KC Resp Flashcards
(119 cards)
*Causes of shifts to the oxygen dissociation curve
CO2, pH, 2,3 -DPG, Exercise, Temperature
Right shift: favours unloading of oxygen - lower pH, increase 2,3-DPG, increased temperature
Left shift: favours higher oxygen binding - higher pH, decreased 2,3-BPG, lower temperature, methhemoglobin
*65M on septra and pyridium, blood draw chocolate brown, sat 85%, what test do you order?
Methemoglobin level
*What is the pathophysiology of methemoglobinemia
Altered state of hemoglobin where iron in its ferrous F++ form is oxidized to ferric Fe+++, and unable to bind O2. Rest of normal hemoglobin is therefore left shifted and holds on to O2 more tightly.
*Why would O2 sat on ABG be measured as normal?
Measured O2 saturation is normal
*Drugs that cause methemoglobinemia (5)
Septra
Dapsone
Local anesthetics: Benzocaine, Prilocaine, Lidocaine
Metoclopramide
Rasburicase
Nitroglycerin, amyl nitrate
Quinones
*Treatment for methemoglobinemia
Methylene blue
*How does methylene blue work to treat methemoglobinemia
Reduces Fe3+ to Fe2+ by providing electron donor → Hgb now able to bind and offload oxygen
List 1 non-drug related cause of methemoglobinemia and 1 chemical cause
(Box 11.1
Hereditary: NADH methemoglobin reductase deficiency, GPPD deficiency
Chemicals: paraquat, chlorobenzene
List 5 causes of peripheral cyanosis
Low cardiac output states: shock, left ventricular failure, hypovolemia
Environmental exposure to air or water, Raynaud’s
Arterial occlusion: thrombosis, embolism, vasospasm, peripheral vascular disease
Venous obstruction
Redistribution of blood flow from the extremities
List 5 causes of central cyanosis
High altitude
Methemoglobinemia, sulfhemoglobinemia
Impaired pulmonary function: V/Q mismatch (pulmonary embolism, ARDS, pulmonary hypertension, pneumonia, pneumothorax
Anatomic shunt: congenital heart disease
List 2 ways that methemoglobin is reduced
NADH cytochrome b5 reductase: this is often affected by drugs
NADPH uses glutathione; this is the pathway accelerated by methylene blue
What is 1 contraindication to methylene blue?
G6PD deficiency
Pt is cyanotic with +ve methemoglobin levels on co-oximetry, but does not respond to methylene blue. What diagnosis should be considered?
Sulfhemoglobinemia
*2 definitive treatments for massive hemoptysis
- Fibreoptic bronchoscopy
- Bronchial arterial embolization (IR) or
- OR for thoracotomy if embolization fails
*Optimal positioning of patient with known bad lung
Place patient with affected side down
*2 airway maneuvers to minimize VQ mismatch in someone with hemoptysis
Intubate mainstem of unaffected lung, or
Double lumen ETT
Also: bronchial artery embolization
*Most accurate way to diagnose cause of hemoptysis
CT pulmonary angiography
*Most commonly bleeding artery
Bronchial artery (pulmonary arteries are higher volumes, but lower pressures)
*Six infectious causes of hemoptysis
TB
Bronchitis
Bronchiectasis
Pneumonia
Lung abscess
Fungal infection
Aspergillosis
What is the definition of massive hemoptysis?
> 600ml in 24 hours
List 10 differential diagnosis for hemoptysis
Infectious: bronchitis, bronchiectasis, tuberculosis, aspergilloma, parasites, septic emboli
Structural: CF, hypersensitivity pneumonitis, PE with infarction, pulmonary HTN, malignancy, cocaine/ crack lung
Vascular: tracheoarterial fistula, arteriovenous fistulas, aneurysm that erodes into the trachea
Vasculitis: Goodpasture’s syndrome, Wegener’s granulomatosis, lupus, Behcet’s syndrome
Hematological: coagulopathy, DIC, platelet dysfunction, thrombocytopenia
Iatrogenic: bronchoscopy, Swan-Ganz, lung biopsy, foreign body
Trauma: lung contusion, penetrating trauma, foreign body
What is bronchiectasis
Chronic necrotizing infection that leads to bronchial wall inflammation and dilation
What is diffuse alveolar hemorrhage
Pulmonary hemorrhage that originates from the pulmonary microcirculation - alveolar capillaries, arterioles, venules. Presents with hemoptysis with diffuse lung infiltration and anemia. Often autoimmune (vasculitis)
More bloody with serial washings
Patient comes in with massive hemoptysis and a recent trach. Describe 2 maneuvers that you can do
Hyperinflating the trach balloon
Intubating from the oral airway with direct pressure from finger in the tracheostomy home
Tracheal-inominate fistula (late) surgical site early