Table 2.
Comparison among groups classified according to Henderson–Hasselbalch approach.
| Study Population | No Acid-Base Disorder | Respiratory Alkalosis | Metabolic Alkalosis |
Respiratory Acidosis |
Mixed Alkalosis |
p | |
|---|---|---|---|---|---|---|---|
| Number (%) | 104 (100) | 14 (13) | 42 (40) | 34 (32) | 5 (5) | 9 (10) | - |
| Age, years | 60 (53–69) | 59 (52–71) | 61 (55–68) | 59 (52–66) | 58 (57–69) | 63 (59–70) | 0.824 |
| Female gender, n (%) | 28 (27) | 21 (3) | 17 (7) | 41 (14) | 100 (5) | 13 (1) | 0.845 |
| BMI, kg/m2 | 28 (25–33) | 25 (25–28) | 28 (25–31) | 28 (26–34) | 30 (30–30) | 30 (26–36) | 0.804 |
| Time from symptoms to ED, days | 6 (4–8) | 6 (4–7) | 5 (4–8) | 6 (3–8) | 7 (5–7) | 6 (5–8) | 0.989 |
| Respiratory rate, bpm | 19 (17–24) | 20 (17–24) | 20 (17–23) | 18 (16–22) | 18 (16–20) | 20 (18–24) | 0.791 |
| FiO2 | 70 (60–70) | 70 (60–80) | 70 (60–80) | 65 (60–70) | 70 (60–75) | 60 (60–70) | 0.286 |
| PEEP, cmH2O | 8 (7.5–10) | 10 (8–10) | 7.5 (7.5–10) | 8 (7.5–10) | 7.5 (7.5–10) | 7.5 (7.5–8) | 0.220 |
| Borg Score | 0 (0–0) | 0 (0–0) | 0 (0–1) | 0 (0–0) | 0 (0–0) | 0 (0–0) | 0.203 |
| WOB Score | 1 (1–2) | 1 (1–2) | 1 (1–2) | 1 (1–2) | 1 (1–4) | 2 (1–3) | 0.684 |
| Arterial pH | 7.44 (7.43–7.46) | 7.40 (7.39–7.42) | 7.44 (7.44–7.46) | 7.45 (7.44–7.46) | 7.36 (7.36–7.36) | 7.48 (7.48–7.49) | <0.001 |
| PaCO2, mmHg | 38 (35–41) | 40 (39–42) | 35 (33–36) | 41 (40–44) | 48 (44–51) | 36 (35–37) | <0.001 |
| PaO2, mmHg | 123 (92–155) | 139 (101–180) | 125 (94–177) | 108 (92–150) | 98 (74–149) | 130 (108–146) | 0.762 |
| PaO2/FiO2 | 199 (139–246) | 212 (173–227) | 199 (139–261) | 167 (140–234) | 163 (124–212) | 221 (180–246) | 0.780 |
| HCO3−, mMol/L | 25.8 (24.1–27.4) | 25.2 (23.8–26.0) | 24.2 (22.9–25.0) | 28.0 (27.1–29.7) | 27 (24.5–28) | 27.0 (26.1–27.4) | <0.001 |
| BE, mMol/L | 1.6 (0.1–3.6) | 1.2 (−0.6–1.7) | 0.2 (−1.0–0.8) | 4.1 (2.9–6.1) | 1.3 (−0.8–3.6) | 3.8 (2.1–4.1) | <0.001 |
| Apparent SID, mEq/L | 36.6 (34.9–38.2) | 37.8 (36.8–38.8) | 35.8 (33.9–37.2) | 37.6 (36.6–38.9) | 35.6 (35.0–36.5) | 36.2 (34.9–37.4) | 0.004 |
| Sodium, mEq/L | 136 (134–138) | 138 (135–139) | 136 (134–139) | 136 (135–138) | 137 (133–137) | 135 (133–137) | 0.333 |
| Potassium, mEq/L | 4.1 (3.8–4.3) | 4.1 (3.8–4.4) | 4.0 (3.8–4.4) | 4.1 (3.8–4.3) | 4.1 (4.0–4.5) | 3.8 (3.6–4.0) | 0.270 |
| Cloride, mEq/L | 103 (100–105) | 102 (100–105) | 104 (101–105) | 102 (100–104) | 100 (99–102) | 102 (100–103) | 0.151 |
| Lactates, mMol/L | 1.3 (1.0–1.7) | 1.3 (1.0–1.8) | 1.4 (1.2–1.7) | 1.2 (1.0–1.4) | 1.5 (1.4–2.5) | 1.3 (1.0–1.4) | 0.075 |
| Anion Gap, mEq/L | 8.1 (6.3–10.0) | 9.9 (7.9–10.8) | 9.0 (8.0–10.7) | 6.6 (5.5–7.9) | 7.7 (6.0–8.8) | 6.9 (5.9–8.0) | <0.001 |
| Creatinine, mg/dL | 0.9 (0.7–1.1) | 0.8 (0.7–0.95) | 0.9 (0.8–1.1) | 0.7 (0.6–0.9) | 1.0 (0.9–1.2) | 1.0 (0.9–1.2) | 0.007 |
| Ventilation type, n (%) | 0.290 | ||||||
| CPAP | 84 (87) | 100 (14) | 81 (34) | 85 (29) | 80 (4) | 67 (6) | |
| NIV | 16 (17) | 0 (0) | 19 (8) | 15 (5) | 20 (1) | 33 (3) | |
| Endotracheal Intubation, n (%) | 19 (20) | 26 (4) | 19 (8) | 9 (3) | 2 (40) | 33 (3) | 0.223 |
| Mortality, n (%) | 14 (13) | 2 (14) | 5 (2) | 15 (5) | 40 (2) | 33 (3) | 0.065 |
Continuous variables are compared using One-Way ANOVA or Kruskal–Wallis Test, as appropriate; categorical variables are compared using χ2 test. Data are presented as median [IQR]. BMI: body mass index; FiO2: inspired oxygen fraction; ED: emergency department; PEEP: positive end-expiratory pressure; WOB: work of breathing; PaCO2: arterial carbon dioxide partial pressure; PaO2: arterial oxygen partial pressure; HCO3−: arterial bicarbonate concentration; BE: base excess; SID: strong ion difference; CPAP: continuous positive airway pressure; NIV: non-invasive ventilation.