title: Change in end-tidal carbon dioxide outperforms other surrogates for change in cardiac output during fluid challenge.
abstract: During fluid challenge, volume expansion (VE)-induced increase in cardiac output (Δ VE CO) is seldom measured.
  
  
  
  In patients with shock undergoing strictly controlled mechanical ventilation and receiving VE, we assessed minimally invasive surrogates for Δ VE CO (by transthoracic echocardiography): fluid-induced increases in end-tidal carbon dioxide (Δ VE E'CO2 ); pulse (Δ VE PP), systolic (Δ VE SBP), and mean systemic blood pressure (Δ VE MBP); and femoral artery Doppler flow (Δ VE FemFlow). In the absence of arrhythmia, fluid-induced decrease in heart rate (Δ VE HR) and in pulse pressure respiratory variation (Δ VE PPV) were also evaluated. Areas under the receiver operating characteristic curves (AUC ROC s) reflect the ability to identify a response to VE (Δ VE CO ≥15%).
  
  
  
  In 86 patients, Δ VE E'CO2 had an AUC ROC =0.82 [interquartile range 0.73-0.90], significantly higher than the AUC ROC for Δ VE PP, Δ VE SBP, Δ VE MBP, and Δ VE FemFlow (AUC ROC =0.61-0.65, all P  <0.05). A value of Δ VE E'CO2  >1 mm Hg (>0.13 kPa) had good positive (5.0 [2.6-9.8]) and fair negative (0.29 [0.2-0.5]) likelihood ratios. The 16 patients with arrhythmia had similar relationships between Δ VE E'CO2 and Δ VE CO to patients with regular rhythm ( r 2 =0.23 in both subgroups). In 60 patients with no arrhythmia, Δ VE E'CO2 (AUC ROC =0.84 [0.72-0.92]) outperformed Δ VE HR (AUC ROC =0.52 [0.39-0.66], P <0.05) and tended to outperform Δ VE PPV (AUC ROC =0.73 [0.60-0.84], P =0.21). In the 45 patients with no arrhythmia and receiving ventilation with tidal volume <8 ml kg -1 , Δ VE E'CO2 performed better than Δ VE PPV, with AUC ROC =0.86 [0.72-0.95] vs 0.66 [0.49-0.80], P =0.02.
  
  
  
  Δ VE E'CO2 outperformed Δ VE PP, Δ VE SBP, Δ VE MBP, Δ VE FemFlow, and Δ VE HR and, during protective ventilation, arrhythmia, or both, it also outperformed Δ VE PPV. A value of Δ VE E'CO2 >1 mm Hg (>0.13 kPa) indicated a likely response to VE.
authors.affiliation: Réanimation chirurgicale polyvalente, service d'anesthésie-réanimation, Hôpital Laënnec, Centre Hospitalier Universitaire, Nantes, France.
authors.forename: K
authors.initials: K
authors.lastname: Lakhal
authors.affiliation: Service de réanimation polyvalente, CHRU de Tours, Tours, France.
authors.forename: M A
authors.initials: MA
authors.lastname: Nay
authors.affiliation: Service de réanimation médicale, Hôpital La Source, centre hospitalier régional, avenue de l'Hôpital, Orléans, France.
authors.forename: T
authors.initials: T
authors.lastname: Kamel
authors.affiliation: Réanimation chirurgicale polyvalente, service d'anesthésie-réanimation, Hôpital Bichat-Claude Bernard, assistance publique-hôpitaux de Paris, France.
authors.forename: B
authors.initials: B
authors.lastname: Lortat-Jacob
authors.affiliation: Service de réanimation polyvalente, CHRU de Tours, Tours, France.
authors.forename: S
authors.initials: S
authors.lastname: Ehrmann
authors.affiliation: Réanimation chirurgicale polyvalente, service d'anesthésie-réanimation, Hôpital Laënnec, Centre Hospitalier Universitaire, Nantes, France.
authors.forename: B
authors.initials: B
authors.lastname: Rozec
authors.affiliation: Service de réanimation médicale, Hôpital La Source, centre hospitalier régional, avenue de l'Hôpital, Orléans, France.
authors.forename: T
authors.initials: T
authors.lastname: Boulain
mesh_terms: D000368:Aged; D002245:Carbon Dioxide / Q000378:metabolism*; D002303:Cardiac Output, Low / Q000175:diagnosis* / Q000378:metabolism* / Q000503:physiopathology; D003422:Critical Care / Q000379:methods; D004452:Echocardiography / Q000379:methods*; D005260:Female; D005440:Fluid Therapy; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012121:Respiration, Artificial; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide
keywords: E′CO2; arterial pressure/physiology; blood pressure determination; capnography; doppler; echocardiography; fluid therapy; heart rate; hypovolaemia; intermittent positive-pressure ventilation; pulse pressure variation; ultrasonography