Abstract

Background: Postoperative hemodynamic adverse severe events (PHASE, severe bradycardia and hypotension) can occur during recovery from spinal anesthesia. The incidence, contributing factors and consequences of PHASE are not well described.

Methods: 232 consecutive patients were included in this prospective observational study. PHASE was defined as a combination of heart rate < 45 bpm, and systolic blood pressure < 70 mmHg. Correlation analysis was used to identify potential predictors of PHASE and then a multivariate logistic regression model was constructed to evaluate independent predictors of PHASE. PACU lengths of stay between patients with and without PHASE were compared.

Results: Fifteen patients presented with severe hypotension (SBP 64.5±10.6 mmHg) and twelve patients with severe bradycardia (heart rate of 40±5 bpm), resulting in PHASE in 10 patients. PHASE occurred on average 307±82 min after spinal anesthesia with a mean spinal anesthesia level of L1 at the time of PHASE. Insertion of spinal anesthesia in the lateral position (PHASE: 80%, no PHASE: 34%, p=0.030) as well as morphine dose (20±12mg versus 9±8 mg, respectively p=0.011) were found to be independently associated with PHASE. PHASE was associated with a 60 minute increase in median PACU length of stay.

Conclusion: PHASE occurs in about 5% of patients recovering from spinal anesthesia. The average time for PHASE onset is 307±82 min. The events are associated with insertion of spinal anesthesia in the lateral compared with sitting position, and with postoperative opioid administration. PHASE during recovery from spinal anesthesia is associated with significantly increased PACU length of stay.

Key words: spinal anesthesia, postoperative care, hypotension