Pulse oximetry for assessment of pulsus paradoxus: a clinical study in children

Objective: To evaluate the relationship between intraarterial measured pulsus paradoxus (PP) and photoplethysmographic wave changes. Setting: Tertiary pediatric intensive care unit. Patients: 62 nonintubated children with or without respiratory disorders. Design: Prospective, clinical study. Measurements and results: Simultaneous paper recordings of photoplethysmographic wave, arterial blood pressure, breathing cycle and electrocardiogram. The respiratory dependent changes of the plethysmographic respiratory wave (delta pleth, mm) were defined as the difference between the highest value of the upper peak of the wave (in expiration) and the lowest value of the upper peak (in inspiration). In each patient, ten consecutive breaths were averaged for analysis. Five recordings could not be evaluated (movement artifacts). In 57 children (median age 2.4 years, range 7 days to 17 years), the photoplethysmographic fluctuations (delta pleth, mm) correlated with PP (mm Hg): r = 0.85; 95 % confidence interval (CI), 0.76 to 0.91. The sensitivity to detect a PP of > 10 mm Hg with a plethysmographic fluctuation of > 8 mm was 89 % (95 % CI, 77 to 100 %) and the specificity was 90 % (95 % CI, 79 to 100 %). Conclusions: Pulse oximetry appears to be a rapid and easily performed, noninvasive method for the objective estimation of the degree of PP. Received: 15 July 1997 Accepted: 1 December 1997