Pulmonary causes CC Flashcards
Causes of mismatch in V/Q
- PE
- Old pulmonary embolisms
- AV malformations
- Vasculitis
- Previous radiotherapy
- COPD gives matched defects
Hypoxemia
Ventilation/Perfusion (V/Q) mismatch
- Asthma
- COPD
- Alveolar disease (e.g., pneumonia)
- Interstitial disease
- Pulmonary vascular disease (e.g., Pulmonary hypertension, pulmonary embolism).
Features: responds well to 100% O2
Right-to-left (R-to-L) shunting
- ARDS
- Alveolar collapse
- Intra-alveolar filling (e.g., pneumonia, pulmonary edema)
- Atelectasis
- Intracardiac shunt
- Vascular shunt.
Features: does not respond well to 100% O2 but responds better to positive end-expiratory pressure (PEEP)
Decreased alveolar ventilation
- Drug overdose
- Neuromuscular disease
- CNS disorder.
Features: high PCO2 with hypoxemia. The A-a gradient is normal
Decreased diffusion
- ILDs
- Emphysema.
Features: has little effect on hypoxemia at rest but it can play a role in exercise-induced desaturations. Low DLCO
- High altitude.
Features: low FiO2, The A-a gradient is normal
Disorders associated with increase D-dimer
- Arterial thromboembolic disease
- Venous thromboembolic disease
- DIC/ severe sepsis
- Preeclampsia and eclampsia
- Vaso-occlusive episode of sickle cell disease
- Systemic inflammatory response syndrome
- Severe liver disease /Renal disease
- Malignancy
- Normal pregnancy
Factors that decrease mixed venous oxygen saturation
Factors that will increase oxygen consumption:
- Fever
- Shivering
- Tachycardia
- Pain
- Agitation
- Seizure
Factors that will decrease oxygen delivery:
- Low hemoglobin
- Low CO due to heart failure or hypovolemia
- Low SaO2
- abnormalities such as carbon monoxide poisoning methemoglobinemia that affect the oxygen-carrying capacity of hemoglobin
Factors that increase mixed venous oxygen saturation
Factors that will increase oxygen delivery:
- High SaO2
- High Hb
- High CO (e.g fluid, inotropes)
Factors that will decrease oxygen consumption:
- Hypothermia
- Anesthesia/sedation/analgesia
- Mitochondrial dysfunction in sepsis
Extrapulmonary causes of decreased chest compliance
- obesity
- ascites
- bowel edema
- pancreatitis
- peritonitis or other intra-abdominal pathologies
Extrapulmonary causes of decreased chest compliance manifest as atelectasis and are responsive to PEEP
Causes of isolated high P peak
- Bronchospasm
- Airway obstruction (plug, kink, FB, ETT cuff herniation)
Causes high peak & plat pressure
- pneumothorax
- atelectasis
- Pul edema
- pneumonia
- bronchial intubation
- pl effusion
- increased abd pressure
Causes of increased dead space ventilation
- Pulmonary embolism
- High PEEP
- Pulmonary hypertension
- Chronic obstructive pulmonary disease
- High rate, low tidal volume
Causes of increased CO2 production
- Fever
- Sepsis
- Hyperthyroidism
- Overfeeding with carbohydrates
- Agitation/seizure
Salvage therapy for refractory hypoxemia
- Extra Corporeal Membrane Oxygenation
- Trial of inverse I:E ratios (APRV)
- Recruitment maneuvers
- Inhaled NO
ECMO: Factors affecting oxygenation
- Blood flow
- FiO2 delivered to the oxygenator
- Oxygen-carrying capacity of the blood
- Degree of recirculation
ECMO: Factor affecting CO₂ removal
- Sweep gas flow
- Blood CO2 concentration
- Surface area for gas exchange
Causes of massive hemoptysis
- Pulmonary infxn
- Bronchiectasis
- Tumor eroding into a bronchial artery or PA
- PA rupture from Swan-Ganz catheter
- Trauma to chest
- Pulmonary HTN
- Primary vascular abnormality (arterio-venous malformation (AVM), aneurysm, vasculitis)
Causes of falsely low oxygen saturation
- Hypothermia,
- hypotension
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