Pediatric Critical Care Capillary blood gases in a pediatric intensive care unit Raffo Escalante-Kanashiro, MD; Jose Tantaleán-Da-Fieno, MD From the Intensive Care Unit, Instituto de Salud del Niño (Drs. Escalante-Kanashiro and Tantaleán-Da-Fieno), Mayor de San Marcos (Dr. Tantaleán-Da-Fieno), and the Department of Pediatrics, Universidad Nacional Federico Villarreal (Dr. Escalante-Kanashiro), Lima, Perú. Address requests for reprints to: Raffo Escalante-Kanashiro, MD, Av. Brasil 600, Lima, Perú. E-mail: postmast@isn.sld.pe; rescalante@amnet.com.pe Objective: To determine if samples obtained from arterial and capillary sources are comparable in children with diverse pathologic conditions during their stay in a pediatric intensive care unit. Study Design: Prospective, descriptive study in patients admitted to a multidisciplinary pediatric intensive care unit. Interventions: Seventy-five simultaneous paired samples (arterial and capillary) were obtained from patients with different degrees of capillary reperfusion, hemodynamic stability, blood pressure, and temperature. Both samples were analyzed ≤5 mins after collection. Measurements and Main Results: The average correlations between arterial and capillary samples were 0.87 for pH, 0.86 for CO 2 , and 0.65 for oxygen. Neither poor perfusion nor low temperature altered the correlation for pH or CO 2 . The only condition that significantly affected the correlation was hypotension. Conclusion: Capillary blood sampling is a useful alternative to gasometric evaluation of critically ill children, even in the presence of hypothermia or hypoperfusion, provided that hypotension is not present. KEY WORDS: arterial; capillary; blood gases; hemodynamic stability; hypoperfusion; hypothermia; children; critically ill The physiologic status of critically ill patients must be followed very closely. Arterial blood gases (ABG) are among the variables most frequently used (1-3). This is accomplished through repeated arterial punctures or by having an indwelling arterial catheter in place. However, arterial puncture requires some expertise, and on occasion it can produce temporal absence of pulse, hemorrhage, false aneurysm, and thrombosis with distal ischemia (4, 5). Noninvasive methods, such as pulse oximetry, transcutaneous monitoring of oxygen and CO 2 , and end-tidal CO 2 , have proven to be useful (5), but they do not give information about pH and bicarbonate. Capillary blood gas (CBG) determination, although performed for the last 30 yrs, remains controversial (6), and it has been done mainly in newborns (6, 7). Moreover, studies have usually excluded patients who are physiologically unstable (8), for whom the data would probably be most useful. To gain a current view of the problem, we decided to study the correlation between ABG and CBG in a pediatric