Deliberate Hypotension (PART 3)

NITROGLYCERIN (TNG) (2,6) Niroglycerin is organic nitrate that acts principally on venous capacitance vessels to produce peripheral pooling of blood,reduction of heart size and decreased cardiac ventricular wall tension. Continuous intravenous infusion of TNG via special delivery tubing to reduce absorbtion of the drugs into plastic,is an ideal approach to maintain a constant plasma concentration of TNG. TNG induced venous dilatation and increased venous capacitance,decreases venous return to the heart(e.g.preload)resulting in reduced ventricular and diastolic pressure and volume and therefore decreases myocardial oxygen requirement (Greenberg et al 1975). In addition...

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Deliberate Hypotension (PART 2)

PHYSIOLOGIC EFFECTS ON VITAL ORGAN:(1) I.Brain : a.Cerebral metabolism may not be at usual levels during     hypotensive period if the blood pressure is very low and     the patient is in the head up position. b.When the blood pressure is reduced below 60 torr,     additional cerebrovasodilatation is not possible.    Therefore lower levels of blood pressure may be     accompanied by a reduction in cerebral blood flow. c.Oxygen consumption does not change significantly. d.Mental function may be altered to a minor degree in the    post operative period however this usually transient.  II.Heart...

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Deliberate Hypotension (PART 1)

INTRODUCTION : Deliberate(controlled)(induced) hypotension has been the special province of neuroanesthetist and has been used to decrease the likelihood of rupture by decreasing aneurysmal transmural pressure, mechanically improving the approach to, handling and actual clipping of the aneu rysm and reducing bleeding should it occurs.(3) This method is potentially dangerous therefore who  intend to use it should be thoroughly conversant with   the farmacology and physiology involved. Before selecting this method one must be sure the advantages outweight. The disadvantages following a thorough review of all the facts. The preparation of the comprenhensive...

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