Covid Scotland: One in four intensive care patients were under 40 during Delta wave

The report also highlighted staffing pressures, with a survey of intensive care units in September this year finding that more than half had been forced to rely on agency, bank or redeployed nurses - contrary to clinical guidelines - in order to meet the recommended nurse-to-patient ratio.

The Scottish Intensive Care Society Audit Group (SICSAG) has charted the changing demographics of critically ill Covid patients since the beginning of the pandemic.

Intensive care admissions in patients who have tested positive for Covid (Source: Scottish Intensive Care Society Audit Group)

Of the 539 Covid patients admitted to intensive care units since May18 - defined as the beginning of the third wave as the now dominant Delta variant began spreading exponentially - it found that 27 per cent were under 40, compared to 8% during the first wave in Spring 2020 and the second wave during winter.

Responding to the figures, Scottish Government Covid advisor and chair of global public health at Edinburgh University, Professor Devi Sridhar tweeted that it was a "shame the 'shield the vulnerable and infect the rest' crowd got so much airtime in the UK in 2020".

"The narrative that those under 50 are not affected by Covid clearly not true," she said, adding that the "main route to protection should be through vaccination".

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Intensive care patients were also younger on average, with a median age of 54 during the third wave compared to 59 and 60 during the previous two Covid waves.

During the Delta wave, 64% of patients had no known co-morbidities - similar to previous waves - but among those who did, diabetes and respiratory disease were the most common pre-existing conditions.

Unlike previous waves, however, 80% of ICU Covid patients since May were rated 'non-frail' on the on the clinical frailty score, signalling the comparatively younger mix of admissions. The figure was around 60% during the first and second waves.

Total ICU Covid admissions for adults aged 16 to 49 overtook those for the over-70s in May, as the third wave took off (Source: SICSAG)

Of the 539 patients treated in ICU during the third wave, 192 had tested positive for Covid 14 days or more after their second vaccination - although further investigation indicated that in the case of 28 patients, their admission to intensive care was unrelated to the infection.

Nearly one in three fully-vaccinated ICU Covid patients (28%) were found to be immuno-suppressed, a factor known to reduce the responsiveness to vaccines. This group of patients has been prioritised for booster doses.

Overall, however, unvaccinated individuals were around six times more likely to require critical care during the Delta wave compared to those who had received both vaccine doses.

The report also highlighted admissions among expectant mothers. In total, 67 pregnant women have been admitted to ICU with Covid since the beginning of the pandemic, but 42 (63%) of these occurred during the third wave.

None of the women had been fully vaccinated against Covid.

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Survival rates were higher during the third wave - at 73% compared to 64% and 66% during the first and second waves respectively - and length of hospital stay was shorter, at around five days compared to seven.

The report noted that a lower proportion of patients during the third wave required interventions such as respiratory support, renal replacement therapy or cardiovascular support compared to the previous waves, adding: "These differences are likely to reflect changes in case-mix and evolving clinical practice.

"Evidence-based treatments from high-quality trials have been adopted rapidly into practice in critical care units in Scotland.

"This includes new treatments, such as dexamethasone and tocilizumab, as well as an increasing role for non-invasive respiratory support in suitable patients."

Survival has improved as the demographics of Covid ICU patients became younger, and new treatment regimes were adopted (Source: SICSAG)

On September 23 - at a point when Covid ICU admissions in Scotland were averaging nine per day, the highest level since February - SICSAG carried out a "snapshot survey" of critical care units.

Charge nurses at all 18 ICU and combined ICU-high-dependency units in Scotland were asked to report their staffing levels and activity on a single day shift. All 18 responded.

The survey found that only 39% of units were able to maintain the recommended nurse-to-patient staffing ratios using ICU-trained registered nurses from within their own unit.

The most seriously ill Level One patients require one-to-one care, or two patients per nurse for less critical patients.

In the remaining units, required staffing ratios were mostly achieved by redeploying registered nurses from other departments into intensive care or by bringing in agency and bank nurses.

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According to the Guidelines for the Provision of Intensive Care Services (GPICS), which set out the clinical standards for ICU delivery in the UK, no more than 20% of registered nurses covering any one shift should be drawn from agency or bank staff.

However, the SICSAG survey found that 22% of Scotland's critical care units were exceeding that threshold.

In addition, only 72% of units were able to retain a supernumerary senior nurse on duty despite GPICS guidelines stipulating that this should always be the case.

This nurse supposed to act as a supervisor who oversees the nursing team to maximise safe practice, without having to manage their own caseload at the same time.

The report states: "This snapshot survey describes nurse staffing on a single day in Scottish ICUs which will vary over time.

"However, it demonstrates that over half of ICUs and combined units in Scotland are currently unable to maintain recommended nurse staffing ratios from within their own staffing complement.

"Two thirds of units are relying on nurses who usually work in other areas of the hospital, or nurses recruited through agencies/staff banks."