///2017 Abstract Details
2017 Abstract Details2019-08-02T15:54:53-06:00

Severe and prolonged hypotension during spinal anesthesia for elective cesarean delivery is associated with transient tachypnea of newborn

Abstract Number: F-18
Abstract Type: Original Research

Shubhangi Singh MBBS1 ; Michaela K Farber MD, MS2; Chuan-Chin Huang ScD3; Arvind Palanisamy MBBS, MD4

Introduction: Transient tachypnea of newborn (TTN) is one of the most common causes of respiratory distress in early life, with the risk 6-7 fold higher for infants born via elective cesarean compared to vaginal delivery. Though multiple hypotheses exist to explain this increased risk, no study has explored spinal anesthesia-induced hemodynamic instability as a possible mechanism. Our study aimed to determine the association between perioperative hemodynamic changes and TTN during elective cesarean delivery.

Materials and methods: In this case-control study, we reviewed the anesthesia records of all elective cesarean deliveries between July 2015 and January 2016 after IRB approval. We excluded women with pregnancy induced or chronic hypertension, diabetes, and babies with known congenital anomalies. Patients received spinal anesthesia according to institutional protocol. We defined intraoperative hypotension as SBP (systolic blood pressure) < 100 mmHg or < 80% of baseline SBP, and severe hypotension as either SBP < 90 mmHg or MAP (mean arterial pressure) < 65 mmHg prior to delivery. Demographic data, details of anesthetic management, degree and duration of hypotension, and total vasopressor requirement (as phenylephrine equivalents) were abstracted. Data were analysed with either Fisher’s exact or student’s t-test as appropriate and expressed as mean ± SD; P < 0.05 was accorded statistical significance.

Results: Overall, we identified 30 cases (Group T) and controls (Group C). Baseline characteristics such as maternal age, body mass index, gestational age, and neonatal birth weight were comparable between groups. The proportion of patients with post-spinal hypotension was not different between groups (26/30 vs. 29/30, Groups T and C, respectively; P=0.35). There was a trend towards a higher incidence of severe hypotension in Group T (20/30) compared to C (12/30) (P=0.07). Both SBP and MAP nadirs were more severe in Group T compared to Group C (83±14 and 60±10 vs. 91±12 and 66±8, mmHg; P=0.014 and 0.025, respectively). Furthermore, the duration of time when SBP < 90 mmHg was significantly higher in Group T (2.4 ± 2.7 min) compared to Group C (0.8 ± 1.4 min) (P=0.005). Similarly, the duration of severe hypotension (MAP < 65 mmHg) was also significantly higher in Group T (2.3 ± 2.8 min) than Group C (1.03 ± 1.8 mins) (P=0.046). Finally, total vasopressor use in terms of phenylephrine (µg) equivalents was significantly higher in Group T (663.95 ± 426.38) compared to Group C (298.85 ± 205.85) (P<0.001).

Conclusions: Our study provides convincing evidence that both the duration and the degree (lowest SBP and MAP attained) of severe maternal hypotension (SBP < 90 and MAP < 65 mmHg) following spinal anesthesia are associated with TTN during elective cesarean delivery. Our findings lend further evidence to support the prevailing notion of pre-emptive, rather than reactive, blood pressure control during elective cesarean delivery.

SOAP 2017