Bruera, E., Macmillan, K., Pither, J., & MacDonald, R.N. (1990). Effects of morphine on the dyspnea of terminal cancer patients. Journal of Pain and Symptom Management, 5(6), 341–344.

The objective of this study was to assess the effect of one dose of subcutaneous (SC) morphine on dyspnea in patients with terminal cancer.

Patients were given 2.5 times their regular dose of morphine, administered at the time of their scheduled analgesic dose. In five patients who were not receiving opioids, the dose was 5 mg of morphine. The average dose administered was 22–28 mg.

The study reported on a sample of 20 consecutive patients with terminal cancer; all patients had severe dyspnea at rest because of restrictive respiratory failure.

The study was conducted on a palliative care unit.

The study was an open, uncontrolled trial.

• Dyspnea visual analog scale (VAS) and pain VAS were measured before the dose and every 15 minutes for 150 minutes.
• Respiratory rate, respiratory effort, arterial oxygen saturation (SO₂), and end-tidal arterial carbon dioxide pressure (PaCO₂) were determined before and 45 minutes after SC morphine.

• A statistically significant improvement in dyspnea was seen without any significant change in respiratory rate, respiratory effort, oxygen saturation, or PaCO₂.
• In patients with pain, the effect of morphine on dyspnea had a shorter duration than the analgesic effect.
• Toxicity was minimal and consisted of nausea.
• Of 20 patients, 19 reported improved dyspnea after SC morphine and continued to receive the same dose for dyspnea on an as-needed basis with continued relief.
• Authors suggest the need for confirmation with a double-blind study.

The study had a small sample size.