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Tidal Volume

A normal breath (about 500 ml/cc) or amount of gas entering or leaving lung during normal breathing


Residual Volume

volume of gas that is left in lungs at the end of maximal expiration


Vital Capacity

Total volume of gas that can be exhaled during maximal expiration (about 4.8 L)


Functional residual Capacity

Amount of gas left in lungs at end of a normal expiration ( about 2.4 L)


Ventilatory Failure

- adequate volume of gas is maldistributed

- Minute ventilation is decreased

- alveolar hypoventilation occurs


Obstructive Pulmonary Diseases

- cause increased airway resistance due to:

- plugging of airways from increased sputum production

- mucosal hypertrophy and edema

- loss of structural integrity of the airway

- airway narrowing from bronchial smooth muscle contraction, when there is hyperactivity of the airways



- deficient blood oxygen as measured by low arterial O2 and low hemoglobin saturation

- hemoglobin doesnt affecct O2 saturation readings

- finger measures how much O2 bound to hemoglobin

- pulse oximeter: normal is 94 - 100%

- if prolonged will lead to hypoxia



- a decrease in tissue oxygentation

- hypoxic hypoxia (high altitude, hypoventilation, obstruction, anything affecting 02 tension)

- Anemic Hypoxia (low hemoglobin, not reflected in pulse oxides)

- Circulatory Hypoxia (low cardiac output, shock)

- Histotoxic hypoxia (decreased O2 carrying capacity from a toxic substance; cyanide poisoning)


3 Categories of Acute Respiratory Failure

- failure of respiration or oxygentation leading to hypoxemia and normal or low carbon dioxide levels (manifestation of if we are breathing properly)

- failure of ventilation leading to hypercapnia

- combination of respiratory failure


Etiology and Causes of Acute Respiratory Failure

- etiology depends on the cause

- causes include central nervous system problems, neuromuscular diseases, chest wall and diaphragm dysfunction, pulmonary parenchymal diseases, airway problems


Clinical Manifestations of Acute Respiratory Failure

- hypoxemia, hypercapnea, headache, dyspnea, confusion, decreased LOC, agitation, dizziness, and restlessness

- early: rapid shallow breathing

- Late: cyanosis, nasal flaring, retractions


Diagnosis and Treatment of Acute Respiratory Failure

- diagnosis: blood gasses, CXR, electrolyte panel, CBC

- Treatment: maintain airway, mechanical ventilation to keep O2 sat > 90%, treat underlying problem, diuretics if necessary, steroids (controversial), low carb nutritional support, supplemental oxygen, antibiotics if necessary


Pulmonary Hypetrtension (HTN)

- normally, pulmonary circulation is high flow and low pressure

- Pulmonary HTN: sustained pulmonary artery systolic pressure > 25 mm Hg

- can be seen on echocardiogram or more directly with swan graft catheter


Primary Pulmonary HTN

- also known as Idiopathic (unknown cause)

- rapidly progressive and occurs more often in women; long-term prognosis is poor and medical treatment usually ineffective

- nothing you can do to make patient feel better

- leads to heart failure (right sided)


Secondary Pulmonary HTN

- causes from a known disease

- 3 mechanisms: increased pulmonary blood flow, increased resistance to blood flow, and increased left atrial pressures


Pathogenesis of Pulmonary HTN

- initially, walls of small pulmonary vessels thicken from an increase in the muscle; internal, layer of pulmonary artery wall becomes fibrotic (fibrosis of small vessels in lungs)

- sustained pulmonary HTN results in formation of a network of blood vessels (plexiform) that impede blood flow


Clinical Manifestations of Pulmonary HTN

- vary according to the severity and duration of the cause

- exercise intolerance, fatigue (cant do any activities)

- syncope

- Hemoptysis (from fluid in the lungs)

- chest pain on exertion

- increasing dyspnea

- cor pulmonale, systolic ejection click (right sides ventricular hypertrophy

- Hoarse voice from compression of laryngeal nerve by engorged pulmonary artery (Ortner's Syndrome)


Diagnosis of Pulmonary HTN

- measurements of pulmonary artery pressures during exercise, ideally

- stress testing

- ECHO (most common non invasive way and the cheapest)

- Cardiac catheterization with medications to increase cardiac output

- ECG and Chest X-ray

- Best way to diagnose is right sided heart catherization but is invasive (gets better # than ECHO)


Treatment of Pulmonary HTN

- treat the underlying cause

- supplemental Oxygen

- Vasodilators (get NO)

- Diuretics (to get rid of extra fluid)

- Prostacyclin (mainstay of therapy; pulmonary vessel dilutater)

- in advanced cases lung or heart-lung transplant

- left to right shunts (surgery)


Pulmonary Venous Thromboembolus

- Pulmonary Embolus: an undissolved, detatched material (blood clot, fat emboli, amniotic fluid, air, tumor, foreign bodies, septic parasites) that occludes blood vessels

- 90% in deep veins of lower extremities


Causes and risk factors of Pulmonary Venous Thromboembolus

Virchow's triad: factors causing thromboemboli formation include :

- Venous Stasis/sluggish blood flow

- hypercoagulability

- damage to the venous wall (intimal injury)

endothelial lining will cause clotting to occur

smoking w/ BC or Long Flight can cause thrombosis in legs

Common risk factors include immobility, trauma, pregnancy, cancer, heart failure, and estrogen use (birth control)

MOVE YOUR PATIENTS! get them out of bed or else they will be predisposed to DVT


Pathogenesis of Pulmonary Venous Thromboembolus

- thrombus dislodged from point of origin by direct trauma, exercise, muscle action, or changes in blood flow

- if superficial its not a big deal, if deep vein it is a problem


Clinical Manifestations of Pulmonary Venous Thromboembolus

- depends on size of thrombus

- usually includes restlessness, apprehension, anxiety, dyspnea, tachycardia, tachypnea, chest pain (on inspiration), and hemoptysis (coughing up blood)


Diagnosis of Pulmonary Venous Thromboembolus

- ventilation/perfusion scan (nuclear medicine scan; inject radioactive isotopes) (4L of air for every 5L of blood) (V/Q scan aka ventillation perfusion)

- Helical angiography (CT scan w/contrast dye; aka ct angiogram; use dye to highlight blood vessels)

- most common are Ventilation /perfusion scan and helical angiography

- ABGs and ECG (dont diagnose, just supplemental)

- Cardiac enzymes

- Pulmonary arteriography (done w/huge clots)

- Ultrasound (not used alot)


Treatment of Pulmonary Venous Thromboembolus

- long term meds such as coumadin/warfarin (measured by INR)

- treatment of underlying problems

- Prevention measures: avoid prolonged bedrest, active ROM (range of motion), low-dose heparin or low molecular weight heparin (aka lovenox) (anticoagulants /blood thinner; given to almost every patient in hospital), compression hose w/pneumatic compression

- If PE confirmed, heparin drip (wont dissolve clot just prevents it from getting bigger), thrombolytics (actually breaks up the clot), oxygen, bedrest

- Umbrella filter or embolectomy (go in with a catheter and suck it out)


Umbrella filter

- also known as a green field filter

- looks like a little umbrella and goes into a major vein

- some patients cant have normal treatment so they get this

- made of mesh so it does not disrupt blood flow