Prevalence Of Incidence, Risk Factors And Outcome Of Delirium In Critically Ill Patients With Mechanical Ventilation

Background and Objective:Delirium is an acute attack syndrome, characterized by declined conscious clarity, attention ability and orientation, with an appearance of emotional stress or dull state, sleep-wake cycle confusion, and delusion or hallucination. Many critically ill patients experienced delirium, but former data show only16%doctors used delirium assessment tools, resulting in misdiagnose, There are more less nationwide data about the incidence, risk factors and outcome of delirium due to the misunderstanding of the disease. It is usually ignored because it is considered to be common, reversible, non-organic and has no effect on prognosis, and attributed to noncooperation of the patients or just emotional instability, so in most of the ICUs, delirium would not be assessed, or even not be diagnosed, let alone be treated. But in fact, delirium could result in worse outcomes including increased mortality, prolonged mechanical ventilation time or total hospital stay, and higher medical expenses. Effective prevention and treatment of delirium can reduce nosocomial infection, mechanical ventilation time and mortality. As an effective way of treating respiratory failure, mechanical ventilation, however, can make patients at a higher risk of delirium due to tracheal intubation and limb constraints. We should find an effective way to prevent mechanical ventilation related delirium.We conducted a prospective investigation on incidence, high risk factors and prognosis in patients with mechanical ventilation, so as to provide an evidence for early identification, prevention and diagnosis of delirium.Objects and Methods:Consecutive patients with Mechanical Ventilation in the department of Critical Care Medicine of Taizhou Enze Medical Center from January2012to December2012. Inclusion criteria:Tracheal intubated patients under mechanical ventilation. Excluding who meet the exclusion criteria. A sedation assessment tool, Richmond Agitation and Sedation Scale (RASS), was evaluated at9:00a.m. Those patients who rated-3through+4on RASS were screened for delirium according to the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) criteria by psychiatrists. A patient who was diagnosed delirium once was considered having occurred delirium once. Patients would be divided into the delirium group and the non-delirium group according to whether they have delirium or not. Characteristic data including the patients’age, gender, Acute Physiology and Chronic Health Evaluation II Turner syndrome (APACHE II), diagnosis, blood gas analysis, electrolyte, duration of mechanical ventilation were collected. Multi-factor regression model was used to analyze the relevant clinical characteristics to identify the risk ones. For the delirium group, Mortality of the follow-up90days after inclusion was also analyzed. Mortality of the follow-up90days after inclusion was also analyzed. Adjust the profiles like severity of the disease, sex, age, etc. to analyze the effect of delirium, type, frequency, and the first occurrence time on the mortality within90days. Results:1. In the total472cases,306cases suffered from delirium, and the incidence of delirium was64.83%, among which114cases were hypoactive delirium (37.25%),112cases were delirium of mixed type (36.60%), and only80cases were hyperactive delirium (26.14%).2. Higher APACHE II score, prolonged mechanical ventilation, older age and midazolam sedation are independent high risk factors of delirium, on the contrary, programmed sedation is the independent low risk factor.3. Higher APACHE II score, delirium and MODS are independent high risk factors of death.4. In the delirium group, the death rate was37.25%in a90days follow-up study, while the death rate of the non-delirium group was13.25%. There was a significant difference between these two groups for survival rate (P<0.05). Hazard ratio in the delirium group was4.07compared with the non-delirium group.5. The death rate of hyperactive delirium was22.50%in a90days follow-up study; while the hypoactive and mixed type delirium group was46.90%in total. There was a significant difference between these two groups for survival rate (P<0.05). Hazard ratio in the hypoactive and mixed type delirium was2.24compared with hyperactive delirium.6. For patients having suffered from delirium for once or twice, the death rate was20.69%in a90days follow-up study; while the ones having suffered from delirium for3-4times with a death rate of30.65%, and those having suffered from delirium for≥5times with a death rate of61.05%. There was a significant difference among these three subgroup for survival rate (P<0.05). Compared with the patients who have suffered from delirium for once or twice, the mortality hazard ratio of the ones having experienced delirium for3-4times and≥5times were1.45and1.63respectively.7. For those patients with delirium already existing at the very beginning of mechanical ventilation, the death rate was34.94%in a90days follow-up study, while the death rate of the ones who had the first incident within1-3days after mechanical ventilation was39.44%and35.80%for those with delirium occurring after more than3days. There was no significant difference among these groups for survival rate (P>0.05).Conclusions:1. The incidence rate of delirium is relatively higher in patients with mechanical ventilation, and it was mainly hypoactive type.2. High APACHE Ⅱ score, prolonged mechanical ventilation, patients of advanced age and midazolam sedation are independent high risk factors of delirium in patients with mechanical ventilation; programmed sedation is the independent low risk factor.3. Delirium is an independent high risk factor which results in death of patients with mechanical ventilation, especially hypoactive or mixed type delirium, and those suffering from recurrent attacks. The time of the first incident of delirium has nothing to do with the patient’s mortality.