Carbon dioxide monitoring in the newborn infant

A Moving Target: Studying the Effect of Continuous Transcutaneous CO2 Monitoring in ELBW Infants During an Equipoise Shift

Objectives: To assess whether continuous non-invasive pCO2 monitoring by transcutaneous pCO2 monitor (TCpCO2) among extremely low birth weight (ELBW) premature infants, during the first week of life, will decrease the rate of high-grade intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL) or the combined outcome of IVH/PVL and death. Methods: This was a prospective, observational, multicenter study. Due to ethical constraints, allocation was based on TCpCO2 monitor availability. ELBW infants were either monitored by TCpCO2 monitor (Sentec, Therwil, Switzerland) (study group), or recruited to the control group if a TCpCO2 monitor was not available. Results: A total of 132 ELBW infants participated in the study. The size of the study group (106 infants) and the control group (26 infants) differed because monitor availability increased during the study period reflecting change in standard of care. The groups had comparable gestational age and baseline characteristics. No difference was found in the rate of IVH/PVL in the study vs. control groups (10% vs. 4%; p = 0.7, respectively), or in the combined outcome of PVL/IVH and death (16% vs. 15%; p = 1.0, respectively). Conclusions: This study demonstrates the challenges in conducting a prospective controlled trial in a rapidly evolving medical field. While the study began with a clear equipoise, this balance shifted as the care team gained more experience with TCpCO2 monitoring among the study population, despite the absence of new clinical evidence to justify such a shift. Consequently, the small control group limited our ability to draw definitive conclusions regarding the study's objective. However, our findings may increase awareness of continuous non-invasive pCO2 monitoring in extremely premature infants.

Capnography waveforms: basic interpretation in neonatal intensive care

End-tidal capnography can provide useful clinical information displayed on the ventilator screen or bedside monitor. It is important that clinicians can assess and utilise this information to assist in identifying underlying complications and pulmonary pathology. Sudden change or loss of the CO2 waveform can act as a safety measure in alerting clinicians of a dislodged or blocked endotracheal tube, considering the concurrent flow and volume waveforms. Visual pattern recognition by the clinicians of commonly seen waveform traces may act as an adjunct to other modes of ventilatory monitoring techniques. Waveforms traces can aid clinical management, help identify cases of ventilation asynchrony between the infant and the ventilator. We present some common clinical scenarios where tidal capnography can be useful in the timely identification of pulmonary complication and for practical troubleshooting at the cot-side.

Exhaled CO2 monitoring to guide non-invasive ventilation at birth: a systematic review

OBJECTIVE

Measuring exhaled carbon dioxide (ECO2) during non-invasive ventilation at birth may provide information about lung aeration. However, the International Liaison Committee on Resuscitation (ILCOR) only recommends ECO2 detection for confirming endotracheal tube placement. ILCOR has therefore prioritised a research question that needs to be urgently evaluated: 'In newborn infants receiving intermittent positive pressure ventilation by any non-invasive interface at birth, does the use of an ECO2 monitor in addition to clinical assessment, pulse oximetry and/or ECG, compared with clinical assessment, pulse oximetry and/or ECG only, decrease endotracheal intubation in the delivery room, improve response to resuscitation, improve survival or reduce morbidity?'.

DESIGN

Systematic review of randomised and non-randomised studies identified by Ovid MEDLINE, Embase and Cochrane CENTRAL search until 1 August 2022.

SETTING

Delivery room.

PATIENTS

Newborn infants receiving non-invasive ventilation at birth.

INTERVENTION

ECO2 measurement plus routine assessment compared with routine assessment alone.

MAIN OUTCOME MEASURES

Endotracheal intubation in the delivery room, response to resuscitation, survival and morbidity.

RESULTS

Among 2370 articles, 23 were included; however, none had a relevant control group. Although studies indicated that the absence of ECO2 may signify airway obstruction and ECO2 detection may precede a heart rate increase in adequately ventilated infants, they did not directly address the research question.

CONCLUSIONS

Evidence to support the use of an ECO2 monitor to guide non-invasive positive pressure ventilation at birth is lacking. More research on the effectiveness of ECO2 measurement in addition to routine assessment during non-invasive ventilation of newborn infants at birth is needed.

PROSPERO REGISTRATION NUMBER

CRD42022344849.

A neonatal in-vitro study on the effect of the inflation pressure on end-tidal carbon dioxide levels

BACKGROUND

Describing the association of the peak inflation pressure (PIP) with end-tidal carbon dioxide (ETCO2) is a prerequisite for the development of closed loop ventilation in neonatal intensive care. We aimed to develop an in-vitro system to study this relationship.

METHODS

A ventilator was connected to a test lung, supplied with a stable CO2 concentration from a cylinder. The PIP was altered and the change in ETCO2 per unit of PIP was calculated in three models mimicking respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD) and viral bronchiolitis.

RESULTS

The median (IQR) change in ETCO2 per unit of PIP was 0.23(0.13-0.38) kPa/cmH2O, using 138 paired measurements of PIP and ETCO2. The median (IQR) change in ETCO2 per unit of PIP, was higher when starting at an ETCO2 > 6 kPa [0.43(0.33-0.58) kPa/cmH2O] compared to starting at an ETCO2 < 6 kPa [0.14(0.08-0.20) kPa/cmH2O, p < 0.001]. The median (IQR) change in ETCO2 per unit of PIP, was larger in the model of RDS [0.33(0.13-0.51) kPa/cmH2O] compared to the BPD [0.23(0.13-0.33) kPa/cmH2O, p = 0.043] and the bronchiolitis models [0.15(0.10-0.31) kPa/cmH2O, p = 0.017].

CONCLUSIONS

The change in ETCO2 in response to increasing PIP was larger for higher ETCO2 values and in a model simulating neonatal RDS, compared to BPD and bronchiolitis.

Physiological effects of N95 respirators on rescuers during cardiopulmonary resuscitation

Objectives

There is a lack of evidence in the medical literature reporting the physiological stress imposed by the wearing of N95 respirators during cardiopulmonary resuscitation (CPR) in healthcare providers. The aim of this study is to monitor the changes in hemodynamics and blood gas profiles in rescuers during the performance of CPR while wearing N95 respirators.

Methods

Thirty-two healthy healthcare workers performed standard CPR on manikins, each participant conducted 2 min of chest compression followed by 2 min of rest for 3 cycles. A non-invasive blood gas measuring device via a fingertip detector was used to collect arterial blood gas and hemodynamic data. Student t-test was used for comparison of various physiologic parameters before and after each session of chest compression.

Results

There were no significant differences in arterial blood gas profiles including partial pressure of arterial carbon dioxide and partial pressure of arterial oxygen before and after each session of chest compression (p > 0.05 for all). Heart rate and cardiac output were significantly higher after CPR (p < 0.05 for all), but no significant changes were found on blood pressure.

Conclusions

Our data suggest that healthcare providers wearing N95 respirators during provision of CPR in a short period of time does not cause any significant abnormalities in blood gas profiles and blood pressure. This may provide evidence to reassure the safe use of N95 respirator during performance of CPR.

Unrecognised oesophageal intubation: time for action

Patients worldwide die every year from unrecognised oesophageal intubation, which is an avoidable complication of airway management usually resulting from human error. Unrecognised oesophageal intubation can occur in any patient of any age whenever intubation occurs regardless of the seniority or experience of the airway practitioner or others involved in the patient's airway management. The tragic fact is that it continues to happen despite improvements in monitoring, airway devices, and medical education. We review these improvements with strategies to eliminate this problem.