Physico-chemical characterization of acid base disorders in patients with COVID-19: A cohort study

Table 1 Clinical and laboratory variables of 211 critically ill coronavirus disease 2019 patients, n (%)

Variable	All patients	Survivors	Non-survivors	P value
Age in years	59.7 ± 17.1	58.6 ± 16.0	79.0 ± 9.0	0.000
Male sex	99 (60.0)	84 (59.0)	15 (65.0)	0.650
T2DM	55 (33.4)	43 (30.0)	12 (50.0)	0.050
Hypertension	87 (53.0)	70 (49.0)	17 (74.0)	0.040
COPD or asthma	23 (14.0)	17 (12.0)	6 (26.0)	0.100
SOFA score	2 (1.0-3.0)	2 (1.0-3.0)	3 (1.5-4.0)	0.110
Charlson’s score	3 (1.0-4.0)	2 (1.0-4.0)	5 (4.0-7.0)	0.000
SAPS 3	42.0 ± 19.0	42.0 ± 16.4	61.0 ± 15.0	0.000
Antimicrobial treatment	89 (54.0)	66 (46.8)	23 (100)	0.000
PO2/FIO2	296 ± 87	308 ± 94	264 ± 116	0.360
HFO2/NIV	83 (50.6)	67 (47.5)	16 (69.5)	0.040
Lung involvement				0.360
< 25%	13.4	12.0	21.7
25%-50%	44.5	46.8	30.4
50%-75%	34.7	34.7	34.7
> 75%	6.7	5.6	13.0
VAD at admission	25 (15.0)	18 (12.0)	7 (30.0)	0.050
VAD any time	60 (37.0)	39 (27.0)	21 (91.0)	0.000
MV	65 (40.0)	43 (30.0)	22 (95.0)	0.000
AKI	50 (30.4)	28 (19.8)	22 (95.6)	0.000
KDIGO 1	18 (11.0)	17 (12.0)	1 (4.3)	0.000
KDIGO 2	7 (4.2)	5 (3.5)	2 (8.7)
KDIGO 3	25 (15.2)	6 (4.2)	19 (82.6)
Dialysis	19 (11.6)	2 (1.4)	17 (73.0)	0.000
Hospital stay in day	13 (10.0-21.0)	17 (9.0-20.5)	22 (13.0-32.0)	0.005
ICU stay in day	12.6 (5-17)	11.0 (9-14)	21.0 (18-25)	0.000
Illness day	7.0 (5.0-9.0)	10.1 (5.0-8.7)	8.2 (3.0-17.0)	0.003
Days in hospital	0 (0-1)	0 (0-1)	0 (0-1)	0.410
Ferritin (normal range: 12 ng/mL-300 ng/mL)	985 ± 1447	1088 ± 1529	679 ± 609	0.170
Leukocyte count (normal range: 3.6 × 109/L-11.0 × 109/L)	7.0 (5.5-9.1)	7.1 (5.1-9.4)	6.6 (4.3-8.9)	0.720
Lymphocyte count (normal range: 1 × 109/L-4 × 109/L)	0.86	0.92	0.78	0.040
Platelet count (normal range: 150 × 109/L-400 × 109/L)	179 (151-237)	191 (151-244)	169 (148-219)	0.290
Creatinine (normal range: 0.5 mg/dL-1.3 mg/dL)	0.83 (0.67-0.98)	0.83 (0.65-0.98)	0.84 (0.69-0.99)	0.770
D dimer (normal range < 250 ng/mL)	832 (563-1740)	880 (536-1651)	1512 (746-2151)	0.040
Fibrinogen (normal range: 200 mg/dL-400 mg/dL)	532 ± 185	555 ± 206	580 ± 179	0.580
Total bilirubin (normal range: 0.2 mg/dL-1.2 mg/dL)	0.5 (0.4-0.7)	0.5 (0.4-0.7)	0.6 (0.4-0.7)	0.930

Data are presented as median and interquartile range or mean ± SD. All laboratorial data were collected at admission to the intensive care unit (ICU). Lung involvement was determined by the percent of lung infiltrates on chest computed tomography. Illness day and days in hospital were counted at the intensive care unit admission. Data were analyzed using Fisher’s exact two-tailed test, Mann-Whitney U test, or Student’s t-test, as appropriate. AKI: Acute kidney injury; COPD: Chronic obstructive pulmonary disease; FIO₂: Fraction of inspired oxygen; HFO₂: High flow nasal oxygen; KDIGO: Kidney disease improving global outcomes; MV: Mechanical ventilation; NIV: Noninvasive ventilation; PO₂: Partial pressure of oxygen; SAPS 3: Simplified acute physiology score 3; SOFA: Sequential organ failure assessment; T2DM: Diabetes mellitus type 2; VAD: Ventilatory assist device.

Table 2 Physicochemical analysis of 211 critically ill coronavirus disease 2019 patients

Parameter	All patients	Survivors	Non-survivors	P value
PH (normal range: 7.38-7.42)	7.46 (7.42-7.53)	7.45 (7.40-7.47)	7.45 (7.40-7.50)	0.850
PCO2 (normal range: 36 mmHg-44 mmHg)	34.1 ± 5.6	34.0 ± 5.7	34.5 ± 4.8	0.660
Bicarbonate (normal range: 24 mEq/L ± 2 mEq/L)	23.3 (21.0-24.8)	23.3 (20.9-24.9)	23.1 (21.7-24.4)	0.630
Lactate normal range: (4 mg/dL-18 mg/dL)	12.1 (2.0-15.9)	11.5 (1.9-15.2)	13.9 (10.7-21.2)	0.130
Albumin (normal range: 4.0 g/dL-5.5 g/dL)	3.6 (3.2-3.8)	3.6 (3.3-3.8)	3.4 (3.2-3.8)	0.650
Phosphorus (normal range: 2.5 mg/dL–4.5 mg/dL)	3.57 ± 0.84	3.58 ± 0.86	3.44 ± 0.68	0.450
Sodium (normal range: 135 mEq/L-142 mEq/L)	135 (133-138)	136 (134-138)	135 (129-136)	0.010
Potassium (normal range: 3.5 mEq/L-5.2 mEq/L)	4.17 ± 0.51	4.17 ± 0.51	4.15 ± 0.52	0.820
Chloride (normal range: 96 mEq/L-106 mEq/L)	100 (97-103)	100 (98-103)	98 (94-100)	0.030
SIDa	37.96 ± 4.30	37.81 ± 4.33	37.86 ± 4.21	0.920
SIDe	35.35 ± 3.50	35.42 ± 3.64	34.94 ± 3.15	0.670
SIG	2.69 (-0.30 to 4.94)	2.67 (0.21-4.99)	2.71 (-0.40 to 4.88)	0.930
SBE	-0.35 (-2.90 to 1.30)	-0.33 (-3.00 to 1.40)	-0.84 (-2.30 to 0.28)	0.740
Chloride effect	-2.44 (-4.80 to 0.28)	-2.44 (-5.50 to 0.70)	-2.58 (-4.80 to 11.58)	0.580
Lactate effect	-1.47 (-1.90 to 1.20)	-1.45 (-1.86 to 1.20)	-1.69 (-2.34 to 1.30)	0.240
Albumin effect	1.51 (0.60-2.60)	1.49 (0.60-2.46)	1.82 (0.76-2.73)	0.730
Phosphorus effect	-0.02 ± 0.50	0 ± 0.52	0.10 ± 0.40	0.270

Data are presented as median with interquartile range or as mean ± SD. Data were analyzed using the Mann-Whitney U test or Student’s t-test. PCO₂: Partial pressure of carbon dioxide; pH: pondus hydrogenii; SBE: Standard base excess; SIDa: Apparent strong ion difference; SIDe: Effective strong ion difference. SIG: strong ion gap.