The literature paints a complex picture of the association between mortality risk and ICU strain. In this study, we sought to determine if there is an association between mortality risk in intensive care units (ICU) and occupancy of beds compatible with mechanical ventilation, as a proxy for strain. A national retrospective observational cohort study of 89 English hospital trusts (i.e. groups of hospitals functioning as single operational units). Seven thousand one hundred thirty-three adults admitted to an ICU in England between 2 April and 1 December, 2020 (inclusive), with presumed or confirmed COVID-19, for whom data was submitted to the national surveillance programme and met study inclusion criteria. A Bayesian hierarchical approach was used to model the association between hospital trust level (mechanical ventilation compatible), bed occupancy, and in-hospital all-cause mortality. Results were adjusted for unit characteristics (pre-pandemic size), individual patient-level demographic characteristics (age, sex, ethnicity, deprivation index, time-to-ICU admission), and recorded chronic comorbidities (obesity, diabetes, respiratory disease, liver disease, heart disease, hypertension, immunosuppression, neurological disease, renal disease). One hundred thirty-five thousand six hundred patient days were observed, with a mortality rate of 19.4 per 1000 patient days. Adjusting for patient-level factors, mortality was higher for admissions during periods of high occupancy (> 85% occupancy versus the baseline of 45 to 85%) [OR 1.23 (95% posterior credible interval (PCI): 1.08 to 1.39)]. In contrast, mortality was decreased for admissions during periods of low occupancy (< 45% relative to the baseline) [OR 0.83 (95% PCI 0.75 to 0.94)]. Increasing occupancy of beds compatible with mechanical ventilation, a proxy for operational strain, is associated with a higher mortality risk for individuals admitted to ICU. Further research is required to establish if this is a causal relationship or whether it reflects strain on other operational factors such as staff. If causal, the result highlights the importance of strategies to keep ICU occupancy low to mitigate the impact of this type of resource saturation.

中文翻译：

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机械呼吸机兼容床位占用与重症监护 COVID-19 患者死亡风险之间的关联：一项全国回顾性队列研究

文献描绘了死亡风险与 ICU 压力之间关系的复杂图景。在这项研究中，我们试图确定重症监护病房 (ICU) 的死亡风险与机械通气兼容床位占用率之间是否存在关联（作为压力的替代指标）。对 89 家英国医院信托机构（即作为单一运营单位运作的医院集团）进行的一项全国回顾性观察队列研究。2020 年 4 月 2 日至 12 月 1 日（含）期间，英格兰 ICU 收治了 7133 名疑似或确诊患有 COVID-19 的成年人，这些人的数据已提交给国家监测计划并符合研究纳入标准。使用贝叶斯分层方法对医院信任水平（机械通气兼容）、床位占用率和院内全因死亡率之间的关联进行建模。结果根据单位特征（大流行前规模）、患者个体人口统计特征（年龄、性别、种族、剥夺指数、入住 ICU 的时间）以及记录的慢性合并症（肥胖、糖尿病、呼吸系统疾病、肝脏疾病）进行了调整。疾病、心脏病、高血压、免疫抑制、神经系统疾病、肾脏疾病）。观察了 135,600 个患者日，死亡率为每 1000 个患者日 19.4 例。调整患者层面的因素后，高入住率期间入院的死亡率较高（> 85% 入住率，而基线为 45% 至 85%）[OR 1.23（95% 后置可信区间 (PCI)：1.08 至 1.39）]。相比之下，低入住率期间的入院死亡率有所下降（相对于基线< 45%）[OR 0.83（95% PCI 0.75 至 0.94）]。与机械通气兼容的床位占用率的增加（操作压力的代表）与入住 ICU 的患者更高的死亡风险相关。需要进一步研究以确定这是否是因果关系，或者是否反映了员工等其他运营因素的压力。如果存在因果关系，则结果凸显了保持 ICU 占用率较低的策略的重要性，以减轻此类资源饱和的影​​响。