Fluid and vasopressor management for Cesarean delivery under spinal anesthesia: Continuing Professional Development

Abstract

Purpose The purpose of this Continuing Professional Development module is to review the physiology of maternal hypotension induced by spinal anesthesia in pregnant women, and the effects of fluids and vasopressors. Principal findings Maternal hypotension induced by spinal anesthesia is caused mainly by peripheral vasodilatation and is not usually associated with a decrease in cardiac output. Although the intravenous administration of fluids helps to increase cardiac output, it does not always prevent maternal hypotension. Three strategies of fluid administrations are equivalent for the prevention of maternal hypotension and a reduced need for vasopressors: (1) colloid preload; (2) colloid coload; and (3) crystalloid coload. Crystalloid preload is not as effective as any of those three strategies. Unlike phenylephrine, ephedrine can cause fetal acidosis. Therefore, phenylephrine is recommended as first line treatment of maternal hypotension. A phenylephrine infusion (25-50 lgÁmin -1 ) appears to be more effective than phenylephrine boluses to prevent hypotension, and nausea and vomiting. In preeclamptic patients, spinal anesthesia produces less hypotension than in normal pregnant women and fluid volumes up to 1,000 mL are usually well tolerated. Therefore mild to moderate intravascular volume loading is recommended, keeping in mind the increased risk for pulmonary edema in this population. In pre-eclamptic patients, hypotension can be treated either with ephedrine or phenylephrine, and phenylephrine infusions are not recommended.Conclusion A volume loading regimen other than crystalloid preload should be adopted. A phenylephrine infusion during elective Cesarean delivery is beneficial for the mother and safe for the newborn. Objectives of this Continuing Professional Development (CPD) module:After reading this module, the reader should be able to:1. Describe the main hemodynamic changes induced by spinal anesthesia in a pregnant woman undergoing a scheduled Cesarean delivery. 2. Recognize the clinical implications of those hemodynamic changes in the mother and fetus. 3. Explain the various strategies of vascular loading, and their main hemodynamic repercussions. 4. Assess the impact of using phenylephrine and ephedrine for the prevention and treatment of maternal hypotension. 5. Plan the fluid and vasopressor therapy in the case of an urgent Cesarean delivery.The increased popularity of regional anesthesia in clinical practice has led to a decrease in maternal mortality and morbidity related to complications in airway management. Spinal anesthesia is now the most popular technique for Cesarean delivery as it is easy to perform and provides a rapid onset, dense surgical block. It is not associated with a maternal or fetal risk of toxicity to local anesthetics. However, spinal anesthesia is often associated with significant maternal hypotension, with potentially significant consequences on maternal comfort, organ perfusion, and fetal well-being. Several studies suggest that the traditional approach that con...

Strategies for prevention of spinal-associated hypotension during Cesarean delivery: Are we paying attention?

“…A robust body of literature now exists comprising numerous well-designed clinical trials, evidence synthesis, 7 and editorials on strategies to address hypotension during CD. 3,4,8,9 There is ongoing advocacy for maintenance of preload and avoidance of aortocaval compression. Although colloids have been found to be marginally more effective than crystalloids in this setting, considering the multiple disadvantages of colloids (such as pruritis, cost, and anaphylaxis), crystalloid co-loading is generally preferred.…”

“…Nevertheless, neither colloid nor crystalloid alone has acceptable efficacy in preventing SA-induced hypotension during CD. 8 With this evidence and a better understanding of maternal hemodynamics extrapolated from preeclampsia, the focus has now moved from venous return and maintenance of preload to strategies sustaining the arteriolar tone for maintenance of arterial pressure. 9,10 Contemporary practice in obstetric anesthesia now advocates vasopressor use as the most important strategy to prevent hypotension during CD.…”

“…Un important corpus de littérature existe aujourd'hui, lequel comprend de nombreuses études cliniques rigoureuses, synthèses de données probantes 7 et éditoriaux présentant les diverses stratégies existantes pour prendre en charge l'hypotension pendant une césarienne. 3,4,8,9 Les données s'accumulent pour promouvoir le maintien de la précharge et éviter la compression aorto-cavale. Bien que les colloïdes soient légèrement plus efficaces que les cristalloïdes dans un tel contexte, étant donné les désavantages multiples des premiers agents (prurit, coût, anaphylaxie), l'hydratation concomitante à l'aide de cristalloïdes est généralement privilégiée.…”

“…Toutefois, ni les colloïdes, ni les cristalloïdes seuls affichent une efficacité acceptable pour prévenir l'hypotension induite par la rachianesthésie pendant une césarienne. 8 Grâce à ces données probantes et une meilleure compréhension de l'hémodynamie maternelle extrapolée de la prééclampsie, l'attention s'est aujourd'hui déplacée du retour veineux et du maintien de la précharge vers des stratégies permettant de soutenir le tonus artériolaire afin de maintenir la tension artérielle. 9,10 La pratique contemporaine, en anesthésie obstétricale, préconise dorénavant l'utilisation de vasopresseurs en tant que stratégie principale pour prévenir l'hypotension pendant un accouchement par césarienne.…”

Role of Incisional infiltration with intraperitoneal instillation analgesia in non descent vaginal hysterectomy

“…In hand with the obtained results and this assumption; Loubert [25] found crystalloid preload is not as effective as either of colloid preload; colloid coload or crystalloid coload which are equivalent for the prevention of maternal hypotension and a reduced need for vasopressors. Recently, Mercier et al [26] documented that crystalloid preloading is clinically ineffective and should be abandoned, while crystalloid coloading at the onset of sympathetic blockade is better, but its efficacy may depend on the volume infused and the speed of administration.…”