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An increased circulating blood volume does not prevent hypotension after pheochromocytoma resection
Takehiko Iijima1, Toshiyuki Takagi, Yasuhide Iwao
1Department of Anesthesiology, Kyorin University School of Medicine, Tokyo, Japan. iijmt@kyorin-u.ac.jp
Insights
Preoperative alpha-blocker therapy in pheochromocytoma patients expands circulating blood volume (CBV), but this expansion is linked to lower post-resection blood pressure. Pulse dye-densitometry aids in managing hypotension by monitoring CBV and cardiac output (CO).
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Surgical Monitoring
Background:
- Pheochromocytoma is a tumor causing significant hemodynamic instability.
- Managing blood pressure and volume in pheochromocytoma patients perioperatively is critical.
- Novel monitoring techniques are needed to assess circulating blood volume (CBV) and cardiac output (CO) in these patients.
Purpose of the Study:
- To investigate the relationship between CBV and post-resection hypotension in pheochromocytoma patients.
- To evaluate the utility of pulse dye-densitometry in monitoring CBV and CO during pheochromocytoma resection.
- To determine if preoperative alpha-blocker therapy affects post-resection hemodynamics.
Main Methods:
- A case control study involving seven pheochromocytoma patients.
- Monitoring CBV and CO using pulse dye-densitometry before, during, and after alpha-blocker therapy and tumor resection.
- Quantifying the effect of alpha-blocker therapy on CBV expansion.
Main Results:
- Alpha-blocker therapy significantly increased CBV from 72.0 ± 10.0 mL/kg to 83.4 ± 12.2 mL/kg (P < 0.001).
- A significant inverse relationship was observed between the increase in CBV after alpha-blockade and post-resection blood pressure.
- CBV expansion did not preclude post-resection hypotension.
Conclusions:
- Expansion of CBV with alpha-blockers is associated with lower post-resection blood pressure in pheochromocytoma patients.
- Preoperative blood volume expansion does not prevent hypotension after tumor resection.
- Pulse dye-densitometry is a valuable tool for simultaneous CO and CBV monitoring, aiding in the management of volume resuscitation and catecholamine use.
Purpose:
Pulse dye-densitometry, a novel monitor that measures circulating blood volume (CBV) and cardiac output (CO), was used in patients with pheochromocytoma to determine the relationship between CBV and post resection hypotension.
Methods:
Case control study. An alpha blocker was administered for approximately two weeks, and its effect on the expansion of CBV was quantified. CBV was monitored in seven patients admitted for resection of suspected pheochromocytoma before preoperative alpha-blocker therapy, after alpha-blocker therapy and three times during the operation. Relationships between the CBV and blood pressure after resection of the tumour were examined.
Results:
CBV increased from 72.0 +/- 10.0 mL.kg(-1) to 83.4 +/- 12.2 mL.kg(-1) after alpha blockade. (P < 0.001). We found a significant inverse relationship between the increase in CBV after alpha-blocker therapy and blood pressure after resection of the tumour.
Conclusions:
Expansion of the CBV by alpha-blocker therapy was related to lower blood pressures after resection of the pheochromocytoma. Expansion of the CBV by an alpha blocker may have increased the elastance of blood vessels. Preoperative blood volume expansion does not preclude hypotension after tumour resection. Although the CBV value itself is not a predictor for hypotension after tumour resection, pulse dye-densitometry provides values of CO and CBV simultaneously, assisting in the management of volume resuscitation and/or the need for catecholamines.
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