Controlled Hypotension for Middle Ear Surgery: A Comparative study among Dexmedetomidine, Magnesium Sulphate and Nitroglycerin.

Abstract

Controlled hypotensive anesthesia represents a great challenge for the anesthetists. It is the elective lowering of arterial blood pressure. The primary advantages of this technique are minimization of surgical blood loss and better wound visualization. Studiesstated a decrease of MAP of 50 to 65 mmHg or a 30% reduction of baseline MAP at the surgical site was believed to decrease blood loss significantly. There are manytechniques to deliberate hypotention as physiological, mechanical and pharmacological methods. In Pharmacologicalmethods reducing BP act either by lowering the systemic vascular resistance (SVR) or by lowering the cardiac output (CO). The ideal pharmacological agent for controlled hypotension would have: • Ease of administration. • Predictable and dose dependent effect. • Rapid onset and recovery from effect. • Quick elimination without production of toxic metabolites • Minimal effects on blood flow to vital organs • The ideal agent should not increase the brain size or affect cerebral auto regulation. Monitoring of Hypotensive Anesthesia should be done by: • Blood pressure measurement. • Electrocardiography. • Gas exchange. • Monitoring of central venous pressure. • Blood gases. • Acid-base balance. • Urine output. • Cerebral blood flow monitoring. When a clear indication for hypotensive anesthesia exists, several relative contraindications must be considered such as hypertension, myocardial ischemia, cerebrovascular diseases, respiratory diseases, Diabetes mellitus, Renal and liver dysfunction, congestive heart failure, anemia, pregnancy and old age. This study included sixty-three patients who underwent microscopic middle ear surgery, they were enrolled after provision of consent to partici