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Updated: Aug 11, 2026
Modeling Brain Metastases Through Intracranial Injection and Magnetic Resonance Imaging
Published on: June 7, 2020
Propofol requirement is decreased in patients with large supratentorial brain tumor
1Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories. mtvchan@cuhk.edu.hk
Background:
The anesthetic requirement is decreased in animals with head injury, but there are no data regarding the effect of intracranial tumor on the potency for intravenous anesthetics. The authors compared the quantal dose-response curves for propofol in patients having large (> or = 30 mm, mass effect) brain tumor with those having smaller (< 30 mm) lesions and with control patients undergoing noncranial surgery.
Methods:
Sixty patients in each group were randomly assigned to receive one of the six doses of propofol (0.5, 0.7, 1.0, 1.3, 1.8, or 2.5 mg/kg) over 10 s. Two minutes after drug administration, patients were asked to open their eyes as a test for response to verbal command. Patients who failed to respond were given a 10-s, 50-Hz, 80-mA transcutaneous tetanic electrical current to the ulnar nerve as a test for response to painful stimulus. Purposeful movement indicated positive response. Log dose-response curves for loss of response to verbal command and tetanic stimulus were calculated after logit transformation.
Results:
The median effective doses (ED50s; 95% confidence interval) for suppressing response to verbal command and tetanic stimulus were 0.75 (0.65-0.86) mg/kg and 1.28 (1.11-1.49) mg/kg, respectively, in patients with large brain tumor. These values were significantly less than the corresponding ED50s in patients with small tumor, 1.01 (0.88-1.15) mg/kg and 1.76 (1.51-2.07) mg/kg, or healthy control subjects, 0.98 (0.86-1.12) mg/kg and 1.89 (1.62-2.23) mg/kg.
Conclusions:
The doses of propofol required to suppress response to verbal command and tetanic stimulus were 23% less and 32% less in patients with large brain tumor compared with control subjects. Small tumor did not affect potency of propofol.
Insights
Large intracranial tumors significantly reduce the anesthetic requirement for propofol, indicating a need for dose adjustments. Smaller tumors, however, did not alter propofol potency in patients.
Area of Science:
- Anesthesiology
- Neurosurgery
- Pharmacology
Background:
- Anesthetic requirements decrease with head injury, but the impact of intracranial tumors on anesthetic potency is unknown.
- This study investigates the effect of intracranial tumor size on propofol's potency.
Purpose of the Study:
- To compare the dose-response curves of propofol in patients with large intracranial tumors versus small tumors and control subjects.
- To determine if intracranial tumors affect the potency of intravenous anesthetics like propofol.
Main Methods:
- Sixty patients in each of three groups (large tumor, small tumor, control) received one of six doses of propofol.
- Response to verbal command and painful stimulus (transcutaneous electrical nerve stimulation) was assessed.
- Log dose-response curves were calculated after logit transformation to determine median effective doses (ED50s).
Main Results:
- Patients with large brain tumors required significantly lower propofol doses (ED50s) to suppress verbal and painful stimuli responses compared to controls.
- The median effective doses for large tumors were 0.75 mg/kg (verbal) and 1.28 mg/kg (painful stimulus).
- Patients with small tumors showed no significant difference in propofol ED50s compared to control subjects.
Conclusions:
- Large intracranial tumors decrease propofol requirements by 23% (verbal) and 32% (painful stimulus) compared to controls.
- Propofol potency is not affected by smaller intracranial tumors.
- Anesthetic management may require dose adjustments in patients with large brain tumors.
