Introduction
Materials and methods
Setting and study population
Adjudication of the final diagnosis
Blood sampling and laboratory methods
Endpoints and follow up
Statistical analysis
Results
Characteristics of study population
Diagnostic accuracy of arterial blood gas parameters
Variable | OR (95% CI) | AUC (95% CI) | |
---|---|---|---|
Acute heart failure
| pH | 0.58 (0.44-0.77) | 0.615 (0.57-0.66) |
PaCO2 | 0.81 (0.69-0.95) | ||
Exacerbated COPD or asthma
| pH | 1.64 (1.14-2.37) | 0.670 (0.63-0.71) |
PaCO2 | 1.44 (1.20-1.73) | ||
Hypoxemia | 1.71 (1.04-2.82) | ||
Pulmonary embolism
| PaCO2 | 0.61 (0.44-0.85) | 0.678 (0.64-0.72) |
Pneumonia or bronchitis
| Hypoxemia | 1.84 (1.07-3.17) | 0.558 (0.51-0.60) |
Anxiety disorder
| pH | 4.50 (2.27-8.92) | 0.855 (0.82-0.88) |
Hypoxemia | 0.21 (0.07-0.65) | ||
Pulmonary disorder
| pH | 1.40 (1.06-1.87) | 0.639 (0.60-0.66) |
PaCO2 | 1.31 (1.12-1.54) | ||
Hypoxemia | 2.01 (1.37-3.13) |
Value of ABGA parameters to predict admission to ICU
ICU admission | OR | 95% CI | AUC | 95% CI | P-value |
---|---|---|---|---|---|
pH | 0.552 | 0.43-0.71 | 0.647 | 0.61-0.69 | < 0.001 |
PaCO2 | 1.309 | 1.15-1.50 | 0.591 | 0.55-0.63 | 0.001 |
PaO2 | 1.029 | 0.98-1.08 | 0.476 | 0.43-0.52 | 0.257 |
HCO3 | 1.00 | 0.96-1.05 | 0.504 | 0.46-0.55 | 0.956 |
Base excess | 0.954 | 0.91-1.00 | 0.541 | 0.50-0.58 | 0.041 |
In-hospital mortality
|
OR
|
95% CI
|
AUC
|
95% CI
|
P
-value
|
pH | 0.645 | 0.49-0.85 | 0.647 | 0.61-0.69 | 0.022 |
PaCO2 | 1.142 | 0.96-1.35 | 0.526 | 0.48-0.57 | 0.125 |
PaO2 | 1.050 | 1.00-1.11 | 0.576 | 0.53-0.62 | 0.133 |
HCO3 | 0.960 | 0.90-1.02 | 0.528 | 0.49-0.57 | 0.191 |
Base excess | 0.943 | 0.89-1.00 | 0.546 | 0.50-0.59 | 0.045 |
30 days mortality
|
OR
|
95% CI
|
AUC
|
95% CI
|
P
-value
|
pH | 0.602 | 0.46-0.79 | 0.650 | 0.61-0.69 | < 0.001 |
PaCO2 | 1.205 | 1.04-1.40 | 0.562 | 0.52-0.61 | 0.015 |
PaO2 | 1.025 | 0.97-1.09 | 0.486 | 0.44-0.53 | 0.409 |
HCO3 | 0.977 | 0.92-1.03 | 0.504 | 0.46-0.55 | 0.416 |
Base excess | 0.950 | 0.90-1.00 | 0.518 | 0.47-0.56 | 0.067 |
12-month mortality
|
OR
|
95% CI
|
AUC
|
95% CI
|
P
-value
|
pH | 0.767 | 0.62-0.94 | 0.584 | 0.54-0.63 | 0.011 |
PaCO2 | 1.160 | 1.03-1.30 | 0.577 | 0.53-0.62 | 0.012 |
PaO2 | 1.040 | 1.00-1.09 | 0.518 | 0.47-0.56 | 0.071 |
HCO3 | 1.021 | 0.98-1.06 | 0.544 | 0.50-0.59 | 0.298 |
Base excess | 1.022 | 0.98-1.06 | 0.559 | 0.52-0.60 | 0.296 |
pH
|
OR
|
95% CI
|
AUC
|
95% CI
|
P
-value
|
ICU admission | 0.533 | 0.41-0.69 | 0.661 | 0.62-0.70 | < 0.001 |
In-hospital mortality | 0.621 | 0.44-0.88 | 0.662 | 0.61-0.71 | 0.007 |
30-day mortality | 0.602 | 0.46-0.79 | 0.650 | 0.61-0.69 | < 0.001 |
12-month mortality | 0.767 | 0.62-0.94 | 0.584 | 0.54-0.63 | 0.011 |
Predictive value of pH at presentation for short-term outcome
Variable | pH ≤7.39 (n= 174) | pH 7.40- 7.44 (n= 177) | pH ≥7.45 (n= 179) | P-value |
---|---|---|---|---|
Age, years | 74 (64-81) | 74 (64-82) | 75 (64-81) | 0.99 |
Male sex, n (%) | 62 (64) | 80 (45) | 75 (42) | 0.18 |
Medical History, n (%) | ||||
Coronary heart disease | 76 (44) | 67 (38) | 65 (36) | 0.33 |
Arterial hypertension | 106 (61) | 119 (67) | 106 (59) | 0.26 |
Stroke/peripheral arterial disease | 37 (22) | 34 (19) | 30 (17) | 0.53 |
Chronic obstructive pulmonary disease | 80 (46) | 85 (48) | 72 (40) | 0.31 |
Asthma | 7 (4.0) | 14 (7.9) | 13 (7.3) | 0.28 |
Any pulmonary disease | 107 (62) | 113 (64) | 94 (53) | 0.07 |
Pulmonary embolism | 14 (8.0) | 20 (11) | 15 (8.4) | 0.51 |
Deep venous thrombosis | 16 (9.2) | 23 (13) | 13 (7.3) | 0.18 |
Diabetes mellitus | 45 (26) | 40 (23) | 35 (20) | 0.37 |
Chronic kidney disease | 51 (29) | 43 (24) | 33 (19) | 0.06 |
Depressive disorder | 22 (13) | 27 (16) | 24 (24) | 0.69 |
Malignancy | 28 (16) | 30 (17) | 38 (21) | 0.40 |
Obesity | 47 (29) | 46 (27) | 32 (18) | 0.06 |
Smoking status, n (%) | 0.01 | |||
never | 14 (8.4) | 21 (13) | 33 (19) | |
current | 73 (44) | 54 (32) | 56 (31) | |
former | 54 (33) | 72 (43) | 71 (40) | |
unknown | 25 (15) | 20 (12) | 17 (9.1) | |
Symptoms, n (%) | ||||
Dyspnea | 0.06 | |||
NYHA II | 12 (6.9) | 20 (11) | 27 (15) | |
NYHA III | 79 (46) | 80 (45) | 89 (50) | |
NYHA IV | 83 (48) | 77 (44) | 63 (35) | |
Thoracic pain | 60 (35) | 62 (35) | 52 (29) | 0.41 |
Orthopnea | 68 (56) | 104 (64) | 103 (62) | 0.61 |
Weight gain | 20 (12) | 25 (15) | 18 (11) | 0.50 |
Cough | 91 (54) | 116 (67) | 106 (62) | 0.04 |
Expectorant | 68 (40) | 78 (45) | 81 (47) | 0.40 |
Fever (> 38.5°C) | 38 (22) | 52 (30) | 54 (32) | 0.11 |
Medication, n (%) | ||||
Diuretics | 92 (53) | 95 (54) | 85 (48) | 0.47 |
Nitrate | 22 (13) | 21 (12) | 20 (11) | 0.92 |
ACE inhibitors, angiotensin receptor blockers | 69 (40) | 88 (50) | 74 (42) | 0.14 |
Beta-blocker | 48 (28) | 49 (28) | 56 (32) | 0.67 |
Aspirin | 52 (30) | 62 (35) | 56 (32) | 0.57 |
Phenprocoumon/LMWH | 39 (22) | 42 (24) | 38 (21) | 0.87 |
Inhaled beta agonists | 59 (34) | 68 (38) | 54 (30) | 0.27 |
Inhaled steroids | 46 (26) | 47 (36) | 54 (30) | 0.65 |
Oral steroids | 23 (13) | 36 (20) | 34 (19) | 0.17 |
Clinical signs, n (%) | ||||
Rales | 81 (47) | 83 (47) | 87 (49) | 0.92 |
Wheezing | 61 (35) | 65 (37) | 48 (27) | 0.10 |
Lower extremity edema | 68 (39) | 70 (40) | 61 (34) | 0.48 |
Jugular venous distension | 47 (27) | 24 (14) | 32 (18) | 0.01 |
Hepatojugular reflux | 22 (13) | 21 (12) | 23 (13) | 0.98 |
Vital status | ||||
Systolic blood pressure (mmHg) | 143 (127-162) | 142 (126-165) | 136 (122-158) | 0.11 |
Diastolic blood pressure (mmHg) | 88 (70-98) | 86 (74-96) | 82 (73-92) | 0.23 |
Heart rate (beats per minute) | 95 (78-110) | 96 (82-111) | 89 (76-110) | 0.12 |
Respiration rate (breaths per minute) | 25 (20-32) | 24 (20-30) | 22 (18-28) | 0.03 |
Temperature (°C) | 37.1 (36.5-37.8) | 37.4 (36.7-39.7) | 37.4 (36.8-38.0) | 0.03 |
Oxygen saturation (%) | 92 (87-96) | 96 (92-98) | 95 (93-98) | < 0.001 |
Body mass index (kg/m2) | 26.2 (22.8-30.5) | 26.3 (22.8-30.6) | 25.3 (22.1-28.7) | 0.20 |
Laboratory values | ||||
Hemoglobin (g/L) | 139 (122-155) | 136 (123-150) | 136 (125-146) | 0.23 |
Leukocytes (109/L) | 10.6 (8.0-15.0) | 10.0 (8.0-13.2) | 10.5 (8.3-13.6) | 0.40 |
C-reactive protein (mg/L) | 15 (5-51) | 21 (6-80) | 27 (7-107) | 0.02 |
Glomerular filtration rate (mL/min/1.73 m2) | 57 (39-86) | 64 (46-87) | 65 (52-90) | 0.06 |
B-type natriuretic peptide (pg/mL) | 305 (93-810) | 254 (52-712) | 192 (65-760) | 0.14 |
Discharge diagnosis, n (%) | ||||
Acute heart failure | 81 (47) | 65 (37) | 60 (34) | 0.03 |
Exacerbation of COPD or asthma | 37 (21) | 43 (24) | 38 (21) | 0.73 |
Pneumonia or bronchitis | 29 (17) | 32 (18) | 33 (18) | 0.90 |
Pulmonary embolism | 6 (3.4) | 10 (5.6) | 12 (6.7) | 0.38 |
Anxiety disorder | 1 (0.6) | 4 (2.3) | 13 (7.3) | < 0.001 |
Others | 20 (12) | 23 (13) | 23 (13) | 0.90 |
Variable | pH ≤7.39 (n= 174) | pH 7.40-7.44 (n= 177) | pH ≥7.45 (n= 179) | P-value |
---|---|---|---|---|
Initial outcome | ||||
Hospital admission, n (%) | 158 (91) | 151 (85) | 153 (86) | 0.12 |
ICU admission, n (%) | 48 (28) | 21 (12) | 22 (12) | < 0.001 |
In-hospital mortality, n (%) | 25 (14) | 8 (4.5) | 9 (5.0) | 0.003 |
Short-term outcome | ||||
30-day mortality, n (%) | 30 (17) | 12 (7.0) | 12 (7.0) | 0.002 |
Long-term outcome | ||||
Mortality rate at 12 months (%) | 37 (3.7) | 28 (3.4) | 23 (3.2) | 0.005 |
Predictive value of pH at presentation for long-term outcome
Variable | Hazard ratio | 95% confidence interval | P-value |
---|---|---|---|
Previous use of oral diuretics | 1.93 | 1.15-2.86 | 0.006 |
Body mass index (per increase of 1 unit) | 0.93 | 0.90-0.97 | < 0.001 |
≥2 causes of dyspnea | 1.91 | 1.22-3.00 | 0.003 |
pH (per decrease of 0.1 unit) | 1.41 | 1.11-1.79 | 0.005 |
Subgroup analysis in patients with lactate values available
Discussion
Conclusions
Key messages
-
ABGA parameters at presentation varied widely among patients with acute dyspnea.
-
ABGA parameters were useful neither to distinguish between patients with pulmonary disorders and other causes of acute dyspnea nor to identify specific disorders responsible for acute dyspnea.
-
pH measured at presentation was a significant predictor of short- and long-term outcome in acutely dyspneic patient.
-
pH was, independently from other predictors, associated with mortality, both in patients with pulmonary disorders and other causes of acute dyspnea.