device was able to monitor rSo 2 . We used this to guide patient manage- ment. Within 7 min of the patient’s arrival in the OR, we administered 40,000 U of heparin, 50 mg ket- amine, and 10 mg vecuronium. Blood was aggressively transfused via a preexisting left subclavian catheter. Right femoral arterial-venous bypass was instituted via a right cut-down. Prebypass frontoparietal rSo 2 values were 30 –32. Bypass was initiated with a pump flow of 4.9 L/min, with arterial inflow line pressure 150 mm Hg, resulting in bilateral rSo 2 values of 35. We transfused five units of packed red blood cells to bring his hemat- ocrit to 18. Once we judged pump flows to be adequate, we titrated with 100 mcg boluses of phenyl- ephrine to maintain rSo 2 values close to 50. His BP measurements were finally available approximately 30 min later, via left femoral cut-down. Initial left femoral BP was 45–50 mm Hg, coin- cidental to the arterial inflow line pressure of 100 mm Hg, pump flow 3.8 – 4.6 L/min, and bilateral INVOS values of 46. Subsequently, we main- tained perfusion pressure at 60 – 65 mm Hg using phenylephrine. rSo 2 values reached 60 by the end of the 67-min bypass. Postoperatively, the patient re- gained consciousness, followed com- mands, and moved all extremities, demonstrating preservation of cen- tral nervous system function. Un- fortunately, the following day he required repair of another right ventricular tear, and died 5 days later of multisystem organ failure. rSo 2 has been documented to as- sist management of cardiac surgery (1) and liver transplantation (2). It does not depend on pulsatile flow, making it useful during bypass. We used it to titrate phenylephrine, in- creasing BP, and directing adequate blood flow to the brain to assure continued oxygen delivery (3,4). Fail- ure of vasopressors to restore rSo 2 is evidence of insufficient pump flow to support the cerebral gas-exchanging circulation (1). We selected target rSo 2 values close to 50 because we did not know the baseline values (1,5). We also used rSo 2 to determine when we had adequately transfused the patient (6). In this manner, the INVOS device guided resuscitation when standard monitors were not available. Edward Gologorsky, MD Angela Gologorsky, MD Department of Anesthesiology doctorsg@bellsouth.net Chris Akins, MD Department of Cardiac Surgery Sean Murtha, CCP Perfusion Services Memorial Hospital East Hollywood, FL REFERENCES 1. Edmonds HL Jr, Ganzel BL, Austin III EH. Cerebral oximetry for cardiac and vascular surgery. Semin Cardiothorac Vasc Anesth 2004;8:147– 66. 2. Plachy J, Hofer S, Volkmann M, et al. Regional cerebral oxygen saturation is a sensitive marker of cerebral hypoperfu- sion during ortothopic liver transplanta- tion. Anesth Analg 2004;99:344 –9. 3. Duebener LF, Hagino I, Schmitt K, et al. Effects of hemodilution and phenyleph- rine on cerebral blood flow and metabo- lism during cardiopulmonary bypass. J Cardiothorac Vasc Anesth 2004;18: 423– 8. 4. Kadoi Y, Fujita N. Increasing mean arte- rial pressure improves jugular venous oxygen saturation in patients with or without preexisting stroke during normo- thermic cardiopulmonary bypass. J Clin Anesth 2003;15:339 – 44. 5. Mille T, Tachimiri E, Klersy C, et al. Near infrared spectroscopy monitoring during carotid endarterectomy: which threshold value is critical? Eur J Vasc Endovasc Surg 2004;27:646 –50. 6. Madl C, Eisenhuber E, Kramer L. Impact of different hemoglobin levels on regional cerebral oxygen saturation, cerebral ex- traction of oxygen and sensory evoked potentials in septic shock [abstract]. Crit Care Med 1997;25:4. DOI: 10.1213/01.ane.0000246266.04799.61 Elevated Burst Suppression Ratio: The Possible Role of Hypoxemia To the Editor: We report a case characterized by the simultaneous occurrence of in- creased suppression ratio number (SR) and hypoxemia without a concomi- tant decrease in bispectral index (BIS). A 59-yr-old man was scheduled for tracheal granuloma removal by laser, using a rigid bronchoscopy. The patient’s history included two lobectomies for epidermoid carci- noma. Anesthesia induction was induced and maintained with infu- sions of propofol and remifentanil. A bolus of succinylcholine was in- jected to facilitate introduction of the bronchoscope. The lungs were mechanically ventilated through the lumen of the bronchoscope us- ing a high frequency jet ventilator. Six minutes after the succinylcho- line bolus, his Spo 2 decreased dramatically below 80% despite ventilation with pure oxygen, and we also observed an increase of the SR. BIS was in the range of 40–60 Figure 1. Acute decrease of Spo 2 during rigid bronchoscopy. BIS, bispectral index; SR, burst suppression ratio; A, high frequency jet-ventilation; B, tracheal intuba- tion; C to D, inhalation of beta2 agonist; E, recovery. Vol. 103, No. 6, December 2006 © 2006 International Anesthesia Research Society 1609 Letters to the Editor