Table 3.
Comparison among groups classified according to Stewart approach.
| Study Population |
No Acid-Base Disorder | Respiratory Alkalosis | Metabolic Alkalosis due to aSID | Other Alkalosis |
Respiratory Acidosis | Mixed Disorder |
p | |
|---|---|---|---|---|---|---|---|---|
| Number (%) | 104 (100) | 8 (8) | 45 (43) | 20 (19) | 14 (14) | 4 (4) | 13 (13) | - |
| Age, years | 60 (53–69) | 58 (53–64) | 60 (53–68) | 61 (50–70) | 60 (54–68) | 64 (58–69) | 62 (58–65) | 0.943 |
| Female gender, n (%) | 28 (27) | 1 (12) | 8 (18) | 11 (52) | 6 (43) | 25 (1) | 8 (1) | 0.654 |
| BMI, kg/m2 | 28 (25–33) | 25 (25–28) | 28 (25–31) | 28 (26–34) | 28 (26–33) | 30 (26–36) | 30 (30–30) | 0.734 |
| Time from symptoms to ED, days | 6 (4–8) | 6 (4–7) | 5 (4–8) | 4 (4–6) | 6 (4–8) | 6 (5–8) | 7 (5–7) | 0.783 |
| Respiratory rate, bpm | 19 (17–24) | 19 (17–26) | 19 (18–22) | 18 (16–22) | 18 (16–22) | 19 (18–22) | 19 (16–24) | 0.668 |
| FiO2 | 70 (60–70) | 70 (60–70) | 70 (60–70) | 70 (60–70) | 60 (60–70) | 75 (70–75) | 60 (60–70) | 0.532 |
| PEEP, cmH2O | 8 (7.5–10) | 10 (7.5–10) | 7.5 (7.5–10) | 8 (7.5–10) | 8 (7.5–10) | 10 (9–10) | 10 (7.5–10) | 0.141 |
| Borg Score | 0 (0–0) | 0 (0–1) | 0 (0–1) | 0 (0–0) | 0 (0–0) | 0 (0–0) | 0 (0–1) | 0.145 |
| WOB Score | 1 (1–2) | 1 (1–3) | 1 (1–2) | 1 (1–2) | 1 (1–2) | 1 (1–2) | 1 (1–2) | 0.971 |
| Arterial pH | 7.44 (7.43–7.46) | 7.41 (7.40–7.42) | 7.45 (7.44–7.48) | 7.45 (7.44–7.46) | 7.44 (7.45–7.46) | 7.36 (7.36–7.36) | 7.41 (7.40–7.42) | <0.001 |
| PaCO2, mmHg | 38 (35–41) | 41 (40–42) | 35 (33–36) | 40 (39–42) | 39 (38–42) | 48 (45–54) | 37 (34–43) | <0.001 |
| PaO2, mmHg | 123 (92–155) | 96 (81–190) | 120 (93–165) | 122 (90–152) | 126 (97–145) | 124 (92–195) | 138 (88–145) | 0.983 |
| PaO2/FiO2 | 199 (139–246) | 221 (118–298) | 199 (138–276) | 173 (150–230) | 168 (146–240) | 188 (148–278) | 198 (143–234) | 0.923 |
| HCO3−, mMol/L | 25.8 (24.1–27.4) | 25.6 (24.2–25.9) | 24.7 (23.6–25.6) | 27.4 (26.4–29.6) | 28.0 (26.9–29.4) | 26.2 (24.4–28.5) | 23.4 (22.0–27.0) | 0.001 |
| BE, mMol/L | 1.6 (0.1–3.6) | 1.6 (0.9–1.9) | 0.5 (−0.6–1.4) | 3.4 (2.4–6.0) | 3.6 (2.5–6.1) | 0.25 (−1.7–2.8) | 1.4 (−2–3.6) | 0.001 |
| Apparent SID, mEq/L | 36.6 (34.9–38.2) | 38.6 (38.0–39.1) | 38.9 (38.4–39.4) | 42.2 (42.1–43.0) | 40.0 (38.6–40.5) | 38.8 (38.0–39.6) | 35.6 (34.4–37.4) | 0.034 |
| Sodium, mEq/L | 136 (134–138) | 139 (136–139) | 136 (133–139) | 137 (135–138) | 137 (135–138) | 137 (136–138) | 137 (134–139) | 0.437 |
| Potassium, mEq/L | 4.1 (3.8–4.3) | 4.2 (4.0–4.4) | 4.0 (3.8–4.3) | 4.0 (3.7–4.2) | 4.1 (3.7–4.3) | 4.3 (4.1–4.5) | 4.3 (4.0–4.4) | 0.198 |
| Cloride, mEq/L | 103 (100–105) | 102 (99–103) | 103 (101–105) | 101 (100–104) | 101 (100–104) | 102 (100–104) | 103 (102–106) | 0.209 |
| Lactates, mMol/L | 1.3 (1.0–1.7) | 1.1 (0.9–1.3) | 1.3 (1.1–1.6) | 1.1 (1.0–1.4) | 1.1 (1.1–1.4) | 2.0 (1.4–2.6) | 1.7 (1.2–1.9) | 0.087 |
| Creatinine, mg/dL | 0.9 (0.7–1.1) | 0.8 (0.7–0.95) | 0.9 (0.8–1.1) | 1.0 (1.0–1.2) | 1.1 (0.9–1.1) | 1.0 (0.9–1.2) | 0.7 (0.6–0.9) | 0.004 |
| Ventilation type, n (%) | 0.489 | |||||||
| CPAP | 84 (87) | 8 (100) | 35 (78) | 10 (50) | 10 (71) | 3 (75) | 12 (92) | |
| NIV | 16 (17) | 0 (0) | 10 (22) | 10 (50) | 4 (29) | 1 (25) | 1 (8) | |
| Endotracheal Intubation, n (%) | 19 (20) | 4 (50) | 9 (20) | 2 (10) | 2 (14) | 2 (50) | 2 (15) | 0.132 |
| Mortality, n (%) | 13 (14) | 1 (12) | 5 (11) | 4 (20) | 1 (7) | 2 (50) | 1 (8) | 0.136 |
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]. AB: acid-base; BMI: body mass index; FiO2: inspired oxygen fraction; PEEP: positive end-expiratory pressure; ED: emergency department; 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.