Background and Goal of Study: Postoperative delirium (PD) relates to increased length of hospital stay and poor outcome including institutionalization, persistent functional and cognitive decline and higher rates of morbidity and mortality. The accurate identification of perioperative risk factors can contribute to design a dedicated work up and to reduce the prevalence of PD. Aim of this literature review is to identify risk factors for PD and to categorize them according timing of occurrence (pre, intra and post operative), susceptibility of correction (modifiable/non-modifiable) and clinical impact (Odds ratio [OR], % increase in incidence of PD).
Materials and Methods:
Preoperative non-modifiable: age >70 years: OR 3.3. Type of surgery: cardiac: OR 3.5; aortic aneurysm: OR 8.3; orthopedic, hip replacement: 16-62%; intra abdominal and intra thoracic: 9.6%. Genetic profile: phenotype Apoe4: 28.3%. Education. Comorbidities. Psychiatric and neurological disorders: presence of dementia: OR 4.2; illicit drug abuse or alcoholism: OR 3.3.
Preoperative modifiable: fluid fasting time >6 hours: OR 10.5. Blood biochemistry abnormalities (sodium, potassium, glycemia, urea nitrogen, serum albumin): OR 4.2. Preoperative premedication with benzodiazepines (each additional mg leads to 7% increase).
Intra operative non-modifiable risk factors: blood loss: hemoglobin < 10 g/L: OR 0.2; whole blood transfusion >800 ml: OR 2.5.
Intra operative modifiable risk factors: opioid: fentanyl 20% (VS remifentanil). BIS-guided anesthesia reduces anesthetics consumption and is associated with lower incidence of PD (24.1% in the control group VS 15.6% in BIS-guided group; P=0.01).
Post operative non-modifiable risk factors: low cardiac output requiring inotropes, new onset atrial fibrillation, persistent hypoxia or hypercarbia.
Post operative modifiable risk factors: use of narcotic analgesics: OR 2.3; benzodiazepine: OR 1.8; cholinergic drugs: OR 1.3. Delayed ambulation, inadequate nutritional status.
Post operative precipitating factors: sensory deprivation (after cataract extraction: 1.7%).
Results and Discussion: The effective identification, prevention and treatment of pre, intra and postoperative risk factors for PD can contribute to select patients that need a dedicated perioperative care path.
Conclusion: Tailored use of anesthetics, anesthesia techniques, nursing surveillance and accurate staff communication can contribute to reduce the incidence and clinical impact of PD.