title: End-tidal CO₂ detection of an audible heart rate during neonatal cardiopulmonary resuscitation after asystole in asphyxiated piglets.
abstract: Even brief interruption of cardiac compressions significantly reduces critical coronary perfusion pressure during cardiopulmonary resuscitation (CPR). End-tidal CO₂ (ETCO₂) monitoring may provide a continuous noninvasive method of assessing return of spontaneous circulation (ROSC) without stopping to auscultate for heart rate (HR). However, the ETCO₂ value that correlates with an audible HR is unknown. Our objective was to determine the threshold ETCO₂ that is associated with ROSC after asphyxia-induced asystole. Neonatal swine (n = 46) were progressively asphyxiated until asystole occurred. Resuscitation followed current neonatal guidelines with initial ventilation with 100% O₂ followed by cardiac compressions followed by epinephrine for continued asystole. HR was auscultated every 30 s, and ETCO₂ was continuously recorded. A receiver operator curve was generated using the calculated sensitivity and specificity for various ETCO₂ values, where a positive test was defined as the presence of HR >60 bpm by auscultation. An ETCO₂ cut-off value of 14 mm Hg is the most sensitive ETCO₂ value with the least false positives. When using ETCO₂ to guide uninterrupted CPR in this model of asphyxia-induced asystole, auscultative confirmation of return of an adequate HR should be performed when ETCO₂ ≥ 14 mm Hg is achieved. Correlation during human neonatal CPR needs further investigation.
authors.affiliation: Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. lina.chalak@utsouthwestern.edu
authors.forename: Lina F
authors.initials: LF
authors.lastname: Chalak
authors.forename: Chad A
authors.initials: CA
authors.lastname: Barber
authors.forename: Linda
authors.initials: L
authors.lastname: Hynan
authors.forename: Damian
authors.initials: D
authors.lastname: Garcia
authors.forename: Lucy
authors.initials: L
authors.lastname: Christie
authors.forename: Myra H
authors.initials: MH
authors.lastname: Wyckoff
mesh_terms: D000322:Adrenergic Agonists / Q000008:administration & dosage; D000818:Animals; D000831:Animals, Newborn; D001238:Asphyxia Neonatorum / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D015415:Biomarkers / Q000378:metabolism; D001794:Blood Pressure; D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism*; D016887:Cardiopulmonary Resuscitation / Q000379:methods; D004195:Disease Models, Animal; D004837:Epinephrine / Q000008:administration & dosage; D045853:Exhalation; D006323:Heart Arrest / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D006326:Heart Auscultation; D006336:Heart Massage; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D011175:Positive-Pressure Respiration; D011237:Predictive Value of Tests; D034421:Sus scrofa; D013997:Time Factors
chemical_list: D000322:Adrenergic Agonists; D015415:Biomarkers; D002245:Carbon Dioxide; D004837:Epinephrine