الفهرس 
Hypotensive Anesthesia & TechniquesOnly 14 pages are availabe for public view
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Abstract
Controlled hypotensive anaesthesia represents a great challenge for the anaesthetists. 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.
Aken and Miller stated 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 many Techniques to deliberate Hypotention as physiological , mechanical and pharmacological methods.
In Pharmacological methods 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 anaesthesia 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, anaemia, pregnancy and old age.The study included sixty three patients underwent microscopic middle ear surgery, they were enrolled after provision of consent to participation. Patients ranged between the ages of twenty and fifty years. All patients were classified as ASA I and II.
After induction of anesthesia, 63 patients were randomly assigned to one of three groups:
Group L (21 patients): for labetalol.
Group D (21 patients): for dexmedetomidine.
Group N (21 patients): for nitroglycrin.
ASA monitoring for Patients was done using electrocardiography (ECG), non- invasive blood pressure, pulse oximetry and capnography.
The primary outcome measure was the amount of blood in the surgical field.
The secondary outcome measures were the overall surgeon’s satisfaction with the operative conditions, anesthetic requirements and occurrence of undesirable effects.In our study, it was confirmed that dexmedetomidine cause significant excellent surgical field and significant surgeon satisfaction compared to other groups. It also causes sedation effect so no extra doses of fentanyl or propofol was used so patient according to Ramsay score awaked sedated with no pain.
Also our study showed that, nitroglycrin caused the worset surgical field and worst surgeon satisfaction as it showed reflex tackycardia which obviously obscured the surgical field so it was counteracted by extra doses of fentanyl which affect Ramsay sedation score post operatively. Some cases showed nusea & vomiting in post operatively.
Also according to our study labetalol showed more hypotension and more bradycardia than dexmedetomidine, but it did not affect the patients clinically, in some cases we gave atropine and ephedrine . Surgical field was good but not better as dexmedetomidine, surgeon satisfaction was good.
Also It had no sedation effect, no extra doses of fentanyl or propofol was in need to control MAP, so patients awaked postoperatively fullyconcious or agitated or in pain. It showed in some cases post-operative hypotension, bradycardia, nusea and vomiting.