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Abstract

We thank Dr. Shiber for his interest in the case report. Because we were preparing for intubation, our goal was complete denitrogenation with 100% oxygen1Weingart S.D. Levitan R.M. Preoxygenation and prevention of desaturation during emergency airway management.Ann Emerg Med. 2012; 59: 165-175.e1Abstract Full Text Full Text PDF PubMed Scopus (345) Google Scholar; thus, the fraction of inspired oxygen for noninvasive positive-pressure ventilation was 100%. Although the patient had acute respiratory acidosis, you correctly point out that the terminology of acute on chronic respiratory acidosis is more accurate. It is debated whether the modest hypercapnia that is sometimes observed after oxygen administration to patients with acute exacerbations of chronic obstructive pulmonary disease is due to ventilation-perfusion mismatch,2Aubier M. Murciano D. Milic-Emili J. 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: 747-754Crossref PubMed Google Scholar, 3Aubier M. Murciano D. Fournier M. et al.Central respiratory drive in acute respiratory failure of patients with chronic obstructive pulmonary disease.Am Rev Respir Dis. 1980; 122: 191-199Crossref PubMed Scopus (237) Google Scholar a modest decrease in minute ventilation,4Robinson T.D. Freiberg D.B. Regnis J.A. 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: 1524-1529Crossref PubMed Scopus (134) Google Scholar or both. Available evidence suggests that abrupt apnea from oxygen administration to a patient with acute chronic obstructive pulmonary disease exacerbation is very unlikely and, to our knowledge, has never been described, unlike ketamine-associated apnea.5Green S.M. Roback M.G. Kennedy R.M. et al.Clinical practice guideline for emergency department ketamine dissociative sedation: 2011 update.Ann Emerg Med. 2011; 57: 449-461Abstract Full Text Full Text PDF PubMed Scopus (357) Google Scholar Although we did not wait until the formal definition of apnea was achieved before intervening with bag-valve-mask ventilation, the patient’s total observed apnea time until the onset of pharmacologic paralysis was approximately 1 minute. We did not wait to observe further clinical deterioration such as hypoxemia or bradycardia, but rather sought to avoid these associated complications for this patient for whom we already had a plan of intubation. Consistent with your described clinical experience with ketamine, this agent has a long history of safe use for procedural sedation with apnea as a rare complication.5Green S.M. Roback M.G. Kennedy R.M. et al.Clinical practice guideline for emergency department ketamine dissociative sedation: 2011 update.Ann Emerg Med. 2011; 57: 449-461Abstract Full Text Full Text PDF PubMed Scopus (357) Google Scholar The use of the phrase “critically ill patients” was not meant to describe the physical location of patients, such as the ICU, but rather to describe patients undergoing active resuscitation, such as those with shock or impending respiratory failure. We believe that this patient population is likely to have higher apnea rates related to ketamine than more stable patients undergoing procedural sedation. Regardless of the mechanism or rarity of ketamine-associated apnea, it is important to recognize that it can occur. Therefore, when performing delayed sequence intubation, physicians should remain at the bedside and be prepared to immediately manage the patient’s airway. Apnea After Low-Dose Ketamine Sedation During Attempted Delayed Sequence IntubationAnnals of Emergency MedicineVol. 69Issue 1PreviewSome patients are agitated and unable to tolerate conventional preoxygenation methods, including face mask oxygen or noninvasive positive-pressure ventilation. Sedation with ketamine for preoxygenation, also known as delayed sequence intubation, is a technique that can be used to achieve preoxygenation in this patient population. No complications of delayed sequence intubation have previously been reported. A 60-year-old woman presented with acute hypoxic respiratory failure. Despite application of high-flow oxygen (60 L/min) with a nonrebreather face mask, her oxygen saturation remained at 93%. Full-Text PDF Ketamine Causing Apnea?Annals of Emergency MedicineVol. 69Issue 5PreviewAfter reading the article by Driver and Reardon1 in the January 2017 edition of Annals, I have several questions for the authors, as well as a few comments from personal experience. Full-Text PDF