Respiratory

Respiratory FAILUREPulmonary system fails to maintain adequate gas exchange (either O2 oxygenation or CO2 elimination) Partial Pressure of O2 less than 60 mmHg |
ACUTE: Develops in minutes/hours - | Clinical markers: ABG’s, pH < 7.3 |
CHRONIC: several days or longer | There is renal compensation w/ increase in bicarb results in pH slightly decreasedClinical markers: polycythemia (RBC’s)Cor Pulmonale (enlargement of the right ventricle of the heart as a response to increased resistance or high blood pressure in the lungs) |
Etiology: RF is deficiency of pulmonary system |
Extrapulmonary deficiency: | Intrapulmonary deficiency: |
CV: HF, pulmonary edema, arrhythmias, valvular disorders | Lower airways and alveoli: COPD, asthma, bronchitis, CF, sepsis r/tpneumonia |
Brain: drug overdose, trauma, post op anesthesia depression, central alveolar hypoventilation | Pulmonary circulation: pulmonary emboli |
Spinal Cord: Gillian Bare, polio, ALS, cord trauma | Alveolar: capillary membrane-ARDS, inhalation of toxic gases, near drowning |
Neuromuscular: Myasthenia Gravis, MS, neuromuscular blockers, muscular dystrophy, organophosphate poisoning | |Thorax: Massive obesity, chest wall trauma, apnea | |
Pleura: plural effusion, pneumothorax | |
Upper Airways: sleep apnea, trachea obstruction, epiglottitis | |
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Types of RF |
Type 1 Hypoxemic | Type 2 Hypercapnic |
PaO2 < 60 with normal or low PaCO2Problem with O2 transfer | PaCO2 over 50 with low PaO2 and pH less than 7.35Problem with CO2 removal |
CHF, pulmonaryedema, pneumonia, atelectasis, pulmonary emboli | Drug overdose, neuromuscular disease, chest wall abnormalities, severe airway disorders like asthma, COPD |
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Pathopysiology: |
Type 1 Hypoxemic | Type 2 Hypercapnic |
Usually results from V/Q mismatching and intrapulmonary shunting | Results from alveolar hypoventilation w/or without V/Q mismatching & shunting |
V/Q mismatching(ventilation/perfusion) means that blood passes through under ventilated alveoli for the given amount of perfusion.V/Q mismatching is the most common cause of hypoxemia and usually happens r/t fluid filled or partially collapsed alveoli | Alveolar hypoventilation means that amount of O2 going into alveoli is insufficient to meet needs. There is either increase O2 needs or decrease ventilation |Intrapulmonary shunting means that the blood reaches arterial w/out participating in gas exchange.Occurs when blood passes through lung tissue not ventilatedResult of alveolar collapse 2nd to atelactisis or flooding. | Associated with hypercapnia and commonly results from extrapulmonary disorders |
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Clinical Manifestations: |
CNS: | Restlessness, agitation, irritability, confusion,LOC |
Cardiovascular: | Tachycardia, bounding pulses, systolic HTN, Widened pulse pressure, dysrythmias, chest pain |
Pulmonary: | Tachypnia, dyspnea, SOB, accessory muscle use |
Skin: | Pallor, cyanosis, cool, clammy |
Renal: | UOP, polycythemia, HTN, edema |
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Diagnostic Tests: | ABG’s (most common), pulse oximetry, chest x-ray, EKG to R/O cardiac etiologies, CBC, CMP, TSH|
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Complications: | Impaired tissue perfusion leading to lactic acidosis, MODS, Ischemia (anoxic encephalopathy=cerebral hypoxia), dysrythmias, thromboembolism, GI bleeding,O2 toxicity |
| O2 toxicity occurs when exposed to over 60% for longer than 24-48 hrs. COPD patients have chronic hypercapnia if they get too much oxygen can have respiratory arrest because hypoxia drives theirbreathing. |
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Rx: | Treat underlying cause. Mostly treated out patient. |
| Oxygenation/Ventilation=positive pressure ventilation. Preferably non invasive NPPV (Venturi mask, CPAP, BiPAP). Invasive positive pressure ventilation (ventilator or Extra Corpular Membrane Oxygenation ECMO better for severe but reversible RF) |
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Pharmacology: | |
Mucolytics: | Acetylcysteine...