19 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Results (Part 3)

Typical preoperative Va/Q distributions are shown in Figure 1. The mean Va/Q of the perfusion distribution was 1.2 ±0.4, and the mean Va/Q of the ventilation distribution was 2.3 ±0.8. Shunt (Va/Q = 0) was not increased on average (5 percent of cardiac output), although a single patient had a shunt of 27 percent. Alveolar deadspace ventilation (Va/Q >100) was elevated, averaging 5.5 ± 1.1 L/min with a range of 4.0 to 7.2 L/min. The Vd/Vt ratio was 0.55 ±0.09.At postoperative follow-up, significant improvement (p<0.05) in almost all variables had occurred (Table 2). The mean pulmonary artery pressure fell 19 mm Hg to 24 ±5 mm Hg, the pulmonary vascular resistance fell to 308 ±128 dyne/s/cm, the right atrial pressure fell to 4±2 mm Hg, and the pulmonary capillary wedge pressure was unchanged (9 ±3 mm Hg, p>0.05). The cardiac output increased by 41 percent to 4.2 ±0.9 L/min (2.4 ±0.6 L/min/m2), and the arterial Po2 increased 27 mm Hg on average to 83 ± 7 mm Hg. The P(A-a)02 difference fell to 19 ± 10 mm Hg, the PaC02 rose to 36 ±4 mm Hg, and the average mixed venous Po2 increased 7 mm Hg to 38 ± 2 mm Hg. buy ortho tri-cyclen
Importantly, Va/Q inequality improved in every case but one, although in four subjects, the improvement was only modest. Typical examples are shown in Figure 1. In four subjects, the breadth of the Va/Q distribution as measured by the log SDq, fell to within the normal range. Overall, the average log SDq fell to just above the normal range (log SDq 0.76 ±0.28), the mean Va/Q of the perfusion distribution fell to 0.80 ±0.13, and the mean Va/Q of the ventilation distribution fell to 1.5 ±0.8. Minute ventilation decreased 21 percent to 8.0 L/min. The Vo2, Vco2, and tidal volume were all unchanged (p>0.05).


Figure 1. Preoperative and postoperative Va/Q distributions, from subjects 3 and 4. The improvement in Va/Q matching experienced by patient 3 is typical of that achieved by five of the nine subjects. The slight improvement experienced by subject 4 is typical of that achieved by four subjects. Closed circles: perfusion Q; open circles: ventilation V 

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