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GENERAL ARTICLES

Laparoscopic Approach to Pheochromocytoma: Is a Lower Intraabdominal Pressure Helpful?

Jayashree Sood, MD, FFARCS^*, Lakshmi Jayaraman, MD, DA.^*, Ved P. Kumra, MD, DA^*, and Pradeep K. Chowbey, MS, MNAMS, FIMSA, FAIS, FICS

Department of *Anaesthesiolgy, Pain & Perioperative Medicine; and Department of Minimal Access Surgery, Sir Ganga Ram Hospital, New Delhi, India

Address correspondence and reprint requests to Jayashree Sood, MD, Flat 507, Adishwar Apartments, 34 Ferozeshah Road, New Delhi 110 001, India. Address e-mail to jayashreesood{at}hotmail.com.

	Abstract

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Laparoscopic adrenalectomy is gaining popularity because of its well-documented benefits. The aim of our study was to see if a decreased intraoperative intraabdominal pressure during laparoscopic adrenalectomy would affect the hemodynamic variables and the serum levels of catecholamines. We randomly divided 9 patients into 2 groups, maintaining either an intraabdominal pressure of 15 mm Hg (group A) or 8–10 mm Hg (group B). Norepinephrine and epinephrine blood levels were measured preoperatively, during endotracheal intubation, carboperitoneum, surgical manipulation of tumor just before the ligation of the adrenal vein, and tracheal extubation; the hemodynamic variables were recorded. The introduction of carboperitoneum resulted in an increase in heart rate and mean arterial blood pressure (MAP), although it was statistically insignificant. The norepinephrine levels showed a statistically significant increase in group A as compared with group B (P = 0.0002). Surgical manipulation of the tumor resulted in a significant increase in MAP and norepinephrine levels in group A (P = 0.007 and P = 0.0001, respectively). The epinephrine levels did not change as much because the tumor was probably predominantly norepinephrine-secreting. Norepinephrine levels continued to be high even during tracheal extubation in group A patients (P = 0.027). We conclude that a low intraabdominal pressure of 8–10 mm Hg causes less catecholamine release and fewer hemodynamic fluctuations.

	Introduction

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Anesthesia for a patient with pheochromocytoma remains a clinical challenge, as its surgical removal may be accompanied by acute and severe hemodynamic changes. A laparoscopic approach to adrenalectomy has gained popularity over the conventional open adrenalectomy because of its well-documented benefits (1). However, carboperitoneum during laparoscopy induces hemodynamic changes and catecholamine release, which could aggravate the situation in pheochromocytoma (1). The conventional intraabdominal pressure during laparoscopic surgery is maintained at 14–16 mm Hg. The aim of our study was to evaluate if a decreased intraabdominal pressure between 8–10 mm Hg could decrease the hemodynamic fluctuations and catecholamine release. Although comparative studies between different levels of intraabdominal pressure have been conducted for laparoscopic cholecystectomy, none have been reported for laparoscopic adrenalectomy.

	Methods

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After approval of our institutional ethics committee and consent of the involved patients, all patients scheduled for laparoscopic adrenalectomy over a period of 1 yr with preoperative proven diagnosis of pheochromocytoma (n = 9) were studied. Diagnosis of pheochromocytoma relied on clinical signs associated with one or more of the following criteria: increased plasma and urinary catecholamines or their metabolites and magnetic resonance imaging scan.

Preoperative preparation was started 10–14 days before surgery. Oral prazocin was given along with IV fluids to stabilize arterial blood pressure <130 and 90 mm Hg respectively and to maintain optimum intravascular volume. Patients with tachycardia were given ß adrenergic blockers, (oral metoprolol 50–100 mg). Patients were considered adequately prepared for surgery when they had a sense of well-being, no more paroxysms of hypertension, were euglycemic, and had a normal hematocrit. Oral prazocin and metoprolol were continued until the day of surgery. Oral alprazolam 0.5 mg was given the night before and on the morning of surgery. There were 4 male and 5 female patients. Patient age ranged from 25–60 yr.

General anesthesia was induced with midazolam 0.01–0.02 mg/kg, propofol 1 mg/kg and fentanyl 1 µg/kg IV. Orotracheal intubation was facilitated by administration of vecuronium 0.08 mg/kg IV. Anesthesia was maintained with nitrous oxide and oxygen 66%:33% along with an infusion of vecuronium at a rate of 0.8 mg · kg^–1 · h^–1 and fentanyl at a rate of 2 µg · kg^–1 · h^–1 along with sevoflurane to achieve a uniform depth of anesthesia. Ventilation was adjusted to maintain end-tidal carbon dioxide between 32–36 mm Hg. The standard monitors were used including airway pressure, invasive arterial blood pressure, central venous pressure, bispectral index, and urine output. The bispectral index was maintained between 40 and 50. All patients underwent a transperitoneal surgical approach in the semilateral position. They were allocated randomly into two groups by computer-generated random numbers. Carboperitoneum was established by the introduction of Verees needle in the abdominal cavity and the desired intraabdominal pressure was set manually on the electronic variable flow Karl Storz insufflator, which terminates flow automatically when a preset intraabdominal pressure is reached. There is a continuous display of intraabdominal pressure and the volume of carbon dioxide insufflated on the monitor of the insufflator. Group A consisted of patients in whom standard insufflation of CO₂ was instituted to maintain an intraabdominal pressure of 15 mm Hg; in group B the intraabdominal pressure was maintained at 8–10 mm Hg. The hemodynamic variables were recorded and the blood samples drawn during tracheal intubation, carboperitoneum (when the desired intraabdominal pressure was reached: 15 mm Hg in group A and 10 mm Hg in group B), surgical manipulation of the tumor just before the adrenal vein was ligated, and tracheal extubation. On completion of surgery neuromuscular blockade was reversed, tracheal extubation was performed, and patients were transferred to the high- dependency area for observation. Oral feeding was resumed at 24 h and all patients were discharged on the second or third postoperative day. The other variables studied were operative time, estimated blood loss, length of hospital stay, postoperative analgesic requirements, and the time needed to achieve normal activity.

	Results

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The data was analyzed statistically using Student's t-test and shown in Table 1. The mean, sd, and P value were calculated. P < 0.05 was considered significant.

There were 4 male and 5 female patients with age ranging from 25 to 60 yr. The laboratory values of plasma catecholamines were determined by using high performance liquid chromatography.

Preoperative and Intubation
The P values of all the parameters calculated during tracheal intubation of patients in group A and group B were not of any statistical significance (P > 0.05).

Carboperitoneum
The introduction of carboperitoneum showed an increase in heart rate and mean arterial blood pressure (MAP) but they were not statistically significant. Norepinephrine levels showed a marked increase in group A patients as compared with group B patients (P = 0.0002).The epinephrine levels varied slightly.

Tumor Handling
There was a difference in both groups in all variables during handling of the tumor. MAP and norepinephrine levels showed a significant increase (P = 0.031, P = 0.007, and P = 0.0001, respectively). The epinephrine levels, however, did not change.

Extubation
During tracheal extubation, there was no significant difference of heart rate and MAP values (P = 0.016 and P = 0.76, respectively) (Figure 1). There was a significant difference in the norepinephrine levels between group A and group B patients showing a higher value in group A (P = 0.027). The epinephrine levels were not significant.

View larger version (33K): [in this window] [in a new window]   Figure 1. Graphic analysis of the nine patients' mean arterial blood pressure (MAP) and norepinephrine levels. *The Norepinephrine values are in pg/mL, MAP values are in mm Hg.

In both groups there was no significant difference regarding the mean operative time, mean estimated blood loss, average hospital stay, and the time needed to return to normal activity.

	Discussion

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The results of our study clearly show a marked decrease in the hemodynamic variables and serum levels of norepinephrine in patients subjected to lower intraabdominal pressure. The epinephrine levels varied slightly, probably because the tumor was norepinephrine-secreting. In our study we maintained anesthesia with continuous infusions of analgesia and muscle relaxant because sudden changes in the levels of both can cause a consequent increase in intraabdominal pressure that can lead to acute ventilatory and hemodynamic changes and further exacerbate catecholamine release. The two events associated with catecholamine release were caused by carboperitoneum and surgical manipulation of the tumor. The comparison of the two groups clearly demonstrates that higher intraabdominal pressure causes more hemodynamic fluctuations and norepinephrine release. The surgeon was very experienced and the duration of surgery was similar in both groups.

The laparoscopic approach to pheochromocytoma removal has gained popularity over the conventional open method since Gagner et al. (2) pioneered the successful laparoscopic resection of adrenals through the transperitoneal approach. Carboperitoneum introduced during the laparoscopic procedure itself induces hemodynamic changes as a result of CO₂ absorption and release of vasoactive hormones such as catecholamines and vasopressin (3). Hypercapnia resulting from CO₂ absorption can cause catecholamine release, leading to hemodynamic fluctuations and arrhythmias. The induction of carboperitoneum results in a marked catecholamine release in pheochromocytoma patients as compared with laparoscopic cholecystectomy patients (4). To avoid this, helium pneumoperitoneum has been tried for laparoscopic pheochromocytoma removal (5). However, Gebbardt et al. (6) found that insufflation of the peritoneal cavity is associated with maximum hemodynamic changes and catecholamine release, irrespective of whether the gas used is helium or CO₂, and that hormonal levels return to normal only after exsufflation (6). The mechanical effect of carboperitoneum on catecholamine release by the pheochromocytoma itself is unknown. All these pathophysiological changes could thus increase the well documented risk of hemodynamic instability. Further, the catecholamine release from pheochromocytoma is independent of neurogenic physiologic control. Surgical manipulation of the tumor definitely causes a marked release of catecholamines.

During laparoscopy, a standard insufflation pressure of 15 mm Hg is used, "The higher the pressure the better the view" was the axiom invoked by the surgeons who needed adequate exposure for laparoscopic procedures. The deleterious effects of increased intraabdominal pressure on stroke volume, cardiac output, and other hemodynamic variables have been well documented in human subjects and animal models (7). Since the introduction of laparoscopic surgery, efforts have been made to reduce the hemodynamic effects of carboperitoneum without compromising the efficacy, feasibility, and safety of the operation. There is a need to maintain a good exposure while reducing the pressure of insufflation as much as possible, especially in high-risk patients. Therefore, in our study we tried to maintain the intraabdominal pressures between 8–10 mm Hg compared with patients in whom a standard intraabdominal pressure of 15 mm Hg was used. Similar studies of the comparison of low and standard intraabdominal pressures have been performed in patients undergoing laparoscopic cholecystectomy, such as Davides et al. (8), who reported fewer hemodynamic variations at low insufflation pressure. Mann et al. (9) described two patients during laparoscopic adrenal pheochromocytoma removal. One patient had a hypertensive crisis and bradycardia with carboperitoneum and an intraabdominal pressure of 10 mm Hg.

We conclude that a lower intraabdominal pressure of 8–10 mm Hg during laparoscopic resection of pheochromocytoma produced a decrease in the hemodynamic variables (10,11) and serum norepinephrine levels as compared with the conventional group (intraabdominal pressure of 14–16 mm Hg). However, our study population was very small. More patients are required to come to a definitive conclusion.

	Footnotes

 
Accepted for publication August 16, 2005.

	References

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1. Kazaryan AM, Kuznetsov NS, Shulutko AM, et al. Evaluation of endoscopic and traditional open approaches to pheochromocytoma. Surg Endosc 2004;18:937–41.[Web of Science][Medline]
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3. Barczynski M, Herman RM. A prospective randomized trial on comparison of lower pressure and standard pressure pneumoperitoneum for laparoscopic cholycystectomy. Surg Endosc 2003;17:533–8.[Medline]
4. Joris JL, Hamoir EE, Harstein GM, et al. Hemodynamic changes and catecholamine release during laparoscopic adrenalectomy for pheochromocytoma. Anesth Analg 1999;88:16–21.[Abstract/Free Full Text]
5. Fernandez-Cruz L, Taura P, Saenz A, et al. Laparoscopic approach to pheochromocytoma: hemodynamic changes and catecholamine secretion. World J Surg 1996;20:762–8.[Web of Science][Medline]
6. Gebbardt M, Bartz A, Ross M, et al. Pathophysiological and clinical aspects of the carbon dioxide pneumoperitoneum. Surg Endosc 1997;11:864–7.[Web of Science][Medline]
7. Dexter SP, Vucevic M, Gibson J, McMahon MJ. Hemodynamic consequences of high and low pressure capnoperitoneum during laparoscopic cholecystectomy. Surg. Endosc 1999;13:376–81.[Web of Science][Medline]
8. Davides D, Birbas K, Vezakis A, McMahon MJ. Routine low pressure pneumoperitoneum during laparoscopic cholecystectomy. Surg Endosc 1999;13:887–9.[Medline]
9. Mann C, Millat B, Boccara G, et al. Tolerance of laparoscopy for resection of pheochromocytoma. Br J Anaesth 1996;77:795–7.[Abstract/Free Full Text]
10. Atallah F, Bastide-Heulin T, Soulie M, et al. Hemodynamic changes during retroperitoneoscopic adrenalectomy for phaeochromocytoma. Br J Anaesth 2001;86:731–3.[Abstract/Free Full Text]
11. Joris JL, Noirot DP, Legrand MJ, et al. Hemodynamic changes during laparoscopic cholecystectomy. Anesth Analg 1993;76:1067–71.[Abstract/Free Full Text]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Sood, J. Articles by Chowbey, P. K. Search for Related Content PubMed PubMed Citation Articles by Sood, J. Articles by Chowbey, P. K.