Table 1. Clinical and procedural characteristics of the study population.
| All (n = 50) | Unaffected (n = 18) | Mild Hypoxaemia (n = 23) | Severe Hypoxaemia (n = 9) | p-value* (2-sided) | |
|---|---|---|---|---|---|
| Subject characteristics | |||||
| Age, mean ± SD, years | 65.8 ± 9.7 | 66.6 ± 8.4 | 65.6 ± 10.7 | 64.8 ± 10.6 | 0.9 |
| Male, n (%) | 41 (82) | 18 (100) | 18 (78) | 5 (56) | 0.01 |
| BMI, mean ± SD, kg/m2 | 27.3 ± 4.0 | 27.8 ± 3.0 | 26.9 ± 4.5 | 27.6 ± 4.6 | 0.8 |
| Diabetes mellitus, n (%) | 14 (28) | 4 (22) | 6 (26) | 3(33) | 0.1 |
| Smokers (yes/no/unknown) | 16/30/4 | 5/11/2 | 6/15/2 | 5/4/0 | 0.4 |
| COPD, n (%) | 7 (14) | 3 (17) | 2 (9) | 2 (22) | 0.6 |
| Cardiothoracic Intensive Care, mean ± SD | |||||
| PaO2/FiO2 before extubation, kPa | 38.2 ± 8.7 | 38.7 ± 6.4 | 40.0 ± 8.1 | 32.7 ± 12.4 | 0.09 |
| Length of mechanical ventilation, h | 7.1 ± 4.1 | 6.9 ± 4.4 | 7.2 ± 4.2 | 7.2 ± 3.4 | 0.9 |
| Length of stay, h | 23 ± 6 | 21.9 ± 1.2 | 22.8 ± 5.5 | 26.3 ± 10.3 | 0.2 |
| Readmission | 2 | 0 | 0 | 2 | 0.5 |
| Surgical procedure, mean ± SD | |||||
| Surgery, min | 196 ± 50 | 177 ± 38 | 205 ± 46 | 211 ± 69 | 0.12 |
| Time on CPB, min | 64 ± 29 | 57 ± 21 | 65 ± 26 | 73 ± 47 | 0.4 |
| Cross clamp, min | 33 ± 19 | 25 ± 11 | 36 ± 19 | 39 ± 26 | 0.09 |
| Gain volume, L | 2.0 ± 0.9 | 1.9 ± 1.1 | 2.1 ± 0.8 | 1.8 ± 0.9 | 0.6 |
| Cardioplegia solution, mL | 437 ± 118 | 413 ± 98 | 447 ± 115 | 458 ± 164 | 0.6 |
| 72 hours post-CPB, mean ± SD | |||||
| PaO2, kPa | 7.8 ± 1.4 | 9.2 ± 0.5 | 7.5 ± 0.5 | 5.6 ± 0.4 | <0.0001 |
| PaO2/FiO2, kPa | 37.0 ± 6.6 | 43.9 ± 2.5 | 35.7 ± 2.3 | 26.5 ± 2.1 | <0.0001 |
| Weight gain, kg | 4.0 ± 3.1 | 2.7 ± 2.0 | 4.2 ± 3.6 | 6.0 ± 2.4 | 0.03 |
| C-reactive protein, mg/L | 146 ± 66 | 111 ± 36 | 152 ± 70 | 196 ± 73 | 0.008 |
| Leukocytes (n × 109) | 9.9 ± 3.2 | 8.5 ± 2.6 | 10.4 ± 3.2 | 11.8 ± 3.3 | 0.03 |
| Pneumonia¤ | 2 | 0 | 0 | 2 | 0.5 |
| Atrial fibrillation | 15 | 4 | 9 | 2 | 0.4 |
| Length of hospital stay, days# | 8 ± 4 | 8 ± 5 | 8 ± 2 | 11 ± 6 | 0.09 |
¤Clinical judgment leading to extended antibiotic treatment.
#Stay at the University Hospital.
*Analysis of variance (ANOVA) and chi-squared tests were used to calculate the significance between groups. Annotations: n, number of subject; SD, standard deviation; BMI, body mass index; COPD, chronic obstructive pulmonary disease; CPB, cardiopulmonary bypass; PaO2, partial pressure of oxygen in arterial blood; FiO2, fraction of inspired oxygen (21%); Surgery, from skin incision to last suture.