A Comparison of Labetalol and Nitroglycerin for The Management of Intraoperative Hypertension in Ambulatory Surgical Patients Who Underwent Cataract Surgery

Background: This is a prospective randomized blinded clinical trial comparing the efficacy and safety of labetalol and nitroglycerin for the management of intraoperative hypertension in ambulatory surgical patients who underwent cataract surgery. Methods: A total of 80 hypertensive patients (systolic blood pressure> 200 mmHg or diastolic blood pressure>100 mmHg) who had increased blood pressure during cataract surgery under topical anesthesia were reviewed. Patients were randomized to receive nitroglycerin (group N, n=40) or labetalol (group L, n=40). The initial dose of nitroglycerin was a bolus of 2 µg/kg and repeat dose of 1ug/kg intravenously every 5 minutes. Labetalol was administered as a bolus of 5 mg followed by 5 mg intravenously as needed every five minutes up to maximum dose of 1 mg/kg. Results: Systolic blood pressure decreased from 21.4±8.6 mm Hg (200 to 260 mm Hg) to 18.8±6.4 mm Hg with administration of nitroglycerin. Labetalol reduced systolic blood pressure from 21.4±6.7 mm Hg (201 to 258 mm Hg) to 17.6±11.6 (p=0.02). Nitroglycerin increased baseline heart rate from 68±8 beats/min to 82±6 beats/min (p=0.04), however, in the labetalol group heart rate reduced from control 72±6 to 64±9 beats/min (P<0.05). The hypotension episode was 18 (45%) cases in the nitroglycerin group and 2 (5%) cases in the labetalol group respectively (p<0.05). The mean of systolic blood pressure during their stay in the recovery room in nitroglycerin group was 20.7±9.6 mm Hg and in labetalol group was 18.5±10.2 mm Hg (p<0.05). Conclusion: Nitroglycerin may produce reflex tachycardia and episode of hypotension especially in elderly patients intraoperatively. Labetalol is a safe and effective antihypertensive agent for management of increased blood pressure during cataract surgery with topical anesthesia.

Effects of Automatic Blood Volume Control over Intradialytic Hemodynamic Stability

Due to the crucial role of hypovolemia in the genesis of dialysis-induced hypotension, we have evaluated whether the automatic control of the intradialytic blood volume (BV) decrease along a preset trajectory might be beneficial to the hemodynamic stability during treatment. Five frequently hypotensive HD patients were studied and a 3-period-protocol (A1-B-A2) was adopted, each period lasting 6 sessions per patient. During the B periods the patient BV decrease was kept along a predefined profile, thanks to an automatic system with a retroactive control of both the ultrafiltration rate (UFR) and dialysate conductivity (DC); instead, during the A periods, conventional HD was performed, with linear UFR and constant DC, inducing a spontaneous decrease in BV. The intradialytic BV behaviour was much more stable during the B-periods (-10.2 ∓ 1.4% by the end of the treatment) than during the A1 (-11.2 ∓ 3%) and A2 periods (-11.5 ∓ 2.5%). Only one dialysis-hypotension episode was observed during the B periods, compared to 8 and 5 during the A1 and A2 periods, respectively (p ≤ 0.05). The automatic control of the BV changes during dialysis could improve the intra-treatment cardiovascular stability in critically-ill patients.