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Original Article
A comparison between nitroprusside and nitroglycerine for hypotensive anesthesia in ear, nose, and throat surgeries: A double-blind randomized study Abhishek Mishra, Raj Bahadur Singh, Sanjay Choubey, Rajni K Tripathi, Arindam Sarkar Department of Anaesthesiology and Critical Care, Era’s Lucknow Medical College and Hospital, Lucknow, Uttar Pradesh, India
ABSTRACT Context: Blood obscures the operative field and makes precise technique difficult, and to the anesthetist, when the volume of blood lost is large. Practice of induced hypotension in the otolaryngology is a common practice owing to its benefits in providing a better visibility and preventing blood loss. Aims: The aim was to compare controlled induced hypotension for facilitating surgical exposure, and reducing intraoperative blood loss using sodium nitroprusside and nitroglycerin in ear, nose, and throat surgeries under general anesthesia. Settings and Design: A prospective, randomized, double-blind study. Materials and Methods: The study was carried out in 60 adults, American Society of Anesthesiologists grade I and II patients, allocated randomly in to three groups: group A was control group, group B patients received nitroprusside (0.5-10 μg/kg/min) and group C patients received nitroglycerine (1-10 μg/kg/min). Mean arterial pressure was maintained in the range of 50-60 mmHg. Statistical Analysis Used: Statistical Package for Social Sciences version 17.0 (ANOVA) followed by independent samples t-test and Chi-square test. Results: The results of the present study indicate that the use of controlled hypotension provides a better surgical field and reduces the blood loss. Of the two modalities under question, use of sodium nitroprusside gives the desired results in a significantly, shorter time as compared to nitroglycerin; however, the use of sodium nitroprusside must be carried out with caution as it has toxic effects. Conclusions: (1) The achievement of target level was quicker in sodium nitroprusside group as compared to nitroglycerin group. (2) Reflex tachycardia was the main side effect of the nitroglycerin group. (3) Rebound hypertension was the associated side effect of the sodium nitroprusside group. Keywords: Hypotensive anesthesia, nitroglycerin, nitroprusside
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Website: www.mjdrdypu.org DOI: 10.4103/0975-2870.153153
Introduction Ever since surgery began, bleeding has been a problem both to the surgeon, when blood obscures the operative field and makes precise technique difficult, and to the anesthetist, when the volume of blood lost is large. The difficulties for the surgeon are greater, when the operation involves very small structures, often located in confined cavities, like the middle ear. In such situations, even small amount of blood makes successful reconstructive surgery very difficult or, sometimes, impossible. It is generally, agreed that a reduction in blood pressure (BP) is useful, though often essential, in these types of surgery. The aim of our study was to compare controlled induced hypotension for facilitating surgical exposure and reducing intraoperative blood loss, using sodium nitroprusside and nitroglycerin in ear, nose, and throat (ENT) surgeries under general anesthesia.
Materials and Methods The present study was a prospective, randomized, doubleblind study carried out in 60 adults of American Society of
Address for correspondence: Dr. Raj Bahadur Singh, Department of Anaesthesiology, Era’s Lucknow medical College and Hospital, Lucknow - 226 003, Uttar Pradesh, India. E-mail:
[email protected] 182
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Anesthesiologists (ASA) grade I and II after obtaining the requisite Hospital Ethics Committee approval. ASA grade III and IV patients, patients with a significant coronary artery disease or ischemic myocardial disease, patients with chronic pulmonary disease, renal failure, hepatic dysfunction, patients with history of hypertension, and patients sensitive to nitroprusside and nitroglycerin were excluded. Patients were allocated randomly into three groups: Group A (control group), group B (nitroprusside-controlled hypotension), and group C (nitroglycerin-controlled hypotension) Mandatory monitoring included direct intra-arterial BP monitoring, heart rate (HR), oxygen saturation (SpO 2), electrocardiogram, and urine output, if required. Direct intraarterial monitoring was done by cannulating the radial artery. The patients were visited a day prior for preanesthetic review, and the standard institutional preoperative advice was given. For evaluating the visibility of the operative field during ENT surgeries, the quality scale Fromm and Boezzart[1] was used Table 1. After wheeling the patients into the operation theatre, they were connected to all noninvasive monitors for baseline parameters including HR, arterial noninvasive blood pressure, and SpO2. Invasive blood pressure monitoring was done by cannulating the radial artery, and connecting it to the transducer. Before the induction of anesthesia, all patients were premedicated on table with a standardized protocol using glycopyrrolate 6 μg/kg and fentany l 2 μg/kg intravenously. All patients were preoxygenated with 100% oxygen for 3 min, thereafter induced with propofol 2 mg/kg body weight. Intubation was carried out with succinylcholine 2 mg/kg. All patients were mechanically,
ventilated with a fresh flow of oxygen and nitrous oxide (40:60 ratio). Hypotensive agents were started just after intubation. In group A, patients underwent surgery without being given any hypotensive agent, and it served as a control group. In group B, hypotension was maintained with nitroprusside in the range of 0.5-10 μg/kg/min, while in group C, nitroglycerin was administered in the range of 1-10 μg/kg/min, through infusion pumps. The aim was to maintain mean arterial pressure (MAP) in the range of 50-60 mmHg, without any complications. First bolus dose of atracurium 0.5 mg/kg was given on the return of respiration followed by 0.1 mg/kg as clinically indicated (on return of respiration). The effect of hypotension was recorded comparing the change in the HR and BP at 5-min intervals. Hypotensive agent infusion was discontinued 15 min before surgeries were over. Patients were reversed with neostigmine 50 μg/kg and glycopyrrolate 10 μg/kg intravenously. Patients were then extubated and transferred to the postoperative ward for further monitoring.
Results The patients were comparable to each other in terms of the demographic profile [Table 2]. Immediately after infusion, the mean HR of groups B and C showed an increment, which continued till 65 min postinfusion time. At 70 and 75 min postinfusion intervals, no statistically significant difference in mean HR among groups was observed (P > 0.05). While shifting the patients, none of the groups showed any significant difference in HR [Table 3]. When the three groups were compared, the mean HR in groups B and C was found to be significantly, higher as compared to that in group A, from immediately after starting infusion till 65 min postinfusion (P < 0.001). From 20 min postinfusion
Table 1: Quality scale Fromm and Boezzart Score 0 1 2 3 4 5
Criteria No bleeding Slight bleeding - No suctioning of blood required Slight bleeding - Occasional suctioning required. Surgical field not threatened Slight bleeding - Frequent suctioning required. Bleeding threatens surgical field a few seconds after suction is removed Moderate bleeding - Frequent suctioning required. Bleeding threatens surgical field directly after suction is removed Severe bleeding - Constant suctioning required. Bleeding appears faster than can be removed by suction. Surgical field severely threatened and surgery not possible
Table 2: Demographic characteristics of three groups Parameter Weight Height Body mass index Age
Group A (control) (n = 20) Mean SD 155.00 7.78 53.55 7.21 22.40 3.50 32.50 9.23
Group B (SNP) (n = 20) Mean SD 156.50 10.78 51.25 5.71 21.29 4.09 36.30 11.89
Group C (NTG) (n = 20) Mean SD 156.62 8.08 53.40 9.28 21.83 3.87 32.40 10.45
Significance F P 0.202 0.817 0.582 0.562 0.417 0.661 0.883 0.419
SD: Standard deviation, NTG: Nitroglycerin, SNP: Sodium nitroprusside
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till 60 min postinfusion interval, the mean HR in group B was found to be significantly higher as compared to group C (P ≤ 0.001) [Table 4].
In all three groups, the mean MAP did not show a significant difference till the time of infusion. After infusion, the mean MAP in groups B and C showed a significantly, lower mean
Table 3: Mean HR in different groups at different time intervals Parameter At baseline At induction At intubation On starting infusion Immediately after starting infusion 5 min p.i. 10 min p.i. 15 min p.i. 20 min p.i. 25 min p.i. 30 min p.i. 35 min p.i. 40 min p.i. 45 min p.i. 50 min p.i. 55 min p.i.* 60 min p.i.* 65 min p.i.* 70 min p.i.* 75 min p.i.* At shifting
Group A (control) (n = 20) Mean SD 86.40 5.66 88.40 3.19 100.45 3.39 92.05 87.60 88.55 87.25 96.00 91.30 90.60 85.50 86.50 85.50 88.00 89.50 94.00 95.50 97.29 98.00 87.15
Group B (SNP) (n = 20) Mean SD 86.25 4.35 89.70 4.32 99.95 3.09 97.50 4.30 100.70 5.54 104.50 5.60 110.15 4.28 111.60 4.75 112.10 2.99 112.90 3.14 116.00 2.68 114.40 3.27 116.80 3.40 110.15 3.62 111.17 3.97 106.47 2.87 99.31 2.15 102.00 1.73 97.20 2.28
4.93 3.15 4.85 4.44 10.38 2.89 4.78 8.75 5.69 2.67 1.26 3.66 2.51 1.70 2.06 5.23 6.42
86.90
4.39
Group C (NTG) (n = 20) Mean SD 87.80 3.61 87.50 4.57 98.55 6.68 97.95 3.35 98.15 5.16 104.25 5.01 108.50 4.05 111.00 2.20 116.50 2.28 116.55 2.01 121.40 5.90 123.10 4.58 125.35 6.60 122.45 2.96 122.45 6.71 116.75 6.04 110.33 6.00 105.00 8.63 101.67 8.65 95.50 5.80 88.45 3.99
Significance F P 0.202 0.817 1.477 0.237 0.885 0.418 0.136 0.714 14.533
