Alterations in Venous Flow Patterns in a Pediatric Patient: Impact of Mechanical Ventilation

Abstract

Lower extremity venous waveforms are normally phasic with respiration and not pulsatile. The following case study describes abnormal venous spectral Doppler waveforms encountered during a pediatric ultrasound examination. A four-year-old female patient presented to the hospital with acute respiratory distress. The patient was immediately intubated and placed on an oscillating ventilator. A lower extremity venous duplex was ordered to rule out a deep venous thrombosis (DVT) due to the presence of lower extremity swelling and a fever. Thrombus was observed in the left common femoral vein surrounding a central venous catheter. The thrombus extended into the external iliac vein. This thrombus appeared hypoechoic and spongy in nature and was interpreted to be acute. Additionally, pulsatile waveforms were noted bilaterally through both lower extremities. There was no history of congestive heart failure or pulmonary hypertension. Subsequently, the patient was found to have Factor V Leiden. A repeat venous ultrasound was ordered 10 days later at which time the patient was no longer intubated. The venous waveforms in the left leg were now continuous while the right leg displayed normal, phasic waveforms. No venous pulsatility was present in either extremity. Continuous venous Doppler signals are expected in the presence of non-occlusive DVT. This case illustrates the unusual occurrence of pulsatile lower extremity venous Doppler signals. These were the result of respiratory pressure changes due to the oscillating ventilator. It is important to consider the effects of mechanical ventilation on venous blood flow patterns.