Uncontrolled Oxygen Administration and Respiratory Failure in Acute Asthma

Hypercapnia and oxygen therapy in older asthmatic patients

“…Chien et al [10] found that the administration of 100% oxygen [fractional inspired oxygen (FIO 2 ) 100%] for 20 min in moderate asthmatic patients with respiratory alkalosis and hypocarbia led to carbon dioxide retention. Hypercapnia was worse the more severe the episode of asthma.…”

“…As SaO 2 less than 90% occurs in less than 2% of asthma exacerbations, adequate oxygenation can usually be attained with oxygen starting at 2-4 l/min [10]. Slowly increasing oxygen administration to maintain a PaO 2 greater than 60 mmHg is recommended in acute asthma [9,12] and COPD [2], especially when there is preexisting or worsening hypercapnia [8,13].…”

“…Unrestricted oxygen administration in a COPD patient with chronic hypercapnia leads to centrally mediated alveolar hypoventilation, reduced hypoxic drive, and worsening respiratory acidosis [3,10,13,20]. Chronic hypercapnia results in reduced chemosensitivity to carbon dioxide and increased reliance on hypoxic drive to maintain breathing during an intercurrent respiratory illness [2,14,17,[20][21][22].…”

Mortality in Asthma-Chronic Obstructive Pulmonary Disease Overlap in the United States

“…Controlled or titrated oxygen therapy gives better clinical outcomes than high-flow 100% oxygen therapy [349][350][351] (Evidence B). Oxygen should not be withheld if oximetry is not available, but the patient should be monitored for deterioration, somnolence or fatigue.…”

“…In severe exacerbations, controlled low flow oxygen therapy using pulse oximetry to maintain saturation at 93-95% is associated with better physiological outcomes than with high flow 100% oxygen therapy [349][350][351] (Evidence B). However, oxygen therapy should not be withheld if pulse oximetry is not available (Evidence D).…”