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LETTER TO THE EDITOR

Regional Cerebral Oxyhemoglobin Saturation-Guided Resuscitation

Department of Anesthesiology; doctorsg{at}bellsouth.net (E. Gologorsky, A. Gologorsky) Department of Cardiac Surgery (Akins) Perfusion Services; Memorial Hospital East; Hollywood, FL (Murtha)

To the Editor:

In vivo optical spectrometry (INVOS), based on near-infrared spectroscopy, continuously monitors regional cerebral oxyhemoglobin saturation (rSo₂) (1). Although the device is not intended as a primary monitor to guide the therapy, we recently used it to guide resuscitation in a patient when there were no other options for monitoring cardiovascular status.

The patient was a morbidly obese (weight 136 kg, height 170 cm, and body mass index 47), 57-year-old male with a history of diabetes mellitus and nonischemic cardiomyopathy (ejection fraction 35%), who had undergone removal of an infected implantable defibrillator and tricuspid valve repair via a sternotomy. Three weeks after surgery, he returned for wide debridement of a sternal wound with reconstruction using bilateral pectoralis muscle flaps. On the 16th postoperative day, while still in the intensive care unit, he coughed, saturated his dressings with blood, and became acutely hypotensive. He was emergently tracheally intubated and brought to the operating room (OR) for a right ventricular tear repair.

In the OR, we were unable to obtain cuff arterial blood pressure (BP), pulse oximetry, or direct BP monitoring. However, the INVOS device was able to monitor rSo₂. We used this to guide patient management. Within 7 min of the patient’s arrival in the OR, we administered 40,000 U of heparin, 50 mg ketamine, 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 rSo₂ 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 rSo₂ values of 35. We transfused five units of packed red blood cells to bring his hematocrit to 18. Once we judged pump flows to be adequate, we titrated with 100 mcg boluses of phenylephrine to maintain rSo₂ 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, coincidental 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 maintained perfusion pressure at 60–65 mm Hg using phenylephrine. rSo₂ values reached 60 by the end of the 67-min bypass.

Postoperatively, the patient regained consciousness, followed commands, and moved all extremities, demonstrating preservation of central nervous system function. Unfortunately, the following day he required repair of another right ventricular tear, and died 5 days later of multisystem organ failure.

rSo₂ has been documented to assist 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, increasing BP, and directing adequate blood flow to the brain to assure continued oxygen delivery (3,4). Failure of vasopressors to restore rSo₂ is evidence of insufficient pump flow to support the cerebral gas-exchanging circulation (1). We selected target rSo₂ values close to 50 because we did not know the baseline values (1,5). We also used rSo₂ to determine when we had adequately transfused the patient (6). In this manner, the INVOS device guided resuscitation when standard monitors were not available.

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.[Medline]
2. Plachy J, Hofer S, Volkmann M, et al. Regional cerebral oxygen saturation is a sensitive marker of cerebral hypoperfusion during ortothopic liver transplantation. Anesth Analg 2004;99:344–9.[Abstract/Free Full Text]
3. Duebener LF, Hagino I, Schmitt K, et al. Effects of hemodilution and phenylephrine on cerebral blood flow and metabolism during cardiopulmonary bypass. J Cardiothorac Vasc Anesth 2004;18: 423–8.[Web of Science][Medline]
4. Kadoi Y, Fujita N. Increasing mean arterial pressure improves jugular venous oxygen saturation in patients with or without preexisting stroke during normothermic cardiopulmonary bypass. J Clin Anesth 2003;15:339–44.[Web of Science][Medline]
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.[Web of Science][Medline]
6. Madl C, Eisenhuber E, Kramer L. Impact of different hemoglobin levels on regional cerebral oxygen saturation, cerebral extraction of oxygen and sensory evoked potentials in septic shock [abstract]. Crit Care Med 1997;25:4.[Web of Science][Medline]

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