Arterial carboxyhaemoglobin levels in children admitted to PICU: A retrospective observational study

Abstract

While carbon monoxide (CO) is considered toxic, low levels of endogenously produced CO are protective against cellular injury induced by oxidative stress. Carboxyhaemoglobin (COHb) levels have been associated with outcomes in critically ill adults. We aimed to describe the distribution of carboxyhaemoglobin in critically ill children and the relationship of these levels with clinical outcomes. This retrospective observational study was conducted at a large tertiary paediatric intensive care unit (PICU). We included all children admitted to the PICU over a two-year period who underwent arterial blood gas analysis. We measured the following: (i) Population and age-related differences in COHb distribution; (ii) Change in COHb over the first week of admission using a multi-level linear regression analysis; (iii) Uni- and multivariable relationships between COHb and length of ventilation and PICU survival. Arterial COHb levels were available for 559/2029 admissions. The median COHb level was 1.20% (IQR 1.00–1.60%). Younger children had significantly higher COHb levels (p-value <2 x 10 −16 ). Maximum Carboxyhaemoglobin was associated with survival 1.67 (95% CI: 1.01–2.57; p-value = 0.02) and length of ventilation (OR 5.20, 95% CI: 3.07–7.30; p-value = 1.8 x 10 −6 ) following multi-variable analysis. First measured and minimum COHb values were weakly associated with length of ventilation, but not survival. In conclusion, children have increased COHb levels in critical illness, which are greater in younger children. Higher COHb levels are associated with longer length of ventilation and death in PICU. This may reflect increased oxidative stress in these children.

Carboxyhemoglobin (CO-Hb) Correlates with Hemolysis and Hospital Mortality in Extracorporeal Membrane Oxygenation: A Retrospective Registry

“…There are only a few reports describing the relationship between arterial CO-Hb and survival of ICU patients. Some previous reports described a positive correlation of CO-Hb and hospital mortality in non-ECMO ICU patients [ 30 ], while others suggested a positive correlation between arterial CO-Hb and survival [ 31 ]. In ECMO patients, data from case series suggested a correlation between elevated CO-Hb concentrations and death [ 14 , 15 , 32 ] but collectives have never been as large as in the present study.…”

Clinical Factors Influencing Endogenous Carbon Monoxide Production and Carboxyhemoglobin Levels in Neonates

“…Therefore, to assess whether COHb could serve as a clinically useful diagnostic marker of hemolysis, it was important to understand the clinical factors that influence COHb levels. Elevated COHb levels have already been demonstrated during stress, sepsis and shock in both adults and children, [14][15][16][17] but, to date, CO production and COHb levels in newborns have not yet been fully investigated during these circumstances.…”

Predictive markers related to local and systemic inflammation in severe COVID-19-associated ARDS: a prospective single-center analysis

“…Another indicator for critical illness which is associated with increased mortality in patients is CO-Hb [ 12 , 13 ], however its relevance in COVID-19 is still being discussed [ 14 – 16 ]. CO-Hb results from the binding of carbon monoxide with hemoglobin, with the predominant source of endogenous carbon monoxide being the degradation of heme by heme oxygenase.…”