Background: As a site of the Thai Anesthesia Incidents Study (THAI Study) of anesthetic adverse outcome, the
authors continued the institutional data collection to determine the incidence and factors related to 24-hour
perioperative cardiac arrest in geriatric patients (aged 65 years and over) representing a Thai university
hospital.

Material and Method: Between July 1, 2003 and March 31, 2007, an anesthesia registry was conducted at
King Chulalongkorn Memorial Hospital. Anesthesiologists and anesthesia residents were requested to record
perioperative variables and adverse outcomes including 24-hour perioperative cardiac arrest on a structural
data record form. Univariable analysis was used to identify factors related to 24-hour perioperative cardiac
arrest. A multivariable generalized linear regression for risk ratio was used to investigate independent
factors with significant association to 24-hour perioperative cardiac arrest. A forward stepwise algorithm
was chosen. A p-value < 0.05 was considered as statistically significant.

Results: Among 54,419 cases in the registry, 8,905 geriatric patients underwent a non-cardiac surgery under
anesthesia. Thirty-six patients experienced cardiac arrest. The incidence of intra-operative cardiac arrest,
within 24 hours postoperative cardiac arrest, and overall 24-hours perioperative cardiac arrest were 18:10000
(mortality rate of 62.5%), 22.5:10000 (mortality rate of 90%), and 40.4:10000 (mortality rate of 77.8%),
respectively. By multivariable analysis, age of 76-85 [RR 2.6 (95% CI: 1.2,5.4)], age > 86 [RR 4.4 (95% CI:
1.7, 11.8)], recent respiratory failure [RR 6.6 (95% CI: 1.9, 22.3)], ASA physical status 3-5 [RR 19.9 (95% CI:
4.6, 86)], emergency surgery [RR 2.8 (95% CI: 1.4, 5.6)], intrathoracic surgery [RR 3.7 (95% CI: 1.4, 9.9)],
upper abdominal surgery [RR 2.8 (95% CI: 1.3, 5.7)], and administration of ketamine [RR 5.4 (95%CI: 1.8,
15.9)] were factors related to 24-hour perioperative cardiac arrest.

Conclusion: The incidence of 24-hour perioperative cardiac arrest of geriatric patients in a Thai university in
the present study was 40.4:10000 anesthetics, which was comparable to others with high mortality rate. Risk
factors for 24-hour perioperative cardiac arrest were older age, ASA physical status 3-5, emergency surgery,
intrathoracic surgery, upper abdominal surgery, recent respiratory failure, and administration of ketamine.
Pre-anesthetic evaluation is important for finding the risks and optimal preparation for preventing perioperative
cardiac arrest in these aging patients.

Keywords: Adverse effects, Aged, Anesthesia, Geriatrics, Cardiac arrest, Intraoperative complications,
Mortality, Postoperative complications, Registry, Risk factors, Patient safety