Pulmonary Vascular Disease Flashcards
Normal ABGs
pH 7.35-7.45
PaCO2 35-45 mmHg
PaO2 80-100 mmHg
22-26 HCO3
Define shock
Hypotension despite 500mL IV fluid and persisting >15min
What is the effect of respiration on CO?
Pooling of blood occurs on inspiration; this decreases venous return to the left heart and in turn decreases CO and SBP (a decrease >10mmHg is termed “pulsus paradoxus”)
What changes occur to the pulmonary pressures with exercise?
CO increases but pulmonary pressures do not due to dilatation and recruitment of pulmonary vessels
List 3 causes of pulmonary HTN
Increased LAP
Increased pulmonary blood flow
Increased pulmonary vascular resistance (vasoconstriction, obstruction or obliteration)
List 3 causes of increased LAP which may result in pulmonary HTN
Mitral stenosis
LVF
Diastolic dysfunction
List 3 causes of increased pulmonary blood flow
Left to right shunt
High flow states
Excess central volume
List a cause of pulmonary vasoconstriction which may result in increased pulmonary vascular resistance and therefore pulmonary HTN
Low alveolar O2 (including hypoventilation)
List 2 causes of pulmonary vasculature obstruction which may result in increased pulmonary vascular resistance and therefore pulmonary HTN
PE
Primary pulmonary HTN
List 3 causes of pulmonary vasculature obliteration which may result in increased pulmonary vascular resistance and therefore pulmonary HTN
Arteritis
Emphysema
Pulmonary fibrosis
What might be the physiological consequences of increased resistance at the pre-capillary level in the pulmonary circulation? What might happen to gas exchange?
Pulmonary HTN leads to RV dilatation and hypertrophy
RV changes lead to increased systemic venous pressure and decreased CO
Increased systemic venous pressure leads to extravasation of fluid into tissues and the peritoneal and pleural spaces
Gas exchange is reduced, leading to hypoxaemia, particularly with exertion
What is the definition of pulmonary HTN?
Mean PA pressure >25 mmHg
PVR >3 Woods units
What are Woods units?
System for measuring PVR that uses increments of pressure
PVR = (pulmonary arterial pressure - pulmonary capillary wedge pressure)/CO
List 7 symptoms of pulmonary vascular disease
SOB Syncope/collapse Lethargy Swelling of ankles Cough Haemoptysis Chest pain (often pleuritic)
List 3 signs of pulmonary HTN
RV heave
Loud P2 with 4th heart sound
Prominent “v” wave in the JVP
List 3 signs of RHF
Elevated JVP +/- v waves
TR (with pulsatile liver)
SOA, ascites
26 year old women presents with sudden episode of collapse
At presentation she has a reduced conscious state
O/E: HR 120, BP 70/50, SaO2 90% on RA, RR 35, normal chest sounds, JVP 5cm, heart sounds normal (?3rd heart sound)
ECG: sinus tachycardia and RV strain pattern
CXR: clear
ABG: pH 7.48, PaCO2 30mmHg, PaO2 55mmHg, HCO3- 24
Assess the patient’s current state
Evidence of severe physiological compromise: shock with reduced conscious state, RV strain/failure, severe type 1 respiratory failure
26 year old women presents with sudden episode of collapse
At presentation she has a reduced conscious state
O/E: HR 120, BP 70/50, SaO2 90% on RA, RR 35, normal chest sounds, JVP 5cm, heart sounds normal (?3rd heart sound)
ECG: sinus tachycardia and RV strain pattern
CXR: clear
ABG: pH 7.48, PaCO2 30mmHg, PaO2 55mmHg, HCO3- 24
What findings might you expect in the case of cardiac tamponade or constrictive pericarditis? What about this presentation makes these diagnoses less likely?
Muffled heart sounds +/- pericardial rub
Pulsus paradoxus
In tamponade there may be signs of LHF as well
Would not expect such profound hypoxaemia (primary cardiac problems usually do not cause this)
List 4 causes of PE
Detached DVT from leg (most common)
Fat (e.g. post-trauma, classically long bone fractures)
Air (e.g. post-laparoscopic surgery)
Amniotic fluid (rare but catastrophic)
What is the % mortality of untreated PE?
30%
What % of acute treated PE are a result of chronic thromboembolic disease?
4%
Describe risk factors for thrombus formation within the framework of Virchow’s triad
Stasis: inpatient stay, after some surgical procedures, prolonged immobility
Hypercoagulable state: genetic abnormalities, factor deficiencies, malignancy, polycythaemia, pregnancy, medication
Abnormal vessels: trauma
What clinical features might help you make a diagnosis of PE? How might the clot burden influence this?
Collapse and hypoxaemia Widened A-a gradient of unclear cause Pleuritic chest pain with no clear cause Unexplained breathlessness Evidence of pulmonary HTN Evidence of a DVT (calf pain and swelling)
Describe the difference in presentation between a patient with a medium clot burden and a patient with repeated small emboli
Medium clot burden (clots tend to travel more distally): dyspnoea, pleuritic chest pain, cough, haemoptysis, fever, tachypnoea, tachycardia, pleural rub/effusion
Repeated small emboli: often unrecognised, pulmonary capillary bed is gradually eroded leading to progressive exertional dyspnoea