Abstract: TH-PO1125
Diagnostic Accuracy of a Central Venous Blood Gas in the Diagnosis of Acid-Base Disorders in the Medical Intensive Care Unit
Session Information
- Fluid, Electrolyte, Acid-Base Disorders
November 02, 2017 | Location: Hall H, Morial Convention Center
Abstract Time: 10:00 AM - 10:00 AM
Category: Fluid, Electrolytes, and Acid-Base
- 704 Fluid, Electrolyte, Acid-Base Disorders
Authors
- Schrauben, Sarah J., University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Negoianu, Dan, University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Cohen, Raphael M., University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Berns, Jeffrey S., University of Pennsylvania, Philadelphia, Pennsylvania, United States
Background
Acid-base disturbances are frequently encountered in critically ill patients. Arterial blood gas (ABG) is the gold standard in the diagnosis but has potential hazards to the patient. For patients with a central venous catheter, venous blood gas (VBG) sampling may be an alternative, less-invasive diagnostic tool. However, little is known about the central VBG diagnostic accuracy. The primary objective of this study was to assess the accuracy of a central VBG for the diagnosis of acid-base disorders in critically ill adult patients.
Methods
This was a cross-sectional single blinded study at two university-based urban hospitals. Study participants were adults in a medical intensive care unit (MICU) that had simultaneously drawn ABG and central VBG samples. Expert acid-base diagnosticians, all nephrologists, were blinded to the clinical data and blood gas origin to interpret the acid-base disorder(s) from each sample. Blood gas samples were classified as: no disorder, metabolic acidosis, metabolic alkalosis, respiratory acidosis, respiratory acidosis, or as a mixed disorder. Diagnostic accuracy of central VBG-based diagnoses were compared to ABG-based diagnoses by assessing percent clinical agreement, sensitivity and specificity.
Results
The study involved 23 participants. The most common underlying primary diagnoses were respiratory-related (45.5%) and sepsis-related (40.9%). Overall, the central VBG had 100% sensitivity for metabolic acidosis, metabolic alkalosis, and respiratory acidosis, and 71% for respiratory alkalosis, and high percent clinical agreement, ranging from 75-94%, with a lower agreement of 57% for respiratory alkalosis. VBG-based diagnoses in vasopressor dependent patients (n=13, 56.5%) performed very similarly.
Conclusion
In critically ill adult patients, central VBG detects acid-base disturbances with good diagnostic accuracy, even in shock states. This study supports the use of central VBG for diagnosis of acid-base disturbances in MICU patients.
Diagnostic Accuracy of VBG-based Diagnosis compared to ABG-based Diagnosis.
| Disorder | Sensitivity | Specificity | % Clinical Agreement |
| Metabolic Acidosis | 100% | 64% | 87.5% |
| Metabolic Alkalosis | 100% | 100% | 75% |
| Respiratory Acidosis | 100% | 60% | 94% |
| Respiratory Alkalosis | 71% | 100% | 57% |
Funding
- NIDDK Support