Research paper summary – Lily Groom

Understanding Heroin Overdose: A Study of the Acute Respiratory Depressant Effects of Injected Pharmaceutical Heroin  Caroline J. Jolley, James Bell, Gerrard F. Rafferty, John Moxham, John Strang

Published in PLoS One, October 2015

Opioids are a class of drug which act by attaching to opioid receptors, found in the brain and spinal cord, reducing the perception of pain. For this reason, opioids are often prescribed for pain relief. When people misuse opioids, they are often unaware of the dangerous side effects that come with them. For example, they are respiratory depressants, meaning they can reduce the breathing rate, which can be fatal. Many of the current methods of measuring respiratory depression under-estimate the true effect these drugs have on the body (especially the breathing rate), which is why this study was undertaken. Respiratory depression is a major cause of overdose and if you cannot detect when it is happening effectively, you have less chance of helping someone suffering from it.

The participants in this study were monitored over a course of 150 minutes, after they had been given their usual opioid dose. This was done using EMGpara (a tool which assesses how hard the breathing muscles are working), pulse oximetry (measuring the blood’s oxygen levels), and measurement of carbon dioxide levels in exhaled breath. The participants were asked to rate how much they felt the drug’s effect at three minutes prior to the drug being given, and then at regular intervals afterwards. Staff ratings of intoxication and level of consciousness were also given. Pulse oximetry and observer ratings are the more commonly used methods of observing patients’ breathing currently.

However, this study found that there was an increase in the level of carbon dioxide per breath in eight of the ten participants and a low blood oxygen level in only four out of the ten patients. The difference in results shows that the traditional approach of measuring the blood’s oxygen level is not as sensitive a method to detect respiratory depression after taking an opioid. There were varying degrees of respiratory depression found in all patients. However, the pulse oximetry only picked up four of these. The study also found that just talking to a patient helped to mask episodes where they were breathing unusually slowly. This means that it is very easy to miss a potentially dangerous symptom.

The findings of this study therefore suggest that we should change the way we test for respiratory depression in clinical settings, to help identify, treat and prevent it in patients taking opioids.

This summary was produced by Lily Groom, Year 13 student from Graveney School, Tooting, as part of our departmental educational outreach programme.

Research paper summary – Lottricia Millett

Parasternal Intercostal Electromyography: a Novel Tool to Assess Respiratory Load in Children Victoria MacBean, Caroline J. Jolley, Timothy G. Sutton, Akash Deep, Anne Greenough, John Moxham, Gerrard F. Rafferty

Published in the journal Pediatric Research, May 11th 2016

Parasternal intercostal electromyography (EMGpara) is a new way to measure breathing difficulty. Research needs to be carried out because body parts used in breathing, like the lungs, need to be properly checked over for breathing problems to be managed, but the testing methods aren’t always suitable for children who are very young or ill. The parasternal intercostal muscles are muscles that move at the same time as the diaphragm (a thin sheet of muscle under the lungs) when you breathe in and out. EMGpara measures signals from the brain which are sent to these muscles without putting any instruments into the body, so it is ideal for children.

EMGpara was measured using stickers on the front of the chest while the participants (92 healthy, 20 wheezy and 25 with a machine (ventilator) to help them breathe) were breathing in and out in a resting state. For the wheezy children, measurements were taken before and after a substance to widen air passages (reliever inhaler, or bronchodilator) was used; for the critically ill children, these were taken during ventilator-assisted breathing, then with just mild air pressure to keep the airways open (continuous positive airways pressure).

It was found that as age, weight and height increased, EMGpara decreased. This is because when children are growing up, big changes take place in the respiratory system, decreasing the effort needed for breathing. EMGpara in the healthy children was the lowest; in the wheezy children it was higher before the bronchodilator was used, dropping to similar levels to the healthy children afterwards. In the critically ill children, EMGpara was higher than in the wheezy children when the ventilator was used, and even higher with continuous positive airways pressure when they were having to breathe without support.

This study has shown that measuring EMGpara is possible in children of a range of ages and levels of health. The results from the healthy children have shown important age-related changes in EMGpara, and those from the wheezy and critically ill children have shown that EMGpara is affected by changes in how hard the breathing muscles have to work because of different diseases and treatments. EMGpara could be a really helpful method in testing the breathing ability of patients who are usually difficult to assess.

This summary was produced by Lottricia Millett, Year 12 student from Burntwood School, Wandsworth, as part of our departmental educational outreach programme.