{
  "abstract": "Introduction Accurate CO2 monitoring during sleep studies is fundamental to optimising ventilation in children. While end-tidal CO2 (EtCO2) and Transcutaneous CO2 (TcCO2) are common alternatives to arterial blood gases (ABG), evidence regarding their agreement is mixed. TcCO2 has shown good agreement with Arterial CO2, whereas there’s mixed evidence regarding EtCO2 measurements during sleep (Orlikowski et al. Respiratory Medicine 2016; 117: 7–13; Won et al. American journal of physical medicine & rehabilitation 2016; 95.2: 91-95). To our knowledge, this is the first study to compare EtCO2 and TcCO2 in tracheostomy-ventilated children.Methods We conducted a prospective study of children on tracheostomy ventilation undergoing cardiorespiratory sleep studies at Great Ormond Street Hospital (Dec 2024-Dec 2025). EtCO2 (Masimo Rad-97® NemoLine® Capnography) and TcCO2 (Radiometer Ltd© TCM5 with Sensor-92) were recorded simultaneously. Stowood Scientific Instrument Ltd© VisiDownload software was used to analyse Rad-97®, and Natus® Embla® Remlogic for TCM5 data. Studies with <4 hours of good quality CO2 recording were excluded. We aimed to compare mean and max CO2, and percentage of sleep with CO2 > 50mmHg. Data was analysed using Bland-Altman plots with GraphPad Prism 10.Results 20 children, Median (IQR) age 7 (4,13) years were studied; 8 (40%) were excluded for unreliable EtCO2 recording, leaving 12 for analysis. Mean CO2: EtCO2 showed a mean bias of -3.4 mmHg compared to TcCO2 (SD 6.1 mmHg), with 95% limits of agreement (LoA) of -8.5 to +15.4 mmHg. Max CO2: EtCO2 showed a mean bias of -0.34 mmHg compared to TcCO2 (SD 11.1 mmHg) with LoA of -22.1 to +21.4 mmHg. Insufficient data to compare percentage of sleep with CO2 >50mmHg.Conclusion A mean bias of -3.4mmHg suggests EtCO2 may systematically underestimate CO2 levels in tracheostomy ventilated children. Although numerically small, this bias combined with wide LoA and a high failure rate (40%) renders EtCO2 unreliable for accurate ventilation monitoring. Limitations of the study include a small sample size, and different software used for EtCO2 and TcCO2 analysis. Future research should focus on larger cohorts and methods to improve EtCO2 signal stability.",
  "authors": [
    {
      "affiliations": [
        "Great Ormond Street Hospital for Children (GOSH), London, United Kingdom"
      ],
      "name": "Ricky Damm"
    },
    {
      "affiliations": [
        "Great Ormond Street Hospital for Children (GOSH), London, United Kingdom"
      ],
      "name": "Leilani Mensah-Manuel"
    },
    {
      "affiliations": [
        "Great Ormond Street Hospital for Children (GOSH), London, United Kingdom"
      ],
      "name": "Matthew Davies"
    },
    {
      "affiliations": [
        "Great Ormond Street Hospital for Children (GOSH), London, United Kingdom"
      ],
      "name": "Vasileios Patelis"
    },
    {
      "affiliations": [
        "Great Ormond Street Hospital for Children (GOSH), London, United Kingdom"
      ],
      "name": "Elaine Chan"
    },
    {
      "affiliations": [
        "Great Ormond Street Hospital for Children (GOSH), London, United Kingdom"
      ],
      "name": "Martin Samuels"
    }
  ],
  "title": "P37 Transcutaneous vs end-tidal CO2 monitoring in tracheostomy-ventilation paediatric sleep studies",
  "uid": "e1aaf115-10cb-5eb5-8938-166015f6dca3"
}