Respiratory Failure

Choo Wei Chong
041303017


RESPIRATORY FAILURE
Def. : dysfunction of gas exchange lead to abnormal oxygenation or carbon dioxide elimination severe enough to impaired the function of vital organs


Type I (hypoxia)
V/Q mismatch
Pa O2 < 60mmHg or 8 kPa
Pa CO2 normal or reduced


ACUTE
Acute asthma
Pulm embolism
Pulm oedema
Pneumothorax
Pneumonia
ARDS

CHRONIC
Emphysema
Pulm fibrosis
R-L shunts
Anaemia
Lymphangitis carcinomatosa





Type II( hypoxia + hypercapnia)
Inadequate ventilation
Pa O2< 60mmHg > 6.6 k Pa
Pa CO2 > 50mmHg


ACUTE
Sev acute asthma
Foreign Body
Chest/head injury
Sleep apnoea
Brain Stem lesion
Narcotics/opioids
High ICT
Resp m paralysis
Ie:GBS, MND,OP poisoning, Polio, myasthenia gravis
Muscular atrophy


CHRONIC
COPD
Kyphoscoliosis
Ankylosing spondylitis
Primary alveolar hypoventilation



TYPE I RESPIRATORY FAILURE
Clinical features
· Central cyanosis
· Tachycardia
· sweating
· Poor peripheral circulation
· Restless , confusion
· LOC (if Pa02 < 4 kpa )
· Cardiac arrthymias

Management
· High conc O2 35% via mask
· Intubation and mechanical ventilation if patient is very ill or no improvement inspite treating the underlying condition
· Treat underlying condition
· Give opiates for pleural pain but not pt with asthma and COPD
· Close monitoring and repeat ABD Within 20 minutes

TYPE II RESPIRATORY FAILURE
Causes of acute on chronic respiratory failure (precipitating)
· Retention of secretion
· Infection
· Bronchospasm
· Pulm embolus
· Cardiac failure
· Rib # or intercostal muscle tear
· Pneumothorax
· Central venous system depression

Clinical features
· Central cyanosis
· Headache
· CO2 retention: warm periphery , bounding pulse ,flapping tremor, drowsy
· Airway obstruction : wheeze , IC indrawing, pursed lip , tracheal ‘tug’
· Conscious level : response to commands, ability to cough
· Right heart failure: peripheral oedema, raised JVP, hepatomegaly , ascites
· Background functional status and quality of life
· Sign of precipitating events
· may not appear distressed despite being critically ill

Treatment of acute
· CO2 retention cause severe acute respiratory acidosis
· Aim at immediate and rapid reversal precipitating event
· If not , support ventilation
· Supportive care
· Prevent peptic ulcer eps on vent support > 48 hours

Treatment of acute on chronic
· Inv : ABG and Cxr
· Maintenance of airway
· Rx specific precipitating events
· Frequent physiotherapy and pharyngeal suction
· Neb bronchodilators
· Controlled oxygen therapy: start with 24% controlled flow mask
Aim for PaO2 >7kpa
· Antibiotic
· Diuretics
· Progress : if PaCO2 cont to rise or pt cannot achieve safe PaO2 w/o severe
hypercapnia and acidaemia , respiratory stimulants (doxapram)
or mechanical ventilatory supprt may be required

Treat precipitating events : Disloged laryngeal FB /tracheostomy, Fixation of ribs, Reversal of narcotics poisoning, severe asthma

Complication
· Sepsis
· MOF : renal , liver, haematological , ileus , shock , metabolic derangement
· Pulmonary oxygen toxicity if O2 > 60% for > 48 hrs

Investigation
· ABG for diagnosis and monitor oxygen therapy
· CxR shows bilat diffuse ill-defined patch shadows on periphery
· r/o sepsis by Blood culture
· r/o MOD by RFT , LFT , haematological
· Serum electrolytes
· PCWP

Prognosis
· Determined by causes
· Mortality > 50% (90% if sepsis occur)
· Cause of death are noosocomial pneumonia , progressive massive fibrosis




OXYGEN THERAPY
Objective :
· Over come reduced partial pressure and quantity of oxygen in blood
· Increase quantity of oxygen carried in solution in the plasma even if Hb is fully saturated

Adverse effect :
· 100% can be irritant and toxic if inhaled for more than few hours
· Premature baby dev retrolental fibroplasias and blindness
· Pulmonary oedema

Administration
· High conc (60%) : via high flow mask
type I resp failure , asthma , pneumonia
· Low conc (24 - 28%) : via controlled mask

· Chronic oxygen delivery

MECHANICAL VENTILATION
· Indication : initially severe resp failure
Who failed to improve despite optimal medical therapy
· Via : endotracheal tube or face mask
· Sometimes IPPV is needed
· But NPPV is proved to be more beneficial in pt with acute on chronic and chronic reps failure , skeletal deformity and NM disease , central alveolar hypoventilation

LUNG TRANSPLANT
· Indication : cystic fibrosis,primary pulm HTN, emphysema,
thromboembolic pulm HTN, Pulm fibrosis, venoocclusive disease,
histiocytosis, Eisenmenger syndrome, obliterative bronchiolitis,
lymphangioleiomyomatosis.

· C/I : chronic bilateral pulmonary infection (CF , bronchiectasis)