COLLOID PRELOAD COMBINED WITH PROPHYLACTIC

Colloid Preload Combined with Prophylactic

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Table of Contents

Introduction3

Non-Pharmacological Methods4

Patient Positionin4

Mechanical Methods5

Intravenous Fluid Prehydration (Preload)5

Pharmacological Methods6

Modification Of Spinal Technique6

Vasopressors6

Choice of Vasopressor6

Reactive use of vasopressors: treatment of hypotension7

Proactive use of vasopressors: prevention of hypotension7

Intramuscular injection8

Intravenous Bolus8

Intravenous Infusion9

Combination Methods10

Literature Review11

Methodology19

Statistical Analysis23

Determinants of Fetal Oxygen Delivery25

References26

Abstract

Spinal anaesthesia was introduced in to clinical practice by German surgeon Karl August Bier in 1898.1 More than a century has passed and today it is one of the most popular techniques for lower limb and lower abdominal procedures, including caesarean section. However one of its important and predicted physiological effect is hypotension.2 The incidence of hypotension has been reported to be 92% in an untreated control group undergoing caesarean section with a spinal anaesthetic.3 Maternal hypotension during spinal anaesthesia is responsible for fetal bradycardia4 and acidosis.5 Even a mild drop in blood pressure must be avoided in high risk patients such as the elderly and in those with underlying organ dysfunction in whom the autoregulatory mechanism may be abnormal. The most important question that seeks attention is its prevention. Mechanical methods, volume loading and vasopressors have been tried from time to time with variable results.6 Most of the studies are centered around the effects of preloading or vasopressors. In our study we evaluated in a double blinded manner the efficacy of combined use of preloading and vasoconstrictors for prevention of spinal hypotension when compared to preloading or vasoconstrictors alone.

Colloid Preload Combined with Prophylactic Intramuscular Injection of Vasopressor Medication to Prevent Spinal Induced Hypotension

Introduction

Hypotension remains the commonest problem of spinal anaesthesia in obstetrics. Although its exact incidence varies according to definition and technique, it is estimated to be greater than 80% during elective Caesarean section. When hypotension occurs, it is unpleasant for the mother as it is commonly associated with nausea, vomiting and dizziness and is one of the likely factors contributing to the large incidence of fetal acidosis reported for spinal anaesthesia for Caesarean section. Hypotension in obstetric regional anaesthesia has been the subject of research for decades yet, surprisingly, it still remains an important clinical problem. Clinicians are divided on the best pharmacological and non-pharmacological methods to manage hypotension and whether these methods should be applied prophylactically (proactive) or as treatment (reactive). This talk will highlight controversies and recent research in this area. The relative merits of different methods of managing hypotension will be evaluated with a focus on the use of vasopressors.

Non-Pharmacological Methods

Non-pharmacological methods for preventing hypotension have been historically popular because of concern that vasopressors might have detrimental effects on uteroplacental circulation. Many methods have been described but all suffer from limited efficacy.

Patient Positionin

Avoidance of aortocaval compression by left uterine displacement is accepted as routine. Its omission complicates interpretation of the results of some older studies.

Mechanical Methods

The main mechanical method described is lower limb compression to augment circulating volume. Although this has been shown to have some efficacy, the technique has not gained popularity probably because it is not viewed as convenient.

Intravenous Fluid Prehydration (Preload)

Intravenous prehydration ...