Table 3 Oxygen variables from isoflurane-anesthetized horses (n = 5) breathing 50% or maximal oxygen concentrations

CaO₂ (mL/dL)

50%

17.9 ± 2.1

16.7 ± 0.5

16.4 ± 0.7

19.3 ± 0.3

18.7 ± 0.3

18.3 ± 0.7

17.4 ± 1.1

16.9 ± 1.0

14.4 ± 0.4

16.2 ± 0.6

>95%

16.4 ± 0.7

17.0 ± 0.5

18.3 ± 1.0

19.4 ± 1.2

19.4 ± 0.6

19.1 ± 0.7

19.2 ± 1.1

18.6 ± 1.2

14.3 ± 0.8

15.4 ± 0.6

CvO₂ (mL/dL)

50%

13.0 ± 1.7

13.1 ± 0.6

13.2 ± 0.5

16.9 ± 0.6

16.6 ± 0.3

15.5 ± 0.9

14.9 ± 1.5

14.1 ± 1.3

9.9 ± 0.7

10.2 ± 0.7

>95%

11.3 ± 0.5

14.3 ± 0.5

15.1 ± 1.0

16.5 ± 1.4

16.4 ± 1.2

15.9 ± 1.3

15.4 ± 1.3

14.7 ± 1.3

9.7 ± 0.8

9.3 ± 1.2

O₂ER (%)

50%

27 ± 4

22 ± 2

19 ± 3

12 ± 3

11 ± 1

15 ± 3

15 ± 4

17 ± 3

32 ± 3

37 ± 4

>95%

31 ± 1

16 ± 2

18 ± 4

15 ± 3

16 ± 4

17 ± 5

20 ± 3

21 ± 3

32 ± 3

40 ± 6

VO₂ (mL/kg bwt/min)

50%

2.9 ± 1

1.5 ± 0.2

1.4 ± 0.2

1.1 ± 0.2^a

1.1 ± 0.1^a

1.0 ± 0.1^a

0.9 ± 0.1^a

1.0 ± 0.1^a

1.4 ± 0.1

3.5 ± 0.5

>95%

2.8 ± 0.2

1.0 ± 0.1^a

1.3 ± 0.2

1.4 ± 0.2

1.1 ± 0.2

1.2 ± 0.2

1.3 ± 0.1

1.3 ± 0.1

1.6 ± 0.1

4.0 ± 0.8

C(a-v)O₂ (mL/dL)

50%

4.87 ± 0.79

3.61 ± 0.40

3.20 ± 0.59

2.34 ± 0.49

2.12 ± 0.29

2.77 ± 0.48

2.53 ± 0.56

2.73 ± 0.38

4.52 ± 0.28

5.93 ± 0.65

>95%

5.12 ± 0.32

2.75 ± 0.40

3.28 ± 0.65

2.86 ± 0.49

3.00 ± 0.74

3.18 ± 0.84

3.75 ± 0.52

3.83 ± 0.46

4.61 ± 0.51

6.08 ± 0.80

PaO₂-IO₂ ratio

50%

0.64 ± 0.05

0.27 ± 0.03^a

0.28 ± 0.02^a

0.30 ± 0.02^a

0.29 ± 0.03^a

0.27 ± 0.03^a

0.23 ± 0.03^a

0.22 ± 0.03^a

0.30 ± 0.01^a

0.64 ± 0.02

>95%

0.64 ± 0.03

0.41 ± 0.05

0.36 ± 0.05^a

0.41 ± 0.07

0.38 ± 0.06^a

0.35 ± 0.07^a

0.32 ± 0.07^a

0.32 ± 0.07^a

0.32 ± 0.02^a

0.55 ± 0.06

P(A-a)O₂ (kPa)

50%

1.84 ± 1.09

27.51 ± 2.07^a,b

27.12 ± 1.00^a,b

26.52 ± 1.05^a,b

26.79 ± 1.29^a,b

27.85 ± 1.23^a,b

30.26 ± 1.60^a,b

29.81 ± 1.44^a,b

5.99 ± 0.67

0.99 ± 0.20

>95%

1.20 ± 0.31

45.93 ± 3.90^a,b

51.07 ± 4.51^a,b

46.77 ± 5.97^a,b

49.22 ± 5.26^a,b

52.08 ± 6.38^a,b

54.36 ± 6.31^a,b

55.33 ± 6.48^a,b

5.74 ± 0.90

2.40 ± 1.04

DO₂ (mL/kg bwt/min)

50%

10.82 ± 3.59

6.84 ± 0.60

7.44 ± 0.84

9.82 ± 0.85

9.91 ± 0.94

7.48 ± 1.07

6.71 ± 1.00

6.24 ± 0.61

4.62 ± 0.26^a

9.47 ± 0.78

>95%

9.16 ± 1.00

6.26 ± 0.24

7.24 ± 0.49

9.55 ± 0.89

8.34 ± 1.19

7.91 ± 1.03

6.65 ± 0.50

6.47 ± 0.44

5.11 ± 0.41

10.20 ± 1.19

Qs/Qt (%)

50%

13 ± 2

28 ± 4

30 ± 5

39 ± 8^a

40 ± 6^a

36 ± 4

40 ± 4^a

40 ± 3^a

43 ± 4^a

9 ± 1

>95%

9 ± 1

35 ± 4^a

36 ± 6^a

36 ± 4^a

38 ± 5^a

37 ± 4^a

33 ± 3^a

32 ± 3

38 ± 5^a

12 ± 2

Vd/Vt (%)

50%

-----

11.9 ± 4.4

11.7 ± 1.3

17.6 ± 1.5

19.4 ± 2.6

19.4 ± 3.1

20.5 ± 2.4

27.2 ± 3.9^c

-----

-----

>95%

-----

13.6 ± 3.2

17.7 ± 1.9

16.4 ± 2.2

18.7 ± 3.8

23.4 ± 2.3

27.6 ± 2.3

29.2 ± 2.2^c

-----

-----