Transcutaneous Carbon Dioxide Research Articles

Paediatric long term continuous positive airway pressure and noninvasive ventilation in France: A cross-sectional study

ObjectiveTo describe the characteristics of children treated with long term continuous positive airway pressure (CPAP) or noninvasive ventilation (NIV) in France. DesignCross-sectional national survey. SettingPaediatric CPAP/NIV teams of 28 tertiary university hospitals in France. PatientsChildren aged <20 years treated with CPAP/NIV since at least 3 months on June 1st, 2019. InterventionAn anonymous questionnaire was filled in for every patient. ResultsThe data of 1447 patients (60% boys), mean age 9.8 ± 5.8 years were analysed. The most frequent underlying disorders were: upper airway obstruction (46%), neuromuscular disease (28%), disorder of the central nervous system (13%), cardiorespiratory disorder (7%), and congenital bone disease (4%). Forty-five percent of the patients were treated with CPAP and 55% with NIV. Treatment was initiated electively for 92% of children, while 8% started during an acute illness. A poly(somno)graphy (P(S)G) was performed prior to treatment initiation in 26%, 36% had a P(S)G with transcutaneous carbon dioxide monitoring (PtcCO2), while 23% had only a pulse oximetry (SpO2) with PtcCO2 recording. The decision of CPAP/NIV initiation during an elective setting was based on the apnea-hypopnea index (AHI) in 41% of patients, SpO2 and PtcCO2 in 25% of patients, and AHI with PtcCO2 in 25% of patients. Objective adherence was excellent with a mean use of 7.6 ± 3.2 h/night. Duration of CPAP/NIV was 2.7 ± 2.9 years at the time of the survey. ConclusionThis survey shows the large number of children treated with long term CPAP/NIV in France with numerous children having disorders other than neuromuscular diseases.

Diagnostic approach to sleep disordered-breathing among patients with grade III obesity

Sleep apnea test (SAT) is a cost-effective approach to evaluate subjects without associated comorbidities suspected for obstructive sleep apnea (OSA), a disorder particularly common in obese subjects. The association of obesity with awake hypercapnia (carbon dioxide arterial pressure, PaCO2 ≥45 mmHg) defines the obesity-hypoventilation syndrome (OHS), which in turn results in increased morbidity and mortality compared to simple OSA. Isolated hypoventilation during sleep in obese patients (obesity-related sleep hypoventilation, ORSH) is now considered as an early stage of OHS. The aim of this study was to assess the performance of SAT in diagnosing OSA and predicting the presence of ORHS among patients with grade III obesity without awake hypercapnia. MethodsOver a 14-months period, patients with grade III obesity (body mass index≥40 kg/m2) presenting moderate-to-severe OSA (apnea-hypopnea index [AHI]≥15) upon SAT and normal awake PaCO2 at arterial blood gas analysis, systematically underwent in-lab nocturnal polysomnography combined with transcutaneous carbon dioxide pressure (PtcCO2) monitoring. ResultsAmong 48 patients included in the study, 16 (33%) presented an AHI<15 upon polysomnography and 14 (29%) had ORSH. The test revealed no difference in ORSH prevalence between patients with AHI <15 or ≥15 (31% vs. 25%). No SAT variables were independently associated with increased PtCO2. ConclusionsThis study shows that SAT overestimates OSA severity and ORSH affects one third of patients with grade III obesity without awake hypercapnia and with moderate-to-severe OSA at SAT, suggesting how polysomnography combined with PtCO2 monitoring is the most appropriate diagnostic approach for OSA and ORSH in this population.

Quality of poly(somno)graphy recordings in children.

The aim of the study was to assess the scorability of the signals of four poly(somno)graphy devices and transcutaneous carbon dioxide tracings (PtcCO2 ) of one device in children. The presence (0%, < 25%, 25%-50%, 50%-75%, 75%-99%, 100% of recording time) and quality (bad, average, good) of the signal of each sensor were analysed. During a 5-month period, 364 poly(somno)graphies were performed in 12 different hospital units. Forty-one children had poor/bad cooperation, and 13 severe behaviour disorders. Seventy-one and 293 poly(somno)graphies were performed in children aged ≤ 2 and > 2years, respectively; nine poly(somno)graphies failed. For the four poly(somno)graphy devices, the signal was present during 99% of recording time for the electroencephalogram, 99% for thoracic belt, 97% for abdominal belt, 97% for body position, 95% for the microphone, 92% for pulse oximetry, 87% for tracheal sound, 71% for oronasal thermistor, 52% (41% for ≤ 2years, 55% for > 2years old) for nasal pressure and 86% for PtcCO2 . The signal was of good quality in 98% of poly(somno)graphies for body position, 96% for microphone, 96% for thoracic belt, 95% for pulse oximetry, 91% for abdominal belt, 91% for tracheal sound, 82% for oronasal thermistor, 78% for electroencephalogram, 73% for nasal pressure and 46% of PtcCO2 recordings. The scorability was comparable between devices. Nasal pressure and oronasal thermistor had the lowest scorability, especially in children aged ≤ 2years. This underlines the necessity of the development or improvement of alternative, ideally face-free, sensors, or miniaturized devices adapted for infants and children.

The effects of wearing facemasks on oxygenation and ventilation at rest and during physical activity.

BackgroundFacemasks are recommended to reduce the spread of SARS-CoV-2, but concern about inadequate gas exchange is an often cited reason for non-compliance.Research questionAmong adult volunteers, do either cloth masks or surgical masks impair oxygenation or ventilation either at rest or during physical activity?Study design and methodsWith IRB approval and informed consent, we measured heart rate (HR), transcutaneous carbon dioxide (CO2) tension and oxygen levels (SpO2) at the conclusion of six 10-minute phases: sitting quietly and walking briskly without a mask, sitting quietly and walking briskly while wearing a cloth mask, and sitting quietly and walking briskly while wearing a surgical mask. Brisk walking required at least a 10bpm increase in heart rate. Occurrences of hypoxemia (decrease in SpO2 of ≥3% from baseline to a value of ≤94%) and hypercarbia (increase in CO2 tension of ≥5 mmHg from baseline to a value of ≥46 mmHg) in individual subjects were collected. Wilcoxon signed-rank was used for pairwise comparisons among values for the whole cohort (e.g. walking without a mask versus walking with a cloth mask).ResultsAmong 50 adult volunteers (median age 33 years; 32% with a co-morbidity), there were no episodes of hypoxemia or hypercarbia (0%; 95% confidence interval 0–1.9%). In paired comparisons, there were no statistically significant differences in either CO2 or SpO2 between baseline measurements without a mask and those while wearing either kind of mask mask, both at rest and after walking briskly for ten minutes.InterpretationThe risk of pathologic gas exchange impairment with cloth masks and surgical masks is near-zero in the general adult population.

A capnography and transcutaneous CO2 profile of bariatric patients during early postoperative period after opioid-sparing anesthesia.

Noninvasive monitoring of partial pressure of carbon dioxide can be accomplished indirectly with capnography (PETCO2) or with transcutaneous carbon dioxide monitoring (PTCCO2). The use of capnography has been shown to offer an advantage over pulse oximetry alone in the early detection of adverse respiratory events when supplemental oxygen is administered. Furthermore, capnography allows for the monitoring of various respiratory measures, including end-tidal carbon dioxide, respiratory rate, tidal volume, and changes in breathing patterns. Transcutaneous CO2 also closely approximates arterial CO2 values, but is not as easy to monitor for prolonged periods. The purpose of this study was to examine the usefulness of capnography and of transcutaneous carbon dioxide monitoring in patients recovering from obesity surgery at high risk of developing postoperative obstructive sleep apnea. In a prospective observational study, 64 bariatric surgery patients at risk of developing obstructive sleep apnea were monitored in the postanesthesia care unit (PACU) with either capnography alone (31 patients) or capnography plus transcutaneous carbon dioxide monitoring (33 additional patients) every 3-5 minutes for the duration of their recovery. Primary endpoints included end-tidal and transcutaneous carbon dioxide, peripheral oxygen saturation, respiratory rate, pain scores, and incidence of adverse respiratory events. Although no adverse pulmonary events were observed, capnography detected several patients who experienced short periods of respiratory apnea while maintaining pulse oximetry readings within normal limits. Transcutaneous values were slow to change and averaged 4.5 ± 5.5 mm Hg (P< .05) higher than corresponding end-tidal measurements. These results indicate the capabilities of both these noninvasive techniques for postoperative monitoring. Capnography acutely monitors changes in respiration, whereas transcutaneous monitoring more accurately reflects arterial CO2 levels.

High flow nasal oxygen during procedural sedation for cardiac implantable electronic device procedures: A randomised controlled trial.

High flow nasal oxygen may better support the vulnerable respiratory state of patients during procedural sedation. The objective of this study was to investigate the effects of high flow nasal oxygen in comparison to facemask oxygen on ventilation during cardiac implantable electronic device procedures performed with procedural sedation. A randomised controlled trial. The study was conducted at one academic hospital in Canada. Adults undergoing elective cardiac implantable electronic device procedures with sedation administered by an anaesthesia assistant, supervised by an anaesthesiologist from August 2019 to March 2020. Participants were randomised 1 : 1 to facemask (≥ 8 l · min-1) or high flow nasal oxygen (50 l · min-1 and a 50 : 50 oxygen to air ratio). The primary outcome was peak transcutaneous carbon dioxide. Outcomes were analysed using Bayesian statistics. The 129 participants who were randomised and received sedation were included. The difference in peak transcutaneous carbon dioxide was 0.0 kPa (95% CI -0.17 to 0.18). Minor adverse sedation events were 6.4 times more likely to occur in the high flow nasal oxygen group. This estimate is imprecise (95% CI 1.34 to 42.99). The odds ratio for oxygen desaturation for the high flow nasal oxygen group compared with the facemask group was 1.2 (95% CI 0.37 to 3.75). The difference in satisfaction with sedation scores between groups was 0.0 (95% CI -0.33 to 0.23). Ventilation, as measured by TcCO2, is highly unlikely to differ by a clinically important amount between high flow nasal oxygen at 50 l min-1 or facemask oxygen at 8 l min-1. Further research with a larger sample size would be required to determine the optimal oxygen:air ratio when using high flow nasal oxygen during cardiac implantable electronic device procedures performed with sedation. NCT03858257.

Transcutaneous carbon dioxide pattern and trend over time in preterm infants.

BackgroundChronic lung disease remains a burden for extremely preterm infants. The changes in ventilation over time and optimal ventilatory management remains unknown. Newer, non-invasive technologies provide insight into these patterns.MethodsThis single-center prospective cohort study enrolled infants ≤32 0/7 weeks. We obtained epochs of transcutaneous carbon dioxide (TcCO2) measurements twice each week to describe the pattern of hypercarbia throughout their hospitalization.ResultsPatterns of hypercarbia varied based on birth gestational age and post-menstrual age (PMA) (p = 0.03), regardless of respiratory support. Infants receiving the most respiratory support had values 16–21 mmHg higher than those on room air (p < 0.001). Infants born at the youngest gestational ages had the greatest total change but the rate of change was slower (p = 0.049) compared to infants born at later gestational ages. All infants had TcCO2 values stabilize by 31–33 weeks PMA, when values were not significantly different compared to discharge. No rebound was observed when infants weaned off invasive support.ConclusionsHypercarbia improves as infants approached 31–33 weeks PMA. Hypercarbia was the highest in the most immature infants and improved with age and growth despite weaning respiratory support.Impact This study describes the evolution of hypercarbia as very preterm infants grow and develop.The pattern of ventilation is significantly different depending on the gestational age at birth and post-menstrual age.Average transcutaneous carbon dioxide (TCO2) decreased over time as infants became more mature despite weaning respiratory support. This improvement was most significant in infants born at the lowest gestational ages.

Validation of transcutaneous carbon dioxide monitoring using an artificial lung during adult pulsatile cardiopulmonary bypass.

Measurements of transcutaneous carbon dioxide (tcCO2) have been used in multiple venues, such as during procedures utilizing jet ventilation, hyperbaric oxygen therapy, as well as both the adult and neo-natal ICUs. However, tcCO2 measurements have not been validated under conditions which utilize an artificial lung, such cardiopulmonary bypass (CPB). The purpose of this study was to (1) validate the use of tcCO2 using an artificial lung during CPB and (2) identify a location for the sensor that would optimize estimation of PaCO2 when compared to the gold standard of blood gas analysis.tcCO2 measurements (N = 185) were collected every 30 min during 54 pulsatile CPB procedures. The agreement/differences between the tcCO2 and the PaCO2 were compared by three sensor locations. Compared to the earlobe or the forehead, the submandibular PtcCO2 values agreed best with the PaCO2 and with a median difference of -.03 mmHg (IQR = 5.4, p < 0.001). The small median difference and acceptable IQR support the validity of the tcCO2 measurement. The multiple linear regression model for predicting the agreement between the submandibular tcCO2 and PaCO2 included the SvO2, the oxygenator gas to blood flow ratio, and the native perfusion index (R2 = 0.699, df = 1, 60; F = 19.1, p < 0.001).Our experience in utilizing tcCO2 during CPB has demonstrated accuracy in estimating PaCO2 when compared to the gold standard arterial blood gas analysis, even during CO2 flooding of the surgical field.

Average volume-assured pressure support vs conventional bilevel pressure support in pediatric nocturnal hypoventilation: a case series.

Average volume-assured pressure support (AVAPS) is a modality of noninvasive ventilation that provides a targeted tidal volume by automatically adjusting the inspiratory pressure support within a set range. Pediatric studies evaluating the efficacy of AVAPS in treating nocturnal hypoventilation are confined to case reports. The aim of this study was to compare AVAPS to conventional bilevel positive airway pressure (BPAP) support in improving hypercarbia in a cohort of pediatric patients with nocturnal hypoventilation. Retrospective review of patient records at an established tertiary pediatric sleep laboratory over a 6-year period. Ventilatory and sleep study parameters from AVAPS and conventional BPAP titration studies were compared. AVAPS was used only if hypoventilation was not controlled using conventional BPAP. Inspiratory pressures, tidal volumes, and adherence were downloaded on final titrated ventilatory settings. Comparisons were made using paired t test. A total of 19 patients (11 boys, 8 girls; median age 10.5 years, range 1 to 20 years) were identified. Diagnoses included neuromuscular disease (n = 9), obstructive hypoventilation (n = 5), parenchymal lung disease (n = 4), and congenital central hypoventilation syndrome (n = 2). AVAPS demonstrated significant improvement in peak (P = .009) and mean (P = .001). Transcutaneous CO₂ parameters compared to conventional bilevel. Oxygenation on AVAPS showed positive trend but did not reach statistical significance. AVAPS delivered higher tidal volumes (P = .04) using similar pressures. There was no statistically significant difference in obstructive apnea-hypopnea index, respiratory arousal index, sleep efficiency, and adherence between AVAPS and conventional BPAP. AVAPS was an effective alternative to conventional BPAP in improving hypercarbia in our selective cohort of pediatric patients. Prospective, longitudinal studies are needed to evaluate the benefits of AVAPS feature in the pediatric population.

The Effect of Nasal High Flow Therapy on Minute Ventilation in Chronic Obstructive Pulmonary Disease.

Nasal high-flow therapy (HFT) has been shown to improve daytime breathing mechanics in healthy adults as well as the lung function and quality of life in chronic obstructive pulmonary disease (COPD) patients. We hypothesized that improved breathing mechanics with HFT may further reduce minute ventilation (i.e. decreased work of breathing) during sleep in patients with COPD. In COPD participants we examined the dose effect of HFT (within night randomization of HFT level; 0, 10, 20 and 30L/min) on minute ventilation, oxyhemaglobin saturation and transcutaneous carbon dioxide during wake and sleep. We assessed overnight polysomnography with and without HFT on two separate nights. Paired t-tests were used to compare overnight sleep quality with and without HFT. The association between ventilatory variables and HFT level was assessed using regression analysis. During sleep, HFT decreased minute ventilation by 0.63±0.02L/min per 10L/min nasal airflow by reducing tidal volume (37±6mL per 10L/min; p<0.001) without affecting respiratory rate (p=0.9) or arterial CO2 (p=0.7). In contrast, during wakefulness reductions in minute ventilation (0.85±0.04L/min per 10L/min) was due to respiratory rate reduction along with prolongation in expiratory time. The reduction in minute ventilation is greater with higher dead-space volumes (r=0.50; p<0.02) and during wakefulness suggesting that ventilatory responses to HFT are mediated through a reduction in dead-space ventilation. The reduction in ventilation in response to HFT is large enough to reduce respiratory loads. Reducing respiratory loads may avert muscle fatigue, preserve respiratory function, or prevent development of respiratory failure.

Evaluating the ventilatory effect of transnasal humidified rapid insufflation ventilatory exchange in apnoeic small children with two different oxygen flow rates: a randomised controlled trial.

Transnasal humidified rapid insufflation ventilatory exchange prolongs safe apnoeic oxygenation time in children. In adults, transnasal humidified rapid insufflation ventilatory exchange is reported to have a ventilatory effect with PaCO2 levels increasing less rapidly than without it. This ventilatory effect has yet to be reproduced in children. In this non-inferiority study, we tested the hypothesis that children weighing 10-15kg exhibit no difference in carbon dioxide clearance when comparing two different high-flow nasal therapy flow rates during a 10-min apnoea period. Following standardised induction of anaesthesia including neuromuscular blockade, patients were randomly allocated to high-flow nasal therapy of 100% oxygen at 2 or 4l.kg-1 .min-1 . Airway patency was ensured by continuous jaw thrust. The study intervention was terminated for safety reasons when SpO2 values dropped <95%, or transcutaneous carbon dioxide levels rose >9.3kPa, or near-infrared spectroscopy values dropped >20% from their baseline values, or after an apnoeic period of 10min. Fifteen patients were included in each group. In the 2l.kg-1 .min-1 group, mean (SD) transcutaneous carbon dioxide increase was 0.46 (0.11)kPa.min-1 , while in the 4l.kg-1 .min-1 group it was 0.46 (0.12)kPa.min-1 . The upper limit of a one-sided 95%CI for the difference between groups was 0.07kPa.min-1 , lower than the predefined non-inferiority margin of 0.147kPa.min-1 (p=0.001). The lower flow rate of 2l.kg-1 .min-1 was non-inferior to 4l.kg-1 .min-1 relative to the transcutaneous carbon dioxide increase. In conclusion, an additional ventilatory effect of either 2 or 4l.kg-1 .min-1 high-flow nasal therapy in apnoeic children weighing 10-15kg appears to be absent.

Safety of conscious sedation in electroanatomical mapping procedures and cryoballoon pulmonary vein isolation

Immobilization of patients during electrophysiological procedures, to avoid complications by patients’ unexpected bodily motion, is achieved by moderate to deep conscious sedation using benzodiazepines and propofol for sedation and opioids for analgesia. Our aim was to compare respiratory and hemodynamic safety endpoints of cryoballoon pulmonary vein isolation (PVI) and electroanatomical mapping (EAM) procedures. Included patients underwent either cryoballoon PVI or EAM procedures. Sedation monitoring included non-invasive blood pressure measurements, transcutaneous oxygen saturation (tSpO2) and transcutaneous carbon-dioxide (tpCO2) measurements. We enrolled 125 consecutive patients, 67 patients underwent cryoballoon atrial fibrillation ablation and 58 patients had an EAM and radiofrequency ablation procedure. Mean procedure duration of EAM procedures was significantly longer (p < 0.001) and propofol doses as well as morphine equivalent doses of administered opioids were significantly higher in EAM patients compared to cryoballoon patients (p < 0.001). Cryoballoon patients display higher tpCO2 levels compared to EAM patients at 30 min (cryoballoon: 51.1 ± 7.0 mmHg vs. EAM: 48.6 ± 6.2 mmHg, p = 0.009) and at 60 min (cryoballoon: 51.4 ± 7.3 mmHg vs. EAM: 48.9 ± 6.6 mmHg, p = 0.07) procedure duration. Mean arterial pressure was significantly higher after 60 min (cryoballoon: 84.7 ± 16.7 mmHg vs. EAM: 76.7 ± 13.3 mmHg, p = 0.017) in cryoballoon PVI compared to EAM procedures. Regarding respiratory and hemodynamic safety endpoints, no significant difference was detected regarding hypercapnia, hypoxia and episodes of hypotension. Despite longer procedure duration and deeper sedation requirement, conscious sedation in EAM procedures appears to be as safe as conscious sedation in cryoballoon ablation procedures regarding hemodynamic and respiratory safety endpoints.

Effect of nocturnal EPAP titration to abolish tidal expiratory flow limitation in COPD patients with chronic hypercapnia: a randomized, cross-over pilot study

BackgroundTidal expiratory flow limitation (EFLT) promotes intrinsic PEEP (PEEPi) in patients with chronic obstructive pulmonary disease (COPD). Applying non-invasive ventilation (NIV) with an expiratory positive airway pressure (EPAP) matching PEEPi improves gas exchange, reduces work of breathing and ineffective efforts. We aimed to evaluate the effects of a novel NIV mode that continuously adjusts EPAP to the minimum level that abolishes EFLT.MethodsThis prospective, cross-over, open-label study randomized patients to one night of fixed-EPAP and one night of EFLT-abolishing-EPAP. The primary outcome was transcutaneous carbon dioxide pressure (PtcCO2). Secondary outcomes were: peripheral oxygen saturation (SpO2), frequency of ineffective efforts, breathing patterns and oscillatory mechanics.ResultsWe screened 36 patients and included 12 in the analysis (age 72 ± 8 years, FEV1 38 ± 14%Pred). The median EPAP did not differ between the EFLT-abolishing-EPAP and the fixed-EPAP night (median (IQR) = 7.0 (6.0, 8.8) cmH2O during night vs 7.5 (6.5, 10.5) cmH2O, p = 0.365). We found no differences in mean PtcCO2 (44.9 (41.6, 57.2) mmHg vs 54.5 (51.1, 59.0), p = 0.365), the percentage of night time with PtcCO2 > 45 mm Hg was lower (62(8,100)% vs 98(94,100)%, p = 0.031) and ineffective efforts were fewer (126(93,205) vs 261(205,351) events/hour, p = 0.003) during the EFLT-abolishing-EPAP than during the fixed-EPAP night. We found no differences in oxygen saturation and lung mechanics between nights.ConclusionAn adaptive ventilation mode targeted to abolish EFLT has the potential to reduce hypercapnia and ineffective efforts in stable COPD patients receiving nocturnal NIV.Trial registration: ClicalTrials.gov, NCT04497090. Registered 29 July 2020—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04497090.

Continuous, transcutaneous carbon-dioxide monitoring to avoid hypercapnia in complex catheter ablations under conscious sedation

Abstract Background Ablation of complex cardiac arrhythmias requires an immobilized patient. For a successful and safe intervention and for patient comfort, this can be achieved by conscious sedation. Administered sedatives and analgesics have respiratory depressant side effects and require close monitoring. Purpose We investigated the feasibility and accuracy of an additional, continuous transcutaneous carbon-dioxide partial pressure (tpCO2) measurement during conscious sedation in complex electrophysiological catheter ablation procedures. Methods We evaluated the accuracy and additional value of tpCO2 detection by application of a Severinghaus electrode in comparison to arterial and venous blood gas analyses. Results We included 110 patients in this prospective observational study. Arterial pCO2 (paCO2) and tpCO2 showed good correlation throughout the procedures (r=0.60–0.87, p&amp;lt;0.005). Venous pCO2 (pvCO2) were also well correlated to transcutaneous values (r=0.65–0.85, p&amp;lt;0.0001). Analyses of the difference of pvCO2 and tpCO2 measurements showed a tolerance within &amp;lt;10mmHg in up to 96–98% of patients. Hypercapnia (pCO2&amp;lt;70mmHg) was detected more likely and earlier by continuous tpCO2 monitoring compared to half-hourly pvCO2 measurements. Conclusion Continuous tpCO2 monitoring is feasible and precise with good correlation to arterial and venous blood gas carbon-dioxide analysis during complex catheter ablations under conscious sedation and may contribute to additional safety. Funding Acknowledgement Type of funding source: None

Transcutaneous CO2 Monitoring in Children Undergoing Tonsillectomy for Sleep Disordered Breathing.

Children undergoing tonsillectomy for sleep-disordered breathing are at risk for respiratory compromise when narcotics are administered. Severe complications resulting from hypoxia can include neuro-devastation and death. The objective of this prospective study was to evaluate the feasibility, accuracy, and utility of transcutaneous carbon dioxide (tcPCO2) monitoring during and after adenotonsillectomy. Prospective, Observational study. Twenty-nine children with sleep-disordered breathing scheduled for adenotonsillectomy were included in the study. Peri-operative measurements of tcPCO2 were compared against a single venous blood sample (PaCO2) and end-tidal (ET) CO2. The differences between ETCO2, tcPCO2 measures, and PaCO2 were examined using non-paired t-tests and linear regression. Parameters from PSG were recorded and associations with tcPCO2 values were performed using linear regression analysis. Group comparisons were made between pre-, intra-, and post-operative tcPCO2 measurements. Similar to ETCO2, there was good correlation of tcPCO2 to PaCO2. Children with lower oxygen (O2) saturation nadirs had higher peak CO2 levels during surgery and spent a greater proportion of time with CO2 > 50 mmHg in the recovery room (P < .01 and P < .08). Other PSG measures (apnea-hypopnea index, O2 desaturation index, and peak CO2) did not have any significant correlation. Frequent episodes of hypercapnia were noted intra- and post-operatively and mean tcPCO2 values during both periods were significantly higher than baseline (P < .001). tcPCO2 monitoring is viable in children undergoing adenotonsillectomy and can provide a good estimate of hypoventilation. tcPCO2 measurements may have particular benefit in the post-operative setting and may assist in identifying children at greater risk for respiratory complications. 4 Laryngoscope, 131:1410-1415, 2021.

Continuous transcutaneous carbon-dioxide monitoring to avoid hypercapnia in complex catheter ablations under conscious sedation

BackgroundAblation of complex cardiac arrhythmias requires an immobilized patient. For a successful and safe intervention and for patient comfort, this can be achieved by conscious sedation. Administered sedatives and analgesics have respiratory depressant side effects and require close monitoring. We investigated the feasibility and accuracy of additional, continuous transcutaneous carbon-dioxide partial pressure (tpCO2) measurement during conscious sedation in complex electrophysiological catheter ablation procedures. MethodWe evaluated the accuracy and additional value of continuous tpCO2 detection by application of a Severinghaus electrode in comparison to arterial and venous blood gas analyses. ResultsWe included 110 patients in this prospective observational study. Arterial pCO2 (paCO2) and tpCO2 showed good correlation throughout the procedures (r = 0.60–0.87, p < 0.005). Venous pCO2 (pvCO2) were also well correlated to transcutaneous values (r = 0.65–0.85, p < 0.0001). Analyses of the difference of pvCO2 and tpCO2 measurements showed a tolerance within <10 mmHg in up to 96–98% of patients. Hypercapnia (pCO2 < 70 mmHg) was detected more likely and earlier by continuous tpCO2 monitoring compared to half-hourly pvCO2 measurements. ConclusionContinuous tpCO2 monitoring is feasible and precise with good correlation to arterial and venous blood gas carbon-dioxide analysis during complex catheter ablations under conscious sedation and may contribute to additional safety.

Transcutaneous carbon dioxide monitoring during flexible bronchoscopy under sedation: A prospective observational study

Aim: It is difficult to maintain the necessary depth of sedation during bronchoscopy, and hypoxemia, hypoventilation, and undesirable cardiovascular effects are often encountered. Transcutaneous carbon dioxide monitoring is a reliable means of detecting hypoventilation. The aim of this study was to determine the effects of transcutaneous carbon dioxide (tPCO₂) monitoring on the amount of propofol required for sedation and examine sedation-induced hypoventilation and other adverse events requiring intervention, such as stopping the procedure to ventilate during flexible bronchoscopy. Methods: This prospective observational study included 60 patients undergoing bronchoscopy who were administered propofol. Of these, 30 patients were observed with transcutaneous carbon dioxide, and 30 were observed without. Propofol was used for sedation in all patients and the amount of propofol was compared between the groups monitored and not monitored transcutaneously for carbon dioxide. The sedation level was determined with the subjective sedation scale of the group that was not monitored. Results: No significant differences were found between the groups in terms of propofol consumption or the number of patients who required airway interventions during the procedure (P>0.05 for both). In this observational study, the partial carbon dioxide pressure in arterial blood was measured with a transcutaneous carbon dioxide monitor, which is a non-invasive method, and the maximum carbon dioxide value measured in prolonged interventions was 85 mmHg. Hypoxia was not observed in patients who developed hypoventilation. Conclusions: Hypoventilation is inevitable during bronchoscopy. Transcutaneous carbon dioxide monitoring may be important for high-risk cardiovascular patients.

Validation of a New Transcutaneous tcPO2/tcPCO2 Sensor with an Optical Oxygen Measurement in Preterm Neonates

Introduction: Traditional transcutaneous oxygen (tcPO₂) measurements are affected by measurement drift, limiting accuracy and usability. The new potentially drift-free oxygen fluorescence quenching technique has been combined in a single sensor with conventional transcutaneous carbon dioxide (tcPCO₂) monitoring. This study aimed to validate optical tcPO₂ and conventional tcPCO₂ against arterial blood gas samples in preterm neonates and determine measurement drift. Methods: In this prospective observational study, during regular care, transcutaneous measurements were paired to arterial blood gases from preterm neonates aged 24–31 weeks of gestational age (GA) with an arterial catheter. Samples were included based on stability criteria and stratified for sepsis status. Agreement was assessed using the Bland-Altman analysis. Measurement drift per hour was calculated. Results: Sixty-eight premature neonates were included {median (interquartile range [IQR]) GA of 26 4/7 [25 3/7–27 5/7] weeks}, resulting in 216 stable paired samples. Agreement of stable samples in neonates without sepsis (n = 38) and with suspected sepsis (n = 112) was acceptable for tcPO₂ and good for tcPCO₂. However, in stable samples of neonates with sepsis (n = 66), tcPO₂ agreement (bias and 95% limits of agreement) was −32.6 (−97.0 to 31.8) mm Hg and tcPCO₂ agreement was 4.2 (−10.5 to 18.9) mm Hg. The median (IQR) absolute drift values were 0.058 (0.0231–0.1013) mm Hg/h for tcPO₂ and 0.30 (0.11–0.64) mm Hg/h for tcPCO₂. Conclusion: The accuracy of optical tcPO₂ in premature neonates was acceptable without sepsis, while electrochemically measured tcPCO₂ remained accurate under all circumstances. Measurement drift was negligible for tcPO₂ and highly acceptable for tcPCO₂.

Transcutaneous Carbon Dioxide Measurement in Adult Patients with Neuromuscular Disorders: A quality Level Assessment

Carbon dioxide tension (PCO2) monitoring during sleep, is crucial to identify respiratory failure in patients with neuromuscular disorders (NMD). Transcutaneous PCO2 monitoring is an available technique to measure PCO2. To assess the quality level of transcutaneous blood gas measurements via SenTec monitor. A 12-month analysis of SenTec measurements was conducted in a Belgian Centre for Home Mechanical Ventilation (HMV). Over two consecutive nights; SpO2 and PCO2 measurements, the presence of PCO2 drift and drift correction with SenTec, were reviewed and scores (0, 1, 2 for poor, medium and high level) were assigned to estimate the quality of measurements. Sixty-nine NMD patients met the inclusion criteria, of which 48/69 used HMV. PCO2 drift and drift correction were present in 15% and 68% of the 138 recordings, respectively. The quality level of measurements throughout night 1, scored 1.55 (0-2). The relevance of our clinical findings from SenTec scoring 1.94 (1-2); was considered highly satisfactory. HMV was ineffective in 24/48 patients. Among 12 patients with hypercapnia, 8 patients improved PCO2 between night 1 and 2. Among 12 patients with hypocapnia, PCO2 improved in 4/12 patients, who reached the range of normal PCO2 (35-47 mmHg). The quality of SenTec measurements was acceptable in the majority of recordings and clinical findings were deemed satisfactory in all cases. A single SenTec measurement was sufficient to determine the need for NIV. However, two SenTec registrations were insufficient to both improve NIV effectiveness in 50% of cases, and, to ensure follow-up of our interventions.

Effects of Nasal Continuous Positive Airway Pressure on Cerebral Hemodynamics in Preterm Infants.

Background: To evaluate the effects of pressure levels on cerebral hemodynamics in premature infants receiving nasal continuous positive airway pressure (nCPAP) during the first 3 days of life.Methods: Forty-four preterm infants treated with nCPAP were divided into two groups: very preterm infants [gestational age 1 (GA1), GA < 32 weeks, n = 24] and moderate/late preterm infants (GA2 group, GA 32–37 weeks, n = 20). During monitoring, pressure levels were set at 4 → 6 → 8 → 4 cmH2O, and cerebral hemodynamics was assessed by near-infrared spectroscopy (NIRS). Vital signs, peripheral oxygen saturation (SpO2) and transcutaneous carbon dioxide pressure (TcPCO2) were simultaneously recorded.Results: Pressures of 4–8 cmH2O had no significant influence on cerebral hemodynamics, TcPCO2, SpO2 or other vital signs. The tissue oxygenation index (TOI), the difference between oxygenated hemoglobin (ΔHbO2) and deoxygenated hemoglobin (ΔHHb) (ΔHbD), and cerebral blood volume (ΔCBV) were all significantly positively correlated with gestational and post-natal age, with fluctuations being greater in the GA1 group. ΔHbD and ΔCBV were also significantly positively correlated with TcPCO2.Conclusions: No significant differences were observed in cerebral hemodynamics when the nCPAP pressure was set to 4–8 cmH2O.