Active Potassium Supplementation Might Be Mandatory During Laparoscopic Adrenalectomy for Primary Hyperaldosteronism

Abstract

Background and Purpose:

It is well recognized that monitoring of the serum potassium level during laparoscopic adrenalectomy for primary hyperaldosteronism is critical. Nevertheless, the guideline for prevention and management of hypokalemia during the operation has not been established to date. In this study, we investigated whether active potassium supplementation could prevent electrolyte imbalance during laparoscopic adrenalectomy for primary hyperaldosteronism.

Patients and Methods:

From January 2007 to May 2011, 35 patients underwent transperitoneal laparoscopic adrenalectomy for primary hyperaldosteronism (Conn's syndrome). The hemodynamic and electrolyte changes during the operation were recorded serially. In first 10 patients (group A), potassium was replaced passively on demand. Based on this result, potassium was actively supplemented during the operation in the subsequent 25 patients (group B). The perioperative parameters, hemodynamic changes, and serum potassium levels were analyzed and compared between the two groups.

Results:

The patients' demographic data, initial blood pressure, and serum electrolyte levels were similar in both groups. The operative time was shorter in group B (P=0.035). The mean serum potassium level was decreased by 0.7 mmol/L during the first 30 minutes in group A. Based on this result, potassium was actively supplemented from the beginning of the operation in group B. The mean hypokalemic events were 4±2 in group A. None of the patients in group B, however, experienced hypokalemia. The hemodynamic events (sudden increase of blood pressure) and mean blood pressure changes during the operation were similar in both groups.

Conclusion:

Our results demonstrate that serum potassium levels are constantly decreasing during laparoscopic adrenalectomy for primary aldosteronism. Active supplementation of potassium during the operation might prevent a hypokalemic event.

Introduction

H ypertension, hypokalemia, suppressed plasma renin activity, and increased aldosterone excretion characterize the syndrome of primary hyperaldosteronism (Conn's syndrome), first described by Conn in 1955.¹ Currently, the treatment of choice for primary hyperaldosteronism is adrenalectomy. Although laparoscopy is now the treatment of choice for benign adrenal tumors and has replaced the conventional open procedure, only a small number of studies regarding the influences of laparoscopy in the treatment of patients with primary hyperaldosteronism have been performed.^2,3

Intraoperative hypertensive crisis is a well-known risk of laparoscopic adrenalectomy for pheochromocytoma, but so far no other studies concerning serum potassium changes during laparoscopic adrenalectomy for primary hyperaldosteronism have been reported.

Our aim for this study is to evaluate the influence of laparoscopy on hemodynamic and electrolyte changes during the operations and to find out whether active potassium supplementation could prevent electrolyte imbalance during laparoscopic adrenalectomy for primary hyperaldosteronism.

Patients and Methods

From January 2007 to May 2011, 35 patients underwent transperitoneal laparoscopic adrenalectomy for primary hyperaldosteronism (Conn's syndrome) and were included in this study. All patients had a consultation with the endocrinologist before surgery concerning control of both blood pressure and serum potassium. Patients received potassium-sparing diuretics (spironolactone) 50 to 100 mg/d and oral potassium chloride according to their serum potassium level. Preoperative blood pressure and serum potassium and intraoperative hemodynamic and electrolyte changes were recorded serially.

In the first 10 patients (group A), potassium was replaced passively on demand. The subsequent 25 patients (group B) were treated actively with a potassium supplement based on the first 10 patients' changes of electrolytes during the operation. Considering the decrease of the serum potassium level after pneumoperitoneum induction in group A, potassium chloride was administered to group B patients intravenously 10 minutes before pneumoperitoneum induction at a rate of 10 to 30 mEq/h. The infusion rate of potassium chloride was adjusted, considering the patients' serum potassium level.

The changes of preoperative systolic and diastolic blood pressure and maximum intraoperative systolic and diastolic blood pressure were compared respectively in both groups. The serum potassium concentration was checked at the time of admission, intubation, 10 and 30 minutes after pneumoperitoneum induction, tumor manipulation and after the tumor removal, and the data were compared respectively in both groups.

All procedures were performed by the transperitoneal approach. Pneumoperitoneum was achieved by using a Veress needle, and three or four ports were placed, depending on the case. After laterocolic incision and mobilization of the colon, the posterolateral ligaments of the spleen were incised, and the spleen was mobilized medially to expose the left adrenal gland. To expose the right gland, the triangular ligament of the right lobe of the liver was incised, and the lobe was retracted in the cephalad direction. Electrocoagulation was used for the dissection, and the main adrenal vein was ligated with 10 or 15 mm Hem-o-lok^™ clips (Weck Closure Systems, Research Triangle Pack, NC) in both sides. All of the specimens were removed without morcellation or fragmentation in an Endo Catch retrieval bag (Covidien, Dublin, Ireland) through a 10-mm port site incision with or without the extension of the incision.

An indwelling Jackson-Pratt drain was placed in the retroperitoneal space through a 5-mm port site in all of the patients. Intra-abdominal pressure was maintained at 12 mm Hg or less, and the tidal CO₂ was carefully monitored and kept below 45 mmHg. Patients were encouraged to have oral intake after the return of bowel function was confirmed. Patients were discharged 4 to 6 days after the surgery.

The data were compared and analyzed with the Student t test and paired t test. A P value of <0.05 was considered statistically significant for all procedures.

Results

The 10 patients who were treated passively (group A) were composed of four males and six females, with an average age of 42.8 years. The 25 patients who were actively treated (group B) were composed of 11 males and 14 females, with an average age of 43.1 years. The body mass index was 23.3 and 24.2 in group A and group B, respectively, and no significant difference was observed. The tumor laterality (right/left ratio) was 1.50 in both groups, and there was no significant difference between the groups (P=0.104). The pathologic data including tumor size did not differ significantly between the groups (P=0.156). The mean operative time in group B was significantly shorter than in group A (P=0.046). There were no major intraoperative complications that necessitated conversion to an open procedure or blood transfusion (Table 1).

Table 1.

Comparison of Patients' Demographic Data and Perioperative Surgical Outcomes Between Passively (Group A) or Actively (Group B) Treated Groups During the Operation

	Group A	Group B	P value
No. of patients	10	25
Age	42.8±10.8	43.1±11.9	0.651
Sex (male/female)	4/6	11/14	0.345
BMI (kg/m²)	23.3±2.7	24.2±3.1	0.134
Tumor size (cm)	2.5±0.5	2.3±0.4	0.156
Tumor laterality (right/left)	6/4	15/10	0.104
Operative time (min)	122.2±10.5	99.3±11.2	0.046
Blood loss (mL)	75.3±11.2	77.2±10.3	0.203

BMI=body mass index.

Preoperatively, the mean systolic and diastolic blood pressure was 155 (110–195) mm Hg and 90 (80–115) mm Hg, 160 (110–195) mm Hg and 85 (75–110) mm Hg in group A and group B, respectively. The maximum systolic and diastolic intraoperative blood pressure was 165 (125–195) mm Hg and 95 (75–125) mm Hg, 170 (120–190) mm Hg and 95 (80–120) mm Hg in group A and group B, respectively. The difference between preoperative and maximum intraoperative systolic and diastolic blood pressure did not differ statistically between the two groups (Table 2).

Table 2.

Changes of Blood Pressure in Patients Who Were Passively (Group A) or Actively (Group B) Treated During the Operation

	Group A (n=10)	Group B (n=25)
Preoperative
Systolic BP	155 (110–195)	160 (110–195)
Diastolic BP	90 (80–115)	85 (75–110)
Maximum intraoperative
Systolic BP	165 (125–195)	170 (120–190)
Diastolic BP	95 (75–125)	95 (80–120)
BP change (preoperative/intraoperative)
Systolic (P value)	0.324	0.146
Diastolic (P value)	0.984	0.652

BP=blood pressure.

The serum potassium level of the preoperative and intubation period was similar in both groups (P=0.342, P=0.423 respectively). After 30 minutes of pneumoperitoneum induction in group A, however, the mean serum potassium level was decreased by 0.7 mmol/L, and the mean serum potassium level decreased constantly until the tumor was removed. The mean hypokalemic events were 4±2 in group A. None of the patients in group B, however, had hypokalemic events that necessitated the cessation of the operation to correct electrolyte imbalances, which could lead to adverse events such as cardiac abnormality. The serum potassium levels at 30 minutes after penumoperitoneum induction, tumor manipulation, and after the tumor removal in group A were significantly lower than those of group B (Table 3).

Table 3.

Serial Changes of Serum Potassium in Both Passively (Group A) or Actively (Group B) Treated Groups During the Operation

Serum potassium (mmol/L)	Group A	Group B	P value
Preoperative	3.4 (2.8–4.9)	3.5 (2.7–4.8)	0.342
Intubation	3.4 (2.9–4.8)	3.4 (2.8–4.9)	0.423
Pneumoperitoneum
10 min	2.9 (2.4–4.1)	3.1 (2.5–4.3)	0.062
30 min	2.7 (2.3–3.9)	3.5 (2.8–4.7)	0.024
Manipulation	2.6 (2.1–3.8)	3.2 (2.5–4.2)	0.034
After tumor removal	2.6 (2.3–3.9)	3.4 (2.7–4.6)	0.045

Discussion

Hypertension and hypokalemia associated with primary hyperaldosteronism can be managed with potassium-sparing diuretic agents except in patients with high operative risk. Laparoscopic adrenalectomy is currently the procedure of choice when operative management is elected.⁴

Gockel and associates⁵ published the changing pattern of intraoperative blood pressure during laparoscopic adrenalectomy in patients with primary hyperaldosteronism. Intraoperative increases in blood pressure necessitating drug therapy were observed in 17 of 40 patients, and blood pressure peaks of >200 mm Hg (>1 min) were noted in 11 of 40 patients. This has not been reported previously by other authors for laparoscopic adrenalectomy in primary hyperaldosteronism. Intraoperative rise in blood pressure as described above was statistically significant compared with the course in patients undergoing laparoscopic surgery for incidentaloma over the same period. The authors pointed out that considering there was no similar increase in patients with incidentaloma, manipulation of the adrenal gland may be responsible for the changes in blood pressure. In our observation as other studies have reported, the difference between preoperative and maximum intraoperative systolic and diastolic blood pressure did not differ statistically between two groups.

Many groups have reported the results of the postoperative serum potassium level and discovered that hypokalemia was normalized in the early postoperative phase.^5,6 Gockel and colleagues⁵ reported that after the first postoperative day, potassium substitution was needed in only 2 of 40 patients (5%, preoperatively 52.6%) and at the time of discharge, the serum potassium concentration had returned to within the normal range in all patients. They were solely focused on the postoperative serum potassium level normalization, even if monitoring of the serum potassium level during laparoscopic adrenalectomy for primary hyperaldosteronism is critical. So far there have been limited data on changes of the intraoperative serum potassium level and the guideline for prevention and management of hypokalemia during the operation.

The goal of our study was to find out whether active supplementation of potassium could be beneficial to patients. Therefore, we set patients who did not receive the active supplementation of potassium chloride as the control group (group A), and we assessed the differences between the active potassium chloride supplementation group (group B). The serum potassium level had decreased significantly after 30 minutes of peumoperitoneum induction in group A, and this phenomenon had continued until the tumor was removed. The fact that the serum potassium level decreased after the penumoperitoneum induction suggests that stimulation and manipulation of the tumor may be responsible for the changes in the serum potassium level during the operation. Based on the results of group A, potassium chloride was given to group B patients intravenously 10 minutes before pneumoperitoneum induction to prevent the hypokalemic events that necessitate cessation of the operation. As a result, none of the patients in group B experienced hypokalemia.

The mean operative time in group B was significantly shorter than in group A (P=0.046). We believe that this is probably the surgeon's increasing comfort and efficiency with the procedure with practice over time.

Our data suggest that stimulation and manipulation of the tumor are responsible for the changes in the serum potassium level during the operation. If so, a nontouching technique may be the ultimate solution for hypokalemic events, and surgeons should avoid touching the tumor; however, in many of the cases, manipulation of the tumor or compressing it is inevitable. We think that in this situation, potassium supplementation is necessary to reduce the rare but possible complications of hypokalemia.

In this series, we successfully identified the benefit of the active supplementation of potassium, but this review has several limitations, of which the most important is failure to establish the guidelines on how to adjust the dosage of potassium chloride at the specific hypokalemic events. This was because there was a small number of patients to analyze and establish such a guideline. Also, we should have included another control groups (group C) that had patients undergoing laparoscopic surgery that did not involve adrenal manipulation. When we first designed this study, however, we had the advantage of previously reported studies as references concerning the effect of CO₂ pneumoperitoneum and anesthesia on potassium changes in laparoscopic surgery that did not involve adrenal manipulation.

Perner and coworkers⁷ published an article about changes in plasma potassium concentration during CO₂ pneumoperitoneum in 1999. In the study, plasma potassium concentrations were unaffected by CO₂ pneumoperitoneum in young and relatively healthy patients during a short laparoscopic procedure. In another study performed by Zhu and associates,⁸ serum potassium decreased during the first 5 minutes of a laparoscopic colorectal operation, but after that, serum potassium returned to the level of the preoperative period. These results from two studies are quite different from our data, which indirectly suggests that hypokalemia in our study is from manipulation of the adrenal gland and not from anesthesia or pneumoperitoneum. Further investigations with modified study design would be necessary to confirm our initial findings in a small patient series.

Conclusions

Our results demonstrate that the serum potassium level decreased constantly during laparoscopic adrenalectomy for primary hyperaldosteronism. Active supplementation of potassium will prevent patients from falling into hyperkalemia. With these precautionary measures, surgeons can perform laparoscopic adrenalectomy in patients with primary hyperaldosteronism more safely.

Footnotes

Acknowledgment

This study was supported by a grant of the Korean Health Technology R&D Project, Ministry of Health and Welfare, Republic of Korea (A111345).

Disclosure Statement

No competing financial interests exist.

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