90.4 2.0 94.1 1.0
Mean nadir sleep SaO,, % 78.4 6.0 89.5 0.7
Mean time at SaO*^89% 15.4 13.6 0.7 1.4
Mean time at SaO*^84% 1.8 3.1 0 0

Table 4—Pulmonary Hemodynamics: Supine Room Air, Hypoxic, and Hyperoxic

Group 1 (NOD, N = 36) Group 2 (Non-NOD, N = 13)
Mean SD Mean SD P
Supine room air:
Sys/Dia Ppa, mm Hg 33/18 6/4 26/17 4/4 C0.001/NS
Mean Ppa, mm Hg 23.3 4.8 20.4 4.2 <0.05
Mean Pew, mm Hg 11.2 4.4 13.1 3.6 NS
Cardiac output, L/m 5.87 1.39 5.74 0.81 NS
Mean PVR, d s cm-5 172.4 53.8 101.8 27.6 <0.0001
Sys/Dia Psa, mm Hg 150/72 16/10 130/62 22/8 <0.005/0.005
Mean Psa, mm Hg 98.4 8.8 84.6 11.5 <0.0004
Mean supine SaOs, % 93.9 2.1 95.4 1.2 <0.02
Mean supine S90a, % 68.6 5.0 70.7 4.3 NS
Supine hypoxia:
Sys/Dia Ppa, mm Hg 43/24 9/7 37/23 7/5 <0.05/NS
Mean PpA, mm Hg 30.0 7.1 27.4 5.0 NS
Mean Pew, mm Hg 13.7 5.0 15.0 4.2 NS
Cardiac output, L/m 7.17 2.19 6.66 1.44 NS
Mean PVR, d*s’cm-5 209.9 67.0 149.4 35.8 <0.0007
Sys/Dia Psa, mm Hg 167/77 24/12 139/62 24/8 <0.001/0.001
Mean Psa, mm Hg 107.1 13.8 87.3 11.4 <0.0003
Mean supine Sa02, % 80.0 1.8 79.0 0.9 NS
Mean supine, StfO*, % 53.2 6.5 52.6 5.1 NS
% Change Ppa air, % + 29.9 1.7 + 30.6 1.1 NS
Supine hyperoxia:
Sys/Dia Ppa, mm Hg 31/18 5/5 26/17 5/4 <0.003/NS
Mean PpA, mm Hg 22.1 4.7 20.2 3.9 NS
Mean Pew, mm Hg 12.1 4.9 13.6 3.9 NS
Cardiac output, L/m 5.42 1.29 5.13 1.05 NS
Mean PVR, d*s*cm-5 163.9 54.2 100.3 31.4 NS
Sys/Dia Psa, mm Hg 159/79 17/10 139/65 22/7 <0.01/0.001
Mean Psa, mm Hg 105.8 10.4 91.0 10.1 <0.0005
Mean supine Sa02, % 98.3 1.2 99.5 0.8 <0.003
Mean supine SCO*, % 79.3 5.3 81.7 4.3 NS
% Change Ppa, % -4.1 10.5 -1.9 6.5 NS

Category: Lung Disease

Tags: chronic lung disease, Pulmonary function, pulmonary vascular hemodynamics