Background
Scorpion stings are a major public health problem in many underdeveloped tropical countries. For every person killed by a poisonous snake, 10 are killed by a poisonous scorpion. In Mexico, 1000 deaths from scorpion stings occur per year. In the United States, only 4 deaths in 11 years have occurred as a result of scorpion stings. Furthermore, scorpions can be found outside their normal range of distribution, ie, when they accidentally crawl into luggage, boxes, containers, or shoes and are unwittingly transported home via human travelers.
A scorpion has a flattened elongated body and can easily hide in cracks. It has 4 pairs of legs, a pair of claws, and a segmented tail that has a poisonous spike at the end. Scorpions vary in size from 1-20 cm in length.
Out of 1500 scorpion species, 50 are dangerous to humans. Scorpion stings cause a wide range of conditions, from severe local skin reactions to neurologic, respiratory, and cardiovascular collapse.
Almost all of these lethal scorpions, except the Hemiscorpius species, belong to the scorpion family called the Buthidae. The Buthidae family is characterized by a triangular-shaped sternum, as opposed to the pentagonal-shaped sternum found in the other 5 scorpion families. In addition to the triangular-shaped sternum, poisonous scorpions also tend to have weak-looking pincers, thin bodies, and thick tails, as opposed to the strong heavy pincers, thick bodies, and thin tails seen in nonlethal scorpions. The lethal members of the Buthidae family include the genera of Buthus, Parabuthus, Mesobuthus, Tityus, Leiurus, Androctonus, and Centruroides. These lethal scorpions are found generally in the given distribution:
- Buthus - Mediterranean area
- Parabuthus - Western and Southern Africa
- Mesobuthus - Asia
- Tityus - Central and South America, Caribbean
- Leiurus - Northern Africa and Middle East
- Androctonus - Northern Africa to Southeast Asia
- Centruroides - Southwest USA, Mexico, Central America
However, these scorpions may be found outside their habitat range of distribution when inadvertently transported with luggage and cargo.
In general, scorpions are not aggressive. They do not hunt for prey; they wait for it. Scorpions are nocturnal creatures; they hunt during the night and hide in crevices and burrows during the day to avoid the light. Thus, accidental human stinging occurs when scorpions are touched while in their hiding places, with most of the stings occurring on the hands and feet.
Pathophysiology
Scorpions use their pincers to grasp their prey; then, they arch their tail over their body to drive their stinger into the prey to inject their venom, sometimes more than once. The scorpion can voluntarily regulate how much venom to inject with each sting. The striated muscles in the stinger allow regulation of the amount of venom ejected, which is usually 0.1-0.6 mg. If the entire supply of venom is used, several days must elapse before the supply is replenished. Furthermore, scorpions with large venom sacs, such as the Parabuthus species, can even squirt their venom.
The venom glands are located on the tail lateral to the tip of the stinger and are composed of 2 types of tall columnar cells. One type produces the toxins, while the other produces mucus. The potency of the venom varies with the species, with some producing only a mild flu and others producing death within an hour. Generally, the venom is distributed rapidly into the tissue if it is deposited into a venous structure. Venom deposited via the intravenous route can cause symptoms only 4-7 minutes after the injection, with a peak tissue concentration in 30 minutes and an overall toxin elimination half-life of 4.2-13.4 hours through the urine. The more rapidly the venom enters the bloodstream, the higher the venom concentration in the blood and the more rapid the onset of systemic symptoms.
Scorpion venom is a water-soluble, antigenic, heterogenous mixture, as demonstrated on electrophoresis studies. This heterogeneity accounts for the variable patient reactions to the scorpion sting. However, the closer the phylogenetic relationship between the scorpions, the more similar the immunological properties. Furthermore, the various constituents of the venom may act directly or indirectly and individually or synergistically to manifest their effects. In addition, differences in the amino acid sequence of each toxin account for their differences in the function and immunology. Thus, any modifications of the amino acid sequence result in modification of the function and immunology of the toxin.
The venom is composed of varying concentrations of neurotoxin, cardiotoxin, nephrotoxin, hemolytic toxin, phosphodiesterases, phospholipases, hyaluronidases, glycosaminoglycans, histamine, serotonin, tryptophan, and cytokine releasers. The most potent toxin is the neurotoxin, of which 2 classes exist. Both of these classes are heat-stable, have low molecular weight, and are responsible for causing cell impairment in nerves, muscles, and the heart by altering ion channel permeability.
The long-chain polypeptide neurotoxin causes stabilization of voltage-dependent sodium channels in the open position, leading to continuous, prolonged, repetitive firing of the somatic, sympathetic, and parasympathetic neurons. This repetitive firing results in autonomic and neuromuscular overexcitation symptoms, and it prevents normal nerve impulse transmissions. Furthermore, it results in release of excessive neurotransmitters such as epinephrine, norepinephrine, acetylcholine, glutamate, and aspartate. Meanwhile, the short polypeptide neurotoxin blocks the potassium channels.
The binding of these neurotoxins to the host is reversible, but different neurotoxins have different affinities. The stability of the neurotoxin is due to the 4 disulfide bridges that fold the neurotoxin into a very compact 3-dimensional structure, thus making it resistant to pH and temperature changes. However, reagents that can break the disulfide bridges can inactivate this toxin by causing it to unfold. Also, the antigenicity of this toxin is dependent on the length and number of exposed regions that are sticking out of the 3-dimensional structure.
Frequency
United States
A total of 13,000 stings have been reported, with the majority being from the nonlethal scorpions. Only 1 of 30 scorpion species found in the United States is dangerous to humans. This lethal scorpion species is the straw-colored Centruroides. Less than 1% of stings from Centruroides are lethal to adults; however, 25% of children younger than 5 years who are stung die if not treated. The epidemiological features of a patient who has been envenomed show a disposition for rural areas (73%), with most of the stings occurring in the summer months between 6:00 pm and 12:00 am (49%) and a second peak from 6:00 am to 12:00 pm (30%). Both of these peaks coincide maximum human activity with maximum scorpion activity. Furthermore, the larger the scorpion population, the larger the incidence rate. Because the offending scorpion is recovered for identification in only 30% of the cases, local knowledge of the type of scorpion populating the area is useful.
International
Scorpion stings occur in temperate and tropical regions, especially between the latitudes of 50°N and 50°S of the equator. Furthermore, stings predominantly occur during the summer and evening times. In addition, the majority of patients are stung outside their home.
A recent 5-year surveillance study in Saudi Arabia found 6465 scorpion sting cases with a mean patient age of 23 years, a male-to-female ratio of 1.9, and a higher incidence of stings in the months of May-October.1
Mortality/Morbidity
The underreporting of scorpion stings is frequent because most envenomations occur in desert and jungle areas that do not have large medical facilities. Furthermore, reporting is not required.
Most deaths occur during the first 24 hours after the sting and are secondary to respiratory or cardiovascular failure.
Children and elderly persons are at the greatest risk for morbidity and mortality. A smaller child, a lower body weight, and a larger ratio of venom to body weight lead to a more severe reaction. A mortality rate of 20% is reported in untreated babies, 10% in untreated school-aged children, and 1% in untreated adults.
Furthermore, patients in rural areas tend to fare worse than patients in urban areas because of the delay in getting medical help due to a longer travel time to medical centers. Fortunately, better public education, improved control of the scorpion population, increased supportive therapies, and more technologically advanced intensive care units have combined to produce a substantial decrease in mortality from these envenomations.
Race
No racial predilection exists. Any differences in individual reactions to the scorpion sting are a reflection of that individual's genetic composition rather than race.
Sex
Females are more susceptible than males to the same amount of scorpion venom because of their lower body weight.
Age
While adults are stung more often than children, children are more likely to develop a more rapid progression and increased severity of symptoms because of their lower body weight. Furthermore, elderly persons are more susceptible to stings because of their decreased physiologic reserves and increased debilitation.
Treatment
Medical Care
Because the clinical manifestations and severity of the symptoms vary among patients, individualize management of scorpion stings. Furthermore, frequent patient monitoring allows earlier recognition of the life-threatening problems of scorpion envenomation. Treatment generally consists of moving the patient away from the scorpion and stabilizing the patient's airway and vital signs, followed by administration of antivenin and institution of symptomatic and local treatment.
- Local treatment is discussed as follows:
- A negative-pressure extraction device (ie, the extractor) may be useful, although the benefit is unproven. The extractor creates a negative pressure of 1 atm. Apply it to the sting site after incision. Oral extraction is contraindicated.
- Use ice bags to reduce pain and to slow the absorption of venom via vasoconstriction. This is most effective during the first 2 hours following the sting.
- Immobilize the affected part in a functional position below the level of the heart to delay venom absorption.
- Calm the patient to lower the heart rate and blood pressure, thus limiting the spread of the venom.
- For medical delay secondary to remoteness, consider applying a lymphatic-venous compression wrap 1 inch proximal to the sting site to reduce superficial venous and lymphatic flow of the venom but not to stop the arterial flow. Only remove this wrap when the provider is ready to administer systemic support. The drawback of this wrap is that it may intensify the local effects of the venom.
- Apply a topical or local anesthetic agent to the wound to decrease paresthesia; this tends to be more effective than opiates.
- Administer local wound care and topical antibiotic to the wound.
- Administer tetanus prophylaxis.
- Administer systemic antibiotics if signs of secondary infection occur.
- Administer muscle relaxants for severe muscle spasms (ie, benzodiazepines.)
- Systemic treatment is instituted by directing supportive care toward the organ specifically affected by the venom.
- Establish airway, breathing, and circulation (ie, ABCs) to provide adequate airway, ventilation, and perfusion.
- Monitor vital signs (eg, pulse oximetry; heart rate, blood pressure, and respiratory rate monitor).
- Use invasive monitoring for patients who are unstable and hemodynamic.
- Administer oxygen.
- Administer intravenous fluids to help prevent hypovolemia from vomiting, diarrhea, sweating, hypersalivation, and insensible water loss from a tropical environment.
- Perform intubation and institute mechanical ventilation with end-tidal carbon dioxide monitoring for patients in respiratory distress.
- For hyperdynamic cardiovascular changes, administration of a combination of beta-blockers with sympathetic alpha-blockers is most effective in reversing this venom-induced effect. Avoid using beta-blockers alone because this leads to an unopposed alpha-adrenergic effect. Also, nitrates can be used for hypertension and myocardial ischemia.
- For hypodynamic cardiac changes, a titrated monitored fluid infusion with afterload reduction helps reduce mortality. A diuretic may be used for pulmonary edema in the absence of hypovolemia, but an afterload reducer, such as prazosin, nifedipine, nitroprusside, hydralazine, or angiotensin-converting enzyme inhibitors, is better. Inotropic medications, such as digitalis, have little effect, while dopamine aggravates the myocardial damage through catecholaminelike actions. Dobutamine seems to be a better choice for the inotropic effect. Finally, a pressor such as norepinephrine can be used as a last resort to correct hypotension refractory to fluid therapy.
- Administer atropine to counter venom-induced parasympathomimetic effects.
- Insulin administration in scorpion envenomation animal experiments has helped the vital organs to use metabolic substrates more efficiently, thus preventing venom-induced multiorgan failure, especially cardiopulmonary failure. Unfortunately, no human studies have been conducted.
- Administer barbiturates and/or a benzodiazepine continuous infusion for severe excessive motor activity.
- The use of steroids to decrease shock and edema is of unproven benefit.
- Antivenin is the treatment of choice after supportive care is established. The quantity to be used is determined by the clinical severity of patients and by their evolution over time. Unfortunately, predicting the evolution of symptoms and, thus, the amount of antivenin that is needed in the future, is difficult.
- The antivenin significantly decreases the level of circulating unbound venom within an hour. The persistence of symptoms after the administration of antivenin is due to the inability of the antivenin to neutralize scorpion toxins already bound to their target receptors.
- Time guidelines for the disappearance of symptoms after antivenin administration are as follows:
- Centruroides antivenin: Severe neurologic symptoms reverse in 15-30 min. Mild-to-moderate neurologic symptoms reverse in 45-90 min.
- Non-Centruroides antivenin: In the first hour, local pain abates. In 6-12 hours, agitation, sweating, and hyperglycemia abate. In 6-24 hours, cardiorespiratory symptoms abate.
- While an anaphylaxis reaction to the antivenin is possible, the patient is at lower risk for this than with other antivenins for other poisonous envenomations because of the huge release of catecholamines induced by the scorpion venom. However, the larger the dose of antivenin, the greater the chance for serum sickness.
- A vaccine preparation was tried in experimental animals but was not pursued because of the need to prepare different antigens according to different geographical areas and to different species of scorpions living in the same area.
- In some cases, be aware that meperidine and morphine may potentiate the venom. Also, the concurrent use of barbiturates and narcotics may add to the respiratory depression in patients who have been envenomated.
Activity
- Rest and immobilization of the sting site is recommended to prevent rapid absorption of the venom into the circulation.
Medication
The goals of pharmacotherapy are to reduce morbidity, to prevent complications, and to neutralize the toxin.
Drug Category: Antivenins
Scorpion toxins are not good antigens because of small size and poor immunogenicity. They do not induce antibodies that cross-react against toxins of other scorpion species unless a 95% amino acid sequence homology exists between the 2 toxins. Thus, no universal antivenin is available. Instead, 22 types of scorpion antivenin exist.
Furthermore, the neurotoxin component of the scorpion venom tends to be the least immunogenic, resulting in the low efficiency for neurological complications. It usually is prepared from horses because they yield larger quantities. Sheep, goat, or bovine antivenin may be prepared if patient sensitivity to horse serum occurs.
A recent idea was to mix a batch of different scorpion antivenin together to create a universal antivenin, but this exposes the patient to unnecessary antivenin from scorpion species not from the patient's region.
Perform a skin test prior to administering the antivenin. First, dilute 0.1 mL of antivenin in a 1:10 ratio with isotonic sodium chloride solution. Second, administer 0.2 mL intradermally. A positive test result is if a wheal develops within 10 minutes. The skin test has a sensitivity of 96% and a specificity of 68%.
The best result occurs when antivenin is administered as early as possible (preferably within the first 2 h after the sting) and with adequate quantities to neutralize the venom (usually 50-100 times the LD50 amount). A decrease in curative effects occurs with longer sting-serotherapy delay and administration of insufficient amounts of antivenin.
| Drug Name | USA-APL Centruroides scorpion antivenin |
|---|---|
| Description | Used to neutralize toxins from scorpions. Produced in Arizona (for use in Arizona only). Not approved by FDA. Use remains controversial, but many physicians recommend it in grade III and IV envenomations. Shown to produce rapid resolution of systemic symptoms but does not affect pain or paresthesias. Results in resolution of symptoms within min to 2 h after administration. Antivenin treatment is based on venom burden, not patient's size. The smaller the victim, the more important it is to administer the full dose because of the venom dose-dependent severity. |
| Adult Dose | Grade I and II: None Grade III and IV: 1 vial (5 mL) in 50 mL saline IV over 30 min; if severe symptoms still persist after 1 h, repeat once prn |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; may administer in severe envenomation, despite hypersensitivity |
| Interactions | None reported |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Due to presence of horse serum, agents for emergency treatment of anaphylaxis should be available; premedicate with antihistamines or steroids |
Drug Category: Benzodiazepines
By increasing the action of GABA (inhibitory neurotransmitter), counteract scorpion-induced excessive motor activity and nervous system excitation.
| Drug Name | Lorazepam (Ativan) |
|---|---|
| Description | Sedative hypnotic with short onset of effects and relatively long half-life. By increasing action of GABA, which is a major inhibitory neurotransmitter in the brain, may depress all levels of CNS, including limbic and reticular formation. |
| Adult Dose | 1-4 mg IV over 2-5 min; may repeat dose in 10-15 min prn |
| Pediatric Dose | 0.05 mg/kg IV over 2-5 min; may repeat dose in 10-15 min prn |
| Contraindications | Documented hypersensitivity; preexisting CNS depression, hypotension, and narrow-angle glaucoma |
| Interactions | Toxicity in CNS increases when used concurrently with alcohol, phenothiazines, barbiturates, and MAOIs |
| Pregnancy | D - Unsafe in pregnancy |
| Precautions | Caution in renal or hepatic impairment, myasthenia gravis, organic brain syndrome, Parkinson disease, hypotension, and respiratory depression |
| Drug Name | Midazolam (Versed) |
|---|---|
| Description | Short-acting benzodiazepine that can be administered in continuous infusion for severe nervous system excitation. |
| Adult Dose | 0.1 mg/kg IV bolus then 0.1 mg/kg/h; titrate dose upward q5min until symptoms controlled |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; preexisting hypotension, narrow-angle glaucoma, and sensitivity to propylene glycol (the diluent) |
| Interactions | Sedative effects may be antagonized by theophyllines; narcotics and erythromycin may accentuate sedative effects because of decreased clearance |
| Pregnancy | D - Unsafe in pregnancy |
| Precautions | Caution in congestive heart failure, pulmonary disease, renal impairment, and hepatic failure; may require intubation and pressor support |
Drug Category: Barbiturates
Used to counteract scorpion-induced hyperactivity.
| Drug Name | Pentobarbital (Nembutal) |
|---|---|
| Description | Short-acting barbiturate with sedative and anticonvulsant properties used to produce barbiturate coma for severe CNS hyperexcitation. Requires patient intubation prior to use. |
| Adult Dose | 12 mg/kg IV bolus, then 5 mg/kg/h; titrate to symptom abatement or EEG inactivity |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; liver failure; porphyria |
| Interactions | Concomitant use with alcohol may produce additive CNS effects and death; chloramphenicol may inhibit metabolism; may enhance chloramphenicol metabolism; MAOIs may enhance sedative effects of barbiturates; valproic acid appears to decrease barbiturate metabolism, increasing toxicity; barbiturates can decrease effects of anticoagulants (patients may require dosage adjustments if barbiturates are added to or withdrawn from regimen); decreased contraceptive effect may occur due to induction of microsomal enzymes (alternate form of birth control is suggested); barbiturates may decrease corticosteroid and digitoxin effects through induction of hepatic microsomal enzymes that increase metabolism; barbiturates decrease theophylline levels and may decrease effects; may decrease verapamil bioavailability |
| Pregnancy | D - Unsafe in pregnancy |
| Precautions | Patient may become tolerant to hypnotic effects; caution in patients with hypovolemic shock, respiratory dysfunction, hypotension, renal dysfunction, congestive heart failure, previous addiction to sedative hypnotics, and congestive heart failure |
Drug Category: Local anesthetics
Tend to be more effective than opiates to control paresthesia and pain at the sting site.
| Drug Name | Bupivacaine (Marcaine) |
|---|---|
| Description | May reduce pain by slowing nerve impulse propagation and reducing action potential, which, in turn, prevents initiation and conduction of nerve impulses. |
| Adult Dose | 1.25 mg/kg/dose intralesionally until pain subsides; not to exceed 3-4 mg/kg |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; septicemia, spinal deformities, severe hypertension, and existing neurologic disease |
| Interactions | May enhance effects of CNS depressants; coadministration may increase toxicity of MAOIs, TCAs, beta-blockers, vasopressors, and phenothiazines |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Test a dose and monitor for CNS toxicity, cardiovascular toxicity, and signs of unintended intrathecal administration; caution with inflammation or sepsis in region of proposed injection; monitor patient's state of consciousness after each injection; caution in hypertension, cerebral vascular insufficiency, peripheral vascular disease or heart block, hypoxia, hypovolemia, and arteriosclerotic heart disease |
Drug Category: Adrenergic blocking agents and vasodilators
Used to counteract the scorpion-induced adrenergic cardiovascular effect.
| Drug Name | Labetalol (Normodyne, Trandate) |
|---|---|
| Description | Blocks beta1-adrenergic, alpha-adrenergic, and beta2-adrenergic receptor sites, decreasing blood pressure. |
| Adult Dose | 20 mg IV then 40 mg IV repeated q10-15min until BP controlled or until the maximum accumulative dose of 300 mg is reached |
| Pediatric Dose | Not established Suggested: 0.1 mg/kg IV; repeat q15-20min as last resort |
| Contraindications | Documented hypersensitivity; cardiogenic shock, pulmonary edema, bradycardia, atrioventricular block, uncompensated congestive heart failure, reactive airway disease, and severe bradycardia |
| Interactions | Decreases effect of diuretics and increases toxicity of methotrexate, lithium, and salicylates; may diminish reflex tachycardia resulting from nitroglycerin use without interfering with hypotensive effects; cimetidine may increase blood levels; glutethimide may decrease effects by inducing microsomal enzymes |
| Pregnancy | C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus |
| Precautions | Caution in impaired hepatic function; discontinue therapy if signs of liver dysfunction occur; in elderly patients, a lower response rate and higher incidence of toxicity may be observed; caution with concomitant beta-blockers; beware of continued hypertension despite decreasing heart rate due to insufficient alpha blockade |
| Drug Name | Prazosin (Minipress) |
|---|---|
| Description | Counteracts scorpion-induced adrenergic cardiovascular effects. May improve pulmonary edema through vasodilatory effects. |
| Adult Dose | 1 mg PO bid/tid; not to exceed 5 mg/dose |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | Acute postural hypotensive reaction from beta-blockers may worsen; indomethacin may decrease antihypertensive activity; verapamil may increase serum levels and may increase patient's sensitivity to prazosin-induced postural hypotension; may decrease antihypertensive effects of clonidine |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Caution in renal insufficiency and hypotension |
| Drug Name | Hydralazine (Apresoline) |
|---|---|
| Description | Decreases systemic resistance through direct vasodilation of arterioles |
| Adult Dose | 10-20 mg IV q4-6h |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | MAOIs and beta-blockers may increase toxicity |
| Pregnancy | B - Usually safe but benefits must outweigh the risks. |
| Precautions | May cause hydralazine-induced tachycardia, SLE-type syndrome, and peripheral neuritis |
Drug Category: Anticholinergics
Used to counteract scorpion-induced cholinergic symptoms.
| Drug Name | Atropine (Atropair) |
|---|---|
| Description | Used to increase heart rate through vagolytic effects, causing an increase in cardiac output. Also treats bronchorrhea associated with scorpion envenomations. |
| Adult Dose | 0.5 mg IV q15min until desired effect (Note: for vagolytic cardiac effects, there is a 3-mg limit) |
| Pediatric Dose | 0.01 mg/kg IV q15min until desired effect (Note: For cardiac vagolytic effects, there is a 3-mg limit) |
| Contraindications | Documented hypersensitivity; thyrotoxicosis, narrow-angle glaucoma, and tachycardia |
| Interactions | Coadministration with other anticholinergics has additive effects; pharmacologic effects of atenolol and digoxin may increase; antipsychotic effects of phenothiazines may decrease; TCAs with anticholinergic activity may increase effects |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Avoid in Down syndrome and/or children with brain damage to prevent hyperreactive response; also avoid in patients with coronary heart disease, tachycardia, congestive heart failure, cardiac arrhythmias, and hypertension; caution in patients with peritonitis, ulcerative colitis, hepatic disease, and hiatal hernia with reflux esophagitis; in patients with prostatic hypertrophy, prostatism may cause dysuria and may require catheterization; monitor patients for anticholinergic effects (eg, hyperthermia, dilated pupils, dry mucous membrane, tachycardia) |
Drug Category: Vasopressors/inotropics
Used to combat hypotension refractory to IV fluid therapy.
| Drug Name | Norepinephrine (Levophed) |
|---|---|
| Description | Indicated for persistent hypotension not responsive to judicious fluid loading and sodium bicarbonate. |
| Adult Dose | 0.05-0.15 mcg/kg/min IV infusion; titrate to effect |
| Pediatric Dose | 0.1-1 mcg/kg/min IV infusion; titrate to effect |
| Contraindications | Documented hypersensitivity |
| Interactions | Chlorpromazine enhances pressor response by blocking reflex bradycardia caused by norepinephrine |
| Pregnancy | D - Unsafe in pregnancy |
| Precautions | Administer into a large vein because extravasation may cause severe tissue necrosis; caution in occlusive vascular disease |
| Drug Name | Dobutamine (Dobutrex) |
|---|---|
| Description | Sympathomimetic amine with stronger beta than alpha effects. Increases inotropic state with afterload reduction. |
| Adult Dose | 5-20 mcg/kg/min IV continuous infusion, titrate to desired response; not to exceed 40 mcg/kg/min |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | Beta-blockers antagonize effects |
| Pregnancy | B - Usually safe but benefits must outweigh the risks. |
| Precautions | Higher dosages may cause increase in heart rate and exacerbate hypotension |
| Drug Name | Milrinone (Primacor) |
|---|---|
| Description | Positive inotropic agent and vasodilator with little chronotropic activity. |
| Adult Dose | 50 mcg/kg loading dose IV over 10 min, followed by 0.375-0.75 mcg/kg/min continuous IV infusion |
| Pediatric Dose | Administer as in adults because has been used in the pediatric ICUs, although safety and efficacy not well established |
| Contraindications | Documented hypersensitivity |
| Interactions | May precipitate if infused in the same IV line as furosemide |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Slow or stop infusion in patients showing excessive decreases in blood pressure |
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