Table 1.
Baseline characteristics of children following unplanned admissions to PICU who underwent arterial blood gas analysis in 2015–16.
Continuous variables expressed as medians and interquartile ranges and categorical variables expressed as fractions and percentages.
Fig 1.
Distribution of carboxyhaemoglobin (COHb) for children admitted to the paediatric intensive care unit in 2015–16 who underwent arterial blood gas analysis.
The continuous line shows the overall distribution for the cohort. The grey dashed line shows the distribution for the first measured COHb value; the pink dotted line shows the distribution of maximum values during admission and the blue dashed line the minimum values during admission.
Fig 2.
The distribution of (A) all carboxyhaemoglobin (COHb) values throughout PICU stay (left), and (B) the first measured value of COHb (right), according to age groups.
There is a statistically significant difference between the groups for all COHb values (Kruskal-Wallis chi-squared 538.8; p-value <2 x 10−16) and first measured COHb values (Kruskal-Wallis chi-squared 47.1; p-value = 3.2 x 10−10).
Table 2.
Mean COHb levels for each day of admission in the first week following multi-level linear regression analysis.
Fig 3.
Box plot of measured COHb values and survival status at PICU discharge.
The first, minimum and maximum COHb values (%) and the survival status at PICU discharge are represented. Neither the first nor the minimum COHb values predicted survival status at ICU discharge. The maximum COHb values were slightly better at predicting survival status at PICU discharge.
Fig 4.
Scatter plot of measured COHb values and length of ventilation (log transformed).
The first, minimum and maximum COHb values (%) and the length of ventilation in hours are represented.
Fig 5.
Risk adjusted mortality according to categories of maximum COHb, relative to a maximum COHb value between 1.0–1.5%.
The shaded blue area represents the 95% confidence interval. Risk of mortality is adjusted for PIM-3, age, and length of ventilation. The U-shaped relationship described by Melley et al in adults is not seen—COHb values < = 1.0 have a non-significantly lower risk adjusted mortality relative to children with a maximum COHb between 1.0–1.5%.