Department of Neurology, Baylor College of Medicine, Houston, TX, USA. yousefhannawi @ yahoo.com
Cerebrovasc Dis. 2013;35(5):430-43. doi: 10.1159/000350199. Epub 2013 May 31.
Stroke-associated pneumonia (SAP) has been implicated in the morbidity, mortality and increased medical cost after acute ischemic stroke. The annual cost of SAP during hospitalization in the United States approaches USD 459 million. The incidence and prognosis of SAP among intensive care unit (ICU) patients have not been thoroughly investigated. We reviewed the pathophysiology, microbiology, incidence, risk factors, outcomes and prophylaxis of SAP with special attention to ICU studies.
To determine the incidence, risk factors and prognosis of acute SAP, PubMed was searched using the terms 'pneumonia' AND 'neurology intensive unit' and the MeSH terms 'stroke' AND 'pneumonia'. Non-English literature, case reports and chronic SAP studies were excluded. Studies were classified into 5 categories according to the setting they were performed in: neurological intensive care units (NICUs), medical intensive care units (MICUs), stroke units, mixed studies combining more than one setting or when the settings were not specified and rehabilitation studies.
The incidences of SAP in the following settings were: NICUs 4.1-56.6%, MICUs 17-50%, stroke units 3.9-44%, mixed studies 3.9-23.8% and rehabilitation 3.2-11%. The majority of NICU and MICU studies were heterogeneous including different neurovascular diseases, which partly explains the wide range of SAP incidence. The higher incidence in the majority of ICU studies compared to stroke units or acute floor studies is likely explained by the presence of mechanical ventilation, higher stroke severity causing higher rates of aspiration and stroke-induced immunodepression among ICU patients. The short-term mortality of SAP was increased among the mixed and stroke unit studies ranging between 10.1 and 37.3%. SAP was associated with worse functional outcome in the majority of stroke unit and floor studies. Mortality was less consistent among NICU and MICU studies. This difference could be due to the heterogeneity of ICU studies and the effect of small sample size or other independent risk factors for mortality such as the larger neurological deficit, mechanical ventilation, and age, which may simultaneously increase the risk of SAP and mortality confounding the outcomes of SAP itself. The pathophysiology of SAP is likely explained by aspiration combined with stroke-induced immunodepression through complex humeral and neural pathways that include the hypothalamic-pituitary-adrenal axis, parasympathetic and sympathetic systems.
A unified definition of SAP, strict inclusion criteria, and the presence of a long-term follow-up need to be applied to the future prospective studies to better identify the incidence and prognosis of SAP, especially among ICU patients.
卒中相关性肺炎（SAP）与急性缺血性卒中后发病率、死亡率和医疗费用增加有关。在美国，SAP 住院期间的年费用接近 4.59 亿美元。重症监护病房（ICU）患者 SAP 的发病率和预后尚未得到充分研究。我们综述了 SAP 的病理生理学、微生物学、发病率、危险因素、结局和预防措施，特别关注 ICU 研究。
为了确定急性 SAP 的发病率、危险因素和预后，我们使用术语“肺炎”和“神经重症监护病房”以及 MeSH 术语“中风”和“肺炎”在 PubMed 上进行了搜索。排除非英文文献、病例报告和慢性 SAP 研究。根据研究进行的环境，研究分为 5 类：神经重症监护病房（NICUs）、内科重症监护病房（MICUs）、卒中单元、混合研究（结合了多个环境或未指定环境）和康复研究。
以下环境中 SAP 的发生率分别为：NICUs 4.1-56.6%、MICUs 17-50%、卒中单元 3.9-44%、混合研究 3.9-23.8%和康复研究 3.2-11%。大多数 NICU 和 MICU 研究存在异质性，包括不同的神经血管疾病，这在一定程度上解释了 SAP 发病率的广泛差异。与卒中单元或急性病房研究相比，大多数 ICU 研究中 SAP 发病率较高，这可能是由于机械通气的存在、较高的卒中严重程度导致较高的误吸率以及 ICU 患者的卒中诱导免疫抑制所致。混合和卒中单元研究中 SAP 的短期死亡率为 10.1%至 37.3%。在大多数卒中单元和病房研究中，SAP 与较差的功能结局相关。NICU 和 MICU 研究中的死亡率不太一致。这种差异可能是由于 ICU 研究的异质性以及小样本量或其他独立死亡率危险因素（如更大的神经功能缺损、机械通气和年龄）的影响，这些因素可能同时增加 SAP 和死亡率的风险，从而混淆 SAP 本身的结局。SAP 的病理生理学可能通过复杂的体液和神经途径来解释，包括下丘脑-垂体-肾上腺轴、副交感和交感系统，这些途径涉及到误吸和卒中诱导的免疫抑制。
未来的前瞻性研究需要应用统一的 SAP 定义、严格的纳入标准和长期随访，以更好地确定 SAP 的发病率和预后，特别是在 ICU 患者中。
