Table 2

Linear association, concordance and equivalence between the findings obtained by direct venous puncture and peripheral venous catheter

DeterminationVariableNrrcClinically accepted intervalAgreement interval
CAInPer cent95% CI95% AInPer cent95% CI
BiochemistryAmylase (U/L)2650.9990.996(−20 to −20)10.4(0.1 to −2.1)(−34.09 to −36.10)10.4(0.1 to −2.1)
Calcium (mg/dL)2660.8990.860(−1 to −1)20.8(0.2 to −2.7)(−0.90 to −0.44)72.6(1.3 to −5.3)
Total cholesterol (mg/dL)2690.9840.983(−10 to −10)124.5(2.6 to −7.6)(−13.64 to −15.56)62.2(1.0 to −4.8)
Creatinine (mg/dL)2710.9820.982(−0.3 to −0.3)41.5(0.6 to −3.7)(−0.25 to −0.27)41.5(0.6 to −3.7)
Creatine kinase (U/L)2620.9990.999(−20 to −20)135.0(2.9 to −8.3)(−28.76 to −25.49)93.4(1.8 to −6.4)
Basal glucose (mg/dL)2720.9600.957(−15 to −15)176.3(3.9 to −9.8)(−34.69 to −26.66)93.3(1.8 to −6.2)
Aspartate aminotransferase (SGOT) (U/L)2690.9980.998(−10 to −10)72.6(1.3 to −5.3)(−8.86 to −7.47)114.1(2.3 to −7.2)
Potassium (mEq/L)2690.9370.936(−0.4 to −0.4)197.1(4.6 to −10.8)(−0.45 to −0.45)134.8(2.8 to −8.1)
Sodium (mEq/L)2710.9500.950(−4 to −4)41.5(0.6 to −3.7)(−2.63 to −3.11)124.4(2.6 to −7.6)
Urea (mg/dL)2690.9970.997(−5 to −5)93.3(1.8 to −6.2)(−6.65 to −6.94)72.6(1.3 to −5.3)
HaematologyRed blood cells (106/μL)2680.9880.988(−0.5 to −0.5)31.1(0.4 to −3.2)(−0.22 to −0.22)124.5(2.6 to −7.7)
Haemoglobin (g/dL)2680.9860.986(−0.6 to −0.6)93.4(1.8 to −6.3)(−0.65 to −0.65)83.0(1.5 to −5.8)
Leucocytes (103/μL)2680.9830.983(−2 to −2)41.5(0.6 to − to 3.8)(−1.78 to −1.75)51.9(0.8 to −4.3)
Platelets (103/μL)2670.9820.982(−50 to −50)31.1(0.4 to −3.3)(−30.32 to −34.37)72.6(1.3 to −5.3)
Prothrombin ratio (%)2690.9180.917(−7 to −)228.2(5.5 to −12.1)(−16.63 to −19.14)51.9(0.8 to −4.3)
Blood gasVenous carbon dioxide potential (pH)2600.8620.853(−0.1 to −0.1)20.8(0.2 to −2.8)(−0.06 to −0.04)114.2(2.4 to −7.4)
Venous carbon dioxide partial pressure (pCO2) (mm Hg)2600.8750.843(−5 to −5)5521.2(16.6 to −26.5)(−6.14 to −10.51)103.8(2.1 to −6.9)
Venous oxygen partial pressure (pO2) (mm Hg)2600.4050.336(−5 to −5)19073.1(67.4 to −78.1)(−40.60 to −22.08)103.8(2.1 to −6.9)
  • N, Number of tests with valid findings for direct venous puncture (DVP) and peripheral venous catheter (PVC); n, Number of tests showing differences between DVP and PVC greater than the interval; r, Pearson's product-moment correlation coefficient; rc, Lin's concordance correlation coefficient; CAI, interval defined by the minimal clinically significant difference (according to investigators) between DVP and PVC; 95% AI, interval of agreement of 95% according to the Bland-Altman method: mean difference between methods±1.96 SD of the difference; 95% CI, CI of 95% for proportion according to the Wilson score method.