What is the role of acetazolamide in the Intensive Care Unit (ICU)?

From the Guidelines

Acetazolamide may be considered for patients with increased intracranial pressure (ICP) in the ICU setting, particularly when used in conjunction with other anti-edema interventions. According to the most recent guidelines from 2024, fluid drainage and acetazolamide are potential considerations for managing increased ICP in patients on extracorporeal membrane oxygenation (ECMO) 1. The use of acetazolamide in this context is aimed at reducing ICP, which is crucial for preventing further brain injury and improving patient outcomes.

Key points to consider when using acetazolamide for increased ICP include:

• Monitoring for signs of decreased ICP and improved cerebral perfusion
• Using acetazolamide in conjunction with other interventions such as raising the head of the bed, hyperosmolar therapy, and sedation/analgesia
• Being cautious of potential side effects, including electrolyte disturbances and renal impairment
• Considering alternative treatments, such as decompressive craniectomy, in severe cases of cerebral edema 1.

In the ICU setting, it is essential to weigh the benefits of acetazolamide against its potential risks and to closely monitor patients for any adverse effects. The decision to use acetazolamide should be made on a case-by-case basis, taking into account the individual patient's condition and the availability of other treatment options.

From the FDA Drug Label

CLINICAL PHARMACOLOGY Acetazolamide is a potent carbonic anhydrase inhibitor, effective in the control of fluid secretion (e.g., some types of glaucoma), in the treatment of certain convulsive disorders (e.g., epilepsy) and in the promotion of diuresis in instances of abnormal fluid retention (e.g., cardiac edema). The role of acetazolamide in ICU is to promote diuresis in instances of abnormal fluid retention, such as cardiac edema.

• It can be used to manage conditions like glaucoma and epilepsy.
• The mechanism of action involves inhibition of carbonic anhydrase, leading to renal loss of HCO3 ion, which results in diuresis and alkalinization of the urine 2.

From the Research

Role of Acetazolamide in ICU

• Acetazolamide is a carbonic anhydrase inhibitor that can be used in ICU for various indications, including idiopathic intracranial hypertension, elevated intracranial pressure, and acute mountain sickness 3, 4.
• It works by inhibiting carbonic anhydrase, leading to reduced hydrogen ion secretion in the proximal renal tubule, resulting in increased bicarbonate and cation excretion and causing urinary alkalization and diuresis 3.
• Acetazolamide can also decrease the production of cerebrospinal fluid (CSF) and aqueous humor, reducing intracranial pressure (ICP) and intraocular pressure 3, 5.
• The potential benefits of acetazolamide in ICU include ventilator weaning for chronic obstructive pulmonary disease patients, avoidance of invasive procedures in patients with a CSF leak or elevated ICP, and prevention of high-dose methotrexate toxicity and contrast-induced nephropathy 3.
• However, uncertainty remains regarding the selection of patients who would best benefit from acetazolamide use, and limited literature exists describing the optimal patients to receive acetazolamide therapy 3.

Clinical Settings for Acetazolamide Use

• Acetazolamide can be useful in several clinical settings, including acute heart failure, acute mountain sickness, post hypercapnic metabolic alkalosis, idiopathic intracranial hypertension, and acute angle-closure glaucoma 4.
• It is a rather handy drug that can be used in emergency situations for patients with potential critical issues, and its safety profile has been evaluated 4.
• Acetazolamide seems to be an overall safe drug, with serious side effects being rare and avoidable by carefully selecting the patients to be treated 4.

Monitoring and Adverse Effects

• Metabolic acidosis is a common laboratory finding among patients with idiopathic intracranial hypertension treated with acetazolamide, but it is not correlated with clinical adverse effects 6.
• Adverse effects such as neurologic, gastrointestinal, and renal effects can occur, but they are not significant in most cases 6.
• Blood tests should be sent during acetazolamide treatment based on clinical judgment, rather than routinely 6.

Comparison with Other Treatments

• Acetazolamide is effective in the treatment of idiopathic intracranial hypertension, and its mechanism of action involves inhibition of carbonic anhydrase isoforms involved in cerebrospinal fluid secretion 5.
• Other treatments such as mannitol and hypertonic saline can also be used for intracranial hypertension, but their relative merits and adverse effects should be considered 7.