CAPILLARY BLOOD SAMPLING IN THE INFANT: USEFULNESS AND LIMITATIONS OF TWO METHODS OF SAMPLING, COMPARED WITH ARTERIAL BLOOD

[摘要] Measurements of simultaneous arterial, histamine capillary (HC), and plain capillary (PC) pH, Pco2 and Po2 in 46 infants have indicated the clinical usefulness and limitations of blood so obtained.Arterial, HC, and PC pH can be used interchangeably for calculation of base deficit (BD). HC and PC Pco2 are identical, but average 10 mm Hg more than Paco2 within the usual clinical range. The resultant error in capillary BD as compared to arterial or venous BD can be minimized by the regression equation: arterial BD = 1.3 (PC BD) + 3.9.For Po2, the two capillary methods are comparable when the Pao2 is less than 60 to 70 mm Hg. By either capillary method, a Po2 of 30 represented an average Pao2 of 30, 50 represented 60 and a capillary Po2 of 60 indicated a Pao2 of approximately 90 mm Hg. A PC or HC Po2 greater than 60 to 70 mm Hg did not allow for an accurate and reliable estimation of Pao2. When concerned with a precise quantitation of cardiopulmonary status in any critically ill infant, therefore, there is still no substitute for arterial sampling.

[学科分类] 儿科学