Sudden patient deterioration due to secretions blocking heat and moisture exchanger filters

Through its targeted surveillance of emerging COVID-19 issues recorded on national systems, such as the National Reporting and Learning System (NRLS), the new Learn from Patient Safety Events service (LFPSE), and other sources, the National Patient Safety Team identified an issue that described a ventilated patient, with COVID-19, who suddenly deteriorated when placed in the prone position. The deterioration had been caused by the heat and moisture exchanger filter (HMEF) being flooded with secretions.

Patients who are mechanically ventilated bypass the body’s normal mechanisms of humidifying inspired air and require additional humidification, this can be provided via a HMEF. The COVID-19 pandemic saw a large increase in the use of HMEFs, due to the number of patients being ventilated, and an increase in prone positioning.

The identified incident highlighted a possible under-recognised patient safety risk of the need to check/replace HMEF due to clogging with secretions.

The issue was raised with the Faculty of Intensive Care Medicine, who published a ViRUS Safety Update: Sudden HME Filter occlusion during proning and requested that the risk be included in future national COVID-19 guidance.

About our patient safety review and response work

The recording and central collection of patient safety events to support learning and improvement is fundamental to improving patient safety across all parts of NHS healthcare.

A core part of the work of the National Patient Safety Team is to review these records to identify new or under recognised patient safety risks, which are often not obvious at a local level. In response to any newly identified risks, we develop advice and guidance, such as National Patient Safety Alerts, or work directly with partners as in the example above, to support providers across the NHS to take the necessary action to keep patients safe.

You can find out more about our processes for identifying new and under recognised patient safety issues on our using patient safety events data to keep patients safe and reviewing patient safety events and developing advice and guidance web pages.

You can also find more case studies providing examples of this work on our case study page.