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 ± 11 mm Hg, the right atrial pressure was 13 ±7 mm Hg, the pulmonary capillary wedge pressure was 11 ±2 mm Hg, the cardiac output was 3.5 ±1.3 L/min (1.7 ±0.6 L/min/ m2), and the pulmonary vascular resistance was 1152 ±1078 dyne/s/cm (range 318 to 3516). All subjects but one were hypoxemic (room air Pa02 64 ± 11 mm Hg) and all had a chronic compensated respiratory alkalosis (pH 7.43 ±0.02, PaC02 32 ±4 mm Hg). The P(A-a)02 difference was 46 ± 15 mm Hg, and the mixed venous Po2 was 31 ±6 mm Hg. The single breath diffusing capacity was depressed at 63 ±11 percent of predicted, and the ratio of single breath diffusing capacity to single breath lung volume was 77 ± 13 percent of predicted. birth control pills
The Va/Q abnormality was moderately severe in every patient. The standard deviation of the perfusion distribution plotted on a logarithmic scale (log SDq) was 0.98 ±0.33. The 95 percent upper confidence limit for this measure in young normal subjects is 0.6. This represents a moderate broadening of the Va/Q distribution in that Va/Q ratios in these patients span two decades on a log scale, about twice the normal span. Radionuclide scanning also demonstrated multiple “mismatched” perfusion defects which were at least segmental in size.

Table 2—Hemodynamic and Gas Exchange Data 

Postop,

Obs,

PaP,

Shunt,

VQ<0.1,

Patient

mo

%

mm Hg

PVR

Cl

Pa02

PiiC02

Pvo2

P(A-a)02

LSDq

%

%

Vd/Vt

1

Pre

53

26

318

2.2

83

31

33

34

0.84

0.0

1.1

.50

Post

17

21

20

125

2.1

80

34

36

41

0.80

1.0

2.0

.39

2

Pre

67

52

1543

2.0

51

30

28

72

1.16

6.7

1.0

.38

Post

18

NA

NA

NA

3.8

75

37

NA

30

0.98

2.5

3.5

.36

3

Pre

91

35

486

1.6

61

31

32

46

0.98

0.6

0.0

.54

Post

10

23

18

210

2.4

91

38

42

3

0.59

0.0

1.0

.53

4

Pre

70

39

454

2.5

68

31

34

45

1.00

0.7

0.5

.56

Post

9

21

NA

NA

2.4

80

34

37

26

0.72

1.0

0.0

.56

Pre

82

55

3516

0.6

71

32

29

36

0.77

3.7

0.5

.68

Post

9

52

25

300

1.9

93

33

38

14

0.47

4.0

0.0

.32

Pre

88

46

1361

1.3

64

31

26

49

1.04

0.0

2.1

.60

Post

8

79

22

327

2.1

83

39

37

22

0.56

2.0

0.0

.61

Pre

91

50

NA

1.3

52

37

NA

52

0.64

1.2

0.0

.58

Post

15

65

37

512

1.9

73

38

36

24

1.09

0.0

4.0

.59

Pre

67

28

338

2.0

74

42

43

21

0.65

1.7

0.0

.64

Post

12

NA

NA

NA

NA

88

44

NA

4

0.46

1.0

0.0

.49

Pre

94

58

1589

1.5

53

28

26

61

1.72

27.1

7.7

.51

Post

10

26

24

425

2.4

88

32

41

21

1.22

2.0

5.5

.45

Preop:

mn

78

43

1.7

64

32

31

46

0.98

4.7

1.4

.55

sd

14

11

0.6

11

4

6

15

0.33

8.6

2.4

.09

Postop:

12

mn

41

24

2.4

83

36

38

19

0.76

2.0

2.0

.48

       sd

4

24

5

0.6

7

4

2

10

0.28

1.0

2.0

.10

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