Phosphorus and Its Functions

Phosphorus

• Phosphorus (PO4) is essential for neuromuscular function, red blood cell function, acid-base balance, and structural integrity of teeth and bones.
• Distribution of phosphorus: 85% in bones, 14% in soft tissues.

Normal Values

• PCO2: 41-51 mm Hg (pulmonary venous carbon dioxide).
• PvO2: 35-49 mm Hg (pulmonary venous oxygen).
• SvO2: 60-80% (pulmonary venous oxygen saturation); a decrease indicates inadequate tissue oxygenation.

Left Atrial Pressure

• Monitored in the postoperative period via catheterization, aiming for 100% oxygen saturation in the left atrium.
• Normal left atrial pressure: 1-2 mm Hg above right atrial pressure (4-12 mm Hg). Pressures greater than 12-14 mm Hg post-surgery signal potential issues.
• Increased pressure may point to ventricular dysfunction, heart failure, mitral valve stenosis, or significant intravascular volume overload.
• Decreased pressure may suggest low intravascular volume or insufficient preload.

Pulmonary Artery Pressure

• Measured via catheter in the pulmonary artery, ideal patient position ≤45° elevation.
• Normal pulmonary artery pressure (PAP): 10-20 mm Hg (mean 15 mm Hg).
• Increased PAP may result from left ventricular failure or mitral insufficiency.

Central Venous Pressure (CVP)

• CVP (right atrial pressure) assesses right ventricle function and venous blood flow, normally ranging from 1-7 mm Hg in children.
• Elevated CVP indicates volume overload, right ventricular dysfunction, or conditions like cardiac tamponade.
• Decreased CVP indicates low intravascular volume or vasodilation.

Intra-Arterial Blood Pressure Monitoring

• Used for evaluating systolic, diastolic, and mean arterial pressure (MAP).
• MAP calculation: [(Diastole x 2) + (Systole × 1)] / 3; normal range is 70-100 mm Hg, with 60 as a critical level.

Inotropic Agents

• Medications to increase cardiac output and myocardial contractility, dosed by weight and age.
• Key inotropes:
  • Dobutamine: Improves cardiac output and treats decompensation.
  • Dopamine: Enhances output, blood pressure, and urine excretion.
  • Digoxin: Strengthens contractions; could be given orally or IV.
  • Epinephrine: Increases output and blood pressure; use cautiously due to increased oxygen demand.
  • Milrinone/Amrinone: Improves output and controls heart failure.

Diuretics

• Increase renal perfusion to reduce preload.
• Common types:
  • Bumetanide, Ethacrynic acid, Furosemide: Loop diuretics for edema control.
  • Spironolactone: Potassium-sparing diuretic for heart failure management.

Antihypertensives

• Control congestive heart failure and reduce cardiac workload.
• Examples:
  • Captopril: ACE inhibitor for hypertension.
  • Propranolol: Non-selective beta-blocker.
  • Labetalol: Alpha-1 and beta-adrenergic blocker.

Miscellaneous Cardiac Drugs

• Calcium chloride/gluconate: Increases myocardial contractility post-surgery.
• Brevibloc (Esmolol): Manages hypertension and arrhythmias.
• Indomethacin: NSAID to close patent ductus arteriosus.
• Prostaglandin: Maintains ductus patency before surgery for certain congenital defects.

Normal Cardiac Rates for Children

• Rates vary with activity levels:
  • Newborns: Rest: 100-180; Asleep: 80-160.
  • 1-12 weeks: Rest: 100-220; Asleep: 80-200.
  • 3-24 months: Rest: 80-150; Asleep: 70-120.
  • 2-10 years: Rest: 70-110; Asleep: 60-90.
  • 10-adulthood: Rest: 55-90; Asleep: 50-90.

Cardiac Output, Stroke Volume, and Heart Rate

• Factors in pediatric hemodynamics vary by age:
  • Newborn: CO 800 mL/min, HR 145.
  • 6 months: CO 1000-1600 mL/min, HR 120.
  • 12 months: CO 1400 mL/min, HR 115.
  • 4 years: CO 2300 mL/min, HR 105.
  • 8 years: CO 3500 mL/min, HR 83.
  • 10 years: CO 4000 mL/min, HR 75.
  • 15 years: CO 5000-6000 mL/min, HR 70.

Pulse Oximetry

• Measures arterial oxygen saturation (SpO2) using a machine attached to fingers or toes.
• Maintain SpO2 >95%; readings may be affected by poor circulation, excessive light, or positioning issues.

Electrocardiography (ECG)

• Displays heart's electrical activity; measures waveforms and intervals.
• Key components include P wave, QRS complex, T wave, U wave.
• Standard 12-lead ECG examines various heart conditions like chest pain and arrhythmias.

Heart Sounds

• Normal heart sounds:
  • S1 (lub): Closure of mitral and tricuspid valves.
  • S2 (dub): Closure of aortic and pulmonic valves.
• Additional sounds indicating conditions:
  • S3/S4: Indicate heart failure or hypertrophy, respectively.
  • Murmurs: Result from turbulent blood flow; classified by location, timing, and intensity.

Congestive Heart Failure (CHF)

• Symptoms include poor exercise tolerance, shortness of breath, and failure to thrive.
• Management includes:
  • Diuretics and antihypertensives for symptom relief.
  • Cardiac glycosides for efficacy if needed.
  • Nutritional support and activity restriction.

Chronic vs. Acute Heart Failure

• Chronic Heart Failure: Develops slowly, leads to myocardial necrosis and fibrosis.
• Acute Heart Failure: Sudden onset, compensatory mechanisms may increase oxygen demand, leading to strain and potential arrhythmias.

Cardiac-Related Pulmonary Edema

• Results from excess fluid in lung tissues due to:
  • Increased pulmonary capillary pressure.
  • Damage to capillary-alveolar membranes.
  • Left ventricular dysfunction.

These notes encapsulate core concepts, normal values, and treatments related to cardiovascular health in children, with a focus on managing heart conditions effectively.### Overview of Cardiac Catheterization in Children

• Cardiac catheterization typically involves the insertion of IVs into the femoral artery and vein.
• A catheter is advanced to the heart for diagnostic or therapeutic purposes.

Preparations Before the Procedure

• Sedation and local anesthetic are administered based on the child's age and requirements.

Procedures Performable During Cardiac Catheterization

• Biopsies can be performed to assess heart tissue.
• Dye injections facilitate angiograms for visualizing blood vessels.
• Blood samples can be withdrawn for laboratory testing.
• Atrial septal defects can be opened or enlarged to improve blood flow.
• Stents can be placed to keep vessels open.
• Occlusive devices can be inserted to close defects.
• Balloon inflation can widen narrowed blood vessels to enhance circulation.

Post-Procedure Care

• Pressure is applied to the catheter insertion site for 10 minutes, followed by a pressure dressing.
• Vital signs and leg circulation (if the femoral site was used) are closely monitored.

Potential Complications

• Risks include vascular injury and anaphylaxis.
• Respiratory issues such as hypoventilation and hypotension can occur.
• Arrhythmias and cardiac perforation pose serious threats.
• Formation of emboli (systemic or pulmonary) is possible.
• Cardiac arrest is a critical risk during or post-procedure.