test 6 pulmonary arterial hypertension- PAH

Question 1

Pulmonary Arterial Hypertension-PAH defined by and surgical mortality

Answer 1

• Mean pulmonary pressure >25 mmHg at rest or >30 mmHg during exercise
• Surgical mortality higher for patients with PAH
  * 4-24%

Question 2

Pulmonary Arterial Hypertension-PAH caused by

Answer 2

• Congenital abnormalities
• Valve disorders
• Volume excess
• LV dysfunction
• Idiopathic

Question 3

Hemodynamics of Pulmonary Arterial Hypertension

Answer 3

• RV failure leads to ↓ pulmonary blood flow
• ↓ pulmonary blood flow leads to hypoxia
• Hypoxia leads to ↑ PVR
• ↑ PVR leads to ↑ strain on RV
• ↓ RV SV= ↓ LV output= ↓ coronary blood flow
• Cardiac arrest

Question 4

Hemodynamic Treatment of Pulmonary Artery Hypertension in the OR Setting Goals

Answer 4

1. Avoid elevations in PVR
2. Maintain SVR
3. Avoid myocardial depressants and maintain contractility
4. Maintain chronic prostaglandin therapy without altering dosage
5. Use low-pressure mechanical ventilation when possible

Question 5

Pharmacologic Treatment of Pulmonary Artery Hypertension in the OR Setting

Answer 5

• Prostacyclin Analogs
• Nitroso Dilators
• Inhaled Nitric Oxide (iNO)

Question 6

Prostacyclin Analogs

Answer 6

• Prostacyclin analogs are potent, effective pulmonary vasodilators
• Significantly reduce PVR
• Short half life

Question 7

Prostacyclin Analogs improve

Answer 7

• Exercise tolerance
• Breathing
• Hemodynamics
• Survival

Question 8

Nitric oxide (Endothelial Derived Relaxation Factor (EDRF)) and how it works

Answer 8

• Produced in the endothelial cells via nitric oxide synthase
• diffuses from the endothelial cells to the vascular smooth muscle where it increases cGMP and reduces intracellular Ca2+
• results in smooth muscle relaxation

Question 9

Nitroso Dilators

Answer 9

• IV
• Reduce PA pressures, but may reduce CO and SVR
• Beneficial for moderate PAH and RV dysfunction
• Not for severe RV dysfunction

Question 10

Nitroprusside (Nipride)

Answer 10

• Direct-acting vasodilator
• Nitrate group converted into NO in vascular smooth muscle
• Increased cGMP -> vasodilation
• Short duration (1-2 min)
• Possible cyanide and thiocyanite toxicity
• Metabolic acidosis
• ↑ mixed venous PO2
-Light sensitive
- Light breaks down the cyanide and not as protected

Question 11

Inhaled Nitric Oxide (iNO)

Answer 11

• Selective pulmonary vasodilator
• Devoid of systemic actions
• Favorably affects lung V/Q relationships because it vasodilates lung regions that are well ventilated
- Unobstructed alveoli diffuse iNO to vasodilate capillaries with high vascular resistance

Question 12

Inhaled Nitric Oxide (iNO) Therapeutic Uses

Answer 12

• Pulmonary hypertension
• Persistent pulmonary hypertension of the newborn
• Adult respiratory distress syndrome

Question 13

Inhaled Nitric Oxide (iNO)

Answer 13

• Administered by blending dilute NO into the ventilator inlet gas
• Concentrations range from 0.05-80 ppm
• Onset of action 1-2 minutes
• Low toxicity with safety precautions

Question 14

Inhaled Nitric Oxide (iNO) Possible Adverse Effects

Answer 14

• Depend on dosage and concentration
• Combines with O2
to form NO2
        • NO2 > 10ppm may cause
                • Cell damage
                • Hemorrhage
                • Pulmonary edema
                • Death
• Methemoglobinemia may occur due to NO inactivation process (blood levels monitored daily)

Question 15

ITC AVOXimeter Systems Measure Hemoglobin

Answer 15

• ITC AVOXimeter
  * Total hemoglobin
  * Oxyhemoglobin
  * Carboxyhemoglobin
  * Methemoglobin