It can be frightening to hear your pediatrician say that your child has a weak pulse, but there are many common causes for this symptom, including hormonal and nutrient imbalances and overexposure to some drugs and toxins. Unusual causes include congenital heart problems, artery disease and infection. Your pediatrician is best suited to diagnose and treat all symptoms that your child experiences.
Normal Pulse
A pulse is a measurement of heart rate in beats per minute (bpm). The normal pulse range for a child aged one to two years is 70 to 150 bpm, with an average of 120. Between two and six years of age the normal range is 68 to 138 bpm, with an average of 100. For children aged six to ten, the normal pulse range is 65 to 125 bpm, with an average of 90.
Metabolic and Nutritional Causes
If children do not consume adequate protein, calories or both, their hearts may become weak and show atrophy. This may cause reduced blood flow from the heart, resulting in a weak pulse. Protein deficiency is known as kwashiorkor and caloric deficiency is known as marasmus. These disorders are common in developing countries, but they can occur anywhere if children are not fed a nutritionally adequate diet.
Dehydration can occur rapidly during summer months. Dehydration is categorized as mild, moderate or severe. In severe dehydration, pulses will be rapid and weak or absent. Additional symptoms include hypotension, decreased urine output, diminished tear production, poor skin turgor and sunken eyeballs. The child with severe dehydration requires immediate intervention in order to maintain adequate circulation.
Thyroid hormones increase metabolism and indirectly increase blood circulation. Deficiency of these hormones can result in weak pulses and a reduction in heart rate and blood pressure. If the thyroid gland is malformed, it may not be able to produce an adequate level of thyroid hormones. Thyroid hormone is transported to receptors where it is bound. If there is any defect in transport or in the receptors, the hormone cannot bind and will not function properly. Thyroid malformation accounts for approximately 85 percent of congenital hypothyroidism. Infants with congenital hypothyroidism may not display symptoms of the condition at birth, according to "Nelson Textbook of Pediatrics." This may be due to the fact that maternal thyroid hormones cross the placenta and account for some of the hormonal activity in the child in the first month of life.
Drugs and Toxins
Envenomation due to hymenoptera stings may cause weak pulses. The hymenoptera order includes bees and wasps that inject venom through an abdominal stinger. An allergy to the venom may present as local swelling, rash, wheezing, hypotension and weak pulses. Envenomation from a marine stingray when swimming in the ocean may also cause weak pulses.
Heavy skin exposure to insect repellents which contain DEET may cause weak pulses and seizures. Insect repellents should be used cautiously on the skin.
A potential side effect of the drug codeine is weak pulses. Codeine may be an ingredient of some cough syrups or pain relievers.
High levels of magnesium can cause weak pulses. Hypermagnesemia is almost always due to high intake of magnesium. High levels of magnesium can be found in some laxatives and antacids. Hypermagnesemia in a newborn may be due to the mother’s treatment with magnesium sulfate for pre-eclampsia or eclampsia during labor. Symptoms of hypermagnesemia include weakness, sleepiness, lethargy, weak pulses, nausea and vomiting.
Heart Problems
Anything that affects the ability of the heart to function or impedes blood flow from the heart to the rest of the body may contribute to a weak pulse. Some of the more common causes include congenital heart malformations and pericardial disease.
Aortic stenosis (AS) is a stiffening of the aortic valve that may obstruct the blood flow from the heart. A distinctive murmur is associated with AS, which your pediatrician can detect. Symptoms include an enlarged heart, weak pulses, pale skin, fatigue, dizziness and diminished urine output.
Coarctation of the aorta is a narrowing of the aorta resulting in diminished blood flow from the heart. It may be genetically associated with Turner syndrome in females. Symptoms may include weakness and painful legs after exercise. While pulses are weak in the lower extremities, they are bounding in the upper extremities. Some children with mild AS or minimal coarctation of the aorta may be asymptomatic.
Pericardial disease has many causes. The pericardium is a sac that surrounds the heart. The sac is ordinarily filled with a small amount of lubricating fluid. If there is any inflammation of the pericardium due to trauma or infection, the pericardial fluid may increase and constrict the heart. If this constriction compromises heart function, then less blood will be pumped out of the heart, which may result in diminished pulses. Other symptoms may include chest pain, cough, fever and vomiting. Symptoms are related to the amount of fluid in the pericardial sac.
Infections
The most notable infections that cause weak pulses in children are generally found in developing countries. However, there was a recent outbreak of Dengue Fever in Key West, Florida in 2009. According to the Florida Department of Health, local transmission of Dengue within the state is continuing and “as of December 11, 2010, 61 individuals have been identified that acquired dengue in Key West in 2010.”
Dengue Fever is caused by the dengue virus which is transmitted by the Aedes aegypti mosquito. Dengue occurs in temperate areas around the globe where the mosquito can thrive. After an incubation period of one to seven days, symptoms may include fever, vomiting, headache, cough, cold clammy extremities and easy bruising. The pulse is weak and rapid with faint heart sounds.
Cholera is caused by the bacterium Vibrio cholerae, found in contaminated food and water. It causes copious watery diarrhea and vomiting, quickly progressing to dehydration. Symptoms may include fever, weak pulses, poor skin turgor, decreased urine output, sunken eyeballs and diarrhea and vomiting without abdominal cramps.
Lassa Fever is found in West Africa and is caused by the arenavirus called Lassa. Symptoms include sore throat, weakness, fever, headache, cough, weak pulses and bleeding from the nose, mouth and eyes.
Artery Disease
Takayasu arteritis is a chronic vasculitis affecting the aorta and its branches. TA is also known as “pulseless disease.” It is uncommon in the United States, but it is one of the most common forms of vasculitis in the world. It is found most often in females who live in Asia and India. There may be a correlation between exposure to tuberculosis and development of TA. Aside from weak pulses, other symptoms include weight loss, fatigue, arthritis, rash and pericarditis.
Hypovolemic shock
Hypovolemic shock is an unusual cause of weak pulses in children. It is usually the result of burns that cause fluid loss or trauma that causes hemorrhage. Severe nausea and vomiting can also be responsible for the lack of fluid volume in hypovolemic shock. Weak pulses are the result of lost blood volume inside the blood vessels. Weak pulses in hypovolemic shock is a medical emergency.
References
- “Harrison’s Principles of Internal Medicine," 17th ed.; Anthony S. Fauci, et al.; 2008
- “Nelson Textbook of Pediatrics," 18th ed.; Robert M. Kliegman, et al; 2007
- “Clinical Anatomy," 7th ed.; Richard S. Snell; 2004
- “Bates’ Guide to Physical Examination and History Taking," 10th ed.; Lynn S. Bickley, et al; 2009
- “American Family Physician”; Recognition and Management of Acute Pesticide Poisoning; William M. Simpson Jr., M.D., and Stanley H. Schuman, M.D., DrPH; April 2002
- Drugs.com: Codeine
- Florida Department of Health
Member Comments