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