title: End-tidal carbon dioxide monitoring in very low birth weight infants: correlation and agreement with arterial carbon dioxide.
abstract: OBJECTIVE
  We aimed to determine the correlation and the agreement between end-tidal carbon dioxide (ETCO(2)) and partial pressure of arterial carbon dioxide (PaCO(2) ) in very low birth weight infants (VLBWI); furthermore, we assessed factors that could affect the ETCO(2)-PaCO(2) relationship.
  
  
  METHODS
  Simultaneous end-tidal and arterial CO(2) pairs were obtained from ventilated VLBWI who were monitored by mainstream capnography and had umbilical arterial catheter. Correlation and agreement between ETCO(2) and PaCO(2) were evaluated by using Spearman test and Bland-Altman method, respectively.
  
  
  RESULTS
  A total of 143 simultaneous ETCO(2)-PaCO(2) pairs were analyzed from 45 ventilated VLBWI. There was a significant correlation (r = 0.69; P < 0.0001) between ETCO(2) and PaCO(2) values. The ETCO(2) value was lower than the corresponding PaCO(2) value in 94% pairs, with a mean bias of 13.5 ± 8.4 mmHg (95% agreement levels, -3.0 to 29.9 mmHg). Mean PaCO(2)-ETCO(2) bias was similar between ELBWI (13.1 ± 7.7 mmHg; 95% agreement levels, -1.9 and 28.2 mmHg) and infants with birth weight 1,001-1,500 g (14.8 ± 9.7 mmHg; 95% agreement levels -4.3 and 33.8 mmHg). The bias between ETCO(2) and PaCO(2) was significantly increased with increasing FiO(2), mean airway pressure and oxygenation index. Within each patient, there was a positive correlation (r = 0.78, P < 0.0001) between the changes in PaCO(2) and the simultaneous changes in ETCO(2).
  
  
  CONCLUSIONS
  In ventilated VLBWI, the correlation between mainstream ETCO(2) and PaCO(2) is good, but the agreement is poor and negatively influenced by the severity of pulmonary disease. Capnography is feasible in ELBWI. ETCO(2) should not replace PaCO(2) measurements in ventilated VLBWI, but may have a role to detect trends of PaCO(2).
authors.affiliation: Pediatric Department, Medical School, University of Padua, Azienda Ospedaliera Padova, Padua, Italy. trevo@pediatria.unipd.it
authors.forename: Daniele
authors.initials: D
authors.lastname: Trevisanuto
authors.forename: Stephanie
authors.initials: S
authors.lastname: Giuliotto
authors.forename: Francesco
authors.initials: F
authors.lastname: Cavallin
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Doglioni
authors.forename: Silvia
authors.initials: S
authors.lastname: Toniazzo
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Zanardo
mesh_terms: D001944:Breath Tests; D019296:Capnography; D002245:Carbon Dioxide / Q000032:analysis / Q000097:blood*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008991:Monitoring, Physiologic; D011446:Prospective Studies; D012121:Respiration, Artificial
chemical_list: D002245:Carbon Dioxide