Archive for the 'Chronic Thromboembolism' Category

24 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Discussion (Part 4)

These vessels anastomose with precapillary pulmonary vessels and thereby have access to the obstructed pulmonary capillary bed. Because of the proliferation of anastomotic bronchial vessels, pulmonary capillaries distal to even completely obstructed pulmonary arteries will not be blood-free, and therefore, will be available for CO exchange. Since CO uptake is diffusion-limited rather than perfusion-limited, even […]

23 Oct

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

A more uniform perfusion distribution returns over the first postoperative year, and it is accompanied by resolution of hypoxemia. This time course suggests that either the nonobstructed vasculature undergoes remodeling which reduces its vascular resistance, or that the previously obstructed areas gradually recover vascular tone and gas exchange function. Shunt and high Va/Q regions were […]

22 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Discussion (Part 2)

Although thromboendarterectomy reduces Va/Q maldistribution over the long term, the mechanism of improvement may be more complicated than the simple relief of central vascular obstruction which then restores segmental Va/Q balance. Over 140 patients with chronic thromboembolic pulmonary hypertension have undergone thromboendarterectomy at the University of California, San Diego and it is our current impression […]

21 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Discussion (Part 1)

The central conclusion of this study is that pulmonary thromboendarterectomy, on average, returns the Va/Q distribution to nearly normal in chronic large vessel thromboembolic pulmonary hypertension. Thus, the improvement in hypoxemia is not simply due to the improvement in cardiac output which follows relief of central obstruction. This conclusion is based on the postoperative reduction […]

20 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Results (Part 4)

In a single case (No. 7), the postoperative log SDq increased, due to the development of a very small amount of perfusion to low Va/Q respiratory units. The remainder of the Va/Q distribution was unchanged postoperatively. Radionuclide scanning revealed resolution of segmental abnormalities in the operated segments in every case, although some subsegmental perfusion defects […]

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 […]

18 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Results (Part 2)

Hemodynamic and gas exchange data are summarized in Table 2. All patients had greater than 50 percent of the central pulmonary vascular bed obstructed prior to surgery, as estimated angiographi-cally. The estimated vascular obstruction averaged 78 ±14 percent before surgery, and 41 ±24 percent (p<0.05) after surgery. Preoperatively, the mean pulmonary artery pressure was 43 […]

17 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Results (Part 1)

The patient population was composed of six men and three women. The average age was 47 ± 9 years at the time of surgery. Patients returned eight to 18 months (average 12 months) after surgery for follow-up evaluation. buy ampicillin Prior to surgery, all had symptoms of dyspnea on exertion for over one year (average […]

16 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Methods (Part 2)

Mixed expired gas samples were also analyzed for respiratory gas concentrations using a mass spectrometer. Arterial and mixed venous blood gases and oxygen contents were measured in duplicate immediately after collection using a blood gas analyzer and COoximeter. A six-view perfusion scan was performed before and after surgery. The subjects were injected intravenously while in […]

15 Oct

Gas Exchange in Chronic Thromboembolism after Pulmonary Thromboendarterectomy: Methods (Part 1)

Nine patients with chronic thromboembolic pulmonary hypertension were studied immediately before and approximately one year following thromboendarterectomy. These patients were referred for initial evaluation and potential surgery but were otherwise unselected. They were a subset of a larger preoperative study of 25 subjects reported previously and represent those patients who were able to return for […]

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