Detection of pulsus paradoxus associated with large pericardial effusions in pediatric patients by analysis of the pulse-oximetry waveform

Objective. To determine whether analysis of the pulse-oximetry waveform can be useful in detecting the pulsus paradoxus associated with large pericardial effusions in pediatric patients. Methods. A retrospective review of charts of 8 pediatric patients (age range: 5-19 years) who had echocardiographic evidence of large pericardial effusion, subsequently underwent pericardiocentesis, and had pulseoximetry waveform tracings obtained before and after pericardiocentesis within an 18-month period was conducted in 2 tertiary-care pediatric intensive care units. We analyzed the pulse-oximetry waveform tracings for the presence of a pulsus paradoxus. Other abstracted data included clinical evidence of tamponade, echocardiographic findings, and the volume of pericardial fluid aspirated. Results. Before pericardiocentesis, a decrease in the highest value of the upper plethysmographic peak of the pulse-oximetry waveform was observed during inspiration in each patient. Echocardiographic evidence of large pericardial effusion with compromised cardiac filling was also present in each patient. Only 6 of these patients had clinical evidence of cardiac tamponade at that time, 4 with a documented pulsus paradoxus using standard methods of blood pressure analysis. After pericardiocentesis, the inspiratory fall in the highest value of the upper plethysmographic peak of the pulse-oximetry waveform lessened in every patient. Echocardiography documented a decrease in the size of the effusion and resolution of the compromised cardiac filling in every patient. Conclusions. Analysis of pulse-oximetry waveforms may be a widely available, easily interpretable, and reliable method of detecting the pulsus paradoxus associated with large pericardial effusions in pediatric patients.