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FEATURES:
Pa O2 < 6O mm of HgPa Co2 – normal or low (< 50 mm Hg)Hydrogen Ion conc. - normalBicarbonate ion conc. - normal
ACUTE CHRONIC
-Acute asthma - emphysema -pulmonary edema - Lung fibrosis-pneumonia - Lymphangitis carcinomatosa -lobar collapse -Rt to Lt shunts-pneumothorax - Brainstem lesion -pulmonary embolus-ARDS
Ventilation-perfusion(v/q)mismatch
Presence of low v/q units contributes to hypoxemia
Intracardiac&intrapulmonary shunts
Bypass of deoxygenated blood from alveoli
FEATURES:
Pa O2 < 60 mm HgPa Co2 > 50 mm HgHydrogen Ion conc. - increasedBicarbonate Ion conc. – increased
ACUTE CHRONIC
-Acute exacerbation -COPD of COPD-upper airway obst. -sleep apnoea-acute neuropathies/ -kyphoscoliosis paralysis-narcotic drugs -myopathies
-flail chest injury -ankylosing spondylitis
PaCo2 is dependent on alveolar ventilation Decrease in minute ventilation in neuro-muscular
disorders Increased airway resistance Increase in the volume of dead space
- Occurs as a result of lung atelectasis- Most common in peri operative period - After gen.anesthesia decrease in functional residual capacity collapse of dependent lung units
Frequent changes of position Non invasive positive pressure
ventilation Chest physiotherapy Aggressive control of incisional pain
In shock hypo perfusion of resp. muscles occurs
Up to 40% of CO may be distributed to the resp. muscles
Dyspnoea
Confusion and somnolence
Restlessness,anxiety,seizures
Asterixes
Cyanosis
Hepatic enlargement,pedaledema
Arrhythmias
Spirometry Blood Gas analysis: PaO2
PaCo2
Pulse oximetry Acedemia Bicarbonate
Maintenance of airway Treatment of underlying cause Oxygen therapy physiotherapy Bronchodilators Antibiotics Respiratory stimulants
100% oxygen cannot be used because, In adults it causes pulmonary oedema
& free radical damage causing fibrosis. premature infants develop retrolental fibroplasia Hence 35-60% O2 (high flow O2) is
used.
In Type II failure Tolerance to raised Co2 develops Depend on hypoxic drive to breathe lower conc. O2(24-28%) used
Mechanical ventilation
negative-pressure - iron lung
positive-pressure - Face mask
Nasal prongs
ETT
pressured targeted&volume targeted
Intubation trauma
Volutrauma
Pneumothorax
Lung infection
Cardiac failure
Weakness of respiratory muscles
WHEN TO CESSATE MECHANICAL VENTILATION ?
Breathe without ventilator support for 30-120 min.
Resp. rate >35 per min for > 5 min O2 saturation <90% Heart rate > 140 per min Systolic BP < 90 or > 180mm Hg