Agreement of carbon dioxide levels measured by arterial, transcutaneous and end tidal methods in preterm infants < or = 28 weeks gestation

Relationship between ETCO2 and PaCO2 under Changing Capnogram in Ventilated Infants with NAVA: An Observational Study

This observational study evaluated the validity of end-tidal CO2 (ETCO2) as a surrogate for arterial PCO2 (PaCO2) in infants on neurally adjusted ventilatory assist (NAVA), particularly considering the influence of variable spontaneous breathing on capnography waveforms. The study involved 16 infants, analyzing 50 paired ETCO2 and PaCO2 values. Deming regression analysis highlighted a notably stronger correlation for maximum ETCO2 (r2 = 0.6783, p <0.0001) compared to mean ETCO2 (r2 = 0.5686, p <0.0001) and demonstrated a significantly weaker association for minimum ETCO2 (r2 = 0.1838). These findings emphasize the superior predictive value of maximum ETCO2 in estimating PaCO2, advocating its reliable use in clinical monitoring, especially given the dynamic capnography associated with NAVA's variable pressures. The results suggest ETCO2's potential to enhance noninvasive respiratory management, reduce the frequency of blood sampling, and improve overall care for infants requiring mechanical ventilation.

Transcutaneous CO2 Monitoring in Extremely Low Birth Weight Premature Infants

Extremely low birth weight (ELBW) premature infants are particularly susceptible to hypocarbia and hypercarbia, which are associated with brain and lung morbidities. Transcutaneous CO2 (TcCO2) monitoring allows for continuous non-invasive CO2 monitoring during invasive and non-invasive ventilation and is becoming more popular in the NICU. We aimed to evaluate the correlation and agreement between CO2 levels measured by a TcCO2 monitor and blood gas CO2 (bgCO2) among ELBW infants. This was a prospective observational multicenter study. All infants < 1000 g admitted to the participating NICUs during the study period were monitored by a TcCO2 monitor, if available. For each bgCO2 measured, a simultaneous TcCO2 measurement was documented. In total, 1828 pairs of TcCO2-bgCO2 values of 94 infants were collected, with a median (IQR) gestational age of 26.4 (26.0, 28.3) weeks and birth weight of 800 (702, 900) g. A moderate correlation (Pearson: r = 0.64) and good agreement (bias (95% limits of agreement)):(2.9 [-11.8, 17.6] mmHg) were found between the TcCO2 and bgCO2 values in the 25-70 mmHg TcCO2 range. The correlation between the TcCO2 and bgCO2 trends was moderate. CO2 measurements by TcCO2 are in good agreement (bias < 5 mmHg) with bgCO2 among premature infants < 1000 g during the first week of life, regardless of day of life, ventilation mode (invasive/non-invasive), and sampling method (arterial/capillary/venous). However, wide limits of agreement and moderate correlation dictate the use of TcCO2 as a complementary tool to blood gas sampling, to assess CO2 levels and trends in individual patients.

Capnometry during neonatal transport-Mini review

AIM

The aim of this review was to give an overview of available data on end-tidal CO2 (etCO2 ) monitoring, also called capnometry, during neonatal transport.

METHODS

Pubmed/MEDLINE database was searched using research question (capno* OR etCO2 OR detCO2 OR (['end tidal' OR 'end-tidal'] AND [CO2 OR 'carbon dioxide']) AND (neonat* OR infant* OR newborn*) AND transport*). All articles relevant to the topic were reviewed and summarised.

RESULTS

The lack of studies relevant to neonatal transport prompted us to extend the search to capnometry in a neonatal intensive care setting. The published studies are showing conflicting results. The different study populations, technologies used to measure etCO2 , types of etCO2 sampling and the diverse sites of blood gas tests make the data unsuitable for systematic comparison.

CONCLUSION

Further research to obtain more data on capnometry during neonatal transport will be necessary to define precisely under what circumstances can end-tidal monitoring of CO2 be reliably used in neonates during transport and also how to interpret the measured values.

Capnography in newborns under mechanical ventilation and its relationship with the measurement of CO2 in blood samples

INTRODUCTION

Monitoring the partial pressure of CO₂ (PCO₂) in newborns who require ventilation would allow avoiding hypocapnia and hypercapnia. The measurement of end-tidal carbon dioxide (ETCO₂) is an alternative rarely implemented in this population.

OBJECTIVE

To evaluate the relationship between ETCO₂ and PCO₂ in newborns.

METHODS

Cross-sectional study comparing two PCO₂ measurement methods, the conventional one by analysis of blood samples and the one estimated by ETCO₂. The study included hospitalized newborns that required conventional mechanical ventilation. The ETCO₂ was measured with a Tecme GraphNet® neo, a neonatal ventilator with an integrated capnograph, and we obtained the ETCO₂-PCO₂ gradient. We conducted correlation and Bland-Altman plot analyses to estimate the agreement.

RESULTS

A total of 277 samples (ETCO₂ / PCO₂) from 83 newborns were analyzed. The mean values ​​of ETCO₂ and PCO₂ were 41.36mmHg and 42.04mmHg. There was a positive and significant correlation between ETCO₂ and PCO₂ in the overall analysis (r=0.5402; P<.001) and in the analysis of each unit (P<.001). The mean difference was 0.68 mmHg (95% CI, -0.68 to 1.95) and was not significant. We observed a positive systematic error (PCO₂ > ETCO₂) in 2 of the units, and a negative difference in the third (PCO₂ < ETCO₂).

DISCUSSION

The correlation between ETCO and PCO₂ was significant, although the obtained values ​​were not equivalent, with differences ranging from 0.1mmHg and 20mmHg. Likewise, we found systematic errors that differed in sign (positive or negative) between institutions.

Monitoring of carbon dioxide in ventilated neonates: a prospective observational study

OBJECTIVE

To assess the reliability, accuracy and precision of distal end-tidal capnography (detCO₂) in neonates compared with transcutaneous (tcCO₂) carbon dioxide measurements.

DESIGN

Observational, prospective clinical study.

SETTING

Neonatal intensive care unit at Medical University of Vienna.

PARTICIPANTS

Conventionally ventilated neonates with a body weight between 1000 g and 3000 g.

INTERVENTION

End-tidal partial pressure of CO₂ was measured in distal position using the separate lumen of a double-lumen endotracheal tube connected to an external side-stream capnometer. Three consecutive detCO₂ and tcCO₂ values were recorded simultaneously and compared with simultaneous arterialised partial pressure of CO₂ (paCO₂) measurements in each patient.

MAIN OUTCOME MEASURES

Reliability, accuracy and precision of detCO₂ and tcCO₂ measurements compared with paCO₂ in neonates.

RESULTS

Twenty-five neonates were included with a median (range) weight at enrolment of 1410 (1010-2980) g, from which 81 simultaneous measurements of detCO₂, tcCO₂ and paCO₂ were obtained. The mean (SD) of paCO₂, detCO₂ and tcCO₂ was 45.0 (8.6) mmHg, 42.4 (8.4) mmHg and 50.4 (20.4) mmHg, respectively. The intraclass correlation between paCO₂ and detCO₂ and between paCO₂ and tcCO₂ reached 0.80 (95% CI 0.71 to 0.87, p<0.001) and 0.59 (95% CI 0.43 to 0.72, p<0.001), respectively. In the Bland-Altman analysis, bias and precision of detCO₂ with respect to paCO₂ amounted to -2.68 mmHg and 10.62 mmHg (95% CI 8.49 to 14.51), respectively. Bias and precision of tcCO₂ with respect to paCO₂ amounted to 5.39 mmHg and 17.22 mmHg (95% CI 13.21 to 23.34), respectively.

CONCLUSION

DetCO₂ had better reliability, accuracy and precision with paCO₂ than tcCO₂ in ventilated neonates without severe lung diseas.

TRIAL REGISTRATION NUMBER

NCT03758313.

Non-invasive carbon dioxide monitoring in neonates: methods, benefits, and pitfalls

Wide fluctuations in partial pressure of carbon dioxide (PaCO2) can potentially be associated with neurological and lung injury in neonates. Blood gas measurement is the gold standard for assessing gas exchange but is intermittent, invasive, and contributes to iatrogenic blood loss. Non-invasive carbon dioxide (CO2) monitoring has become ubiquitous in anesthesia and critical care and is being increasingly used in neonates. Two common methods of non-invasive CO2 monitoring are end-tidal and transcutaneous. A colorimetric CO2 detector (a modified end-tidal CO2 detector) is recommended by the International Liaison Committee on Resuscitation (ILCOR) and the American Academy of Pediatrics to confirm endotracheal tube placement. Continuous CO2 monitoring is helpful in trending PaCO2 in critically ill neonates on respiratory support and can potentially lead to early detection and minimization of fluctuations in PaCO2. This review includes a description of the various types of CO2 monitoring and their applications, benefits, and limitations in neonates.

Carbon dioxide monitoring in the newborn infant

Carbon dioxide (CO₂ ) monitoring is vital during mechanical ventilation of newborn infants, as morbidity increases when CO₂ levels are inappropriate. Our aim was to review the uses and limitations of such noninvasive monitoring methods. Colorimetry is primarily utilized during resuscitation to determine whether successful intubation has occurred. False negative and positive results can however lead to delays in detecting tracheal versus esophageal intubation. Transcutaneous carbon dioxide sensors have limited use during resuscitation, but can be utilized to provide continuous trend data during on-going ventilation. End-tidal capnography can provide clinicians with quantitative end-tidal CO₂ (EtCO₂ ) values and a continuous real-time capnogram waveform trace. These devices are becoming more widely accepted for use in the neonatal population as the new devices are lightweight with minimal additional dead space. Nevertheless, they have been reported to have variable accuracy when compared to arterial CO₂ measurements, however, divergence of results may be related to disease severity rather than technological limitations. During resuscitation EtCO₂ can be detected by capnography more rapidly than by colorimetry. Furthermore, capnography can be currently utilized in neonatal research settings to determine the physiological dead space and ventilation inhomogeneity, and thus has potential to be beneficial to clinical care. In conclusion, novel modes of noninvasive carbon dioxide monitoring can be safely and reliably utilized in newborn infants during mechanical ventilation. Future randomized trials should aim to address which device provides the most optimal form of monitoring in different clinical contexts.

Recent Insights into the Measurement of Carbon Dioxide Concentrations for Clinical Practice in Respiratory Medicine

In the field of respiratory clinical practice, the importance of measuring carbon dioxide (CO2) concentrations cannot be overemphasized. Within the body, assessment of the arterial partial pressure of CO2 (PaCO2) has been the gold standard for many decades. Non-invasive assessments are usually predicated on the measurement of CO2 concentrations in the air, usually using an infrared analyzer, and these data are clearly important regarding climate changes as well as regulations of air quality in buildings to ascertain adequate ventilation. Measurements of CO2 production with oxygen consumption yield important indices such as the respiratory quotient and estimates of energy expenditure, which may be used for further investigation in the various fields of metabolism, obesity, sleep disorders, and lifestyle-related issues. Measures of PaCO2 are nowadays performed using the Severinghaus electrode in arterial blood or in arterialized capillary blood, while the same electrode system has been modified to enable relatively accurate non-invasive monitoring of the transcutaneous partial pressure of CO2 (PtcCO2). PtcCO2 monitoring during sleep can be helpful for evaluating sleep apnea syndrome, particularly in children. End-tidal PCO2 is inferior to PtcCO2 as far as accuracy, but it provides breath-by-breath estimates of respiratory gas exchange, while PtcCO2 reflects temporal trends in alveolar ventilation. The frequency of monitoring end-tidal PCO2 has markedly increased in light of its multiple applications (e.g., verify endotracheal intubation, anesthesia or mechanical ventilation, exercise testing, respiratory patterning during sleep, etc.).

Correlation of End-Tidal Carbon Dioxide with Arterial Carbon Dioxide in Mechanically Ventilated Neonates: A Scoping Review

Monitoring CO2 levels in intubated neonates is highly relevant in the face of complications associated with altered CO2 levels. Thus, this review aims to present the scientific evidence in the literature regarding the correlation between arterial carbon dioxide measured by non-invasive methods in newborns submitted to invasive mechanical ventilation. The search was carried out from January 2020 to January 2021, in the Scopus, Medline, The Cochrane Library, Web of Science, CINAHL and Embase databases. Also, a manual search of the references of included studies was performed. The main descriptors used were: "capnography," "premature infant," "blood gas analysis," and "mechanical ventilation." As a result, 221 articles were identified, and 18 were included in this review. A total of 789 newborns were evaluated, with gestational age between 22.8 and 42.2 weeks and birth weight between 332 and 4790 g. Capnometry was the most widely used non-invasive method. In general, the correlation and agreement between the methods evaluated in the studies were strong/high. The birth weight did not influence the results. The gestational age of fewer than 37 weeks implied, in its majority, a moderate correlation and agreement. Therefore, we can conclude that there was a predominance of a strong correlation between arterial blood gases and non-invasive methods, although there are variations found in the literature. Even so, the results were promising and may provide valuable data for future studies, which are necessary to consolidate non-invasive methods as a reliable and viable alternative to arterial blood gasometry.

Interventions to minimize blood loss in very preterm infants-A systematic review and meta-analysis

Blood loss in the first days of life has been associated with increased morbidity and mortality in very preterm infants. In this systematic review we included randomized controlled trials comparing the effects of interventions to preserve blood volume in the infant from birth, reduce the need for sampling, or limit the blood sampled. Mortality and major neurodevelopmental disabilities were the primary outcomes. Included studies underwent risk of bias-assessment and data extraction by two review authors independently. We used risk ratio or mean difference to evaluate the treatment effect and meta-analysis for pooled results. The certainty of evidence was assessed using GRADE. We included 31 trials enrolling 3,759 infants. Twenty-five trials were pooled in the comparison delayed cord clamping or cord milking vs. immediate cord clamping or no milking. Increasing placental transfusion resulted in lower mortality during the neonatal period (RR 0.51, 95% CI 0.26 to 1.00; participants = 595; trials = 5; I2 = 0%, moderate certainty of evidence) and during first hospitalization (RR 0.70, 95% CI 0.51, 0.96; 10 RCTs, participants = 2,476, low certainty of evidence). The certainty of evidence was very low for the other primary outcomes of this review. The six remaining trials compared devices to monitor glucose levels (three trials), blood sampling from the umbilical cord or from the placenta vs. blood sampling from the infant (2 trials), and devices to reintroduce the blood after analysis vs. conventional blood sampling (1 trial); the certainty of evidence was rated as very low for all outcomes in these comparisons. Increasing placental transfusion at birth may reduce mortality in very preterm infants; However, extremely limited evidence is available to assess the effects of other interventions to reduce blood loss after birth. In future trials, infants could be randomized following placental transfusion to different blood saving approaches. Trial registration: PROSPERO CRD42020159882.

Evaluation of time courses of agreement between minutely obtained transcutaneous blood gas data and the gold standard arterial data from spontaneously breathing Asian adults, and various subgroup analyses

BACKGROUND

Usual clinical practice for arterial blood gas analysis (BGA) in conscious patients involves a one-time arterial puncture to be performed after a resting period of 20-30 min. The aim of this study was to evaluate the use of transcutaneous BGA for estimating this gold standard arterial BGA.

METHODS

Spontaneously breathing Asian adults (healthy volunteers and respiratory patients) were enrolled (n = 295). Transcutaneous PO₂ (PtcO₂) and PCO₂ (PtcCO₂) were monitored using a transcutaneous monitor (TCM4, Radiometer Medical AsP, Denmark) with sensors placed on the chest, forearm, earlobe or forehead. Transcutaneous BGA at 1-min intervals was compared with arterial BGA at 30 min. Reasonable steps to find severe hypercapnia with PaCO₂ > 50 mmHg were evaluated.

RESULTS

Sensors on the chest and forearm were equally preferred and used because of small biases (n = 272). The average PCO₂ bias was close to 0 mmHg at 4 min, and was almost constant (4-5 mmHg) with PtcCO₂ being higher than PaCO₂ at ≥8 min. The limit of agreement for PCO₂ narrowed over time: ± 13.6 mmHg at 4 min, ± 7.5 mmHg at 12-13 min, and ± 6.3 mmHg at 30 min. The limit of agreement for PO₂ also narrowed over time (± 23.1 mmHg at 30 min). Subgroup analyses showed that the PaCO₂ and PaO₂ levels, gender, and younger age significantly affected the biases. All hypercapnia subjects with PaCO₂ > 50 mmHg (n = 13) showed PtcCO₂ ≥ 50 mmHg for until 12 min.

CONCLUSIONS

Although PtcCO₂ is useful, it cannot completely replace PaCO₂ because PCO₂ occasionally showed large bias. On the other hand, the prediction of PaO₂ using PtcO₂ was unrealistic in Asian adults. PtcCO₂ ≥ 50 mmHg for until 12 min can be used as a screening tool for severe hypercapnia with PaCO₂ > 50 mmHg.

Tools to assess lung aeration in neonates with respiratory distress syndrome

AIM

Respiratory distress syndrome is a common condition among preterm neonates, and assessing lung aeration assists in diagnosing the disease and helping to guide and monitor treatment. We aimed to identify and analyse the tools available to assess lung aeration in neonates with respiratory distress syndrome.

METHODS

A systematic review and narrative synthesis of studies published between January 1, 2004, and August 26, 2019, were performed using the OVID Medline, PubMed, Embase and Scopus databases.

RESULTS

A total of 53 relevant papers were retrieved for the narrative synthesis. The main tools used to assess lung aeration were respiratory function monitoring, capnography, chest X-rays, lung ultrasound, electrical impedance tomography and respiratory inductive plethysmography. This paper discusses the evidence to support the use of these tools, including their advantages and disadvantages, and explores the future of lung aeration assessments within neonatal intensive care units.

CONCLUSION

There are currently several promising tools available to assess lung aeration in neonates with respiratory distress syndrome, but they all have their limitations. These tools need to be refined to facilitate convenient and accurate assessments of lung aeration in neonates with respiratory distress syndrome.

Transcutaneous blood gas monitoring among neonatal intensive care units in Japan

BACKGROUND

This study aimed to investigate the utility of transcutaneous (tc) measurements of partial pressure of oxygen (tcPO₂ ) and carbon dioxide (tcPCO₂ ) monitoring in neonatal intensive care units (NICUs) in Japan.

METHODS

At the end of 2016,we sent a survey questionnaire on tc monitoring to all 106 NICUs registered with the Japanese Neonatologist Association. The questions included usage, subjects, methods, management, and the practical usefulness of tc monitoring.

RESULTS

The questionnaire was returned by 69 NICUs (65.1% of response rate). Seventeen institutions (24.6%) measured both tcPCO₂ and tcPO₂ , and 42 (60.9%) measured tcPCO₂ alone. Transcutaneous PCO₂ or tcPO₂ monitoring was applied for "pre-viable" infants born at 22-23 weeks' gestational age (18.6% vs 23.5%), and infants of <500 g birthweight (30.5% vs 17.6%). The tcPCO₂ and tcPO₂ monitoring was started at birth in 49.2% and 70.6% of the newborn infants, respectively. The temperature of the sensor was set at <38°C for tcPCO₂ in 54.3% and >42°C for tcPO₂ in 58.9% of NICUs. The accuracy for tcPO₂ was rated as good in 35.3% or moderate in 64.7%, of institutions but or for tcPCO₂ as 1.7% or 93.2%of institutions , respectively.

CONCLUSION

Transcutaneous monitoring was widely, but limitedly, used for preterm infants. The lower temperature of the tcPCO₂ sensor compared to that reported in other developed countries might compromise the accuracy but increase the feasibility of tc monitoring in Japan.

The Organ-Protective Effect of Higher Partial Pressure of Arterial Carbon Dioxide in the Normal Range for Infant Patients Undergoing Ventricular Septal Defect Repair

Hypercapnia has been reported to play an active role in protection against organ injury. The aim of this study was to determine whether a higher level of partial pressure of arterial carbon dioxide (PaCO₂) within the normal range in pediatric patients undergoing cardiac surgery had a similar organ-protective effect. From May 2017 to May 2018, 83 consecutive infant patients undergoing ventricular septal defect (VSD) repair with cardiopulmonary bypass were retrospectively enrolled. We recorded the end-expiratory tidal partial pressure of carbon dioxide (Pet-CO₂) as an indirect and continuous way to reflect the PaCO₂. The patients were divided into a low PaCO₂ group (LPG; 30 mmHg < Pet-CO₂ < 40 mmHg) and a high PaCO₂ group (HPG; 40 mmHg < Pet-CO₂ < 50 mmHg). The regional cerebral oxygen saturation (rScO₂), cerebral blood flow velocity (CBFV), and hemodynamics at five time points throughout the operation, and perioperative data were recorded and analyzed for the two groups. In total, 34 LPG and 49 HPG patients were included. Demographics and perioperative clinical data showed no significant difference between the groups. Compared with LPG, the HPG produced lower postoperative creatine kinase isoenzyme-MB (40.88 versus 50.34 ng/mL, P = 0.038). The postoperative C-reactive protein of HPG trended lower than in LPG (61.09 versus 73.4 mg/L, P = 0.056). The rScO₂ and mean CBFV of HPG were significantly higher compared with LPG (P < 0.05) except at the end of cardiopulmonary bypass. Hemodynamic data showed no significant difference between the groups. As a convenient and safe approach, higher-normal PaCO₂ could attenuate brain injury, heart injury, and inflammatory response in infant patients undergoing VSD repair.

Continuous Noninvasive Carbon Dioxide Monitoring in Neonates: From Theory to Standard of Care

Ventilatory support may affect the short- and long-term neurologic and respiratory morbidities of preterm infants. Ongoing monitoring of oxygenation and ventilation and control of adequate levels of oxygen, pressures, and volumes can decrease the incidence of such adverse outcomes. Use of pulse oximetry became a standard of care for titrating oxygen delivery, but continuous noninvasive monitoring of carbon dioxide (CO₂) is not routinely used in NICUs. Continuous monitoring of CO₂ level may be crucial because hypocarbia and hypercarbia in extremely preterm infants are associated with lung and brain morbidities, specifically bronchopulmonary dysplasia, intraventricular hemorrhage, and cystic periventricular leukomalacia. It is shown that continuous monitoring of CO₂ levels helps in maintaining stable CO₂ values within an accepted target range. Continuous monitoring of CO₂ levels can be used in the delivery room, during transport, and in infants receiving invasive or noninvasive respiratory support in the NICU. It is logical to hypothesize that this will result in better outcome for extremely preterm infants. In this article, we review the different noninvasive CO₂ monitoring alternatives and devices, their advantages and disadvantages, and the available clinical data supporting or negating their use as a standard of care in NICUs.

Delivery of sevoflurane using a neonatal ventilator

BACKGROUND

Most anesthetic ventilators are designed to cope with a wide range of patient sizes and may lack precision at the lowest end of the minute volume scale. Neonatal intensive care ventilators on the other hand are designed specifically for this patient group, but are not able to deliver volatile anesthesia.

AIMS

We aimed to adapt the neonatal ventilator currently in use in our institution to deliver sevoflurane by incorporating a vaporizer and a scavenging system.

METHODS

We used a Diamedica draw-over vaporizer incorporated into the ventilator circuit and a custom designed open interface scavenging system. A number of safety measures are described to ensure that this equipment is correctly inserted into the circuit.

RESULTS

Bench testing revealed that the vaporizer output is linear and stable within the circuit flow range 4-8 L/min in all modes except high frequency oscillation where concentrations are not predictable. The scavenging system was found to be effective and did not affect volumes, pressures or waveforms when ventilating a test lung over a wide range of flows and pressures. This remained the case over the full range of scavenger flow adjustment.

CONCLUSION

The addition of a Diamedica vaporizer to a Fabian neonatal ventilator was shown in bench testing to provide stable, linear vapor concentrations without compromise of ventilator function. The system should not be used in high frequency oscillation mode because concentrations will exceed those expected and will not maintain a linear relationship with the vaporizer setting.

Accuracy of Transcutaneous Carbon Dioxide Measurement in Premature Infants

Background. In premature infants, maintaining blood partial pressure of carbon dioxide (pCO₂) value within a narrow range is important to avoid cerebral lesions. The aim of this study was to assess the accuracy of a noninvasive transcutaneous method (TcpCO₂), compared to blood partial pressure of carbon dioxide (pCO₂). Methods. Retrospective observational study in a tertiary neonatal intensive care unit. We analyzed the correlation between blood pCO₂ and transcutaneous values and the accuracy between the trends of blood pCO₂ and TcpCO₂ in all consecutive premature infants born at <33 weeks' gestational age. Results. 248 infants were included (median gestational age: 29 + 5 weeks and median birth weight: 1250 g), providing 1365 pairs of TcpCO₂ and blood pCO₂ values. Pearson's R correlation between these values was 0.58. The mean bias was −0.93 kPa with a 95% confidence limit of agreement of −4.05 to +2.16 kPa. Correlation between the trends of TcpCO₂ and blood pCO₂ values was good in only 39.6%. Conclusions. In premature infants, TcpCO₂ was poorly correlated to blood pCO₂, with a wide limit of agreement. Furthermore, concordance between trends was equally low. We warn about clinical decision-making on TcpCO₂ alone when used as continuous monitoring.

Transcutaneous carbon dioxide monitoring for the prevention of neonatal morbidity and mortality

BACKGROUND

Carbon dioxide (CO2) measurement is a fundamental evaluation in a neonatal intensive care unit (NICU), as both low and high values of CO2 might have detrimental effects on neonatal morbidity and mortality. Though measurement of CO2 in the arterial blood gas is the most accurate way to assess the amount of CO2, it requires blood sampling and it does not provide a continuous monitoring of CO2.

OBJECTIVES

To assess whether the use of continuous transcutaneous CO2 (tcCO2) monitoring in newborn infants reduces mortality and improves short and long term respiratory and neurodevelopmental outcomes.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 11), MEDLINE via PubMed (1966 to November 1, 2015), EMBASE (1980 to November 1, 2015), and CINAHL (1982 to November 1, 2015). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomized controlled trials and quasi-randomized trials.

SELECTION CRITERIA

Randomized, quasi-randomized and cluster randomized controlled trials comparing different strategies regarding tcCO2 monitoring in newborns. Three comparisons were considered, that is, continuous tcCO2 monitoring versus 1) any intermittent modalities to measure CO2; 2) other continuous CO2 monitoring; and 3) with or without intermittent CO2 monitoring.

DATA COLLECTION AND ANALYSIS

We used the standard methods of the Cochrane Neonatal Review Group. Two review authors independently assessed studies identified by the search strategy for inclusion.

MAIN RESULTS

Our search strategy yielded 106 references. Two review authors independently assessed all references for inclusion. We did not find any completed studies for inclusion, nor ongoing trials.

AUTHORS' CONCLUSIONS

There was no evidence to recommend or refute the use of transcutaneous CO2 monitoring in neonates. Well-designed, adequately powered randomized controlled studies are necessary to address efficacy and safety of transcutaneous CO2 monitoring in neonates.

Noninvasive Measurement of Carbon Dioxide during One-Lung Ventilation with Low Tidal Volume for Two Hours: End-Tidal versus Transcutaneous Techniques

BACKGROUND

There may be significant difference between measurement of end-tidal carbon dioxide partial pressure (PetCO2) and arterial carbon dioxide partial pressure (PaCO2) during one-lung ventilation with low tidal volume for thoracic surgeries. Transcutaneous carbon dioxide partial pressure (PtcCO2) monitoring can be used continuously to evaluate PaCO2 in a noninvasive fashion. In this study, we compared the accuracy between PetCO2 and PtcCO2 in predicting PaCO2 during prolonged one-lung ventilation with low tidal volume for thoracic surgeries.

METHODS

Eighteen adult patients who underwent thoracic surgeries with one-lung ventilation longer than two hours were included in this study. Their PetCO2, PtcCO2, and PaCO2 values were collected at five time points before and during one-lung ventilation. Agreement among measures was evaluated by Bland-Altman analysis.

RESULTS

Ninety sample sets were obtained. The bias and precision when PtcCO2 and PaCO2 were compared were 4.1 ± 6.5 mmHg during two-lung ventilation and 2.9 ± 6.1 mmHg during one-lung ventilation. Those when PetCO2 and PaCO2 were compared were -11.8 ± 6.4 mmHg during two-lung ventilation and -11.8 ± 4.9 mmHg during one-lung ventilation. The differences between PtcCO2 and PaCO2 were significantly lower than those between PetCO2 and PaCO2 at all five time-points (p < 0.05).

CONCLUSIONS

PtcCO2 monitoring was more accurate for predicting PaCO2 levels during prolonged one-lung ventilation with low tidal volume for patients undergoing thoracic surgeries.

Agreement of Mixed Venous Carbon Dioxide Tension (PvCO2) and Transcutaneous Carbon Dioxide (PtCO2) Measurements in Ventilated Infants

Background:

Noninvasive transcutaneous carbon dioxide monitoring has been shown to be accurate in infants and children, limited data are available to show the usefulness and limitations of partial transcutaneous carbon dioxide tension (PtCO₂) value.

Objectives:

The current study prospectively determines the effectiveness and accuracy of PtCO₂ measurements in newborns.

Materials and Methods:

Venous blood gas sampling and monitoring of the PtCO₂ level (TCM TOSCA, Radiometer) were done simultaneously. All measurements are performed on mechanically ventilated infants. Partial venous carbon dioxide tension (PvCO₂) values divided into three groups according to hypocapnia (Group 1: < 4.68 kPa), normocapnia (Group 2: 4.68–7.33 kPa), hypercapnia (Group 3: > 7.33 kPa) and then PvCO₂ and PtCO₂ data within each group were compared separately.

Results:

A total of 168 measurements of each PvCO₂ and PtCO₂ data were compared in three separated groups simultaneously (13 in Group 1, 118 in Group 2, and 37 in Group 3). A bias of more than ± 0.7 kPa was considered unacceptable. PtCO₂ was related to PvCO₂ with acceptable results between the two measurements in hypocapnia (mean difference 0.20 ± 0.19 kPa) and normocapnia (0.002 ± 0.30 kPa) groups. On the other hand in hypercapnia group PtCO₂ values were statistically significant (P < 0.001) and lower than PvCO₂ data (mean difference 0.81 ± 1.19 kPa)

Conclusions:

PtCO₂ measurements have generally good agreement with PvCO₂ in hypocapnic and normocapnic intubated infants but there are some limitations especially with high level of CO₂ tension. Monitoring of PtCO₂ is generally a useful non-invasive indicator of PvCO₂ in hypocapnic and normocapnic infants.

Monitoring Oxygenation and Gas Exchange in Neonatal Intensive Care Units: Current Practice in the Netherlands

BACKGROUND

Although recommendations in oxygenation and gas exchange monitoring in the neonatal intensive care unit (NICU) are available, little is known of the current practice.

AIM

To evaluate the current practice in oxygenation and gas exchange monitoring of the NICUs in the Netherlands.

METHODS

An online survey-based questionnaire concerning preferences and current practice of monitoring oxygenation and gas exchange was sent out to all 107 neonatal staff members (neonatologists, neonatal fellows, and physician assistants) of the 10 NICUs in the Netherlands.

RESULTS

The response rate was 42%. Pulse oximetry (PO), partial pressure of oxygen in arterial blood gas (paO2), and oxygen saturation in arterial blood gas (saO2) was used by, respectively, 100, 80, and 27% of the staff members for monitoring oxygenation. Of all staff members, 76% considered PO as the best parameter for monitoring oxygenation, 22% paO2, and 2% saO2. Blood gas, transcutaneous gas monitoring, endotracheal gas monitoring, and near-infrared spectroscopy was used by, respectively, 100, 82, 40, and 18% of the staff members for monitoring gas exchange. During endotracheal ventilation, 67% of the caregivers would exclusively accept arterial blood gas for gas exchange monitoring. In contrast, during non-invasive ventilation, 68% of the caregivers did not prefer arterial or capillary blood gas (CBG). CBG is found reliable in infants with warm extremities by 76% of the caregivers. Venous blood gas would be accepted by 60% of the caregivers, independent of the mode of respiratory support, and only when venous blood sample was needed for other reasons.

CONCLUSION

This survey identified a wide variation in preference in monitoring oxygenation and gas exchange monitoring among Dutch neonatal staff members.

Review of respiratory management of extremely premature neonates during transport

INTRODUCTION

The objective was to evaluate the respiratory management of neonates of 23 to 26 weeks' gestation transported after birth outside a tertiary center. Another objective was to collect data regarding survival, intraventricular hemorrhage (IVH), and chronic lung disease.

METHODS

This was a retrospective study of transports from a statewide dedicated neonatal and pediatric transport service over a 3-year period. Data were collected from the local databases. Neonates with and without transcutaneous carbon dioxide (TcCO2) monitoring were compared. Outcomes were compared with the inborn group from the same period.

RESULTS

A total of 43 mechanically ventilated neonates were included. Significant hypocarbia and/or hypercarbia were seen in 49%. Hyperoxia was noted in 46.5%. Despite the moderate correlation between PCO2 and TcCO2 readings, no clinical benefit was seen with TcCO2 monitoring. Survival was 65.1%. Rates of IVH were 60% for any IVH and 27.5% for severe IVH. IVH was more common in the study cohort.

CONCLUSIONS

Neonates born at 23 to 26 weeks' gestation outside tertiary centers have high rates of mortality and morbidity. The avoidance of hypocarbia, hypercarbia, and hyperoxia is challenging in the transport environment. Transcutaneous monitoring is an imperfect tool for following PCO2 levels.

Monitoring lung aeration during respiratory support in preterm infants at birth

Background

If infants fail to initiate spontaneous breathing, resuscitation guidelines recommend respiratory support with positive pressure ventilation (PPV). The purpose of PPV is to establish functional residual capacity and deliver an adequate tidal volume (V_T) to achieve gas exchange.

Objective

The aim of our pilot study was to measure changes in exhaled carbon dioxide (ECO₂), V_T, and rate of carbon dioxide elimination (VCO₂) to assess lung aeration in preterm infants requiring respiratory support immediately after birth.

Method

A prospective observational study was performed between March and July 2013. Infants born at <37 weeks gestational age who received continuous positive airway pressure (CPAP) or PPV immediately after birth had V_T delivery and ECO₂ continuously recorded using a sensor attached to the facemask.

Results

Fifty-one preterm infants (mean (SD) gestational age 29 (3) weeks and birth weight 1425 (592 g)) receiving respiratory support in the delivery room were included. Infants in the CPAP group (n = 31) had higher ECO₂ values during the first 10 min after birth compared to infants receiving PPV (n = 20) (ranging between 18–30 vs. 13–18 mmHg, p<0.05, respectively). At 10 min no significant difference in ECO₂ values was observed. V_T was lower in the CPAP group compared to the PPV group over the first 10 min ranging between 5.2–6.6 vs. and 7.2–11.3 mL/kg (p<0.05), respectively.

Conclusions

Immediately after birth, spontaneously breathing preterm infants supported via CPAP achieved better lung aeration compared to infants requiring PPV. PPV guided by V_T and ECO₂ potentially optimize lung aeration without excessive V_T administered.

Noninvasive Monitoring during Interhospital Transport of Newborn Infants

The main indications for interhospital neonatal transports are radiographic studies (e.g., magnet resonance imaging) and surgical interventions. Specialized neonatal transport teams need to be skilled in patient care, communication, and equipment management and extensively trained in resuscitation, stabilization, and transport of critically ill infants. However, there is increasing evidence that clinical assessment of heart rate, color, or chest wall movements is imprecise and can be misleading even in experienced hands. The aim of the paper was to review the current evidence on clinical monitoring equipment during interhospital neonatal transport.

Sidestream microstream end tidal carbon dioxide measurements and blood gas correlations in neonatal intensive care unit

OBJECTIVE

The study was designed to assess the use of newer sidestream microstream end tidal carbon dioxide (ETCO(2) ) device in predicting blood carbon dioxide (PCO(2) ) measurements in very low birth weight (VLBW = birth weight <1,500 g) and non-VLBW NICU neonates.

STUDY DESIGN

Sidestream microstream ETCO(2) detectors were allowed time to calibrate and reach steady state prior to blood gas measurements. Blood CO(2) (PCO(2) ) and simultaneous ETCO(2) were recorded. Ratio of dead space to tidal volume (VD/VT) was calculated using modified Bohr's equation. Correlation coefficient, estimates of difference, standard deviation, and 95% limits of agreement between ETCO(2) and PCO(2) concentrations were calculated.

RESULTS

Two hundred eighty-six paired samples were collected from 48 ventilated NICU patients. Average PCO(2) and ETCO(2) were 58.4 and 50.6 with a correlation of 0.76. Subgroup analysis showed a correlation of 0.73 in 204 paired blood from 34 VLBW infants and 0.82 in 82 paired samples from non-VLBW infants. Estimates of difference ± standard deviation between PCO(2) and ETCO(2) concentrations in these three groups, respectively (ALL, VLBW, and non-VLBW) were 7.84 ± 9.96, 8.2 ± 10.16, and 6.95 ± 9.45. The correlation coefficient significantly improved in the VLBW group to 0.86 with dead space to tidal volume ratio (VD/VT) <30% (0.86 vs. 0.42; P < 0.001).

CONCLUSION

ETCO(2) measurements using sidestream microstream technology in VLBW demonstrated that the correlation of ETCO(2) and PCO(2) was moderate, but the agreement was less than adequate (bias > 5 mmHg in all groups). The results improved with lower VD/VT, suggesting that sidestream capnography is more reliable in conditions of less severe lung disease.

Influence of respiratory acidosis and blood glucose on cerebral activity of premature infants

Fluctuations of physiologic parameters in extremely preterm infants may significantly affect their cerebral activity. This study assessed the correlation between blood gas indices and other clinical parameters with cerebral activity, as recorded by amplitude integrated electroencephalography in the first three days of life of a prospective cohort study of infants born at <28 weeks gestation. Amplitude integrated electroencephalography was assessed according to a nine-grade pattern scale. For univariate analysis, the Spearman rank coefficient, Student t test, and χ(2) test were used. For multivariate analysis, generalized estimating equations were used. Overall, 255 blood samples from 24 recruited infants were analyzed. The pattern scale demonstrated a significant positive correlation with pH (ρ = 0.45, P < 0.0001) and base excess (ρ = 0.37, P < 0.0001), and a significant negative correlation with partial pressure of carbon dioxide (pCO(2)) (ρ = -0.35, P < 0.0001) and blood dextrose (ρ = -0.36, P < 0.0001). When amplitude integrated electroencephalography was used as dependent variable, the best generalized estimating equation models yielded significant correlations for pH, pCO(2), and HCO(3)(-). When pH was used as dependent variable, the best models yielded significant correlations for amplitude integrated electroencephalography pattern scale and blood dextrose. We suggest that depression in cerebral function early in life should prompt clinicians to assess acid/base status and respiratory parameters of the extremely premature infant as well as other known causes of cerebral depression.

Noninvasive capnometry for end-tidal carbon dioxide monitoring via nasal cannula in nonintubated neonates

BACKGROUND

Arterial blood gas analysis is the gold standard for assessing the adequacy of ventilation. However, arterial blood sampling may be associated with serious complications in neonates. The aim of the study was to utilize the side-stream capnometry measurement of end-tidal carbon dioxide (PetCO₂) via nasal cannula circuits and to verify the reliability of PetCO₂ in reflecting the arterial blood carbon dioxide(PaCO₂) level in nonintubated neonates.

METHODS

A retrospective medical record review analysis was performed in nonintubated neonates admitted to the neonatal ward in a medical center. Simultaneous arterial PaCO₂ and PetCO₂ levels were evaluated. PaCO₂ and PetCO₂ levels were compared by paired t test and were correlated using Pearson's correlation. The PetCO₂ bias was defined as the difference between PaCO₂ and PetCO₂, and was assessed by Bland-Altman plot analysis.

RESULTS

A total of 34 neonates were recruited, and data of 54 pairs of PaCO₂ and PetCO₂ levels were available for comparison. The average (mean ± SD) gestational age was 32.5 ± 4.2 weeks, and the average birth weight was 1881 ± 1077 g. There was a good correlation between PetCO₂ and PaCO₂ levels among all paired samples (r = 0.809, p < 0.001). When the data were divided into those with respiratory disease (n = 34) and those without (n = 20), significant correlation between PetCO₂ and PaCO₂ levels were both noted in the former group (r = 0.823, p < 0.001) and the latter group (r = 0.770, p < 0.001). The overall average mean value of PetCO₂ was lower than that of PaCO₂ (39.4 ± 8.8 mmHg vs. 41.3 ± 9.2 mmHg, p = 0.014). The difference between PetCO₂ and PaCO₂ levels was significant only among those with respiratory disease (38.8 ± 9.8 mmHg vs. 41.2 ± 10.3 mmHg, p = 0.027), but not among those without (40.5 ± 7.0 mmHg vs. 41.6 ± 7.2 mmHg, p = 0.289).

CONCLUSIONS

End-tidal CO₂ measurement by side-stream capnometry through nasal cannula could provide an accurate and noninvasive estimate of PaCO₂ levels in nonintubated neonates.

Detection of carbon dioxide thresholds using low-flow sidestream capnography in ventilated preterm infants

BACKGROUND

Monitoring CO2 levels in preterm infants receiving mechanical ventilation is designed to avoid the harmful consequences of hypocapnia or hypercapnia. Capnography is of questionable accuracy for monitoring PCO2 in preterm infants.

OBJECTIVES

To determine the accuracy of sidestream capnography in ventilated preterm infants by comparing end-tidal carbon dioxide (EtCO2) values to mixed venous carbon dioxide pressure (PvCO2) and to transcutaneous carbon dioxide pressure (TcPCO2).

METHODS

Simultaneous recordings of EtCO2, TcPCO2 and PvCO2 in 37 ventilated preterm infants. The PvCO2-EtCO2 gradient was calculated. The Bland-Altman technique and the intra-class correlation coefficient (ICC) were used to assess agreement between methods. The area under the curve (AUC) was calculated.

RESULTS

Ninety-nine EtCO2/PvCO2 pairs were studied from 37 preterm infants with a mean gestational age of 27.7 +/- 1.9 weeks and a mean birth weight of 1,003 +/- 331 g. The mean PvCO2-EtCO2 gradient was 11.2 +/- 8.0 mmHg, and the ICC was 0.28. The mean PvCO2-TcPCO2 gradient was 0 +/- 7.8 mmHg, and the ICC was 0.78. AUCs for EtCO2 and TcPCO2 were similar in detecting high or low PvCO2.

CONCLUSION

Despite an insufficient correlation between EtCO2 and PvCO2, capnography was able to detect low and high CO2 warning levels with a similar efficacy to that of TcPCO2, and may therefore be of clinical interest.

Transcutaneous PCO2 monitors are more accurate than end-tidal PCO2 monitors

PURPOSE

The accuracy of monitors for measuring transcutaneous PCO2 (TcPCO2), end-tidal PCO2 (EtPCO2), and nasal EtPCO2 was evaluated.

METHODS

The measuring devices included a TcPCO2 monitor (TCM3; Radiometer Trading), an EtPCO2 monitor (Ultima; Datex-Ohmeda), and a nasal EtPCO2 monitor (TG-920P; Nihon Kohden). The sensor electrode of the TCM3 TcPCO2 monitor was applied to the skin of the subject's upper arm. A sampling tube attached to the proximal end of the tracheal tube was connected to the Ultima EtPCO2 monitor. The miniature sensor of the TG-920P nasal EtPCO2 monitor was attached to the nostril. The values obtained were compared with direct measurements of arterial PCO2 (PaCO2) obtained by means of an ABL700 blood gas analyzer (Radiometer Trading) in surgically treated patients. The means +/- 2 SD of the differences between variables were calculated.

RESULTS

The TcPCO2 monitor (0.19 +/- 4.8 mmHg, mean +/- 2-SD) was more accurate than the EtPCO2 monitor (-4.4 +/- 6.5 mmHg, mean +/- 2-SD) in patients receiving artificial ventilation via an endotracheal tube and the TcPCO2 monitor was also more accurate than the nasal EtPCO2 monitor (-6.3 +/- 9.8 mmHg, bias +/- 2-SD) in patients breathing spontaneously.

CONCLUSION

We found that the TcPCO2 monitor was more accurate than the EtPCO2 or nasal EtPCO2 monitor in surgically treated patients.

Are carbon dioxide detectors useful in neonates?

Maintenance of neonatal normocarbia may prevent chronic lung disease and periventricular leucomalacia, but this requires frequent arterial sampling, which has risks. Alternative methods for measuring CO2 are therefore desirable. These include end tidal CO2, capillary sampling, and transcutaneous measurements. CO2 detectors have also proved effective and rapid indicators of endotracheal intubation. However, this method relies on the presence of exhaled CO2, which may be reduced in certain situations, such as cardiopulmonary arrest. Colorimetric CO2 detectors are therefore valuable adjuncts for airway management, especially during resuscitation, but Pa(CO2) is still the best measure of CO2 in neonatal practice.