Question | Answer |
3 pieces of info needed to determine underlying mechanism of hypoxemia? | 1. PaCO2 level
2. A-a gradient
3. Response to supplemental oxygen |
Definition of hypoxia. | PaO2 <60 or PaCO2 >50 (hypercapnia). |
Hypoxia or hypercapnea?: V/Q mismatch | Hypoxia withOUT hypercapnea (CO2 levels low or normal) |
Hypoxia due to a shunt is/is not responsive to supplemental oxygen. | Is NOT |
How does the A-a gradient help distinguish between different causes of hypoxemia? | If hyperventilation is the cause, A-a gradient will be normal. In most other causes, A-a gradient will be increased. |
Which pts have the highest risk of developing ARDS? | Sepsis or septic shock |
What is the key pathophysiologic event in ARDS? | Massive intrapulmonary shunting of blood--> severe hypoxemia with no significant improvement on 100% O2. Shunting is 2/2 widespread atelectasis, collapse of alveoli, and surfactant dysfunction |
Classical criteria for diagnosing ARDS? | *Hypoxemia refractory to oxygen therapy (ratio of PaO2/FiO2 </= 100)
*Bilateral diffuse pulmonary infiltrates on CXR
*No evidence of CHF: PCWP </= 18mmHg |
Where should the tip of the ET tube be in relation to the carina? | 3-5cm above the carina |
Minute ventilation formula? | Minute ventilation= RR x Tidal volume |
Normal I:E ratio used in ventilators? | 1:2 (twice as much time spent in expiration as in inspiration) |
Definition of pulmonary HTN? | Mean arterial pulmonary pressure >25mmHg at rest or >30mmHg during exercise |
CXR findings in primary pulmonary HTN? | Enlarge central pulmonary aa, enlarged RV, and clear lung fields. PFTs show restrictive pattern. EKG shows R axis deviation and RV hypertrophy. |
Tx for primary pulmonary HTN? | Pulmonary vasodilators (IV prostacyclins/epoprostenol and CCBs), anticoagulation with warfarin, and lung transplantation (optional) |
Definition of cor pulmonale? | RV hypertrophy with eventual RV failure resulting from pulmonary HTN 2/2 pulmonary disease |
MCC cor pulmonale? | COPD |
Nature of the A-a gradient in PE? | Elevated |
Situations in which pts with PE should be considered as candidates for treated with thrombolytics (streptokinase, TPA)? | 1. Massive PE + hemodynamic instability
2. Evidence of R heart failure (thrombolysis can reverse this) |
MCC of hemoptysis? | Bronchitis (50% of cases) |