Is the patient's hypotension a concern given their scheduled administration of morphine (opioid analgesic) for chronic pain?

From the Guidelines

I strongly recommend administering IV fluids to address the patient's hypotension before administering the scheduled morphine, as morphine can cause further hypotension through vasodilation, which would be concerning given the patient's current BP of 92/54. For IV fluids, start with a 500mL bolus of normal saline over 1-2 hours.

Key Considerations

• Monitor blood pressure before giving the scheduled morphine, aiming for a systolic BP of at least 100mmHg.
• If hypotension persists despite fluid administration, consider using midodrine, an alpha-1 agonist, to increase peripheral vascular resistance and raise blood pressure, starting with 5mg orally and repeating every 4 hours as needed, not to exceed 30mg in 24 hours 1.
• Be cautious with morphine administration, as it can cause hypotension, especially in the presence of volume depletion and/or vasodilator therapy, and consider reducing the morphine dose or using an alternative pain management approach with less hemodynamic effect if necessary.

Rationale

• The patient's current blood pressure of 92/54 is a concern, and administering morphine without addressing the hypotension could lead to further decreases in blood pressure, potentially compromising perfusion of vital organs.
• IV fluids will help expand intravascular volume, while midodrine can help increase peripheral vascular resistance to raise blood pressure.
• The use of morphine in patients with hypotension requires careful consideration, as it can exacerbate hypotension and lead to adverse outcomes, as noted in the guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction 1.

From the FDA Drug Label

1. 8 Hypotensive Effect Morphine sulfate injection may cause severe hypotension in an individual whose ability to maintain their blood pressure has been compromised by depleted blood volume, shock, impaired myocardial function or concurrent administration of sympatholytic drugs, and drugs such as phenothiazines or general anesthetics Orthostatic hypotension is a frequent complication in single-dose parenteral morphine analgesia in ambulatory patients.

The patient's blood pressure is already low (92/54), and morphine can cause severe hypotension. Caution is advised when administering morphine to this patient.

• Consider the patient's current hypotensive state and the potential for morphine to worsen it.
• The FDA drug label does not provide guidance on ordering fluids or midodrine in this scenario 2.

From the Research

Patient's Condition

• The patient's blood pressure has been running soft, with the last reading being 92/54.
• The patient has chronic pain and is scheduled to receive morphine at 2100.

Treatment Options

• Midodrine is a peripheral alpha-adrenergic agonist that can be used to treat orthostatic hypotension and secondary hypotensive disorders 3, 4, 5.
• Studies have shown that midodrine is effective in increasing standing blood pressure and improving symptoms of orthostatic hypotension, such as weakness, syncope, and fatigue 3, 4, 6.
• Midodrine has been compared to other sympathomimetic agents and has been found to be at least as effective, with fewer adverse effects 3, 4.

Administration and Dosage

• Midodrine is typically administered orally, with doses ranging from 2.5 to 10 mg, two to three times daily 5, 6.
• The most commonly reported adverse events associated with midodrine include piloerection, pruritus, and urinary retention 4, 5.

Efficacy in Hypotension

• A study found that midodrine did not accelerate liberation from intravenous vasopressors in critically ill patients with persistent hypotension 7.
• However, other studies have shown that midodrine is effective in treating orthostatic hypotension and improving symptoms in patients with neurogenic orthostatic hypotension 3, 4, 6.