Oxygen for COPD
The danger of hyperoxia to patients with COPD was recognized by Westlake in 1955. Westlake EK, Simpson T, Kaye M. Carbon dioxide narcosis in emphysema. The Quarterly journal of medicine. 24(94):155-73. 1955.
Knowledge translation, as ever, has been slow. Hospital audits continue to show that these patients are treated with high flow oxygen, resulting in hypercarbia, acidosis and increased mortality. Aubier et al found that Hypoxia does not appear to decrease minute ventilation. They also found that the release of CO2 bound to Hemoglobin by the Haldane effect accounted for about 25% of the increase in PaCO2 in their COPD patients on high flow O2. Aubier M et al. Effects of the administration of O2 on ventilation and blood gases in patients with chronic obstructive pulmonary disease during acute respiratory failure. Am Rev Respir Dis.1980;122(5):747–754.
But the largest contribution to hypercarbia and acidosis in these patients is thought to be due to an oxygen induced reversal of a beneficial v/q mismatch. Robinson et al. The role of hypoventilation and ventilation-perfusion redistribution in oxygen-induced hypercapnia during acute exacerbations of chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2000;161(5):1524– 1529.
Brochard showed that NIV resulted in lower rates of intubation and shorter hospital stays for paitents with COPD exacerbation. And in 2001 Plant showed that long term survival was better as well. Brochard L, Mancebo J, Wysocki M, Lofaso F, Conti G, Rauss A, Simonneau G, Benito S, Gasparetto A, Lemaire F, et al. Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease. N Engl J Med. 1995 Sep 28;333(13):817-22.
Plant found that long term mortality was improved by NIV in copd. Plant PK, Owen JL, Elliott MW. Non-invasive ventilation in acute exacerbations of chronic obstructive pulmonary disease: long term survival and predictors of in-hospital outcome. Thorax 2001;56:708-712.
GOLD and ATS/ERS Guidelines promote NIV as first line therapy in COPD exacerbation. GOLD Guidelines (goldcopd.it). Celli BR, MacNee W; ATS/ERS Task Force. Standards for the diagnosis and treatment of patients with COPD: a summary of the ATS/ERS position paper. Eur Respir J. 2004 Jun;23(6):932-46.
PAP PAL was published by Rose on the satirical Gomerblog in 2015.
NIV failure results in higher mortality per Demoule. Demoule A, Girou E, Richard JC, Taille S, Brochard L (2006) Benefits and risks of success or failure of noninvasive ventilation. Intensive Care Med 32:1756– 1765.
Scott Weingart’s concept of HOP killers as a mnemonic for predicted difficult physiology during intubation appear on his emcrit podcast in 2012 with subsequent appearances in his Laryngoscope as a murder weapon series. emcrit.org.
In 2006 Baillard showed that NIV preoxygenates better than face mask. Baillard C, Fosse JP, Sebbane M, Chanques G, Vincent F, Courouble P, Cohen Y, Eledjam JJ, Adnet F, Jaber S. Noninvasive ventilation improves preoxygenation before intubation of hypoxic patients. Am J Respir Crit Care Med. 2006 Jul 15;174(2):171-7.
Weingart’s 2016 paper is a great review of early ED vent management. Weingart SD. Managing Initial Mechanical Ventilation in the Emergency Department. Ann Emerg Med. 2016 Jun 8. pii: S0196-0644(16)30164-0.
Mosier’s review of mechanical ventilation is more comprehensive if you want to go deeper. Mosier JM, Hypes C, Joshi R, Whitmore S, Parthasarathy S, Cairns CB. Ventilator Strategies and Rescue Therapies for Management of Acute Respiratory Failure in the Emergency Department. Ann Emerg Med. 2015 Nov;66(5):529-41.