respiratory failure Flashcards
what is respiratory failure
is the inability of the lung to meet the metabolic demands of the body
no ventilation - tissue oxygenation not taking place
clinically defined as PaO2 less than 60 mmhg while breathing
PaCO2 more than 50 mmhg
what is the classification of respiratory failure
acute /chronic
severity - hypoxemic and hypercapnic
type 1 - hypoxemic -
not providing enough oxygen to meet metabolic needs
criteria to meet - po2 less than 60 mmHg
normal or low pCO2
lung diseases - pneumonia , intersitial lung disease , pulmonary edema
2 - hypercapneic
criteria - partial pco2 is more than 50 mmhg
and hypoxemia always present
renal response over days to weeks
acute rest acidosis - cellular buffering system of HCO3
chronic resp acidosis more than 24 hrs - renal caption
impaired rest drive - peripheral and central receptors defect - carotid body dysfunction
brainstem respiratory neurone defect - bulbar poliomyelitis , encephalitis , infractionf brain stem
defect in nueromuscular system - spinal cords - poliomyelitis , peripheral nerves - peripheral neuropathy , respiratory muscles - myasthenia gravis and gullian barre
impaired respiratory apparatus - chest wall - kyphscoliosis , obesity
airways and lugs - laryngeal , tracheal stenosis
obstructive sleep apnea , cops
3 - perioperative - residual aesthetic effect
4- shock - patient intubated and ventilated
basic causes for type 1 in respiratory failure
ventilation perfusion mismatch
right to left shunt
what is the cause of hypercapnia
increased co2 production fever sepsis infections gullian barr increased dead space - no perfusion
how do you diagnose respiratory failure
arterial blood gas analysis
chest x ray - bilateral infiltrate
lung functioning test
pathogenesis of respiratory failure ?
systemc inflammatory response - due to infection
damagedone to the gas exchange surface
this leads to increasing perm- pulmonary edema
alveoar collapse - reduction in type 2 pneumocytes they are damaged or destroyed - decrease in surfactant
what is the gold standard of therapy in respiratory failure
hypoxemia causes death - first treate hypoxemia and secondary partial pressure of co2
oxygen therapy - does not correct hypoxemia caused by shunt - e.g. pneumonia , collapsed lung
invasive - endobronchial tube
Mechanical ventilation
what are the hypercapnic symptoms / or respiratory failure
anxiety , dyspnea , confusion , psychosis
chronic hypercapnea - sleep disturbances
central cynosis - mucus embraces and lips
what are the clinical progress of respiratory failure ?
tachycardia
pumonary hypertension -
cor pulmonale , due to constriction of the pulmonary arteries
polycethmia vera in chronic hypoxia
what are the risks for oxygen therapy ?
02 toxicity in high levels - seizures
paO2 greater than 150 = retrolental fibroplasia
lower levels of Fi02 more than 60 percent with long exposure - capillary damage , pulmonary fibrosis
35 - 40 percent is safely tolerated
co2 narcosis - too much o2 leads to decreased respiration - leading to increased hypercapnia - somnolence and coma
what is primary alveolar hypoventilation ?
chronic hypercapnea and hypoxemia - absence of identifiable neuromuscular problems
due to defect in metabolic respiratory control
central hypopnea or apnea in sleep
diagnostic criteria of acute respiratory distress or acute respiratory failure?
fio2(fraction of inspired oxygen) less than 200mmhg
arterial pressure less than 18 mmHg
bilateral diffuse opacities
what s the aetiology of acute respiratory distress syndrome ?
primary - direct - chesttrauma , toxic gas inhalation , aspiration pneumonia
indirect - sepsis , acute pancreatitis , burning , massive trauma
what is the pathophysiology to acute respiratory distress syndrome?
diffuse damage to gas exchanging either alveolar or capillary surface due to unregulated over expression of systemic inflammatory response
increased vas perm- pulm edema
and necrosis of pnemocytes -alveolar collapse - reduced surfactants
management of cards ?
lowest of 60mmhg oxygen therapy
