Background and Goal of Study: Postoperative delirium (POD) is the most commonly encountered serious mental disturbance in the postoperative period. Adverse respiratory events (ARE) remain one of the most important major causes of morbidity and mortality during the postoperative period. The purpose of this study was to assess the incidence of critical respiratory events amongst patients who developed POD.
Materials and Methods: Observational prospective study approved by the Centro Hospitalar São João Ethics Committee and written informed consent was obtained. It was conducted in a Post Anesthesia Care Unit (PACU) during a 6-week period. Inclusion criteria were as follows: all consecutive adult Portuguese-speaking patients submitted to elective non-cardiac, non-obstetrics and non-neurological surgery admitted to the PACU; a total of 221 patients were enrolled to the study. Demographics data and perioperative variables were recorded. Acute respiratory events were defined as upper-airway obstruction, hypoxia (mild/moderate and severe), respiratory failure, inability to breathe deeply, respiratory muscle weakness, reintubation and pulmonary aspiration after tracheal extubation. Descriptive statistics was used to summarize data and the Mann-Whitney U test, Fisher's exact test or Chi-square test were used. Each patient included was evaluated for diagnosis of POD using the Nursing Delirium Screening Scale (NUDESC) in the PACU and on the first postoperative day.
Results and Discussion: Postoperative delirium incidence in the PACU was 11.3% (95% Confidence Interval 7.1-15.5). Postoperative ARE occurred in 37 patients (17%). Patients with POD had more frequently overall critical respiratory events (32% versus 15%, p=0.030), mild-moderate hypoxemia (24% versus 10%, p=0.033) and respiratory muscle weakness (24% versus 10%, p=0.033). There were no significant differences for the other considered ARE: upper-airway obstruction (p=0.696), severe hypoxemia (p=0.617), respiratory failure (p=0.617) and inability to breathe deeply (p=0.730). There were no reintubations and pulmonary aspiration after tracheal extubation.
Conclusion(s): This study suggests that POD is common in the Post Anesthesia Care Unit and was associated more frequently with critical respiratory events.