Children undergoing craniectomy for repair of craniosynostosis may be especially at risk for venous air embolism (VAE). Evolving surgical procedures are more involved and entail greater blood loss, further exacerbating this risk. Faberowski et al. conducted a prospective study using precordial Doppler to continuously monitor children during surgery for changes characteristic of VAE. From August 1, 1996 to October 1, 1998, 23 children undergoing surgical repair for craniosynostosis were enrolled in the study.
Anesthesia was maintained with isoflurane or halothane in oxygen and air. After patients were positioned for their surgical procedures, the Doppler was secured and its placement verified by observation of characteristic tones following IV injection of 5-10 ml of agitated saline. The audio recording of Doppler tones was later reviewed by a neuroanesthesiologist blinded to intraoperative events.
VAE episodes were noted and correlated with data regarding blood pressure and end-tidal CO2, and their severity graded on a scale of I-III. If hemodynamically significant changes were noted intraoperatively, therapeutic measures, including administration of fluid, packed red blood cells, bone wax, and flooding the surgical field, were employed. None of the patients developed cardiovascular collapse.
Of the 23 patients in the study, 19 (82.6%) demonstrated 64 episodes of VAE. Six patients (31.6%) had hypotension associated with VAE, and 32 episodes of hypotension were noted in 8 patients. Only one-third of the total episodes of intraoperative hypotension were associated with VAE. Children undergoing craniectomy in the supine position may be more predisposed to VAE than adults, because their heads are larger in comparison to total body weight, and because the volume of entrained air is greater in comparison to their cardiac volume. Preemptive placement of a precordial Doppler appears to be a safe, noninvasive method for early detection of VAE and may expedite institution of therapeutic maneuvers.