Summary of the evidence
| Parameter | No. studies | No. patients | Weighted mean difference (bias) | 95% limits of agreement* | Clinical interpretation |
|---|---|---|---|---|---|
| pH | 13 | 2009 | −0.033 | Approximately ±0.1 | Clinically interchangeable |
| pCO2 | 8 | 965 | 6.2 mm Hg (0.83 kPa) | −17.4 to 23.9 mm Hg (−2.32 to +3.19 kPa) | Poor, unpredictable agreement |
| Bicarbonate | 8 | 1211 | −1.3 mmol/L | Approximately ±5 mmol/L | Probably close enough agreement for classification as high, normal or low |
| Base excess | 2 | 429 | Divergent results | Up to −4.4 to 3.9 BE units | Agreement unclear |
| Lactate | 3 | 338 | 0.25 mmol/L | −2 to +2.3 mmol/L | May be close enough agreement for classification as high or normal |
| Parameter | No. studies | No. patients | Sensitivity for hypercarbia | NPV for hypercarbia | Clinical interpretation |
|---|---|---|---|---|---|
| pCO2 ≤45 mm Hg (6 kPa) as a screening test for hypercarbia | 4 | 529 | 100% (95% CI 97% to 100%) | 100% (95% CI 97% to 100%) | Reliable screening test; congruence with clinical assessment required |
*Interpreted from available data; not reported by all studies.
BE, base excess; NPV, negative pressure ventilation.