Before or after you listen to Episode 84 podcast, take a look at Effortless Rapid Breathing, Infant Respiratory Distress Signs, Tachycardia, and Apnea (Apparent Life-Threatening Event [ALTE]) Posted on December 23, 2015 by Tom Wade MD
And before or after you listen to the Episode 84 podcast, be sure to listen to the podcast Best Case Ever 47 – Cyanotic Infant. In addition to the outstanding brief lecture on “question of intermitent cyanosis”, there are outstanding links to other resources on congenital heart disease. Be sure and review those links in the BCE 47 show notes.
Dr. Anton Helman, the host of this podcast, interviews Drs. Joubert and Strobel, both experts in the subject.
Dr. Helman notes that the incidence of critical congenital heart disease is almost as high as the incidence of infant sepsis.
And further, that critical congential heart disease occurs in two out of a thousand live births and that half of those infants will be discharged without the diagnosis being recognized in the newborn nursery.
And half of those babies will present to the emergency department for emergency diagnosis and management.
The following is from the show notes of EMC #84:
General Approach to Congenital Heart Disease Emergencies: Age, Colour & Tests
Rather than learning all the complicated details of every congenital heart lesion, this simple approach let’s you focus on time-sensitive life-saving treatments and practical management of the child.
1. Age: Less than one month or greater than one month?
Any infant < 1 month of age with cyanosis or shock should be considered to have duct-dependent critical congenital cardiac disease until proven otherwise. This is almost always a left heart lesion/ductal dependent lesion such as Tetralogy of Fallot, which almost always benefit from prostaglandins. Shunting or mixing lesions such as VSD or PDA and heart failure typically present later during infancy, usually after 1-6 months of age.
2. Colour: Are they Pink, Grey or Blue?
Infants with congenital cardiac conditions usually appear on observation to the clinician in one of three ways:
Pink: think heart failure (adequate pulmonary blood flow, relatively well-perfused and oxygenated; usually due to a shunting lesion)
Grey: think shock/circulatory collapse (not enough systemic flow, not oxygenating well; usually left-sided obstructive, ductal-dependent lesion). These patients are very sick with hypotension, tachypena and poor capillary refill. They will almost always benefit from fluids and prostaglandins if less than 1 month in age.
Blue: think right obstructive duct-dependent in the first month of life or mixing lesion (inadequate pulmonary blood flow: usually right-sided obstructive ductal-dependent lesion or a mixing lesion) after one month of life. These patients also almost always require prostaglandins.
Bedside Pearl: The tachypneic infant who appears to be struggling to breath (i.e. increased work of breathing) usually has an underlying respiratory cause vs. the infant who is displaying ‘silent tachypnea’, without increased work of breathing is usually secondary to metabolic acidosis from a cardiac or metabolic cause.
When faced with a blue baby in the ED, there are 4 etiologies to always consider.
The big 4 Causes of Neonatal Cyanosis
1.Congenital Heart Disease
3.Respiratory disorders (i.e., pneumonia, ARDS)
4.Hemaglobinopathy (i.e., polycythemia, methemoglobinemia)
To distinguish central cyanosis from peripheral cyanosis, look for bluish discoloration inside the mouth – tongue, mucous membranes and lips [Emphasis added].
3. Bedside and Physical Examination Tests in Congenital Heart Disease Emergencies
Hyperoxia Test: Differentiating pulmonary disorders from cardiac disorders
One clue on history for differentiating respiratory disease from cardiac disease in the sick infant who presents to the ED is asking about the timing of symptoms: Symptoms of respiratory conditions tend to start at birth as apposed to cardiac conditions tend to present a few days after birth, when the ductus begins closing. On physical exam, dyspnea in the absence of the classic signs of respiratory distress should trigger you to consider a cardiac or metabolic cause as described above. However, in infants these historical and physical exam clues aren’t always so clear. This is where the hyperoxia test comes in:
The hyperoxia test was originally described using the PAO2 garnered from the ABG. Although accurate, this was a cumbersome, painful and lengthy method. A simpler method involves using a pulse oximeter before and after the patient receives 100% oxygen (or as close to a 100% FIO2 as possible) for 5-10 minutes and noting whether or not the oxygen saturation improves. If the oxygen saturation improves then the underlying cause of the oxygen desaturation favours a respiratory etiology, whereas if the oxgygen saturation does not improve, a cardiac cause is favoured.
Caution! 100% oxygen is a pulmonary vasodilator and could worsen respiratory distress in a patient with ductal-dependent lesions, by decreasing PVR and increasing pulmonary blood flow, leading to pulmonary over-circulation
Pulse Delay or Absence: Decreased or absent femoral pulses may suggest coarctation of the aorta
Brachial-femoral pulse differential: pulses should arrive at the brachial and femoral pulse simultaneously, if there is a brachial-femoral delay there may be an issue
Blood pressure differential: Difference between preductal (i.e. right arm) blood pressure and lower extremity blood pressure of > 10 mmHg, think of an obstructive process to the lower extremities.
O2 saturation differential: Difference in O2 saturation > 3% between right upper and right lower extremity, <94% in lower extremities, or < 90% in any extremity are considered clinically significant
ECG in Congenital Heart Disease Emergencies
Look for LVH as well as Persistent RVH after 1 month of age
One of the most important considerations in the infant ECG to help determine whether your patient has a congenital heart defect (in particular a ductal dependent lesion), is to determine whether left ventricular hypertrophy is present (which is always abnormal regardless of age) and to determine whether right ventricular hypertrophy is present after the age of one month. Normal newborns have high right sided pressures (right axis deviation) with ECG signs of RVH. However, persistent high right sided pressures and RVH after one month of life is likely due to a cardiac obstructive lesion.
Criteria for diagnosing RVH:
Positive T wave in V1 after day of life 5-7;
R in V1 > 98th percentile for age, or
S in V6 > 98th percentile for age
Criteria for diagnosing LVH:
S wave in V1 > 98th percentile, or
R wave in V6 > 98th percentile for age
Point of Care Ultrasound Clues for Congenital Heart Disease Emergencies
With bedside ECHO, ask yourself 3 simple questions:
Is the global cardiac function poor?
Are there four chambers of the heart?
Is the septum intact?
Blood Tests to consider in suspected Congenital Heart Disease Emergencies
Blood glucose (ABC Don’t Ever Forget Glucose)
Electrolytes (to assess for adrenal insufficiency)
Methemoglobin if cyanosis without respiratory distress
Ammonia (metabolic diseases)
BNP: ongoing debate about usefulness of this test, particularly in the ED setting.
BNP < 100pg/mL to identify significant congenital heart disease had a sensitivity of 100% and specificity of 98%
BNP > 132.5pg/mL to detect hemodynamically significant left-to-right shunts had a 93% sensitivity and 100% specificity
BNP > 40pg/mL to differentiate cardiac from pulmonary causes of respiratory distress had an accuracy of 84%
Treatment of Grey or Blue Infants Suspected of Duct Dependent Lesions
Any neonate in distress should be presumed to be septic until proven otherwise. Early empiric antibiotics should be started as soon as possible. Prostaglandin therapy should be implemented for any grey or blue infant less than a month of age to keep the PDA open [Emphasis added].
Caution! Prostaglandins can cause apnea and hypotension so be prepared to intubate and resuscitate.
Be judicious with fluids. Use 5-10 cc/kg NS boluses to improve preload, and encourage further opening of the PDA and pulmonary blood flow through the duct. Give Oxygen. aim for an oxygen saturation of 85% (depending on diagnosis and lesion). The use of sodium bicarbonate is controversial. It may be given empirically based on the blood gas, as acidosis aggravates hypoxic pulmonary vasoconstriction. Inotropes/vasopressors may be necessary to maintain adequate systemic perfusion and encourage pulmonary perfusion in consultation with a pediatric intensivist.
Intubation Considerations in Congenital Heart Disease Emergencies: Say No to Ketamine! [Emphasis added]
Etomidate is a good first line choice as an induction agent because it maintains hemodynamics. If unavailable, fentantyl is a second option. Ketamine should be avoided in patients suspected of congenital heart disease emergencies as it increases SVR, which worsens left-to-right shunting and can lead to cardiovascular collapse. [Emphasis added]
Positive pressure ventilation can increase PVR and decrease SVR and preload which can affect shunting flow, especially in a cyanotic baby. If starting positive pressure ventilation, start with a very low PEEP in these patients. [Emphasis added]
The Pink Infant: Pediatric Congestive Heart Failure (CHF)
Heart failure usually presents with a ‘pink’ relatively well-perfused and oxygenated infant 1 to 6 months of age. Always consider CHF in the wheezing child! [Emphasis added]
The most sensitive and specific clinical findings for acute CHF in infants:
< 3 ounces of formula per feed or > 40 minutes per breast feed
Respiratory rate > 60 breaths per minute or irregular breathing
Hepatomegaly – Start palpation at the iliac crest and slowly move superiorly, and feel for the liver edge. Normally, the liver edge should be < 2 cm below the costal margin. Also percuss for the size of the liver – normally, the liver should be < 8 cm wide.
Other clues include poor weight gain, ventricular hypertrophy on ECG. [Emphasis added]
Common causes of CHF in the pediatric patient include structural causes such as VSD, ASD, Aortic Stenosis and PDA as well as other causes such as SVT, AV block, cardiomyopathy and myocarditis. [Emphasis added]
Management of Acute CHF in infants
It seems intuitive that kids in acute congestive heart failure should receive oxygen, however oxygen is a potent pulmonary vasodilator and could worsen hypoxemia in some congenital heart defects situations. Infants are able to tolerate oxygen saturations lower than adults and so aiming for an oxygen saturation of >85% (as apposed to >93% in adults) is a reasonable goal.
Furosemide, as in adults, is indicated for pediatric patients in acute congestive heart failure.
Inotropes or vasodilators (i.e., milrinone, dobutamine) may be indicated in severe heart failure in consultation with your pediatric intensivist.
Emerg Med Clin North Am. 2015 Aug;33(3):501-18. doi: 10.1016/j.emc.2015.04.002.
The Critically Ill Infant with Congenital Heart Disease [PubMed Abstract]
Alprostadil (Prostaglandin E1) 2016 from Neonatal Medicines Formulary Consensus Group.