Download Management of Scorpion Sting: Prazosin or

JOURNAL OF TROPICAL PEDIATRICS, VOL. 56, NO. 2, 2010
Brief Report
Management of Scorpion Sting: Prazosin or Dobutamine
by B. D. Gupta, M. Parakh, and A. Purohit
Department of Pediatrics, Umaid Hospital for Women & Children, Regional Institute of Maternal & Child Health,
Dr Sampurnanand Medical College, Jodhpur, India
Summary
Objective: To compare the efficacy of Dobutamine and Prazosin in the management of cases with
scorpion sting.
Setting: Pediatric intensive care unit of an affiliated hospital of a medical university.
Subjects: Forty-two children with scorpion sting.
Intervention: The involved victims were divided alternatively into two groups. Twenty-one patients were
treated with intravenous Dobutamine infusion and other 21 received oral Prazosin.
Outcome measures: Percent-rise in left-ventricular ejection fraction in first 24 h after institution of the
therapy, time taken in recovery from pulmonary edema, requirement of any additional drug and
supportive measures, and mortality.
Results: The time taken in recovery from pulmonary edema was significantly shorter in cases treated
with prazosin (28 18.3 vs. 72 0 h), the p-value being <0.05. Faster improvement of various
parameters was observed in prazosin group in comparison to the dobutamine group. Mortality in both
the groups was equal.
Conclusion: Prazosin and dobutamine, both are useful drugs for management of cardiovascular features
of scorpion envenomation, nevertheless, prazosin is slightly better than dobutamine in terms of faster
recovery, and also because of its ease of administration and low cost of therapy.
Key words: dobutamine, prazosin, scorpion sting.
Introduction
Scorpion sting is a dreadful medical emergency, more
so in pediatric victims because of their smaller body
size. It is fairly common in many parts of India like
Maharashtra, Andhra Pradesh, Pondicherry, Tamil
Nadu, Madhya Pradesh, Orissa and western
Rajasthan [1–3]. Scorpion stings cause a wide range
of symptoms, from severe local reactions to cardiovascular, respiratory and neurological manifestations. Scorpion envenomation can involve many
organs in the body simultaneously producing multiorgan dysfunction. Scorpion envenomation in India
(Mesobuthus tamulus) predominantly manifests
with cardiorespiratory features like hypertension
and pulmonary edema. Most of the deaths due
to scorpion sting are also attributed to
Correspondence: A. Purohit, Department of Pediatrics,
Umaid Hospital for Women & Children, Regional Institute
of Maternal & Child Health, Dr Sampurnanand Medical
College, Jodhpur, India.
E-mail: <[email protected]>.
cardiopulmonary complications like myocarditis
and acute pulmonary edema [4].
There is still a great controversy regarding specific
drug therapy for similar clinical profile and different
regimens have been tried so far, such as, steroids,
adrenaline, lytic cocktail regimen and many more.
Scorpion antivenom is also available, but its utility in
the management of these cases is still doubtful. Thus,
till date, there is no consensus guideline available for
the management of these children [5, 6]. Prazosin has
been suggested by some as the first line drug for the
management of severe scorpion envenomation [6, 7].
On the contrary, dobutamine infusion alone has also
been shown to improve the hemodynamic performance in patients presenting with severe scorpion
envenomation [8]. It has been found to be life saving
in patients of scorpion envenomation presenting with
shock and pulmonary edema, as the shock has been
found to be cardiogenic in origin.
In search for the best drug in treatment of scorpion envenomed children, we carried out a study at
Umaid hospital for women and children, Jodhpur,
comparing the efficacy of dobutamine and prazosin
in the management of cases with scorpion sting, as
these are the two most promising drugs in such cases.
ß The Author [2009]. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected]
doi:10.1093/tropej/fmp070 Advance Access Published on 26 August 2009
115
BRIEF REPORT
TABLE 1
Characteristics and manifestations in dobutamine and prazosin groups
Age of the patients (years)
Weight of the patients (kg)
Male:female
Time elapsed between sting and admission (h)
Tachycardia
Hypertension
Serum CPK-MB (IU/l)
Pulmonary edema
Prolonged QTc interval
ST and T-wave changes
LVEF (%)
Materials and Methods
The present study was conducted in the Department
of Pediatrics, Umaid Hospital, Dr Sampurnanand
Medical College, Jodhpur. All the patients admitted
with the definite history of scorpion sting (scorpion
being seen or killed by the relatives or bystander)
were included in the study.
On admission, particulars of the patient were
noted in a specially designed, pre-tested proforma,
for the study. This was followed by thorough
physical examination and continuous monitoring of
vitals including NIBP and pulse oximetry. All the
recordings were taken by a multipara monitor (BPL
Accura).
All the patients were subjected for blood investigations including renal and hepatic profile and serum
CPK-MB before starting the treatment in the
emergency ward. An electrocardiogram and chest
X-ray were done on the day of admission and if
found abnormal, were repeated daily, till abnormality got corrected. A 2D-echocardiography (L&T
Medicals USG Machine) was done to find out the
cardiac status of the patient including the ejection
fraction and any regional wall motion abnormality
(RWMA) before starting treatment and then daily
(if general condition of the patient allowed) till
hospital stay.
Forty-two patients were enrolled in the study. The
patients were divided into two groups on alternate
basis for treatment. First group was given intravenous dobutamine infusion and another was given
oral prazosin hydrochloride. The patients falling into
dobutamine group were given continuous dobutamine infusion at the rate of 10 mg/kg body weight/
min. This was further titrated as per the condition of
the patient. This infusion was continued for 48 h of
hemodynamic stability and till the left ventricular
ejection fraction (LVEF) increased to >60% and
then was tapered downwards at the rate of 5 mg/kg
body weight every 12 h. A child referred from
peripheral hospital that had already been started
116
Dobutamine
Prazosin
5.17 3.93
14.14 5.97
2.5:1
7.29 6.76
5/21 (23.8%)
12/21 (57.1%)
122.28 82.82
2/21
7/19 (36.8%)
3
49 13%
4.67 2.58
13.29 4.39
2.5:1
6.69 10.17
9/21 (42.9%)
9/21 (42.9%)
109.32 62.5
3/21
9/21 (52.9%)
6
55 13%
dobutamine infusion at a rate >10 mg/kg body
weight/min, was continued the same rate of infusion,
if stable hemodynamically. The patients falling into
prazosin group were given prazosin tablet (orally or
by nasogastric tube) at the dose of 30 mg/kg body
weight every 6 h for 48 h and till LVEF reached
>60%.
Statistics
The data are expressed as mean standard deviation
for descriptive purposes. Chi-square and Student’s
t-test were used to compare various variables between
the dobutamine and prazosin groups. Yate’s correction was applied, as the sample size was small.
In present study, p-value < 0.05 for corresponding
value of Chi-square was considered as significant and
null hypothesis was rejected, meaning that difference
between two proportions was significant.
Results
Forty-two patients were enrolled in the study, the
baseline characteristics of whom are given in Table 1.
The two groups were age-, weight- and sex-matched.
The patients in the dobutamine group presented
7.29 6.76 h after the sting while those in prazosin
group reached 6.69 10.17 h after the accident.
At admission, there was no significant difference in
the presentation of cases in the two groups.
The rise of LVEF during first 24 h was greater with
prazosin (4.8%) than with dobutamine (2.55%).
Inspite of therapy, left ventricular output decreased
in few patients in the next 24 h; number of such
patients being six (28.57%) in dobutamine and three
(14.28%) in prazosin group. The time taken in
recovery from pulmonary edema was significantly
shorter in cases treated with prazosin (28 18.3 h),
the p-value being <0.05. Therefore, faster improvement of various parameters was observed in prazosin
group in comparison with the dobutamine group
(Table 2).
Journal of Tropical Pediatrics
Vol. 56, No. 2
BRIEF REPORT
TABLE 2
Dobutamine vs. prazosin
Rise in LVEF in first 24 h (%)
Number of patients in whom LVEF decreased in first 24 h in spite of treatment
Total time taken in normalization of decreased LVEF (days)
Time taken in recovery from pulmonary edema (h)
Total duration of stay of patients with pulmonary edema (h)
Number of patients requiring digoxin
Number of patients requiring frusemide
Number of patients requiring mechanical ventilation
TABLE 3
Comparing outcome in dobutamine and prazosin group
Total
Number
Number Mortality
patients of patients of patients rate (%)
recovered
expired
Dobutamine
Prazosin
21
21
19
20
2
1
9.5
4.7
Three patients expired during the study with a
mortality rate of 7.1%. The mortality rate in
dobutamine group was 9.5% in comparison with
4.7% in prazosin group, but the difference was not
significant (Table 3).
Discussion
Alpha-receptors play vital role in the pathogenesis of
cardiac failure and pulmonary edema due to scorpion
sting. Prazosin is a selective alpha-1 adrenergic
receptor blocker. It dilates veins and arterioles,
there by reducing pre-load and left ventricular
impedance without rise in heart rate and renin
secretion. It also inhibits sympathetic outflow in
central nervous system. It enhances insulin secretion,
which is inhibited by venom action. It has also been
found useful even in cases with hypotension. Thus, its
pharmacological properties can antagonize the
hemodynamic, hormonal and metabolic effects of
scorpion venom action [3, 7, 9, 10–14]. However, few
doubts have been raised over its mechanism and
efficacy in scorpion envenomation [12, 15]. It has
been said that alpha-blockers can stimulate the
gastric acid secretion, which in turn may, aggravate
the existing sub-clinical or clinical acute pancreatitis
into a fully blown-up fulminating acute pancreatitis
in some scorpion sting victims. In addition, prazosin
cannot reverse the tissue damage that has already
been caused by catecholamines [16].
Dobutamine infusion alone has been reported to
be able to improve the impaired heart function (left
as well as right ventricular). It evokes substantial
increases in cardiac output and systemic arterial
Journal of Tropical Pediatrics
Vol. 56, No. 2
Dobutamine
Prazosin
p-value
2.22 7.77
6
2.1 1.5
72 0
156 118.8
2
2
2
4.8 7.54
3
2.1 0.8
28 18.3
88 13.9
Nil
Nil
Nil
>0.20
<0.05
>0.20
pressure while lowers pulmonary artery occlusion
pressure (PAOP). Right ventricular function and
tissue oxygenation variables also improve with its
use. Many authors have recommended its use in the
management of these victims [5, 6, 8, 12].
The present study was aimed at comparing the
efficacy of two potent drugs, dobutamine and
prazosin in better management of scorpion envenomed cases. There is no other study comparing
these two most effective drugs in management of this
fearsome emergency. In the present study, time taken
in recovery from pulmonary edema in scorpion
envenomed cases was 72 0 h in patients treated
with dobutamine, while it was only 28 18.3 h in
patients treated with prazosin (p < 0.05). Besides,
both the cases with pulmonary edema treated with
dobutamine required digoxin, frusemide and
mechanical ventilation as well. Rise in left ventricular
function during first 24 h of therapy was also higher
in cases treated with prazosin (4.8 7.54%) in
comparison to those treated with dobutamine
(2.22 7.77%); however, the difference was not
statistically significant. Thus, most of the cardiovascular parameters improved faster with prazosin in
comparison to dobutamine.
Our study points to the fact that both dobutamine
and prazosin are useful in the treatment of cardiovascular features of scorpion envenomation; however, prazosin has an edge over dobutamine in
management of these cases. Besides its efficacy, the
low cost of therapy and ease of administration with
prazosin make it a better option than dobutamine
infusion. During our study, all the patients expired
because of encephalopathy and no patient died of
pulmonary edema or other cardiovascular complications. None of the drugs was found useful in patients
of scorpion envenomation associated with encephalopathy. Thus, we further suggest that more multicentric, large-sample studies are required to evaluate
the effects of other drugs, besides dobutamine and
prazosin, in scorpion-induced encephalopathy. On
top of all these factors, this study has also shown that
intensive management of these victims is vital for
better outcomes.
117
BRIEF REPORT
References
1. Balasubramaniam P, Murthy KRK. Liver glycogen
depletion in acute myocarditis produced by scorpion
venom (Buthus tamulus). Indian Heart J 1984;36:101–6.
2. Bawaskar HS, Bawaskar PH. Management of cardiovascular manifestations of poisoning by the Indian red
scorpion (Mesobuthus tamulus). Br Heart J 1992;
68:478–80.
3. Bawaskar HS, Bawaskar PH. Clinical profile of severe
scorpion envenomation in children at rural setting.
Indian Pediatr 2003;40:1072–7.
4. Biswal N, Charan MV, Betsy M, et al. Management of
scorpion envenomation. Pediatr Today 1999;2:420–6.
5. Mahadevan S. Scorpion sting. Indian Pediatr 2000;
37:504–13.
6. Biswal Niranjan, Bashir Rani A, Murmu Uday C, et al.
Outcome of scorpion sting envenomation after a
protocol guided therapy. Indian J Pediatr 2006;
73:577–82.
7. Bawaskar HS, Bawaskar PH. Severe envenoming by
Indian red scorpion M. tamulus – the use of prazosin
therapy. Quart J Med 1996;89:701–4.
8. Elatrous S, Nouria S, Besbes-Ouanes L, et al.
Dobutamine in severe scorpion envenomation. Chest
1999;116:748–53.
118
9. Bawaskar HS. Scorpion Sting: Current Management.
http://www.pediatric oncall.com (5 February 2009, date
last accessed).
10. Bawaskar HS. Management of severe scorpion sting
at rural settings: what is the role scorpion antivenom.
J Venom Anim Toxins Incl Trop Dis 2005;11:3–7.
11. Bawaskar H. Management of Scorpion Sting.
http://heart..bmj.com/cgi/content/extract/82/2/253 (20
January 2009, date last accessed).
12. Santhanakrishnan BR. Scorpion sting-letter to editor.
Indian Pediatr 2000;37:1154–7.
13. Bawaskar HS, Bawaskar PH. Vasodilators: scorpion
envenoming and the heart (an Indian experience).
Toxicon 1994;32:1031–40.
14. Bawaskar HS, Bawaskar PH. Prazosin for
vasodilator treatment of acute pulmonary oedema due
to scorpion sting. Ann Trop Med Parasitol 1987;
81:719–23.
15. Radha Krishna Murthy K. On scorpion envenoming
syndrome – problems of medical ethics and accountability in medical research in India. J Venom Anim
Toxins 2002;8.
16. Mahadevan S, Choudhury P, Puri RK, Srinivasan S.
Scorpion envenomation and the role of lytic cocktail in
its management. Indian J Pediatr 1981;48:757–61.
Journal of Tropical Pediatrics
Vol. 56, No. 2