In patients suffering from major burns, outline the possible physiologic derangements and their underlying mechanisms that could contribute to problems of oxygenation and ventilation.
Answer and interpretation
a) List the differential diagnoses for his weakness.
Can affect 4 anatomic areas of the respiratory tract:
- Supraglottal, tracheobronchial, and pulmonary parenchymal, and chest/abdominal wall.
Loss of airway patency due to mucosal oedema
Loss of airway reflexes due to coma (e.g. blast Traumatic brain injury, intoxications such as carbon monoxide,)
Bronchospasm resulting from inhaled irritants
Mucosal oedema and endobronchial sloughing causing small airway occlusion, leading to intrapulmonary shunting.
- Pulmonary Parenchymal
Pulmonary (alveolar) oedema and collapse leading to decreased compliance, and further intrapulmonary shunting.
Loss of tracheobronchial epithelium and airway ciliary clearance contributing to tracheobronchitis and pneumonia.
Barotrauma, ARDS, pleural effusions, Ventilator associated pneumonia, TRALI and tracheobronchitis may all result from Intensive Care resuscitation, and treatments of the above.
Circumferential full thickness burns of the chest and abdomen may cause reduced static compliance resulting in restrictive ventilator defect, made worse by large volumes of oedema with fluid resuscitation and capillary leak.
Toxic inhalation of carbon monoxide (CO) resulting in a left shift of the ODC and oxygen transport capacity (Carboxy Hb) and decreased cellular oxidative processes.
Other toxic gases NH3, HCL – pulmonary oedema,mucosal irritation and ALI
CN- poisoning, cellular hypoxia
Increased metabolic requirements may overwhelm a respiratory system already impaired by all the above.