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Not Too much, Not Too Little: The ‘Goldilocks Zone’ of Intensive Care

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Delivering healthcare is a complex affair at the best of times. So for patients on Intensive Care wards, where proper delivery of care is a matter of life or death, clinicians need to make sure they always make clinically optimal treatment decisions.

In any given ICU unit, a patient in a critical condition can be hooked up to as many as 15 different machines, including monitors, ventilators and infusion pumps. Powerful sedative drugs are routinely administered and can cause respiratory depression, a very serious side effect where breathing can stop entirely. There are also devices that take over patients’ breathing completely. Arguably, the ICU can be a dangerous place without constant monitoring.

Doctors tend to go for as little a dose of sedatives as possible with ICU patients, to make sure they can tolerate their critical care treatment and mechanical ventilation. But no two patients are the same; figuring out the minimum dose each individual needs is both challenging and can significantly impact the patient.

Both under-sedation and over-sedation carry serious risks. Under-dose, and the patient could become agitated, show fear and anxiety, try to get out of the bed, pull out vital IV-lines and tubes, and cause harm to themselves. Over-dose, and the sedatives could suppress spontaneous breathing, delay ventilator weaning, and put the patient at risk of a ventilator-acquired infection. All this causes a longer ICU stay, and increased risk of death.

“Each individual patient has their optimal sedation level depending on their clinical status and their response to the sedative drugs,” said Dr. Walsh, Professor of Critical Care, at the University of Edinburgh. “It is not possible to give every patient the same amount of sedative drugs, both over and under- sedation carry grave risks… under-sedation causes adverse events, over-sedation suppresses breathing and lengthens ICU stay.”

Effectively dosing patients with the right amount of sedatives – keeping them in a ‘Goldilocks zone’ of sedation – is an area of ICU care where clinicians could benefit from extra support for their decisions.

A study conducted at the University of Edinburgh indicates that there could be one such technology on the horizon. It’s called Responsiveness Index (RI), developed through a collaboration between GE healthcare and the University of Edinburgh, and at present only used for research purposes. It continuously monitors the status of ICU patients based on facial electromyography (fEMG) activity. Facial electromyography measures muscle activity in the face by detecting and amplifying tiny electrical impulses that are generated by muscle contractions in the forehead. By measuring these electrical impulses through electrodes stuck to the forehead, RI uses the previous 60 minutes of RI activity to assess the frequency and intensity of a patient’s alertness during treatment.

From the 3 rd to the 7 th October this year, the ESICM (European Society of Intensive Care Medicine) will hold its 28 th Annual Congress in Berlin. There, Dr Walsh will present results from a new study (called the DESIST trial) which included Responsiveness Index monitoring as one of three interventions designed to improve the quality of sedation in ICU. The study suggested that the combination of a comprehensive web-based education program used in conjunction with Responsiveness monitoring can improve sedation quality. This work builds on another recently published study (called IMPROVE) which suggested that Responsiveness Index monitoring can support nurse decision-making at the bedside.

“Responsiveness Index is a measure of the balance between the patients’ need for sedation and the effect of sedative drugs,” added Dr Walsh. “The IMPROVE study has shown that, as a proof of concept, this technique is promising and is worthy of further study.”

The study used a cohort of 78 patients, which is too small to be of any statistical significance, but the fact that nurses felt they could make better decisions using RI, and the number of adverse events did not increase for any patient who was hooked up to RI, shows that this medical technology shows a lot of promise.

More Information

IMPROVE study
Dr Tim Walsh, University of Edinburgh
ESICM 2015