COMPARISON OF EPHIDRINE INFUSION WITH FLUID PRELOADING: PREVENTION OF HYPPOTENSION DURING CAESAREAN SECTION UNDER SUB ARACHNOID BLOCK
Lt. Col. Apple Mahmud Anwar*, Lt. Col. Nasrin Hasan and Lt. Col. Abu Hasnat MD Habibur Rahman
Subarachnoid block in caesarean section has become a popular technique. Its popularity has grown further due to introduction of narrower gauge spinal needle. This has remarkably lessened the incidences of postdural puncture headache. But the most common serious problem associated with subarachnoid block in caesarean section is rapid onset of profound hypotension. The anaesthetic texts continue to emphasize both uterine displacement and intravenous volume preloading prophylactic measures to reduce the incidence of hypotension. Recent invasive studies have confirmed the decrease in cardiac output associated with the supine position and hence, the mandatory use of lateral tilt. However the incidences of hypotension varying between 4.1% and 83%, may compromise the welfare of both mother and foetus. The acceptable explanation of these are excess peripheral vasodilatation resulting from sympathetic block leading to decreased venous return enhanced by pre-existing pregnancy induced low vessel tone, induced by falling of gravid uterus on inferior vena cava. Marx and co-workers suggested that hypoglycaemia might be a factor involved in the genesis of hypotension during regional anaesthesia, especially when the parturients fasting period is prolonged beyond 11 hours. Various prophylactic measures have been taken to prevent the incidence and severity of hypotension andrelated untoward effects include intravascular volume expansion using IV fluid (preload) immediately before spinal anaesthesia, use of left lateral tilt or manual uterine displacement, or both, and administration of IV fluids and IM or IV vasopressor drugs both prophylactically and in response to the cardiovascular changes subsequent to neural block. The rate of administration, total volume and type of fluid used remain controversial. Volumes in excess of 2 litre have been infused rapidly and while the normal healthy patient can tolerate this without difficulty, there may be problems if practice routinely. Colloids may stay in the intravascular compartment longer but is more expensive and some of the solutions confer small but significant risk of anaphylaxis. It may also affect blood grouping and cross-matching, so caesarian section patient where blood transfusion is essential may be problematic. The aim of the study was to evaluate the efficacy of ephedrine infusion to replace the conventional preblock crystalloid administration in reducing the incidence of hypotension during spinal Anaesthesia.
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