Time taken to wake post sedation hold and the impact on functional performance at intensive care unit (ICU) discharge: Do COVID rehabilitation phenotypes exist?

ABSTRACT

Introduction: The COVID-19 pandemic caused a sudden and unprecedented surge in ICU admissions for severe acute respiratory failure. Whilst there is a wealth of knowledge surrounding risk factors for developing critical care myopathy and effects of prolonged ICU stay on functional outcomes,1,2 little was known about the pathophysiology, treatment or physical outcomes of patients admitted to ICU with COVID-19. In our organisation, patients recovering from the acute phase of COVID-19 demonstrated a range of presentations impacting rehabilitation whist in ICU. Objective: To explore whether time taken to wake post sedation hold impacts on functional outcomes of patients surviving ICU admission for COVID-19. Methods: A retrospective review of patients admitted to ICU with a primary diagnosis of COVID-19 between March-April 2020 was conducted at a large London NHS Foundation Trust. Electronic clinical notes were reviewed and the following data extracted age, ethnicity, sex, BMI, pre-admission clinical frailty score, duration of sedation, days taken to wake from sedation, duration of mechanical ventilation (MV), ICU length of stay (LOS) and hospital LOS. Functional outcomes were defined using the Intensive Care Unit Mobility Score (ICUMS). Data were analysed using descriptive statistics, reported as absolute numbers, percentages (%) and median (range). Results: 203 patients were identified, 137 were excluded as 58 died, 3 were incidental findings of COVID-19, 67 had missing data due to paper notes or transfers in/out of the Trust and 9 were duplicate records. Sixty-six patients were included in the final analysis (Table 1). Patients could be categorised into four rehabilitation groups 1 = Never requiring sedation and MV, 2 = Woke from sedation (defined as RASS ≥-1) within 72 hours with preserved muscle power (defined as ICUMS ≥5 on ICU discharge), 3 = Woke from sedation within 72 hours but myopathic (defined as ICUMS ≤4 on ICU discharge), 4 = Slow to wake (> 72 hrs). Those slow to wake following sedation hold (group 4) had an increased age, BMI, and higher proportion of nonwhite ethnicity. Neuromuscular blocking agents (NMBA) and steroid use was more prevalent in group 4 compared to the other groups. There was also increased midazolam administration and higher number of total sedative agents received by these patients. Those slow to wake had a lower ICUMS at ICU discharge than those waking with preserved strength or never sedated (3, 6, 9 respectively). Those who were slow to wake were ventilated for longer than the other groups. Time taken to wake from sedation also resulted in longer ICU and hospital LOS. Similar functional outcomes at hospital discharge were noted between all 4 groups (Table 1). Conclusion: Patients slow to wake from sedation following ICU admission for a primary diagnosis of COVID-19 had a longer ICU LOS, reduced functional ability at ICU discharge and a longer hospital LOS. These preliminary observational clinical data support the testable hypothesis that within in the ICU, COVID rehabilitation phenotypes may exist which warrants further investigation.