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Department of Anaesthesia and Surgical Intensive Care; Singapore General Hospital; Singapore; ng.ju.mei{at}sgh.com.sg (Ng)
To the Editor:
A 28-yr-old women presented for elective laparoscopic resection of bilateral pheochromocytoma. Her arterial blood pressure (BP) was maintained with phenoxybenzamine 10 mg twice daily and atenolol 25 mg once a day. The noninvasive partial CO2 rebreathing (NICO; Novametrix Medical Systems, Wallingford, CT) cardiac output monitor was attached to the anesthesia circuit for measurement of continuous cardiac output after induction of anesthesia. An arterial blood sample was drawn, and results of arterial oxygen pressure, CO2 partial pressure, and hemoglobin concentrations were entered for calibration. Anesthesia was maintained with an air/oxygen/desflurane mixture with end-tidal desflurane concentrations maintained at 5.5%–6.5% and end-tidal CO2 at 35–45 mm Hg. She was positioned in the left lateral decubitus position for laparoscopic resection of the right pheochromocytoma, and then in the right lateral decubitus position for resection of the left. Remifentanil and norepinephrine infusions were used for control of arterial BP. The remifentanil infusion rate ranged from 0.05 to 0.25 µg · kg–1 · min–1, and norepinephrine at 0.05 µg · kg–1 · min–1 was used for 15 min after right adrenalectomy. Her trachea was extubated uneventfully at the end of surgery, she was monitored overnight in the intensive care unit and discharged home 4 days later.
The patient’s systolic BP, central venous pressure, and cardiac output are shown in Figure 1. Phases where BPs were more than ±1 sd from the mean include just before and after induction of anesthesia, during positioning, the two periods of tumor manipulation (left and right) and before the second incision after repositioning when her BP was low. Although creation of the pneumoperitoneum results in a significant catecholamine release (1,2), and has been associated with a marked hypertensive response (2), it appeared to be well tolerated in this patient; tumor manipulation produced much greater effects on BP and cardiac output (Fig. 1) than did peritoneal insufflation. Her central venous pressure was mildly increased during the periods of pneumoperitoneum. Her cardiac output was highest during tumor manipulation. After right adrenalectomy (during positioning and preparation for left adrenalectomy), her hypotension was managed with norepinephrine as her total peripheral resistance was low.
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Measurement of cardiac output is often considered useful in the presence of heart disease or in patients with poor preoperative BP control. As this patient did not have evidence of heart disease or poorly controlled BP, a readily available and noninvasive method of cardiac output measurement was chosen to guide intraoperative hemodynamic management. The NICO has been reported to show good correlation with cardiac output measured by thermodilution during laparoscopic surgery and CO2 pneumoperitoneum (3). Pulse contour cardiac output might have been a viable alternative, as arterial and central venous lines were already planned for this patient, and cardiac output measurements could be continued into the postoperative period if necessary.
REFERENCES
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), central venous pressure (x), and cardiac output (
) changes during surgery.
