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Neonatal end tidal CO2 detection and waveform capnography

Last post 28 Oct 2018, 10:03 PM by fiona kelly. 1 replies.
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  •  10 Oct 2018, 1:44 PM 2666

    Neonatal end tidal CO2 detection and waveform capnography

    In response to Foy et al. and in relation to waveform capnography following neonatal intubation, it is important to distinguish between end tidal CO2 (ETCO2) detection and waveform capnography [1].

    Waveform capnography is not a standard of care in intubated neonates or in newborn intensive care because uncuffed tracheal tubes are used and ETCO2 trends have not proven to be useful. There is no evidence to inform neonatal preterm ICU waveform capnography at intubation. However, exhaled carbon dioxide detection (unspecified, although most research has been done with colorimetry) is recommended by the Resuscitation Council UK (RCUK), the International Consensus on Cardiopulmonary Resuscitation (ILCOR) and the European Resuscitation Council (ERC) guidelines for confirmation of tracheal intubation for all neonates at all gestations.

    The current (2015) RCUK guidelines state ‘Detection of exhaled carbon dioxide confirms tracheal intubation in neonates with a cardiac output more rapidly and more accurately than clinical assessment alone’ [2], while the 2015 ERC guidelines state ‘exhaled CO2 detection is effective for confirmation of tracheal tube placement in infants, including VLBW infants and neonatal studies suggest that it confirms tracheal intubation in neonates with a cardiac output more rapidly and more accurately than clinical assessment alone’ [3], and ILCOR state ‘exhaled CO2 detection is useful to confirm tracheal tube placement. During cardiac arrest, if exhaled CO2 is not detected, tube placement should be confirmed with direct laryngoscopy’ [4].

    The suspension of the NHS Improvement ‘never event’ relating to unintended oesophageal intubation in January 2018 occurred because of concerns raised by the British Association of Perinatal Medicine (BAPM) about neonatal waveform capnography, with ETCO2 being preferred. An updated version is due to be published soon.

    Both the RCUK Newborn Life Support (NLS) [5] and Advanced Resuscitation of the Newborn Infant (ARNI) [6] courses recommend ETCO2 detection rather than waveform capnography.

    It should be noted that ETCO2 detection can give false negatives in poor cardiac output situations leading to unnecessary extubation. False positives in ETCO2 detection by colorimetry can be caused by contamination with surfactant, epinephrine or atropine.

    In neonates correct tracheal tube placement can be confirmed by a combination of visual inspection on insertion and a prompt rise in heart rate. Other measures include evaluation of condensed humidified gas during exhalation and presence or absence of chest movement, but these have not been evaluated systematically in newborn babies. The relative merits of different ways of evaluating tracheal tube placement are more likely to be resolved through the now continous cycle of evidence reviews by ILCOR and associated Resuscitation Councils through knowledge synthesis units than through a survey of UK practice.

    The authors sensibly highlight shared learning that can occur across different ICU settings and report interesting findings around the incidence of neonatal pre-intubation checklists and the availability of difficult airway equipment. BAPM currently has a working group on neonatal difficult airways and this is covered in the ARNI course.

    J. Fawke

    Chair, Resuscitation Council (UK) NLS Subcommittee & ARNI Working Group

    University Hospitals Leicester NHS Trust,

    Leicester , UK.

    J. Wyllie

    President, Resuscitation Council UK

    James Cook University Hospital,

    Middlesbrough, UK.

    Email: joefawke@btinternet.com

     

    No external funding and no conflicts of interest declared.

     

    References

    1. Foy KE, Mew E, Cook TM. Paediatric intensive care and neonatal intensive care airway management in the United Kingdom: the PIC-NIC survey. Anaesthesia 2018 do:10.1111/anae.14259 (epub ahead of print).
    2. Research Council (UK) http://www.resus.org.uk/resuscitation-guidelines/resuscitation-and-support-of-transition-of-babies-at-birth/ (accessed 10/10/2018).
    3. Wyllie J, Bruinberg J, Roehr CC, et al. European Resuscitation Council Guidelines for Resuscitation 2015 Section 7. Resuscitation and support of transition of babies at birth. Resuscitation 2015; 95: 249-63.
    4. Wyllie J, Perlman J, Kattwinkel J et al. part 7: Neonatal Resuscitation 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Resuscitation 2015; 95: e169-e201.
    5. Resuscitation Council (UK). Newborn Life Support, 4th edn. Resuscitation Council (UK), London, 2016.
    6. Resuscitation Council (UK) Advanced resuscitation of the newborn infant. Resuscitation Council (UK), London, 2014.

     

  •  28 Oct 2018, 10:03 PM 2677 in reply to 2666

    Re: Neonatal end tidal CO2 detection and waveform capnography

    Dear Editor

    We thank Fawke and Wyllie for their comments [1]. Many of the issues raised by them are covered in our reply to Mactier and colleagues [2], but we would like to reply to some additional points.

    There does appear to be some confusion about the differences between capnometry and capnography. Capnometry is the measurement of carbon dioxide (CO2) in a sample of gas [3]. Capnography is the continuous monitoring of the concentration or partial pressure of CO2 in respiratory gases and representation in graphical form: the capnography waveform or capnogram [4]. The end tidal CO2 (ETCO2) is the partial pressure or concentration of CO2 at the end of an exhaled breath. A capnometry monitor displays the ETCO2 value alone, or changes from one colour to another if carbon dioxide is detected. Importantly, colour change capnometers rely on a change in colour in response to detection of CO2. In comparison, a waveform capnograph displays the ETCO2 value plus a continuous capnography waveform [4].

    All the guidelines Fawkes and Wyllie cite describe detection of carbon dioxide in exhaled gas. Both colorimetric devices and waveform capnography do this: both would therefore meet the requirements of the guidelines, and the guidelines as written do not appear to support one over the other.

    Fawke and Wyllie mention the many methods of confirming the correct placement of a tracheal tube at intubation [1]. Several studies show detection of exhaled carbon dioxide is faster, more accurate and associated with fewer false positives than clinical assessment [2]. Such clinical methods can also be used in adults, and indeed reliance on such clinical methods used to be prevalent in adult practice. The American Society of Anesthesiologists’ Closed Claims studies have shown that reliance on clinical techniques can lead to missed diagnoses of oesophageal intubation resulting in brain damage and death: 63% of such cases were preceded by auscultation of the chest, in 90% this auscultation (wrongly) “confirmed tracheal intubation” [5] and 91% of cases of oesophageal intubation were judged to represent substandard care [6]. Fawke and Wyllie note that “false positives in ETCO2 detected by colorimetry can be caused by contamination with surfactant, epinephrine or atropine” [1]. In addition to the limitations described above, other false positives may occur if the colorimetric device comes into contact with acid such as stomach contents. Continuous waveform capnography has none of these pitfalls and it would therefore seem less prone to false positives, particularly in the critically ill infant.

    Airway management continues during mechanical ventilation, when continuous waveform capnography monitoring can be used to detect a displaced, obstructed or kinked tracheal tube [4,6]. Simple pattern recognition is sufficient for junior doctors and ICU nurses to safely monitor the airway in this way [7]. Fawke and Wyllie state that “ETCO2 trends have not proven to be useful” [1]. Of note, we have not mentioned the use of capnography to track ‘trends’ at all in our paper [8] as we were interested in airway management rather than ventilatory management. In this regard it is the presence of exhaled CO2 that is important rather than trends. However, it is notable that when capnography was used to monitor ventilation accuracy in NICU Kugelman et al reported that this was associated with improved accuracy of ventilation and reduction in intracranial complications in ventilated neonates [9].

    Fawke and Wyllie also discuss the use of ‘exhaled carbon dioxide detection’ during a cardiac arrest [1]. There is much confusion about this issue in adult medicine, with many practitioners believing that a lack of ETCO2, and/or a flat capnography trace, can be attributable to the patient having no cardiac output. In fact, an attenuated ETCO2 trace will be seen during a cardiac arrest if CPR is being performed with a patent tracheal tube in the trachea [4]. Deaths still occur in adult practice because of this misunderstanding and this led the Royal College of Anaesthetists and the Difficult Airway Society to initiate the ‘No trace wrong place’ campaign [10]. Waveform capnography has additional benefits at cardiac arrest including assessing the adequacy of chest compressions and identifying the return of spontaneous circulation. We note that several of the documents Fawke and Wyllie quote seem to imply that a low cardiac output is associated with absent carbon dioxide detection in a neonate and we recommend this advice is urgently reassessed.

    We, like many others, fully acknowledge and are grateful for the enormous amount of synthesis of evidence that ILCOR and its constituent bodies have done in recent decades. There is no doubt many lives have been saved as a result. Notwithstanding that, guidance and evidence is of no value if it is not implemented. What our survey has done is ‘hold a mirror’ to current practices. A survey may identify deficits in implementation of best practice, confirm good practice or identify areas of variable practice. Our survey has perhaps noted all three of these and we noted high rates of education on airway matters in UK NICUs. The rate of significant airway complications reported to our survey from NICUs confirms that airway management in NICU is high risk [8] in a similar manner to the high-risk nature of airway management in adult ICUs [11-13]. Importantly, we did identify significant variations in practice between NICUs in several areas, with the availability and use of capnography being the most prominent. That some units are using the technology widely and others not at all is the same situation that we saw in adult practice a decade ago. At the very least this variation in practice merits further investigation to seek its cause. In this regard the work planned by BAPM on the ‘difficult airway’ is welcome. However, capnography for detection of tracheal intubation and for confirmation of tube position and patency in patients reliant on artificial ventilation is not about difficult airways, but rather about the routine airway: in short about every airway and every breath.

    We are somewhat surprised that our paper has led to so much interest. However, one aim of publishing our paper [8], and indeed presenting the results at the European Society of Paediatric and Neonatal Intensive Care and the British Association of Perinatal Medicine prior to publication, was to promote discussion amongst paediatric and neonatal intensivists. We hope the paper and letters will promote more constructive discussion, evaluation and clarification around what seems to be something of a gulf between adult, paediatric and neonatal practice.

     

    FE Kelly

    TM Cook

    KE Foy

    E Mew

    J Bower

    Department of anaesthesia and intensive care medicine, Royal United Hospitals Bath NHS Foundation Trust, Bath, UK

    S Dean

    P Knight

    Department of paediatric intensive care, Bristol Royal Hospital for Children, Bristol, UK

    B Marden

    Department of paediatric and neonatal medicine, Royal United Hospitals Bath NHS Foundation Trust, Bath, UK

    K Herneman

    Department of anaesthesia and intensive care medicine, North Bristol NHS Trust, Bristol

     

    Conflict of interests

    The Department of Anaesthesia has received free or at-cost airway equipment from numerous companies for evaluation or research. No author, nor their families, has any financial interest in any airway company. T.M.C. is an associate editor of the British Journal of Anaesthesia. He has spoken at a Storz GmbH meeting about airway management and was not paid. All other authors declare no conflicts of interest.

     

    References

    1.       Fawke J, Wyllie J. Neonatal end tidal CO2 detection and waveform capnography

    http://www.respond2articles.com/ANA/forums/thread/2666.aspx (accessed 21st October 2018)

    2.       2. Cook TM, Foy K, Kelly FE. Reply to Mactier H, Jackson A, Davis J et al. Re: Paediatric intensive care and neonatal intensive care airway management in the United Kingdom: the PIC-NIC survey.  http://www.respond2articles.com/ANA/forums/thread/2669.aspx (accessed 21st October 2018)

    3.       Samuels M, Wieteska S. Support of the airway and ventilation. Advanced Paediatric Life Support: A Practical Approach to Emergencies, Sixth Edition. Wiley Blackwell, 2016.

    4.       Kerslake I, Kelly FE. Uses of capnography on the critical care unit. BJA Education 2017; 17: 178–183.

    5.       Caplan RA, Posner KL, Ward RJ, Cheney FW. Adverse Respiratory Events in Anesthesia: A Closed Claims Analysis. Anesthesiology 1990; 72: 828-833

    6.       Cheney FW, Posner KL, Lee LA et al. Trends in Anesthesia-related Death and Brain Damage: A Closed Claims Analysis. Anesthesiology 2006; 105: 1081-1086.

    7.      TM Cook, FE Kelly, A Goswami. Hats and caps capnography training on intensive care. Anaesthesia 2013; 68: 421.

    8.       Foy K, Mew E, Cook TM et al. Paediatric intensive care and neonatal intensive care airway management in the United Kingdom: the PIC-NIC survey. Anaesthesia 2018; 73: 1337-1344

    9.       Kugelman A, Golan A, Riskin A et al. Impact of Continuous Capnography in Ventilated Neonates: A Randomized, Multicenter Study. Journal of Pediatrics 2016; 168: 56-61

    10.   Royal College of Anaesthetists ‘No trace wrong place’ initiative https://www.rcoa.ac.uk/standards-of-clinical-practice/capnography-no-trace-wrong-place (accessed 21st October 2018)

    11.   11. Cook TM, Woodhall N, Harper J et al. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Dif´Čücult Airway Society. Part 2: intensive care and emergency departments. British Journal of Anaesthesia 2011; 106: 632–4212.

    12.   JP Nolan, FE Kelly. Airway challenges in critical care.  Anaesthesia 2011; 66: 1-13.

    13.   Higgs A, McGrath BA, Goddard C et al. Guidelines for the management of tracheal intubation in critically ill adults. British Journal of Anaesthesia 2018; 120: 323-352

     

     

     

     

      

     

     

     

     

     

     

      

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