Cyanotic spells/ TET Spells

1. Cyanotic ( Tet ) spells Muhammad Adnan PGR Paeds ATH Abbottabad

2. C yanosis Cyanosis specifically refers to a bluish tone visible in the mucous membranes and skin when desaturated or abnormal hemoglobin is present in the peripheral circulation Central cyanosis occurs when poorly oxygenated blood enters the systemic circulation right-to-left” shunt and may occur within the heart or in the pulmonary circulation itself. When there is primary parenchymal lung disease or neurologic disease causing alveolar hypoventilation, an “intrapulmonary” right-to-left shunt can occur.

3. Causes of cyanosis Abnormal hemoglobins may be fully saturated with oxygen, yet unable to release it to the tissues like Methemoglobinemia Anemia at hb = 3-5gm/dl cyanosis will be visible Typical cyanotic lesions are the “five Ts” of congenital heart disease ( tetralogy of Fallot , transposition of the great vessels, total anomalous pulmonary venous return, tricuspid atresia , and truncus arteriosus ), but others may also be present. Pulmonary diseases like upper airway obstructive problems (croup, epiglottitis ) lower airway diseases ( bronchiolitis , asthma, cystic fibrosis, pneumonia with lobar consolidation). Foreign body

4. Differentiating cardiac from pulmonary causes Differentiating cardiac from pulmonary etiologies is critical breath sounds are usually normal in cardiac disease while wheezes, rhonchi , and chest wall abnormalities usually accompany a pulmonary process. hyperoxia test cyanotic cardiac disease little response to increased ambient oxygen, pulmonary disease the saturation increase may be dramatic with Oxygen. ABG may also be useful, since an elevated pCO2 indicating impaired ventilatory status, usually not seen with cyanotic congenital heart disease unless there is associated pulmonary congestion.

5. The chest X-ray may reveal cardiomegaly , an abnormal pulmonary circulatory pattern, or overt pulmonary parenchymal abnormalities such as atelectasis or pneumothorax . Heart murmer The absence of a heart murmur does not rule out cyanotic cardiac disease; in most conditions with right-to-left shunting there is no murmur. Tachypnea may be present with most pulmonary diseases Hyperpnea , or deep breathing with only a mild increase in rate, is more characteristic of a primary cardiac disorder where alveolar ventilation is maximized but pulmonary blood flow is reduced. Hyperpnea can also reflect metabolic acidosis or elevated intracranial pressure

6. Cyanotic ( Tet ) spells Acute hypoxemic attacks represent a true emergency and initial treatment is crucial to long term outcome . Usually , the underlying diagnosis is tetralogy of Fallot . In a Tet spell, an acute increase in obstruction to pulmonary blood flow (either in heart or in pulmonary circulation) results in increase in right-to-left shunting through an intracardiac septal defect. Alternatively , if systemic perfusion is reduced, as with hypovolemia or the development of a tachyarrhythmia , right-to-left shunting will also increase and a cyanotic spell develop .

7. Clinical presentation and diagnosis They are characterised by: Period of uncontrollable crying / panic, Rapid and deep breathing (hyperpnoea), Deepening of cyanosis, Decreased intensity of heart murmur, Limpness, convulsions and rarely, death. common in the early morning , shortly after the patient awakens ,. Prolonged agitation and crying are also cited as precipitants, Also , noxious stimuli , such as phlebotomy or a bee sting, or any circumstance which leads to enhanced catecholamine output can precipitate a spell in a susceptible child . A decrease in systemic vascular resistance (SVR) during exercise, bathing, or fever potentiates a right-to-left shunt and precipitates hypoxemia In such cases( tet spells), the absence of a heart murmur is a worrisome indicator that pulmonary blood flow is severely compromised .

8. Differential Diagnoses Aortic stenosis Acute Respiratory Distress Syndrome Apnea Bronchiolitis Foreign Body Ingestion Pediatric Patent Ductus Arteriosus Surgery Pneumonia Pneumothorax Pulmonic Valvular Stenosis Sickle Cell Anemia

9. Workup Hemoglobin and hematocrit values are usually elevated in proportion to the degree of cyanosis. Prolonged cyanosis causes reactive polycythemia that increases the oxygen-carrying capacity. While in cyanosis due to Anemia hb is 3-5g/dl ABG results show varying oxygen saturation, but pH and partial pressure of carbon dioxide (pCO 2 ) are normal, unless the patient is in extremis, such as during a tet spell . Oximetry is particularly useful in a dark-skinned patient or an anemic patient whose level of cyanosis is not apparent. Generally, cyanosis is not evident until 3-5 g/ dL of reduced hemoglobin is present.

10. Echocardiography Echocardiograms will usually reveal a large VSD with an overriding aorta and variable degrees of right ventricular (RV) outflow tract obstruction (RVOTO) Radiography The hallmark of tetralogy of Fallot is the classic boot-shaped heart 

11. Emergency management Management is directed at manipulating the relative resistances of the systemic and pulmonary vascular beds, as well as maintenance of appropriate circulating volume and heart rate 1. Knee-to-chest / Squatting : Placing the child in the knee-chest position either lying supine or over the parent’s shoulder (see below).  This calms the infant, reduces systemic venous return and increases systemic vascular resistance. . Some older patients will instinctively squat to achieve the same result.

12. 2 . Oxygen  (100%) can be administered which also increasessystemic resistance and may help enhance oxygen delivery   but usually has minimal effect. 3. Morphine:  0.1-0.2 mg/kg IM .  (Caution in infants under 3 months).  morphine may cause pulmonary vasodilatation and also provide a beneficial sedative effect, with consequent reduction of catecholamine secretion.

13. If the above procedures are ineffective or have suboptimal effect, the following treatments may need to be given. Establish IV access and discuss with a senior colleague.   4. Crystalloid or colloid fluid bolus: 10-20ml/kg by rapid IV push .  give an IV fluid bolus of 20 mL /kg normal saline Obtain an ABG. Treat metabolic acidosis with sodium bicarbonate, 1–2 mEq /kg slowly IV, only if ventilation is adequate (low or normal pCO2)  5. . phenylephrine If cyanosis persists, give phenylephrine (10 mcg/kg by slow IV push ) to pharmacologically increase the systemic vascular resistance

14. 5. beta blocker (e.g. propranolol or esmolol )  In severe episodes, IV propranolol ( Inderal ) may be administered, which relaxes the infundibular muscle spasm causing right ventricular (RV) outflow tract obstruction (RVOTO) Esmolol (BREVIBLOC ® )  500 mcg/kg over one minute IV, then maintenance of 50 mcg/kg/min can be increased  in steps of 50mcg/kg/min to maximum dose of 300mcg/kg/min   ultra-short acting cardioselective beta blocker, reducing dynamic muscular stenosis of the right ventricular outflow tract and increasing pulmonary blood flow The availability of these medications may be limited in some centres . . Progressive hypoxemia and the occurrence of cyanotic spells are indications for early surgery .

15. For chronic cyanotic congenital heart conditions supportive treatment is all that can be done until a surgical or catheter-directed intervention can be accomplished. Give supplemental oxygen, even though dramatic changes in saturation will not occur with oxygen alone. Secure IV access and give fluid to maintain an adequate circulating volume. Treat systemic acidosis once adequate ventilation is ensured. Most of all, immediately consult with a cardiologist to arrange for more definitive treatment and to prevent unnecessary interventions.