Hypotension during spinal anaesthesia for Caesarean section in a resourcelimited setting: towards a consensus definition

  • Sabelo F Zwane University of KwaZulu-Natal
  • David G Bishop University of KwaZulu-Natal
  • Reitze Nils Rodseth University of KwaZulu-Natal
Keywords: Caesarean section, hypotension, incidence, neuraxial anaesthesia, regional anaesthesia, spinal anaesthesia

Abstract

Background: Intraoperative hypotension following spinal anaesthesia for Caesarean section is associated with maternal morbidity and mortality. Because of inconsistent definitions the reported incidence of hypotension varies between 7% and 74%, making it almost impossible to set standard targets. Developing and adopting a clinically significant threshold for intraoperative hypotension will allow for benchmarking, comparison between studies, and consistency in guidelines and recommendations.

Methods: Common definitions for spinal hypotension were first identified from a recent systematic review of the literature and a consensus statement on spinal hypotension. These definitions were applied to haemodynamic data taken from a prospective interventional obstetric spinal hypotension study conducted at Edendale Hospital, to determine the incidence of hypotension when applying these different thresholds. Finally, a definition was proposed based on these incidences and a review of the relevant literature.

Results: Fifteen different definitions were identified. These were then applied to the study population with a resultant incidence of hypotension ranging from 15.8% to 91.4%. Based on a literature review of obstetric and other relevant perioperative and critical care medicine, targeting a mean arterial pressure > 70 mmHg and systolic blood pressure > 100 mmHg is recommended, and it is proposed that the lowest absolute values at which vasopressor therapy should be initiated are a mean arterial blood pressure < 65 mmHg or systolic blood pressure < 90 mmHg. Optimally, practitioners should maintain systolic blood pressure at greater than 90% of the baseline pre-spinal anaesthesia value.

Conclusion: This study confirmed a wide variation in the incidence of obstetric spinal hypotension in a South African setting, depending on the definition used. An absolute threshold for intervention with vasopressor and an optimal target relative to baseline blood pressure are suggested. Further work is required to establish the effect of the adherence to these recommendations on important maternal and foetal outcomes.

Author Biographies

Sabelo F Zwane, University of KwaZulu-Natal

Discipline of Anaesthesia and Critical Care, University of KwaZulu-Natal, Durban; and Department of Anaesthetics, Critical Care and Pain Management, University of KwaZulu-Natal, Pietermaritzburg, South Africa

David G Bishop, University of KwaZulu-Natal

Department of Anaesthetics, Critical Care and Pain Management, University of KwaZulu-Natal, Pietermaritzburg, South Africa

Reitze Nils Rodseth, University of KwaZulu-Natal

Department of Anaesthetics, Critical Care and Pain Management, University of KwaZulu-Natal, Pietermaritzburg; and Jones, Bhagwan and Partners, Pietermaritzburg, South Africa

Published
2019-03-01
Section
Research Articles