Table 1.
Model parameters for responses of ΔPmax and cardiac variables to hypercapnia and hypocapnia
| ΔPmax |
HR |
SV |
Q̇ |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Subject | M, Torr | G, Torr/Torr | τ, min | M, beats/min | G, beats·min·−1·Torr−1 | τ, min | M, ml | G, ml/Torr | τ, min | M, ml/min | G, ml·min−1·Torr−1 | τ, min |
| Hypercapnia protocol | ||||||||||||
| 1229 | 22.46 | 0.90 | 4.27 | — | — | — | — | — | — | — | — | — |
| 1096 | 26.28 | 0.64 | 2.63 | 49.89 | 1.12 | 2.04 | 98.52 | 1.00 | 0.01 | 4,895 | 172.5 | 1.66 |
| 1236 | 16.54 | 0.66 | 7.90 | 52.37 | 1.26 | 4.02 | 76.67 | 3.10 | 20.07 | 4,015 | 240.1 | 8.71 |
| 1238 | 14.96 | 0.39 | 4.99 | 40.92 | 0.59 | 7.56 | 64.31 | 1.78 | 7.82 | 2,624 | 119.3 | 7.77 |
| 1156 | 19.24 | 0.76 | 6.29 | 88.35 | −0.75 | 1.66 | 60.28 | 0.59 | 0.94 | 5,304 | 7.240 | 0.02 |
| 1142 | 23.05 | 0.33 | 2.35 | 72.88 | 1.01 | 4.59 | 45.94 | 0.85 | 5.94 | 3,340 | 116.1 | 5.36 |
| 1091 | 23.06 | 0.72 | 2.74 | 51.85 | 1.22 | 5.21 | 123.74 | 1.46 | 3.85 | 6,402 | 240.5 | 4.63 |
| 1252 | 19.92 | 0.54 | 3.05 | 62.70 | 1.64 | 4.79 | — | — | — | 3,991 | 164.9 | 8.12 |
| 1198 | 18.83 | 0.80 | 6.98 | 55.30 | 0.57 | 0.55 | 63.81 | 0.69 | 1.01 | 3,534 | 76.12 | 0.69 |
| 1250 | 20.04 | 0.92 | 6.75 | 59.05 | 1.60 | 5.89 | 80.00 | 0.63 | 2.34 | 4,725 | 168.1 | 4.36 |
| 1256 | 21.55 | 1.53 | 7.22 | 46.13 | 0.72 | 2.76 | 74.17 | 2.67 | 11.12 | 3,418 | 177.7 | 6.78 |
| 1209 | 20.77 | 0.90 | 3.08 | 59.36 | 0.63 | 3.17 | 89.33 | 1.57 | 6.95 | 5,303 | 152.6 | 4.92 |
| Means ± SE | 20.56 ± 0.88 | 0.76 ± 0.09 | 4.85 ± 0.60 | 58.07 ± 3.98 | 0.87 ± 0.20 | 3.84 ± 0.62 | 77.68 ± 6.99 | 1.43 ± 0.28 | 6.01 ± 1.92 | 4,323 ± 333.4 | 148.6 ± 20.46 | 4.82 ± 0.90 |
| Hypocapnia protocol | ||||||||||||
| 1229 | 25.50 | 0.42 | 5.66 | 55.25 | −0.22 | 0.02 | 120.21 | 2.09 | 11.70 | — | — | — |
| 1096 | 27.41 | 0.35 | 3.34 | 54.42 | 1.14 | 16.73 | 109.67 | 1.41 | 12.44 | 5,964 | 186.5 | 14.28 |
| 1236 | 15.82 | 0.22 | 4.46 | — | — | — | — | — | — | — | — | — |
| 1238 | 16.33 | 0.20 | 1.41 | — | — | — | 80.94 | 0.32 | 16.03 | 5,122 | 105.7 | 25.24 |
| 1156 | 25.74 | 0.66 | 5.36 | 89.00 | 0.73 | 2.13 | 62.19 | 0.51 | 7.84 | 5,515 | 81.01 | 4.03 |
| 1142 | 20.62 | 0.40 | 3.43 | 79.91 | 0.93 | 10.59 | 51.01 | 1.02 | 15.33 | 4,070 | 119.5 | 13.04 |
| 1091 | 25.84 | 0.47 | 5.98 | 52.64 | 0.68 | 12.59 | 112.19 | 0.66 | 5.83 | 5,902 | 103.2 | 9.39 |
| 1252 | 21.44 | 0.31 | 2.72 | 71.59 | 0.97 | 16.24 | 66.52 | 0.69 | 1.97 | 4,710 | 85.58 | 5.27 |
| 1198 | 19.02 | 0.39 | 4.12 | 47.89 | −0.41 | 0.01 | 79.22 | 0.51 | 0.01 | 3,792 | −6.65 | 0.01 |
| 1250 | 19.24 | 0.37 | 4.28 | 80.52 | 1.85 | 9.81 | 82.58 | 0.78 | 6.30 | 6,632 | 199.1 | 8.47 |
| 1256 | 20.50 | 0.57 | 6.54 | 47.57 | 0.34 | 13.79 | — | — | — | 4,185 | 83.62 | 19.87 |
| 1209 | 22.05 | 0.41 | 2.72 | 65.37 | 1.35 | 15.06 | 93.78 | 0.84 | 3.55 | 6,111 | 152.2 | 8.34 |
| Means ± SE | 21.63 ± 1.10 | 0.40 ± 0.04 | 4.17 ± 0.44 | 64.42 ± 4.76 | 0.74 ± 0.22 | 9.70 ± 2.09 | 85.83 ± 7.25 | 0.88 ± 0.16 | 8.10 ± 1.76 | 5,200 ± 308.9 | 111.0 ± 18.67 | 10.79 ± 2.39 |
M, value of variable under conditions of steady eucapnia; G, sensitivity of response to alterations in end-tidal Pco2; τ, time constant for response; ΔPmax, maximum pressure difference across tricuspid valve; HR, heart rate; SV, stroke volume; Q̇, cardiac output. Parameter values for individual fits have been excluded for cases in which the models could not fit the data meaningfully.