Approach to Dyspnea and Acute Respiratory Failure

Posted by e-Medical PPT Tuesday, August 2, 2011
Life Threatening Causes of Dyspnea
  • Pulmonary Embolism
  • Tension Pneumothorax
  • Severe metabolic acidosis
  • Florid Pulmonary Edema
  • Status asthmaticus
  • Hypercapneic Respiratory Failure
  • Severe upper airway obstruction
  • ARDS
A 60 year old woman, longterm smoker, developed an upper respiratory infection followed by a productive cough, fever, chest tightness, wheezing and progressive dyspnea
After two days of struggling to breath, she came in to the emergency room.
On exam she was a middle-aged woman in acute respiratory distress T 101 P 130 R36 O2 Sat 78% on room air. The lungs were hyper-resonant, breath sounds were diminished and there was expiratory wheezing
Room air blood gas: pH 7.32, pCO2 72, pO2 42, HCO3 35 /Hct 48, WBC 12,500

Acute on chronic hypercapneic and hypoxemic respiratory failure related to COPD
There is partial compensation: the hematocrit is high and the serum bicarbonate is elevated
Treatment -Patient is awake and able to protect airway (intact cough and gag)-therefore supplemental oxygen and non-invasive face mask ventilation
Inhaled bd, iv corticosteroids

Acute Respiratory Failure May Result from Problems in Many Sites
  • Brain  (stroke, trauma or drugs affecting respiratory drive)
  • Spinal cord (345 keep the diaphragm alive)
  • Phrenic nerve (traumatic interruption, ALS)
  • Neuromuscular system (myasthenia, Guillain Barre)
  • Muscles (myopathy, myositis, muscular dystrophy)

ARF May Result from Problems in Many Sites
  • Thorax (kyphoscoliosis, flail chest)
  • Pleura (effusion, pneumothorax)
  • Upper airway (foreign body, edema, tumor)
  • Cardiovascular (pulmonary edema, PE)
  • Lower airway and alveoli (pneumonia, asthma)

Types of Respiratory Failure
Oxygenation failure: low arterial oxygen level (on room air p02 <60, on 100% oxygen p02 <300)
Ventilatory failure: pCO2 >50
In neuromuscular weakness, low VC (<10cc/kg) or poor muscle strength
Combined oxygenation and ventilatory failure (COPD with muscle weakness and aspiration pneumonia)..

Acute respiratory failure: Occurring in context of no underlying disease and therefore limited compensatory mechanisms
Chronic respiratory failure: Gradually progressive allowing compensatory mechanisms, such as increased hemoglobin(hypoxemia) and increased serum bicarbonate (hypercapnia)

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