Pulm HTN Flashcards
How is pulmonary hypertension (PH) different from systemic hypertension?
Complex diagnosis and treatment
What is the mean pulmonary artery pressure (mPAP) threshold for defining pulmonary hypertension?
> 20 mmHg
What are some symptoms of pulmonary hypertension?
Accentuated S2 & S4, LE swelling
How is pulmonary hypertension classified based on PA wedge pressure and pulmonary vascular resistance?
3 hemodynamic profiles
-Isolated precapillary PH
-isolated postcapillary PH
-Combined pre and postcapillary PH
What is precapillary PH defined as?
PVR ≥3.0 wood units w/o elevated LAP or PAWP
What characterizes isolated postcapillary PH?
PAWP >15mmHg, normal PVR
What defines combined pre- and postcapillary PH?
PAWP >15mmHg, PVR >3.0 WU
How is high-flow PH characterized?
No elevation in PAWP or PVR
What are the three Groups of Pulmonary Hypertension?
Isolated precapillary, Isolated postcapillary, Combined pre- and postcapillary
What is required for diagnosis, classification, and treatment planning of Pulmonary Artery HTN?
Right heart catheterization
What can elevate mean pulmonary arterial pressure (mPAP)?
1) elevated resistance within arterial circulation 2) increased pulmonary venous pressure 3) chronically increased pulmonary blood flow 4) a combination of processes
How is Pulmonary Vascular Resistance (PVR) calculated?
(mPAP - PAWP)/COP
What components of lung circulation can contribute to Pulmonary Hypertension?
Arterial or venous abnormalities, sometimes both
What can TTE reveal in pulmonary hypertension?
RA & RV enlargement, elevated tricuspid-regurgitation velocity
Why is an echocardiogram commonly used in PH?
Estimate PASP as screening tool
How is the severity of PH determined after a right heart catheterization?
By mPAP values
What are the classifications based on mPAP values in PH?
Mild, moderate, severe
How much can normal pulmonary circulation accommodate in terms of COP increase without a notable change in mPAP?
Fourfold increase
What does PH stand for?
Pulmonary Artery HTN
What is the classification of PAH according to the World Health Organization?
Rare disease affecting 15 people per million per year
What is the significance of Idiopathic PAH?
No identifiable risk factor
What percentage of PAH cases are inheritable and what is the associated mutation?
3%, mutations in BMPR2
How are the remaining cases of PAH designated?
Associated PAH” due to drugs
What is the demographic shift seen in PAH patients according to current data?
Now more older patients and men being diagnosed
What is the 1-year mortality rate despite improved diagnosis and therapy for PAH?
Approximately 15%
What are the 3 main classes of pulmonary vasodilator drugs for PAH?
Prostanoids, Endothelin receptor antagonists (ERAs), Nitric oxide/guanylate cyclase pathway drugs
What leads to pathologic distortion of small pulmonary arteries in PAH?
Sustained vasoconstriction and remodeling processes
Is combination therapy often needed for the treatment of PAH?
Yes
What is the mechanism of action of prostanoids in PAH treatment?
Mimic prostacyclin to produce vasodilation and inhibit platelet aggregation.
Which prostanoid in PAH treatment has been proven to reduce mortality?
Epoprostenol
What is the role of Endothelin Receptor antagonists (ERAs) in PAH treatment?
Improve hemodynamics and exercise capacity
How does nitric oxide produce pulmonary vasodilation?
Stimulating guanylate cyclase and cGMP formation in smooth muscle cells
Why is the effect of nitric oxide transient?
Quickly bound by hgb and degraded by phosphodiesterase type 5
What is a common route of administration for nitric oxide in perioperative and critical care settings?
Continuously inhaled
What type of therapy has chronic treatment for PAH been directed towards?
PD-5 inhibitors
What are some preoperative considerations for patients with PAH?
Venous embolism, elevated pressure, hypoxic vasoconstriction
What are common presenting symptoms of PAH?
Fatigue, dyspnea, cough
What are some advanced symptoms of PAH?
Angina, syncope
What might be observed on physical exam in a patient with PAH?
Parasternal lift, accentuated heart sounds, JVD
What rare complication of PAH may lead to hoarseness?
Compression of dilated PA on RLN
What should a history of PH prompt further evaluation of?
Functional status, cardiac performance, pulmonary function tests
What is recommended for patients with moderate or severe PH prior to moderate-high risk surgery?
Right heart catheterization
What should be performed in patients with coexisting left heart disease due to potential discrepancies?
Left heart catheterization
What testing is performed during right heart catheterization to determine responsiveness to vasodilator therapy?
Vasoreactivity testing, often with inhaled nitric oxide
What percentage of PAH patients are nonresponsive to inhaled nitric oxide?
85-90%
What may PAH patients responsive to inhaled nitric oxide also benefit from?
CCBs and other targeted therapy
What is the confirmed diagnosis after right heart catheterization with mPAP 20 and PAWP 15?
PAH
What is the next step after confirmed PAH diagnosis?
Vasodilator testing
What is the treatment if vasodilator testing is positive?
CCB
What is the management if there is no sustained response to initial therapy?
PAH specific therapy
What treatment approach is recommended for low-risk PAH patients?
Oral meds
What is the suggested treatment for high-risk PAH patients?
IV meds
What is the appropriate approach if there is an inadequate response to initial therapy?
Continue therapy
What patient factors increase the risk of morbidity and mortality in noncardiac surgery in patients with pulmonary arterial hypertension?
PE, CAD, chronic renal disease, NYHA/WHO FC >II, higher ASA class, RAD on ECG, Echo parameters (RVH, RVMPI 0.75), Hemodynamics (higher PAP, RVSP/SBP ratio >0.66)
What are some operative factors that increase the risk of morbidity and mortality in noncardiac surgery in patients with pulmonary arterial hypertension?
Emergency surgery, Intermediate- or high-risk operations, High risk for venous embolism, Elevation in venous pressure, Reduction in lung vascular volume, Induction of severe systemic inflammatory response, Longer duration of anesthesia, Intraoperative vasopressor use
What is the primary intraoperative goal in perioperative physiology?
Maintaining optimal ‘mechanical coupling’ btw right ventricle and pulmonary circulation
Why is it important to consider any intervention that may affect RV preload, inotropy, afterload, and oxygen supply/demand relationships?
To promote adequate left-sided filling and systemic perfusion
What perioperative complexities can have serious complications?
Transient HoTN, mechanical ventilation, modest hypercarbia, small bubbles in IV, T-burg position, Pneumoperitoneum, single-lung ventilation
What is a hallmark of PAH?
Increased RV afterload
What does increased RV afterload lead to?
RV dilation, increased wall stress, and RV hypertrophy
How is the interaction between the RV and the pulmonary circulation described?
Pulsatile and dynamic
What affects RV pulsatile load during surgeries?
Acute insults
How can ventilator management affect RV afterload?
PEEP, hypoventilation, hypercarbia, acidosis, and atelectasis
Why is the thinner-walled RV subject to greater wall tension than the LV for the same increase in end-diastolic volume?
Increased RV myocardial oxygen demand
What happens to RV intramyocardial pressure compared to aortic root pressure under normal circumstances?
Lower than aortic root pressure
How does PAH affect coronary flow and RV vulnerability to systemic HoTN?
Increased coronary flow during diastole, vulnerable to systemic HoTN
What is the ‘lethal combination’ in the context of systemic HoTN and RV issues?
RV dilatation, insufficient LV filling, reduced stroke volume
How does perioperative morbidity and mortality change in patients with PH during hip and knee replacement?
Substantial increase
What effect does CO2 pneumoperitoneum have on biventricular load and pump function?
Acute impact
How does the combination of pneumoperitoneum, head-down position, and increased inspiratory pressure affect right ventricular pressures and afterload?
Affects RV pressures and afterload
What are the 3 features of lung collapse that are particularly relevant in thoracic surgery?
Transient chest pressurization, systemic hypoxia, hypoxic pulmonary vasoconstriction
What therapy is recommended during single-lung ventilation for PAH patients?
Inhaled pulmonary vasodilators
