Non-invasive carbon dioxide monitoring in the UK: a survey of practice within neonatal intensive care.

Abstract

Newborns may require ventilatory support after birth; hence, confirmation of correct tracheal tube placement is vital. The most suitable method to determine intubation success and monitoring of carbon dioxide is a matter of contention, specifically regarding the use of capnography in the newborn population. In 2018, a UK survey on airway management in neonatal intensive care reported that only 18% of units always used capnography during neonatal tracheal intubations. The authors made recommendations for waveform capnography to be available and more widely implemented in order to improve safety [1]. Such recommendations, however, were extrapolated from studies in adult intensive care. The results of that survey [1] were thus met with scepticism from members of the British Association of Perinatal Medicine (BAPM), which highlighted differences in physiological characteristics of newborn infants compared with adults. Furthermore, BAPM emphasised alternative techniques in determining intubation success in neonates, such as qualitative colorimetric devices, flow sensors and clinical judgement [2]. The development of devices more suitable for use in newborns has subsequently provided clinicians with the means to continuously and non-invasively monitor carbon dioxide during resuscitation and mechanical ventilation. Novel capnographs are lightweight and have a small dead space, and are thus ideal for use in the newborn population. Indeed end-tidal carbon dioxide (ETCO2) values from small dead space sidestream capnographs have been shown to accurately reflect alveolar carbon dioxide levels in a cohort of healthy infants [3]. Capnography could also be utilised to alert clinicians to changing pulmonary pathology, with greater divergence of the end-tidal, compared with the arterial, carbon dioxide in those with more severe disease [4]. We therefore aimed to describe current clinical practice in UK neonatal units with respect to non-invasive carbon dioxide monitoring, specifically the use of capnography. All level two and level three neonatal ICUs (151 units) within the UK were identified from the BAPM Neonatal Network. The survey took place between January and May 2021 using a structured online questionnaire. Units that did not complete the survey online were followed-up with a maximum of three telephone calls by a member of the research team, with responses sought from senior clinical staff (as a minimum a registrar or band 7 nurse). A total of 126 (83.4%) units provided a complete response, 72/80 (90%) were level two and 54/71 (76.1%) were level three units. A total of 104 (82.5%) units reported monitoring carbon dioxide during all intubations. Seventy-nine (62.7%) units utilised colorimetric devices to confirm tracheal tube placement. Thirty-five (27.8%) reported use of continuous capnography monitoring, of which 10 (7.9%) also used qualitative colorimetry. Videolaryngoscopy was used to confirm successful intubation in 26 (20.6%) units. Furthermore, 23 (18.3%) confirmed tracheal tube position using clinical interpretation and chest radiography. Regarding the utility of capnography on the neonatal unit, 43 (34.1%) confirmed it formed part of routine clinical care. Specific criteria and other clinical settings for capnography use are shown in Table 1. Regarding capnography interpretation during day-to-day practice in neonatal intensive care, 14 (32.6%) units utilised only the ETCO2 value, six (13.9%) evaluated the carbon dioxide waveform trace and 21 (49%) reported evaluating both the ETCO2 value and the waveform in combination. Thirty-nine (30.9%) confirmed that capnography was part of their difficult airway trolley. We found that exhaled carbon dioxide monitoring during tracheal intubation was undertaken by over 80% of neonatal units in the UK, with the majority utilising qualitative methods. Previous concern was expressed over the lack of routine monitoring of exhaled carbon dioxide during neonatal intubation [1]; however, the 2018 survey considered only capnography to be an appropriate monitoring tool. Our results demonstrate that neonatal intensivists do now routinely monitor carbon dioxide during tracheal intubation, utilising either qualitative or quantitative methods. Indeed, one colorimetric ETCO2 device was shown to be 91% sensitive and 100% specific in confirming tracheal tube placement during neonatal resuscitation [5]. Quantitative waveform analysis during newborn resuscitation has, however, been shown to detect ETCO2 more rapidly than qualitative methods [6]. In conclusion, exhaled carbon dioxide during tracheal intubation is now monitored in the majority of neonatal units, but this is usually undertaken by qualitative methods despite increasing evidence that the new capnography devices are useable and accurate in the neonatal population. EW was supported by a grant from the Charles Wolfson Charitable Trust and a non-conditional educational grant from SLE. This research was supported by the National Institute for Health Research Biomedical Research Centre at Guy's and St Thomas' NHS Foundation Trust and King's College London. No competing interests declared.