A comparison between nitroprusside and nitroglycerine for hypotensive anesthesia in ear, nose, and throat surgeries: A double-blind randomized study

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.

Full text

182 Medical Journal of Dr. D.Y. Patil University | March-April 2015 | Vol 8 | Issue 2
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: virgodocraj36@yahoo.co.in
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 eld and makes
precise technique difcult, 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
benets 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 eld and reduces the blood loss.
Of the two modalities under question, use of sodium
nitroprusside gives the desired results in a signicantly,
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) Reex 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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DOI:
10.4103/0975-2870.153153
Original Article
Introduction
Ever since surgery began, bleeding has been a problem both
to the surgeon, when blood obscures the operative eld and
makes precise technique difcult, and to the anesthetist,
when the volume of blood lost is large. The difculties for
the surgeon are greater, when the operation involves very
small structures, often located in conned cavities, like
the middle ear. In such situations, even small amount of
blood makes successful reconstructive surgery very difcult
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, double-
blind study carried out in 60 adults of American Society of
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Mishra, et al.: Nitroprusside and Nitroglycerine for Hypotension in ENT surgeries
Medical Journal of Dr. D.Y. Patil University | March-April 2015 | Vol 8 | Issue 2 183
Anesthesiologists (ASA) grade I and II after obtaining the
requisite Hospital Ethics Committee approval. ASA grade III
and IV patients, patients with a signicant 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 (SpO2),
electrocardiogram, and urine output, if required. Direct intra-
arterial 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
eld 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 ow 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 prole [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 signicant
difference in mean HR among groups was observed
(
P
> 0.05). While shifting the patients, none of the groups
showed any signicant difference in HR [Table 3]. When
the three groups were compared, the mean HR in groups B
and C was found to be signicantly, 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 Criteria
0 No bleeding
1 Slight bleeding - No suctioning of blood required
2 Slight bleeding - Occasional suctioning required. Surgical field not threatened
3 Slight bleeding - Frequent suctioning required. Bleeding threatens surgical field a few seconds after suction is removed
4 Moderate bleeding - Frequent suctioning required. Bleeding threatens surgical field directly after suction is removed
5Severe 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 Group A (control) (n = 20) Group B (SNP) (n = 20) Group C (NTG) (n = 20) Signicance
Mean SD Mean SD Mean SD F P
Weight 155.00 7.78 156.50 10.78 156.62 8.08 0.202 0.817
Height 53.55 7.21 51.25 5.71 53.40 9.28 0.582 0.562
Body mass index 22.40 3.50 21.29 4.09 21.83 3.87 0.417 0.661
Age 32.50 9.23 36.30 11.89 32.40 10.45 0.883 0.419
SD: Standard deviation, NTG: Nitroglycerin, SNP: Sodium nitroprusside
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Mishra, et al.: Nitroprusside and Nitroglycerine for Hypotension in ENT surgeries
184 Medical Journal of Dr. D.Y. Patil University | March-April 2015 | Vol 8 | Issue 2
till 60 min postinfusion interval, the mean HR in group B
was found to be signicantly higher as compared to group
C (
P
≤ 0.001) [Table 4].
In all three groups, the mean MAP did not show a signicant
difference till the time of infusion. After infusion, the mean
MAP in groups B and C showed a signicantly, lower mean
Table 3: Mean HR in different groups at different time intervals
Parameter Group A (control) (n = 20) Group B (SNP) (n = 20) Group C (NTG) (n = 20) Signicance
Mean SD Mean SD Mean SD F P
At baseline 86.40 5.66 86.25 4.35 87.80 3.61 0.202 0.817
At induction 88.40 3.19 89.70 4.32 87.50 4.57 1.477 0.237
At intubation 100.45 3.39 99.95 3.09 98.55 6.68 0.885 0.418
On starting infusion 97.50 4.30 97.95 3.35 0.136 0.714
Immediately after starting infusion 92.05 4.93 100.70 5.54 98.15 5.16 14.533 <0.001
5 min p.i. 87.60 3.15 104.50 5.60 104.25 5.01 84.777 <0.001
10 min p.i. 88.55 4.85 110.15 4.28 108.50 4.05 148.924 <0.001
15 min p.i. 87.25 4.44 111.60 4.75 111.00 2.20 245.817 <0.001
20 min p.i. 96.00 10.38 112.10 2.99 116.50 2.28 57.360 <0.001
25 min p.i. 91.30 2.89 112.90 3.14 116.55 2.01 501.985 <0.001
30 min p.i. 90.60 4.78 116.00 2.68 121.40 5.90 250.375 <0.001
35 min p.i. 85.50 8.75 114.40 3.27 123.10 4.58 214.869 <0.001
40 min p.i. 86.50 5.69 116.80 3.40 125.35 6.60 286.074 <0.001
45 min p.i. 85.50 2.67 110.15 3.62 122.45 2.96 733.153 <0.001
50 min p.i. 88.00 1.26 111.17 3.97 122.45 6.71 293.400 <0.001
55 min p.i.* 89.50 3.66 106.47 2.87 116.75 6.04 188.807 <0.001
60 min p.i.* 94.00 2.51 99.31 2.15 110.33 6.00 82.521 <0.001
65 min p.i.* 95.50 1.70 102.00 1.73 105.00 8.63 14.461 <0.001
70 min p.i.* 97.29 2.06 97.20 2.28 101.67 8.65 1.402 0.272
75 min p.i.* 98.00 5.23 95.50 5.80 0.410 0.546
At shifting 87.15 6.42 86.90 4.39 88.45 3.99 0.544 0.583
*Number of cases in different group vary from that taken at baseline as the operative procedure was over in some. p.i.: Postinfusion, SD: Standard deviation, NTG: Nitroglycerin,
SNP: Sodium nitroprusside, HR: Heart rate
Table 4: Intergroup comparison for mean HR in different groups
Time interval Group A versus Group B Group A versus Group C Group B versus Group C
t P t P t P
Baseline 0.094 0.926 −0.933 0.357 −1.226 0.228
At induction −1.084 0.285 0.722 0.474 1.565 0.126
At intubation 0.487 0.629 1.133 0.264 0.850 0.400
On starting infusion −0.369 0.714
Immediately after starting infusion −5.221 <0.001 −3.823 <0.001 1.506 0.140
5 min p.i. −11.767 <0.001 −12.572 <0.001 0.149 0.883
10 min p.i. −14.929 <0.001 −14.126 <0.001 1.252 0.218
15 min p.i. −16.755 <0.001 −21.453 <0.001 0.513 0.611
20 min p.i. −6.667 <0.001 −8.628 <0.001 −5.232 <0.001
25 min p.i. −22.636 <0.001 −32.098 <0.001 −4.373 <0.001
30 min p.i. −20.724 <0.001 −18.139 <0.001 −3.729 0.001
35 min p.i. −13.836 <0.001 −17.028 <0.001 −6.920 <0.001
40 min p.i. −20.450 <0.001 −19.947 <0.001 −5.154 <0.001
45 min p.i. −24.536 <0.001 −41.451 <0.001 −11.763 <0.001
50 min p.i. −24.763 <0.001 −22.575 <0.001 −6.217 <0.001
55 min p.i.* −15.466 <0.001 −17.246 <0.001 −6.414 <0.001
60 min p.i.* −6.710 <0.001 −11.149 <0.001 −6.951 <0.001
65 min p.i.* −9.467 <0.001 −4.827 <0.001 −1.023 0.316
70 min p.i.* 0.068 0.947 −1.303 0.214 −1.115 0.287
75 min p.i.* 0.640 0.546
At shifting 0.144 0.886 −0.769 0.447 −1.168 0.250
*Number of cases in a different group vary from that taken at baseline as the operative procedure was over in some. p.i.: Postinfusion, HR: Heart rate
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Mishra, et al.: Nitroprusside and Nitroglycerine for Hypotension in ENT surgeries
Medical Journal of Dr. D.Y. Patil University | March-April 2015 | Vol 8 | Issue 2 185
value as compared to that in the group A [Table 5]. On the
comparison between the three groups, the mean MAP of
group A was signicantly higher as compared to groups B
and C, respectively, from 5 min postinfusion interval till
60 min postinfusion. Mean MAP of group B was found to
be signicantly lower as compared to that of group C from
5 min postinfusion to 30 min postinfusion, whereas mean
MAP of group B was signicantly higher as compared to
group C from 30 min postinfusion to 65 min postinfusion
except at 35 min postinfusion when the difference between
two groups was not signicant statistically (
P
= 0.252).
At all-time intervals, the SpO2 in the range of 98-100%.
At none of the time intervals, a statistically signicant
difference among groups was observed (
P
> 0.05) [Table 6].
Mean time to achieve hypotension was 18.25 ± 2.45 min in
group B, whereas, in group C, it was 30.00 ± 5.13 min. The
time to achieve hypotension was signicantly lower in group
B as compared to group C (
P
< 0.001). In group A, at no time
interval, the MAP was in the range 50-60 mm of Hg [Graph 1].
Mean score for surgical ease (Fromm and Boezzart criteria)
was observed to be 3.50 ± 0.51 in group A, followed
by 2.65 ± 0.49 in group C, and minimum for group B
(2.40 ± 0.50). The difference was found to be signicant
among groups (
P
< 0.001) [Graph 2].
Intergroup comparisons revealed that both groups B and
C had signicantly a better quality of the surgical eld
as compared to the group A (
P
< 0.001). However, no
statistically signicant difference was observed between
groups B and C (
P
= 0.183) [Table 7].
None of the patients in any group had toxicity. Reex
tachycardia was observed in three patients of group C and
rebound hypertension was observed in three patients of
Group B. Statistically, a signicant difference among groups
was seen for reex tachycardia and rebound hypertension
(
P
= 0.042) [Graph 3].
Table 5: Mean MAP in different groups at different time intervals
Parameter Group A (control) (n = 20) Group B (SNP) (n = 20) Group C (NTG) (n = 20) Signicance
Mean SD Mean SD Mean SD F P
At baseline 94.93 4.31 96.87 3.66 94.97 4.31 1.452 0.243
At induction 96.50 3.36 96.80 4.41 97.55 5.68 0.279 0.758
At intubation 106.50 3.09 104.60 3.78 106.05 2.80 1.871 0.163
On starting infusion 102.80 4.02 103.40 2.66 0.310 0.581
Immediately after starting infusion 91.05 14.18 95.20 3.17 94.55 4.06 1.314 0.277
5 min p.i. 91.10 8.22 83.15 3.92 85.85 3.23 10.497 <0.001
10 min p.i. 85.40 5.92 71.65 2.41 80.10 5.88 38.309 <0.001
15 min p.i. 85.90 5.81 61.45 2.48 73.45 7.44 94.155 <0.001
20 min p.i. 90.10 6.82 57.75 0.85 68.95 6.18 189.624 <0.001
25 min p.i. 82.50 6.71 58.55 1.85 64.25 5.60 117.727 <0.001
30 min p.i. 92.95 12.51 57.85 1.84 61.75 2.15 135.005 <0.001
35 min p.i. 81.50 1.54 59.35 2.35 58.70 0.86 1172.94 <0.001
40 min p.i. 81.25 3.86 59.55 1.73 58.25 1.37 505.513 <0.001
45 min p.i. 81.00 1.26 62.60 4.11 58.30 0.47 466.886 <0.001
50 min p.i. 80.00 4.17 68.17 6.33 60.45 2.96 90.494 <0.001
55 min p.i.* 83.00 1.26 74.12 7.00 69.55 6.54 30.948 <0.001
60 min p.i.* 93.50 1.54 86.81 10.01 79.56 6.56 20.605 <0.001
65 min p.i.* 94.50 1.70 92.40 10.01 87.50 5.90 6.909 0.002
70 min p.i.* 95.86 2.85 96.80 0.84 95.56 2.88 0.387 0.684
75 min p.i.* 95.00 2.58 97.50 1.00 3.261 0.121
At shifting* 104.40 2.51 105.07 4.21 103.80 4.34 0.562 0.573
*Number of cases in different group vary from that taken at baseline as the operative procedure was over in some. p.i.: Postinfusion, NTG: Nitroglycerin, SNP: Sodium nitroprusside,
MAP: Mean arterial pressure, SD: Standard deviation
Graph 1: Time to achieve hypotension (t = 85.48; P < 0.001)
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Mishra, et al.: Nitroprusside and Nitroglycerine for Hypotension in ENT surgeries
186 Medical Journal of Dr. D.Y. Patil University | March-April 2015 | Vol 8 | Issue 2
Discussion
Tympanoplasty surgeries involve various methods and
agents administered to minimize bleeding in the surgical
area. If inhaled anesthetics are used to decrease BP, larger
inspired concentrations are used than required to provide
surgical anesthesia, and this can result in more bleeding
because of the peripheral vasodilator effects of these
anesthetics.[2] Therefore, use of additional medications with
hypotensive effects is more appropriate.
Use of controlled hypotension to obtain better surgical
conditions during tympanoplasty has been well-reported
in the literature.[3,4] Although some researchers have
raised doubt on the efciency of induced hypotension in
reducing blood loss, there is enough evidence to support
that controlled/induced hypotension signicantly decreases
blood loss.[5] In the present study, we observed that compared
to the control group (group A), both study groups (groups B
and C) had signicantly lower blood loss and signicantly a
Table 6: Intergroup comparison for mean MAP in different groups
Time interval Group A versus Group B Group A versus Group C Group B versus Group C
t P t P t P
Baseline −1.528 0.135 −0.024 0.981 1.502 0.141
At induction −0.242 0.810 −0.711 0.481 −0.467 0.644
At intubation 1.742 0.090 0.483 0.632 −1.380 0.176
On starting infusion −0.556 0.581
Immediately after starting infusion −1.277 0.209 −1.061 0.295 0.564 0.576
5 min p.i. 3.903 <0.001 2.658 0.011 −2.375 0.023
10 min p.i. 9.626 <0.001 2.843 0.007 −5.950 <0.001
15 min p.i. 17.303 <0.001 5.899 <0.001 −6.845 <0.001
20 min p.i. 21.049 <0.001 10.279 <0.001 −8.033 <0.001
25 min p.i. 15.393 <0.001 9.340 <0.001 −4.323 <0.001
30 min p.i. 12.415 <0.001 10.994 <0.001 −6.160 <0.001
35 min p.i. 35.308 <0.001 57.765 <0.001 1.163 0.252
40 min p.i. 22.917 <0.001 25.083 <0.001 2.632 0.012
45 min p.i. 19.150 <0.001 75.667 <0.001 4.650 <0.001
50 min p.i. 6.875 <0.001 17.096 <0.001 4.895 <0.001
55 min p.i.* 5.584 <0.001 9.031 <0.001 2.050 0.048
60 min p.i.* 2.955 0.006 9.236 <0.001 2.527 0.017
65 min p.i.* 0.927 0.362 5.080 <0.001 1.638 0.113
70 min p.i.* −0.708 0.495 0.209 0.838 0.930 0.371
75 min p.i.* −1.806 0.121
At shifting −0.609 0.546 0.535 0.596 0.937 0.355
*Number of cases in different group vary from that taken at baseline as the operative procedure was over in some. p.i.: Postinfusion, MAP: Mean arterial pressure
Table 7: Intergroup comparison of quality of surgical eld
Comparison Z P
Group A versus Group B 4.649 <0.001
Group A versus Group C 4.110 <0.001
Group B versus Group C 1.563 0.183
Graph 2: Comparison of three groups for quality of the surgical eld
(Fromm and Boezzart criteria) (c2 = 27.461; P < 0.001 (Kruskal-Wallis test)
Graph 3: Side effects
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Mishra, et al.: Nitroprusside and Nitroglycerine for Hypotension in ENT surgeries
Medical Journal of Dr. D.Y. Patil University | March-April 2015 | Vol 8 | Issue 2 187
better surgical conditions. Between the two study groups,
though no signicant difference was observed for surgical
conditions, yet the time to achieve the desired level of
hypotension was signicantly shorter in group B (sodium
nitroprusside) as compared to group C (nitroglycerin). Similar
ndings have been made by Porter
et al
.[6] and Yaster
et al
.,[7]
who reported sodium nitroprusside to be more effective
in inducing hypotension as compared to nitroglycerin
in patients undergoing spinal surgery. In another study
comparing nitroprusside, nitroglycerin, and deep isourane
anesthesia for induced hypotension, Maktabi
et
al.
[8] did
not nd a clear superiority of any agent over the other to
induce hypotension, although nitroprusside appeared to be
better than nitroglycerin in inducing hypotension. However,
Tobias[9] compared nitroprusside and nitroglycerin to produce
induced hypotension during coronary artery surgery and
found that both drugs signicantly, decreased arterial pressure
without affecting the HR or cardiac output.
Beierholm
et
al.
[10] in their study found that HR, central
venous pressure, and pulmonary vascular resistance did
not change significantly following infusion of sodium
nitroprusside. However, Landauer found that the infusion of
sodium nitroprusside was accompanied by a 22.5% increase
in HR. In the present study, an increase in HR was observed
both in sodium nitroprusside and nitroglycerin groups. But
HR in the nitroglycerin group remained at a signicantly
higher level than in the sodium nitroprusside group. Suttner
et
al.
[11] also made similar observations, though the extent
of the rise in HR was not up to the extent as observed in
the present study. Similar ndings have been observed in
animal models too.[12]
In group C (nitroglycerin), three cases with reex tachycardia
(15%) were reported. Khan and Carleton[13] have cautioned
the use of nitroglycerin for induction of hypotension owing
to its role in the causation of reex tachycardia.
As in our study, Rodrigo[14] also reported absence of
rebound hypertension with nitroglycerin. In our study,
three cases with rebound hypertension were reported
with nitroprusside. It has been reported that if an adequate
reduction in BP is not achieved in 10-15 min at the highest
recommended dose of sodium nitroprusside, the infusion
should be stopped to prevent cyanide toxicity.[15] However,
in the present study, no such toxicity was noticed, though
the time to achieve desired hypotension reached 25 min.
This might be due to rational use of the dose instead of using
the maximum permissible dose.
The mean time of onset was observed to be 18.25 ± 2.45
min in the sodium nitroprusside group, whereas, in the
nitroglycerin group, this time was 30.00 ± 5.13 min. At
the highest dose, the time to achieve the target level of
hypotension in the sodium nitroprusside group has been
reported to be 10-15 min. However, in the present series,
the earliest onset was 15 min. There are different reports
regarding the time to achieve controlled hypotension by
using sodium nitroprusside. Halpern
et
al.
[16] have reported
a mean time of 30 min. The time taken to achieve the
desired level of hypotension generally depends on the dose
being used. Owing to the known toxic effects of sodium
nitroprusside, the present study adopted an approach of
optimal use instead of maximum use. However, even this
optimum approach produced signicantly better results as
compared to nitroglycerin.
The results of the present study indicate that the use of
controlled hypotension provides better surgical eld and
reduces blood loss. Of the two modalities under question,
use of sodium nitroprusside gives the desired results in a
signicantly shorter time as compared to nitroglycerin;
however, the use of sodium nitroprusside must be carried out
with caution as it has toxic effects. One of the shortcomings
of the controlled hypotension is the time taken to achieve
the desired MAP level. However, this could be offset with
the fact that it reduces blood loss to a signicant degree,
and thus provides a better surgical eld, which not only
reduces the overall surgical time but also provides scope for
a better surgical outcome. Although in the present study,
no attempt was made to compare the results of surgical
outcomes, it was observed that the overall surgical time
despite a substantial time being taken to achieve the desired
MAP levels, was shorter in the two study groups as compared
to the control group.
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Mishra, et al.: Nitroprusside and Nitroglycerine for Hypotension in ENT surgeries
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How to cite this article: Mishra A, Singh RB, Choubey S, Tripathi
RK, Sarkar A. A comparison between nitroprusside and nitroglycerine
for hypotensive anesthesia in ear, nose, and throat surgeries: A
double-blind randomized study. Med J DY Patil Univ 2015;8:182-8.
Source of Support: Nil. Conict of Interest: None declared.
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