DOI: 10.1097/01.sa.0000185359.76318.47
,
Issn Print: 0039-6206
Publication Date: 2005/12/01
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Excerpt
Myron M. Kwapisz,* Wolfgang Deinsberger,† Matthias Müller,* Heike Nopens,* Christoph Neuhäuser,* Joachim Klasen,* and Gunter Hempelmann*
(J Neurosurg Anesthesiol, 16:277-281, 2004)
*Department of Anesthesiology, Intensive Care Medicine, Pain Therapy, and †Clinic of Neurosurgery, University Hospital Giessen, Giessen, Germany.
Patients with a patent foramen ovale (PFO) who undergo neurosurgical procedures performed in a semi-sitting position are at risk for paradoxical air embolism, resulting in cerebral and myocardial ischemia. This risk could be even greater if positive end-expiratory pressure is applied to increase intracranial venous pressure. The ability of contrast transesophageal echocardiography (TEE) to identify a PFO was studied in patients scheduled to undergo neurosurgical procedures in a semi-sitting position.
The 35 patients included in the study were 20 men and 15 women with a median age of 58 years. Thirty were undergoing surgery for a posterior fossa tumor, 3 for cervical spondylosis, and 2 for Arnold Chiari malformation. To reduce preoperative stress for the patient, contrast TEE was done after induction of anesthesia and placement of a central line. Contrast TEE was combined with a ventilation maneuver to increase right atrial pressure. An examination was considered positive for a PFO when more than 4 bubbles appeared in the left atrium near the fossa ovalis within the first 3 cardiac cycles after release of intrathoracic pressure.
The average time required for the TEE examination was 25 minutes. Contrast TEE detected a PFO in 3 patients, all of whom were operated in a supine instead of a semi-sitting position. As determined by postoperative neurologic assessment, no paradoxical air embolism occurred. Insertion of the TEE probe caused 5 patients to experience hypertension of short duration, despite adequate analgesia and sedation.
Contrast TEE, combined with a ventilation maneuver, was highly effective in detecting a PFO in patients who were to undergo neurosurgical procedures in a semi-sitting position. Patient positioning was changed to supine when a PFO was detected, thus reducing the risk of paradoxical air embolism. The investigators concluded that performing contrast TEE in anesthetized patients before surgery reduces physical and psychologic stress and delays surgery by approximately 30 minutes.
