This retrospective cohort study approved by the institutional review board (IRB) enrolled survivors of OHCA victims from January 1999 to May 2004. We reviewed both electronic and handwritten medical records of OHCA patients, who were successfully resuscitated in the emergency department (ED) and admitted to the intensive care unit (ICU) of the university hospital from January 1999 to May 2004. This university hospital is a tertiary referred center hospital with about 100,000 ED visits per year [1, 7]. The successfully resuscitated OHCA patients were admitted to the ICU and received postresuscitation care. Eligible samples were from nontraumatic OHCA patients who survived more than 24 h and were older than 18 years old.
From the individual charts we collected the following information: underlying comorbidity (preexisting medical conditions in addition to OHCA), the possible cause and initial electrocardiographic (ECG) rhythm of cardiac arrest, the duration of cardiopulmonary resuscitation (CPR), the presence of witnessed collapse and bystander CPR, the best Glasgow Coma Score (GCS), and highest Acute Physiology and Chronic Health Evaluation (APACHE) II score in the first 24 h after ROSC, mean blood pressure 30 min after ROSC, leukocyte count sampled at resuscitation, development of infection in the first 7 days after ROSC, and laboratory and radiological findings. We also collected the timing of antibiotic administration. The presence or absence of witnessed aspiration, diarrhea, and GI bleeding during the first 24 h after ROSC were recorded. The hospital mortality and the hospitalization duration of the survivors were also recorded.
The causes of OHCA were divided into two major parts, namely cardiac causes and noncardiac causes. The cardiac causes included acute coronary syndrome and fatal arrhythmia without electrolyte imbalance. The noncardiac causes included respiratory cause, infectious cause, massive GI bleeding, hyperkalemia, central nervous system (CNS) lesion, and others. Respiratory events included asthma attack, chronic obstructive lung disease with exacerbation, sputum impaction, and suffocation. Infectious causes were considered when previously existing infections were noted at ROSC and no other cause of OHCA could be found. Massive GI bleeding was recorded when hematemesis or bulky tarry stool with profoundly decreased hemoglobin level (<8 gm/dl). Hyperkalemia was considered when blood potassium level exceeded 6 mmol/l, and no other OHCA cause could be found. CNS lesions included brainstem infarct, cerebral ischemic infarct, and subarachoid hemorrhage documented by brain image, such as brain computed tomography (CT) and magnetic resonance image.
The events occurred within 24 h after ROSC were defined as following: witnessed aspiration was defined when such event was documented in the chart; diarrhea was defined as one or more liquid stools per hour within 3 h according to the nurse’s recording; GI bleeding was considered when the guaiac test was positive for stool sample or nasogastric tube drainage. Patients discharged with full GCS (15 points) were considered to have good neurological recovery.
Pneumonia was defined by the presence of new pulmonary infiltrate on chest radiography, persistent for at least 48 h plus two of the followings: body temperature higher than 38.5°C or lower than 35°C, leukocyte count higher than 10,000/µl or lower than 3,000/µl, purulent sputum or change in the character of the sputum. Ventilator-associated pneumonia was considered when a patient on mechanical ventilation at least 48 h developed pneumonia without initial pulmonary infiltrate at ROSC [8, 9]. Urinary tract infection (UTI) was defined by the presence of pyuria plus isolation of more than 105 organisms per milliliter of urine. Bacteremia was defined as positive blood cultures for at least two sets at separate sites or single blood culture with clinical compatibility. Coagulase-negative staphylococci and other common skin flora isolated in single blood culture without clinical risk and compatible disease course were judged as contamination [10, 11, 12, 13]. Intra-abdominal infection was considered when the leukocyte of the ascite was more than 250/µl, or imaging studies of the abdomen including ultrasonography and CT showed swollen or perforated bowel in a febrile patient. Vascular catheter-related infection was defined by positive catheter culture (≥15 colony forming units on semiquantitative culture) considered to be the source of infection. Skin defect associated Infections were defined by the presence of pus and inflammation of the site. Empyema was considered when pleural effusion showed frankly pus plus positive Gram’s stain.
There were 898 OHCA patients in the university hospital during the review period. Of these, 374 gained ROSC; 288 were admitted to ICU. We collected 174 non-traumatic adult patients who were admitted to the ICU of the university hospital. Fifty-six patients survived less than 24 h and one patient with missing data were excluded from final analyses. Finally, 117 patients were included in the study. Figure 1 presents the flow diagram. Their mean age was 71.7±15.4 years; there were 55 men and 62 women. The cardiac causes accounted for one-fourth of OHCA (n=29, 25%). Asystole was the most common initial rhythm of ECG (n=77, 66%) followed by pulseless electrical activity (n=26, 22%) and ventricular tachycardia/fibrillation (n=14, 12%). Forty-five patients (38%) survived hospitalization. Among survivors six patients (5%) were discharged with full GCS (15 points), and 23 (19%) were dependent on others for daily support due to moderate to severe overall disability. Sixteen patients (14%) entered a vegetative state when discharged. Patients were divided into two groups, those with (n=83) and those without infection (n=34), according to the presence or absence of any documented infection in the first 7 days after ROSC. Table 1 compares the demographics, resuscitation condition, and outcome in the two groups. There were more patients with dementia and the noncardiac causes of cardiac arrest in the infection group. All the patients with dementia had infection.
Data were saved in a Microsoft Excel database (Excel 2002; Microsoft, Seattle, Wash., USA) and then analyzed with SPSS software for Windows (release 10.0, SPSS, Chicago, Ill., USA). Mean and standard deviation values were used to describe approximately normally distributed data. Student’s t test was used for comparisons of normally distributed continuous data of the two groups. Binomial variables were analyzed by the χ2 or Fisher’s exact test. Survival curves were determined by the Kaplan-Meier method. The log-rank test was used to compare curves. A p value less than 0.05 was regarded as statistically significant.