The ratio of chest compressions to ventilations is 15:2. This ratio has not been proven through experiments, but it has been validated through mathematical studies. When performing chest compressions on a child, it is recommended to make them at least 1/3 of the depth of the child’s chest. Additionally, the optimal compression rate is between 100 and 120 compressions per minute.
To protect the airway of an unconscious child, the oropharyngeal (Guedel) airway is the best option. However, it should not be used on awake patients as there is a risk of vomiting and aspiration.
In children, asystole is the most common arrest rhythm. This occurs when the young heart responds to prolonged hypoxia and acidosis by progressively slowing down, eventually resulting in asystole.

The timing of the initial rise, peak, and return to normality of various cardiac enzymes can serve as a helpful guide. Creatine kinase, the main cardiac isoenzyme, typically experiences an initial rise within 4-8 hours, reaches its peak at 18 hours, and returns to normal within 2-3 days. Myoglobin, which lacks specificity due to its association with skeletal muscle damage, shows an initial rise within 1-4 hours, peaks at 6-7 hours, and returns to normal within 24 hours. Troponin I, known for its sensitivity and specificity, exhibits an initial rise within 3-12 hours, reaches its peak at 24 hours, and returns to normal within 3-10 days. HFABP, or heart fatty acid binding protein, experiences an initial rise within 1.5 hours, peaks at 5-10 hours, and returns to normal within 24 hours. Lastly, LDH, predominantly found in cardiac muscle, shows an initial rise at 10 hours, peaks at 24-48 hours, and returns to normal within 14 days.

Pericarditis refers to the inflammation of the pericardium, which can be caused by various factors such as infections (typically viral, like coxsackie virus), drug-induced reactions (e.g. isoniazid, cyclosporine), trauma, autoimmune conditions (e.g. SLE), paraneoplastic syndromes, uraemia, post myocardial infarction (known as Dressler’s syndrome), post radiotherapy, and post cardiac surgery.

The clinical presentation of pericarditis often includes retrosternal chest pain that is pleuritic in nature. This pain is typically relieved by sitting forwards and worsened when lying flat. It may also radiate to the shoulders. Other symptoms may include shortness of breath, tachycardia, and the presence of a pericardial friction rub.

The pericardium receives sensory supply from the phrenic nerve, which also provides sensory innervation to the diaphragm, various mediastinal structures, and certain abdominal structures such as the superior peritoneum, liver, and gallbladder. Since the phrenic nerve originates from the 4th cervical nerve, which also provides cutaneous innervation to the front of the shoulder girdle, pain from pericarditis can also radiate to the shoulders.

Mitral regurgitation is characterized by several clinical features. One of the main signs is a pansystolic murmur that can be heard throughout the entire systolic phase of the cardiac cycle. This murmur often radiates to the left axilla. Another notable feature is a soft S1 heart sound, which is the first heart sound heard during the cardiac cycle. Additionally, a 3rd heart sound, also known as an added sound, can be detected in patients with mitral regurgitation. As the condition progresses to moderate to severe levels, signs such as a laterally displaced apex beat with a heave may become apparent.

Further Reading:

Mitral Stenosis:
– Causes: Rheumatic fever, Mucopolysaccharidoses, Carcinoid, Endocardial fibroelastosis
– Features: Mid-late diastolic murmur, loud S1, opening snap, low volume pulse, malar flush, atrial fibrillation, signs of pulmonary edema, tapping apex beat
– Features of severe mitral stenosis: Length of murmur increases, opening snap becomes closer to S2
– Investigation findings: CXR may show left atrial enlargement, echocardiography may show reduced cross-sectional area of the mitral valve

Mitral Regurgitation:
– Causes: Mitral valve prolapse, Myxomatous degeneration, Ischemic heart disease, Rheumatic fever, Connective tissue disorders, Endocarditis, Dilated cardiomyopathy
– Features: pansystolic murmur radiating to left axilla, soft S1, S3, laterally displaced apex beat with heave
– Signs of acute MR: Decompensated congestive heart failure symptoms
– Signs of chronic MR: Leg edema, fatigue, arrhythmia (atrial fibrillation)
– Investigation findings: Doppler echocardiography to detect regurgitant flow and pulmonary hypertension, ECG may show signs of LA enlargement and LV hypertrophy, CXR may show LA and LV enlargement in chronic MR and pulmonary edema in acute MR.

One way to assess for digoxin toxicity is by examining the patient’s electrocardiogram (ECG) for specific characteristics. In the case of digoxin toxicity, ECG findings may include downsloping ST depression, prolonged QT interval, tall tented T-waves, and possibly delta waves. However, a short PR interval (< 120ms) is not typically associated with digoxin toxicity. Further Reading: Digoxin is a medication used for rate control in atrial fibrillation and for improving symptoms in heart failure. It works by decreasing conduction through the atrioventricular node and increasing the force of cardiac muscle contraction. However, digoxin toxicity can occur, and plasma concentration alone does not determine if a patient has developed toxicity. Symptoms of digoxin toxicity include feeling generally unwell, lethargy, nausea and vomiting, anorexia, confusion, yellow-green vision, arrhythmias, and gynaecomastia. ECG changes seen in digoxin toxicity include downsloping ST depression with a characteristic Salvador Dali sagging appearance, flattened, inverted, or biphasic T waves, shortened QT interval, mild PR interval prolongation, and prominent U waves. There are several precipitating factors for digoxin toxicity, including hypokalaemia, increasing age, renal failure, myocardial ischaemia, electrolyte imbalances, hypoalbuminaemia, hypothermia, hypothyroidism, and certain medications such as amiodarone, quinidine, verapamil, and diltiazem. Management of digoxin toxicity involves the use of digoxin specific antibody fragments, also known as Digibind or digifab. Arrhythmias should be treated, and electrolyte disturbances should be corrected with close monitoring of potassium levels. It is important to note that digoxin toxicity can be precipitated by hypokalaemia, and toxicity can then lead to hyperkalaemia.

The timing of the initial rise, peak, and return to normality of various cardiac enzymes can serve as a helpful guide. Creatine kinase, the main cardiac isoenzyme, typically experiences an initial rise within 4-8 hours, reaches its peak at 18 hours, and returns to normal within 2-3 days. Myoglobin, which lacks specificity due to its association with skeletal muscle damage, shows an initial rise within 1-4 hours, peaks at 6-7 hours, and returns to normal within 24 hours. Troponin I, known for its sensitivity and specificity, exhibits an initial rise within 3-12 hours, reaches its peak at 24 hours, and returns to normal within 3-10 days. HFABP, or heart fatty acid binding protein, experiences an initial rise within 1.5 hours, peaks at 5-10 hours, and returns to normal within 24 hours. Lastly, LDH, predominantly found in cardiac muscle, shows an initial rise at 10 hours, peaks at 24-48 hours, and returns to normal within 14 days.

Adrenaline is recommended to be administered after the third shock in a shockable cardiac arrest (Vf/pVT) once chest compressions have been resumed. The recommended dose is 1 mg, which can be administered as either 10 mL of 1:10,000 or 1 mL of 1:1000 concentration. Subsequently, adrenaline should be given every 3-5 minutes, alternating with chest compressions, and it should be administered without interrupting the compressions. While there is no evidence of long-term benefit from the use of adrenaline in cardiac arrest, some studies have shown improved short-term survival, which justifies its continued use.

Amiodarone is a medication that is recommended to be administered after the third shock in a shockable cardiac arrest (Vf/pVT) while chest compressions are being performed. The prescribed dose is 300 mg, given as an intravenous bolus that is diluted in 5% dextrose to a volume of 20 mL. It is important to note that amiodarone is not suitable for treating PEA or asystole.

In cases where VF/pVT persists after five defibrillation attempts, an additional dose of 150 mg of amiodarone should be given. However, if amiodarone is not available, lidocaine can be used as an alternative. The recommended dose of lidocaine is 1 mg/kg. It is crucial to avoid administering lidocaine if amiodarone has already been given.

Amiodarone is classified as a membrane-stabilizing antiarrhythmic drug. It works by prolonging the duration of the action potential and the refractory period in both the atrial and ventricular myocardium. This medication also slows down atrioventricular conduction and has a similar effect on accessory pathways.

Additionally, amiodarone has a mild negative inotropic action, meaning it weakens the force of heart contractions. It also causes peripheral vasodilation through non-competitive alpha-blocking effects.

It is important to note that while there is no evidence of long-term benefits from using amiodarone, it may improve short-term survival rates, which justifies its continued use.

Brugada syndrome is a genetic disorder that is passed down from one generation to another in an autosomal dominant manner. It is characterized by abnormal findings on an electrocardiogram (ECG) and can lead to sudden cardiac death. The cause of death in individuals with Brugada syndrome is typically ventricular fibrillation, which occurs as a result of specific defects in ion channels that are determined by our genes. Interestingly, this syndrome is more commonly observed in South East Asia and is actually the leading cause of sudden unexplained cardiac death in Thailand.

One of the key features seen on an ECG that is consistent with Type 1 Brugada syndrome is a pattern known as right bundle branch block. Additionally, there is a distinct downward sloping coved ST elevation observed in leads V1-V3. These specific ECG findings help to identify individuals who may be at risk for developing Brugada syndrome and experiencing its potentially fatal consequences.

Radiation to the trapezius ridge is a distinct symptom of acute pericarditis. The patient in question exhibits characteristics that align with a diagnosis of pericarditis. Pericarditis is a common condition affecting the pericardium, and it is often considered as a potential cause for chest pain. It is worth noting that the specific radiation of pain to the trapezius ridge is highly indicative of pericarditis, as it occurs when the phrenic nerve, which also innervates the trapezius muscle, becomes irritated while passing through the pericardium.

Further Reading:

Pericarditis is an inflammation of the pericardium, which is the protective sac around the heart. It can be acute, lasting less than 6 weeks, and may present with chest pain, cough, dyspnea, flu-like symptoms, and a pericardial rub. The most common causes of pericarditis include viral infections, tuberculosis, bacterial infections, uremia, trauma, and autoimmune diseases. However, in many cases, the cause remains unknown. Diagnosis is based on clinical features, such as chest pain, pericardial friction rub, and electrocardiographic changes. Treatment involves symptom relief with nonsteroidal anti-inflammatory drugs (NSAIDs), and patients should avoid strenuous activity until symptoms improve. Complicated cases may require treatment for the underlying cause, and large pericardial effusions may need urgent drainage. In cases of purulent effusions, antibiotic therapy is necessary, and steroid therapy may be considered for pericarditis related to autoimmune disorders or if NSAIDs alone are ineffective.