I appreciate Dr. Friedberg’s comments and efforts to reduce the incidence of postsurgical pulmonary embolism.
The choice of anesthetic technique is important to obtain optimal surgical care. In addition to anesthesia, patient selection with attention to thorough medical evaluation in view of the procedure or procedures to be performed is of utmost importance.
The development of a deep vein thrombosis or pulmonary embolism in postoperative patients is a multifactorial problem. Iverson et al.1 have delineated the multiple components of diagnosis and care necessary to minimize the potential for initiation of either event. It is unfortunate that we do not yet have statistics on hospital-based postoperative patients who develop pulmonary embolism for comparison with our outpatient data.2
There are two topics I would like to address in discussing Dr. Friedberg’s technique: the definition of general anesthesia and the cause of pulmonary embolisms.3,4
General anesthesia commences when a patient is unarousable, even by painful stimulation, and has loss of consciousness through the administration of an inhalation agent or intravenous drug, such as propofol or ketamine. These patients may be able to maintain a patent airway and adequate ventilation, although airway support is often required. The potential for ketamine or propofol, used alone or in combination, to induce a state of general anesthesia must be considered when choosing their use for any procedure.
The level of analgesia necessary to perform an abdominoplasty may require a patient’s consciousness to be on the border of general anesthesia and, as such, would render the patient immobile. In this scenario, attendant potential sequelae related to airway management may occur. Dr. Friedberg has adopted the use of the Bispectral Index (Aspect Medical Systems, Inc., Natick, Mass.) monitor to assess brain function during the delivery of intravenous ketamine and propofol to “prevent” general anesthesia from occurring based on the Bispectral Index numerical value.4
The American Society of Anesthesiologists advisory on intraoperative monitoring of depth of anesthesia recommends the use of multiple modalities, including clinical signs and conventional monitoring systems (e.g., electrocardiogram, blood pressure, heart rate, capnography). The use of brain function monitors, in general, parallels other established correlates of depth of anesthesia. The general applicability of these monitors in assessing intraoperative awareness has not been firmly established.5
Numerous studies have reported a significant reduction in the incidence of deep vein thrombosis when regional anesthesia is used for both fractured and elective hip surgery.6 In the report by Lofsky, six of the 12 patients who sustained pulmonary emboli were managed intraoperatively with intravenous sedation.7 The choice of anesthetic technique and its effect on the incidence of pulmonary embolism require further study.
I suspect prolonged surgery and immobilization as the culprits in the genesis of deep vein thromboses, particularly in patients with a hereditary or clinical predisposition. However, deep vein thromboses and pulmonary embolisms occur in a variety of clinical settings and their evolution—specifically, with abdominoplasty—has yet to be elucidated.
A random case study would be helpful to further clarify anesthetic choice for abdominoplasty surgery.
Geoffrey R. Keyes, M.D.
American Association for Accreditation of Ambulatory Surgery Facilities, Inc.
Keyes Surgery Center
Los Angeles, Calif. 90069
1. Iverson RE, Lynch DJ, ASPS Task Force on Patient Safety in Office-Based Surgery Facilities. Patient safety in office-based surgery facilities: I. Procedures in the office-based surgery setting. Plast Reconstr Surg.
2. Keyes GR, Singer R, Iverson R, et al. Mortality in outpatient surgery. Plast Reconstr Surg
3. Friedberg BL. Preface. In: Anesthesia in Cosmetic Surgery
. New York: Cambridge University Press; 2007:xviii.
4. Friedberg BL. Propofol-ketamine technique, dissociative anesthesia for office surgery: A five-year review of 1264 cases. Aesthetic Plast Surg.
5. Practice advisory for intraoperative awareness and brain function monitoring: A report by the American Society of Anesthesiologists Task Force on Intraoperative Awareness. Anesthesiology
6. Prins MH, Hirsh J. A comparison of general anesthesia and regional anesthesia as a risk factor for deep vein thrombosis following hip surgery: A critical review. Thromb Haemost
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