Question 22

College answer

Not available.

Discussion

a) 

In brief, the WHO recognises  5 major groups of disease which fall under the pulmonary hypertension heading:

1. Pulmonary arterial hypertension 
2. Pulmonary hypertension due to left heart disease
3. Pulmonary hypertension due to lung disease or hypoxia
4. Pulmonary hypertension due to chronic PE​​
5. Pulmonary hypertension due to "unclear multifactorial mechanisms"

These "PH WHO" groups are also known as the Dana Point classification system, so named because the original 2008 symposium on pulmonary hypertension was held in Dana Point, Ca.  

b)

Management of right heart failure 

• Preload management:
  • Acute failure: increase preload to CVP 8-12 mmHg
  • Chronic failure: decrease preload to CVP 8-12 mmHg (this is the most likely scenario, as they are telling us the patient has known pulmonary hypertension). Thus, the options are:
    • Diuretics (potentially as an infusion)
    • Dialysis for fluid removal (potentially even SCUF)
  • The exact preload is difficult to find, is individual, and is best titrated by using  a PA catheter (CO measurements) or serial TTE/TOE
• Afterload management:
  • Prevent pulmonary vasoconstriction:
    • Keep PEEP 6-10 cm H₂O
    • Keep SpO₂ >92%
    • Keep PaCO₂ 35-45 mmHg
    • Keep pH 7.35-7.45
    • Avoid high dose noradrenaline; prefer to use vasopressin
      • But: keep systemic BP at least above pulmonary BP
    • Position the patient with the "good" lung dependent to encourage blood flow into a more compliant system
  • Increase pulmonary vasodilation:
    • Nitric oxide
    • IV or inhaled prostacycline
    • Bosentan, ambrisentan
    • Sildenafil, tadalafil
    • Riociguat
• Contractility:
  • Milrinone, for where PA pressure is raised
  • Levosimendan, for where you really need a cardiac output boost
  • Dobutamine is probably not the best choice, but can be resorted to if the patient is in renal failure and cannot tolerate the systemic vasodilation from the other agents