Validity of transcutaneous PCO 2 in monitoring chronic hypoventilation treated with non-invasive ventilation

Targeting Hypercapnia in Chronic Lung Disease and Obesity Hypoventilation: Benefits and Challenges

Hypoventilation is a complication that is not uncommon in chronic obstructive pulmonary disease and calls for both medical treatment of the underlying disease and, frequently, noninvasive ventilation either during exacerbations requiring hospitalization or in a chronic state in the patient at home. Obesity hypoventilation syndrome by definition is associated with ventilatory failure and hypercapnia. It may or may not be accompanied by obstructive sleep apnea, which when detected becomes an additional target for positive airway pressure treatment. Intensive research has not completely resolved the best choice of treatment, and the simplest modality, continuous positive airway pressure, may still be entertained.

Prospective, observational study investigating the level of agreement between transcutaneous and invasive carbon dioxide measurements in critically ill emergency department patients

BACKGROUND

Transcutaneous carbon dioxide (Ptcco2) measurement is a non-invasive surrogate marker for arterial carbon dioxide (Paco2), which requires invasive arterial blood sampling. Use of Ptcco2 has been examined in different clinical settings, however, most existing evidence in the adult emergency department (ED) setting shows insufficient agreement between the measurements. This study assessed the level of agreement between Ptcco2 and Paco2 in undifferentiated adult ED patients across multiple timepoints.

METHODS

This prospective observational study (study period 2020-2021) assessed paired Ptcco2 and Paco2 measurements at four consecutive timepoints (0, 30, 60 and 90 min) in adult (aged 18 years or over) Australian ED patients requiring hospital admission and arterial catheter insertion. Agreement between the pairs was assessed using Bland-Altman analysis. It was prospectively determined by expert consensus that limits of ±4 mm Hg would be a clinically acceptable level of agreement between Ptcco2 and Paco2.

RESULTS

During the study period 168 paired Ptcco2 and Paco2 readings were taken from 42 adult ED patients. Bland-Altman analysis showed a mean Ptcco2 reading 3.85 mm Hg higher than Paco2, although at each timepoint the 95% CIs breached the limit of 4 mm Hg difference. In addition, only 66% (111/168) of results fell within the clinically acceptable range.

CONCLUSION

The level of agreement between Ptcco2 and Paco2 measurements may not be sufficiently precise for the adoption of Ptcco2 monitoring in patients presenting to the ED.

Daytime Hypercapnia Impairs Working Memory in Young and Middle-Aged Patients with Obstructive Sleep Apnea Hypopnea Syndrome

Purpose

Obstructive sleep apnea hypopnea syndrome (OSAHS) can lead to cognitive impairment, though few studies have so far examined hypercapnia as its causal mechanism, due to the invasive nature of conventional arterial CO2 measurement. The study aims to investigate the effects of daytime hypercapnia on working memory in young and middle-aged patients with OSAHS.

Patients and Methods

This prospective study screened 218 patients and eventually recruited 131 patients (aged 25-60 years) with polysomnography (PSG)-diagnosed OSAHS. Using a cut-off of 45mmHg daytime transcutaneous partial pressure of carbon dioxide (PtcCO2), 86 patients were assigned into the normocapnic group and 45 patients into the hypercapnic group. Working memory was evaluated using the Digit Span Backward Test (DSB) and the Cambridge Neuropsychological Test Automated Battery.

Results

Compared with the normocapnic group, the hypercapnic group performed worse in verbal, visual, and spatial working memory tasks. PtcCO2≥45mmHg was an independent predictor for lower DSB scores (OR=4.057), lower accuracy in the immediate Pattern Recognition Memory (OR=2.600), delayed Pattern Recognition Memory (OR=2.766) and Spatial Recognition Memory (OR=2.722) tasks, lower Spatial Span scores (OR=4.795), and more between errors in the Spatial Working Memory task (OR=2.734 and 2.558, respectively). Notably, PSG indicators of hypoxia and sleep fragmentation did not predict task performance.

Conclusion

Hypercapnia may be plays an important role in working memory impairment in patients with OSAHS, perhaps more so than hypoxia and sleep fragmentation. Routine CO2 monitoring in these patients could prove of utility in clinical practices.

Effect of Intensity of Home Noninvasive Ventilation in Individuals With Neuromuscular and Chest Wall Disorders: A Systematic Review and Meta-Analysis of Individual Participant Data

INTRODUCTION

Home noninvasive ventilation (NIV), targeting a reduction of carbon dioxide with a combination of sufficient inspiratory support and backup-rate improves outcomes in patients with chronic obstructive pulmonary disease. The aim of this systematic review with individual participant data (IPD) meta-analysis was to evaluate the effects of intensity of home NIV on respiratory outcomes in individuals with slowly progressive neuromuscular (NMD) or chest-wall disorders (CWD).

METHODS

Controlled, non-controlled and cohort studies indexed between January-2000 and December-2020 were sought from Medline, Embase and the Cochrane Central Register. Outcomes were diurnal PaCO₂, PaO₂, daily NIV usage, and interface type (PROSPERO-CRD 42021245121). NIV intensity was defined according to the Z-score of the product of pressure support (or tidal volume) and backup-rate.

RESULTS

16 eligible studies were identified; we obtained IPD for 7 studies (176 participants: 113-NMD; 63-CWD). The reduction in PaCO₂ was greater with higher baseline PaCO₂. NIV intensity per se was not associated with improved PaCO₂ except in individuals with CWD and the most severe baseline hypercapnia. Similar results were found for PaO₂. Daily NIV usage was associated with improvement in gas exchange but not with NIV intensity. No association between NIV intensity and interface type was found.

CONCLUSION

Following home NIV initiation in NMD or CWD patients, no relationship was observed between NIV intensity and PaCO₂, except in individuals with the most severe CWD. The amount of daily NIV usage, rather than intensity, is key to improving hypoventilation in this population during the first few months after introduction of therapy.

Moving from Inpatient to Outpatient or Home Initiation of Non-Invasive Home Mechanical Ventilation

Home mechanical ventilation (HMV) is an effective treatment for patients with chronic hypercapnic respiratory failure caused by restrictive or obstructive pulmonary disorders. Traditionally, HMV is initiated in the hospital, nowadays usually on a pulmonary ward. The success of HMV, and especially non-invasive home mechanical ventilation (NIV), has led to a steep and ongoing increase in the incidence and prevalence of HMV, in particular for patients with COPD or obesity hypoventilation syndrome. Consequently, the number of available hospital beds to accommodate these patients has become insufficient, and models of care that minimize the use of (acute) hospital beds need to be developed. At present, the practices for initiation of NIV vary widely, reflecting the limited research on which to base model-of-care decisions, local health system features, funding models, and historical practices. Hence, the opportunity to establish outpatient and home initiation may differ between countries, regions, and even HMV centres. In this narrative review, we will describe the evidence regarding the feasibility, effectiveness, safety, and cost savings of outpatient and home initiation of NIV. In addition, the benefits and challenges of both initiation strategies will be discussed. Finally, patient selection and execution of both approaches will be examined.

Monitoring Long Term Noninvasive Ventilation: Benefits, Caveats and Perspectives

Long term noninvasive ventilation (LTNIV) is a recognized treatment for chronic hypercapnic respiratory failure (CHRF). COPD, obesity-hypoventilation syndrome, neuromuscular disorders, various restrictive disorders, and patients with sleep-disordered breathing are the major groups concerned. The purpose of this narrative review is to summarize current knowledge in the field of monitoring during home ventilation. LTNIV improves symptoms related to CHRF, diurnal and nocturnal blood gases, survival, and health-related quality of life. Initially, patients with LTNIV were most often followed through elective short in-hospital stays to ensure patient comfort, correction of daytime blood gases and nocturnal oxygenation, and control of nocturnal respiratory events. Because of the widespread use of LTNIV, elective in-hospital monitoring has become logistically problematic, time consuming, and costly. LTNIV devices presently have a built-in software which records compliance, leaks, tidal volume, minute ventilation, cycles triggered and cycled by the patient and provides detailed pressure and flow curves. Although the engineering behind this information is remarkable, the quality and reliability of certain signals may vary. Interpretation of the curves provided requires a certain level of training. Coupling ventilator software with nocturnal pulse oximetry or transcutaneous capnography performed at the patient's home can however provide important information and allow adjustments of ventilator settings thus potentially avoiding hospital admissions. Strategies have been described to combine different tools for optimal detection of an inefficient ventilation. Recent devices also allow adapting certain parameters at a distance (pressure support, expiratory positive airway pressure, back-up respiratory rate), thus allowing progressive changes in these settings for increased patient comfort and tolerance, and reducing the requirement for in-hospital titration. Because we live in a connected world, analyzing large groups of patients through treatment of “big data” will probably improve our knowledge of clinical pathways of our patients, and factors associated with treatment success or failure, adherence and efficacy. This approach provides a useful add-on to randomized controlled studies and allows generating hypotheses for better management of HMV.

Transcutaneous CO2 monitoring as indication for inpatient non-invasive ventilation initiation in patients with amyotrophic lateral sclerosis

INTRODUCTION/AIMS

Amyotrophic lateral sclerosis (ALS) is characterized by profound muscle weakness, including diaphragmatic weakness resulting in hypercapnic respiratory failure. While non-invasive ventilation (NIV) is usually initiated in the home, patients presenting with hypercapnic respiratory failure may be at high risk of adverse outcomes with delays in treatment. We aim to describe the clinical utility of transcutaneous CO₂ (TCO₂ ) to assess the need for inpatient initiation of NIV.

METHODS

Eight patients from the University of Michigan Pranger ALS clinic were directly admitted to the hospital for urgent initiation of NIV between May 2020-May 2021. A retrospective review of electronic medical records, including pre-hospital pulmonary function assessments, hospitalization blood gases, and NIV use metrics was performed.

RESULTS

All eight patients had symptoms of respiratory insufficiency at time of admission, although not all patients had forced vital capacity (FVC) measurements that would identify need for NIV. All patients had measured TCO₂  > 45 mmHg. Seven of eight patients had worsening hypercapnia after admission, indicating advanced respiratory failure. All patients were titrated to tolerance of continuous nocturnal NIV while in the hospital, with an average length of stay of 6.5 days (range, 3-8). All patients demonstrated compliance with NIV, >4 h, at post-hospital follow-up.

DISCUSSION

Many current ambulatory measurements underestimate, or incompletely evaluate, respiratory dysfunction, and arterial blood gases are not typically readily available. Outpatient TCO₂ measurements can serve as a useful screening tool to identify ALS patients who would benefit from inpatient initiation and titration of NIV.

Transcutaneous and End-Tidal CO₂ Measurements in Hypoxia and Hyperoxia

BACKGROUND: Transcutaneous measurement of carbon dioxide (CO₂) has been proposed for physiological monitoring of tactical jet aircrew because in some clinical settings it mirrors arterial CO₂ partial pressure (P_aco₂). End-tidal monitoring in laboratory settings is known to give high-fidelity estimates of P_aco₂.METHODS: The correspondence between end-tidal (P_ETco₂) and transcutaneous Pco₂ (tcPco₂) was examined in healthy volunteers under laboratory conditions of hyperoxia and hypoxia. Rest and exercise, skin heating and cooling, hyperventilation, and induced CO₂ retention were employed.RESULTS: Neither measure followed all known changes in P_aco₂ and tcPco₂ changed when the skin temperature near the probe changed. Bland-Altman analysis showed significant nonzero slopes under most conditions. Regression analysis indicated that oxygen partial pressure (Po₂) in tissue measured as transcutaneous Po₂ (tcPo₂) is an important explanatory variable for tcPco₂ in addition to P_ETco₂, and that local skin temperature also has an effect. Additionally, absorption atelectasis from breathing 100% O₂ may cause P_ETco₂ to deviate from P_aco₂.DISCUSSION: Even as a trend indicator for P_aco₂, tcPco₂ is not useful under conditions that resemble those in the highly dynamic tactical jet aircraft environment. P_ETco₂ is also not a good indicator of CO₂ status in pilots who breathe nearly 100% O₂.Shykoff BE, Lee LR, Gallo M, Griswold CA. Transcutaneous and end-tidal CO₂ measurements in hypoxia and hyperoxia. Aerosp Med Hum Perform. 2021; 92(11):864-872.

Nocturnal Transcutaneous Blood Gas Measurements in a Pediatric Neurologic Population: A Quality Assessment

Objective: To assess the quality of SpO2 and PCO2 recordings via transcutaneous monitoring in children with neurological conditions.Methods: Overnight transcutaneous SpO2 and PCO2 were analyzed. The presence of drift and drift correction was noted, and the rate of disrupted recordings scored (0: absence, 1; presence). The quality of recordings was also scored (0, 1, 2 for poor, medium, and high).Results: A total of 228 recordings from 64 children aged 9.7 ± 6 years were analyzed of which 42 used positive pressure respiratory support. The mean quality of the recordings was scored as 1.27 (0-2). PCO2 drift, drift correction, and disrupted recordings were present in 25%, 58%, and 26% of recordings, respectively. Satisfactory clinical decisions were taken in 91% of cases.Conclusion: The quality of transcutaneous sensor recordings was acceptable and clinical findings were deemed as satisfactory in the large majority of cases. Correction of PCO2 drift was challenging.

Telemonitoring for Home Assisted Ventilation: A Narrative Review

The recent advent of remote ventilator telemonitoring has the potential to revolutionize home-assisted ventilation care in the United States and elsewhere. Home ventilation machines (i.e., respiratory assist devices and portable ventilators) can now wirelessly transmit usage and performance data to cloud-based web servers for remote access by participating clinicians. In this Focused Review, we provide an update on available technology, suggest practical applications for clinical care and research, and review supporting literature. Remote monitoring permits early data review, refinement of device settings to optimize ventilatory function, and troubleshooting if a new problem arises after initial setup. Data from home spirometry and noninvasively measured blood gas tensions can complement ventilator data to reflect physiological response. Acknowledging a paucity of published outcome studies, remote telemonitoring may be a cost-effective strategy to reduce emergency room visits, urgent clinic appointments, and hospitalizations. Ongoing clinical trials in Europe aim to expand on the benefit of this rapidly evolving technology. However, several barriers may hinder widespread implementation, especially in the United States. Clinicians must familiarize themselves with each ventilator manufacturer’s proprietary software to safely leverage this technology for improving care. Legal and ethical considerations threaten clinician interest. Medical insurance payers must adapt a reimbursement scheme to incentivize clinicians and durable medical equipment companies to perform this time-consuming service. Cohort-level ventilator data will facilitate multicenter clinical trials focused on improving the respiratory care of this vulnerable population.

Management of respiratory complications and rehabilitation in individuals with muscular dystrophies: 1st Consensus Conference report from UILDM - Italian Muscular Dystrophy Association (Milan, January 25-26, 2019)

Respiratory complications are common in the patient with muscular dystrophy. The periodic clinical and instrumental respiratory evaluation is extremely important. Despite the presence in the literature of updated guidelines, patient associations often report lack of knowledge of these pathologies, particularly in peripheral hospitals. The purpose of this work, inspired by the Italian Muscular Dystrophy Association (UILDM) is to improve management of respiratory problems necessary for the management of these patients complex. To this end, the main items that the specialist can meet in the follow-up of these pathologies have been analyzed and discussed, among which the respiratory basal evaluation, the criteria of adaptation to non-invasive ventilation, management of bronchial secretions, situations of respiratory emergency, indications for tracheostomy and the subject of advance directives of treatment (DAT).

Titration and follow-up for home noninvasive positive pressure ventilation in chronic obstructive pulmonary disease: The potential role of tele-monitoring and the Internet of things

INTRODUCTION

Home noninvasive positive pressure ventilation (NIPPV) has become a well-established treatment for stable hypercapnic chronic obstructive pulmonary disease (COPD) patients. There are still other challenges including appropriate titration of ventilator parameters, adequacy of follow-up, monitoring, and management at home to ensure effectiveness and security, and to improve quality of life. The Internet of Things (IoT) is the name given to the network of devices and other "things" with built-in sensors, software, electronics, and network connectivity, which can communicate these objects over wireless networks and then send data to a cloud platform. Reliable tele-monitoring and transmission of clinical parameters from home to hospitals have prompted the development of IoT-based home NIPPV.

OBJECTIVES

This review provides an overview of titration and follow-up of home NIPPV and focuses on different technologies, modalities, managements, and cost-effectiveness used in IoT-based tele-monitoring of home mechanical ventilation.

DATA SOURCE

Literature search of Web of Science, PubMed, and EMBASE was made to find relevant articles about tele-monitoring and the IoT in home mechanical ventilation over the last 15 years. We used the following search terms: NIPPV, COPD, home mechanical ventilation, telemedicine, tele-monitoring, and management.

CONCLUSION

IoT-based management of home NIPPV, such as home titration and follow-up with the use of tele-monitoring, are emerging and yielding positive findings. However, clear conclusions based on RCT of tele-monitoring in COPD patients with NIPPV at home are only a few and large-scale multicenter studies are required for replication and further validation.

Complex home assessment of long-term non-invasive ventilation efficacy using transcutaneous monitoring of PCO2 and polygraphy - A feasibility study

PURPOSE

Home non-invasive ventilation (HNIV) during sleep is a standard treatment for chronic hypercapnic respiratory failure (CHRF). The aim of this study was to evaluate the feasibility of the complex overnight assessment of HNIV in adults performed at home and the efficacy of HNIV after one year of treatment.

METHODS

Stable patients with CHRF on HNIV for more than 12 months had unattended polygraphy (PG) with transcutaneous monitoring of PCO₂ (tcPCO₂) at home during one night. The recording quality was regarded as excellent when 100% and good if 80-99% of the analysis time was registered. The following efficacy criteria were approved: (1) SpO₂<90% for <10% of analysis time, (2) increase in PtcCO₂ ≤7.5 ​mmHg between baseline and average value at night, (3) apnea-hypopnea index (AHI) ≤5/h.

RESULTS

Eighteen patients with CHRF (median age 66 [60-74] years, 10 female) were included. The quality of the PG tracings was good to excellent in 16 (89%) patients and the quality of the tcPCO₂ data was good to excellent in 14 (78%) patients. There was no difference in the quality of tcPCO₂ between patients who lived alone and those who lived with family (100 [50-100]% vs. 100 [90-100]% of analysis time, respectively). Only 4 (22%) patients fulfilled all three efficacy criteria.

CONCLUSIONS

Home-based monitoring using PG and tcPCO₂ is a feasible and adequate tool to assess the efficacy of HNIV. In most of the patients on HNIV for more than 12 months, the treatment was not effective based on the predefined efficacy criteria.

Management of Chronic Respiratory Failure in Chronic Obstructive Pulmonary Disease: High-Intensity and Low-Intensity Ventilation

A significant body of literature supports the benefit of noninvasive ventilation (NIV) for acute hypercapnia in the setting of exacerbations of chronic obstructive pulmonary disease (COPD). In those with severe COPD with chronic hypercapnic respiratory failure, however, the role of NIV has been more controversial. This article reviews the physiologic basis for considering NIV in patients with COPD, summarizes existing evidence supporting the role of NIV in COPD, highlights the patient population and ventilatory approach most likely to offer benefit, and suggests a potential clinical pathway for managing patients.

Long-Term Mechanical Ventilation: Recommendations of the Swiss Society of Pulmonology

Long-term mechanical ventilation is a well-established treatment for chronic hypercapnic respiratory failure (CHRF). It is aimed at improving CHRF-related symptoms, health-related quality of life, survival, and decreasing hospital admissions. In Switzerland, long-term mechanical ventilation has been increasingly used since the 1980s in hospital and home care settings. Over the years, its application has considerably expanded with accumulating evidence of beneficial effects in a broad range of conditions associated with CHRF. Most frequent indications for long-term mechanical ventilation are chronic obstructive pulmonary disease, obesity hypoventilation syndrome, neuromuscular and chest wall diseases. In the current consensus document, the Special Interest Group of the Swiss Society of Pulmonology reviews the most recent scientific literature on long-term mechanical ventilation and provides recommendations adapted to the particular setting of the Swiss healthcare system with a focus on the practice of non-invasive and invasive home ventilation in adults.

Monitoring of noninvasive ventilation: comparative analysis of different strategies

Background

Noninvasive ventilation (NIV) represents an effective treatment for chronic respiratory failure. However, empirically determined NIV settings may not achieve optimal ventilatory support. Therefore, the efficacy of NIV should be systematically monitored. The minimal recommended monitoring strategy includes clinical assessment, arterial blood gases (ABG) and nocturnal transcutaneous pulsed oxygen saturation (SpO₂). Polysomnography is a theoretical gold standard but is not routinely available in many centers. Simple tools such as transcutaneous capnography (TcPCO₂) or ventilator built-in software provide reliable informations but their role in NIV monitoring has yet to be defined. The aim of our work was to compare the accuracy of different combinations of tests to assess NIV efficacy.

Methods

This retrospective comparative study evaluated the efficacy of NIV in consecutive patients through four strategies (A, B, C and D) using four different tools in various combinations. These tools included morning ABG, nocturnal SpO₂, TcPCO₂ and data provided by built-in software via a dedicated module. Strategy A (ABG + nocturnal SpO₂), B (nocturnal SpO₂ + TcPCO₂) and C (TcPCO₂ + builtin software) were compared to strategy D, which combined all four tools (NIV was appropriate if all four tools were normal).

Results

NIV was appropriate in only 29 of the 100 included patients. Strategy A considered 53 patients as appropriately ventilated. Strategy B considered 48 patients as appropriately ventilated. Strategy C misclassified only 6 patients with daytime hypercapnia.

Conclusion

Monitoring ABG and nocturnal SpO₂ is not enough to assess NIV efficacy. Combining data from ventilator built-in software and TcPCO₂ seems to represent the best strategy to detect poor NIV efficacy.

Trialregistration Institutional Review Board of the Société de Pneumologie de Langue Française (CEPRO 2016 Georges)

Respiratory Monitoring: Current State of the Art and Future Roads

In this article, we present current methodologies, available technologies, and demands for monitoring various respiratory parameters. We discuss the importance of noninvasive techniques for remote and continuous monitoring and challenges involved in the current "smart and connected health" era. We conducted an extensive literature review on the medical significance of monitoring respiratory vital parameters, along with the current methods and solutions with their respective advantages and disadvantages. We discuss the challenges of developing a noninvasive, wearable, wireless system that continuously monitors respiration parameters and opportunities in the field and then determines the requirements of a state-of-the-art system. Noninvasive techniques provide a significant amount of medical information for a continuous patient monitoring system. Contact methods offer more advantages than non-contact methods; however, reducing the size and power of contact methods is critical for enabling a wearable, wireless medical monitoring system. Continuous and accurate remote monitoring, along with other physiological data, can help caregivers improve the quality of care and allow patients greater freedom outside the hospital. Such monitoring systems could lead to highly tailored treatment plans, shorten patient stays at medical facilities, and reduce the cost of treatment.

Noninvasive Ventilation Downloads and Monitoring

"Home noninvasive ventilation (NIV) is indicated for numerous conditions including neuromuscular disease, thoracic cage disorders, chronic obstructive pulmonary disease, and hypoventilation syndromes. Effective management of patients on home NIV requires clinicians to interpret data downloads from NIV devices. Clinicians must first look at adherence and factors that may impact this including mask comfort and fit. Next, leak assessment is undertaken. Once these are addressed, such information as apnea-hypopnea index, exhaled tidal volume, and percent triggered breaths help clinicians troubleshoot setting changes. Finally, overnight oximetry and transcutaneous CO2 monitoring are useful adjuncts to the data download to optimize NIV settings."

Noninvasive Ventilator Devices and Modes

Noninvasive ventilation has become an increasingly common treatment strategy for patients with diverse conditions involving chronic respiratory failure. An intimate understanding of various advanced respiratory devices and modes is essential in the management of these patients. Pressure-limited modes of ventilation are more commonly used than volume modes for noninvasive ventilation owing to enhanced patient comfort and synchrony with the ventilator, as well as improved leak compensation. Common pressure modes include spontaneous/timed and pressure control, with volume-assured pressure support being an additive feature available on certain devices. Evidence guiding the optimal mode of ventilation for specific diseases is limited.

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.

European Respiratory Society guidelines on long-term home non-invasive ventilation for management of COPD

Background

While the role of acute non-invasive ventilation (NIV) has been shown to improve outcome in acute life-threatening hypercapnic respiratory failure in COPD, the evidence of clinical efficacy of long-term home NIV (LTH-NIV) for management of COPD is less. This document provides evidence-based recommendations for the clinical application of LTH-NIV in chronic hypercapnic COPD patients.

Materials and methods

The European Respiratory Society task force committee was composed of clinicians, methodologists and experts in the field of LTH-NIV. The committee developed recommendations based on the GRADE (Grading, Recommendation, Assessment, Development and Evaluation) methodology. The GRADE Evidence to Decision framework was used to formulate recommendations. A number of topics were addressed under a narrative format which provides a useful context for clinicians and patients.

Results

The task force committee delivered conditional recommendations for four actionable PICO (target population-intervention-comparator-outcome) questions, 1) suggesting for the use of LTH-NIV in stable hypercapnic COPD; 2) suggesting for the use of LTH-NIV in COPD patients following a COPD exacerbation requiring acute NIV 3) suggesting for the use of NIV settings targeting a reduction in carbon dioxide and 4) suggesting for using fixed pressure support as first choice ventilator mode.

Conclusions

Managing hypercapnia may be an important intervention for improving the health outcome of COPD patients with chronic respiratory failure. The task force conditionally supports the application of LTH-NIV to improve health outcome by targeting a reduction in carbon dioxide in COPD patients with persistent hypercapnic respiratory failure. These recommendations should be applied in clinical practice by practitioners that routinely care for chronic hypercapnic COPD patients.

Transcutaneous partial pressure of carbon dioxide monitoring during EUS-guided drainage of peripancreatic fluid collections using carbon dioxide insufflation: A prospective study

Background:

Carbon dioxide (CO₂) insufflation has become more commonly used in EUS-guided interventions in recent years. However, there is a paucity of information regarding methods by which to monitor in vivo CO₂ levels. This study aimed to assess the feasibility of a novel noninvasive method to monitor transcutaneous partial pressure of CO₂ (P_CO2) (P_tcCO2) levels during EUS-guided drainage of peripancreatic fluid collections (PFCs). The safety of CO₂ insufflation in EUS-guided interventions was also investigated.

Patients and Methods:

Patients who underwent EUS-guided PFC drainage between September 2015 and December 2016 at Shengjing Hospital of China Medical University were prospectively enrolled in this study. P_tcCO2 was measured in all patients using a noninvasive sensor throughout the procedure.

Results:

There were 25 patients eligible to be included in this study. The mean procedure time was 53.1 min. The mean P_tcCO2 level was 40 ± 4 mmHg and 48 ± 5 mmHg before and after the procedure, respectively. The mean peak P_tcCO2 during the procedure was significantly higher at 53 ± 6 mmHg (P < 0.0001). No complications associated with CO₂ insufflation such as CO₂ narcosis, gas embolism, or arrhythmias were encountered.

Conclusions:

P_tcCO2 monitoring can accurately reflect the level of P_CO2 continuously and noninvasively. CO₂ insufflation is safe for patients undergoing relatively complicated EUS-guided drainage of PFCs.

Frontiers in Clinical Practice of Long-Term Care of Chronic Ventilatory Failure

Home mechanical ventilation (HMV) is an effective long-term treatment for chronic hypercapnic respiratory failure. In addition to the established practice of providing HMV for the treatment of chronic ventilatory failure in slowly progressive neuromuscular and chest wall disease, there is accumulating evidence for improvement of quality of life and prolongation of survival by HMV in highly prevalent diseases like chronic obstructive pulmonary disease and ever-increasing obesity hypoventilation syndrome as well as rapidly progressive neuromuscular disease. The key concepts for successful HMV are an experienced team selecting the right patients, timely initiation of adequate ventilation via an appropriate interface, and monitoring effectiveness during regular long-term follow-up. Coaching of patients with chronic respiratory failure on long-term HMV within a dedicated service and collaborations with community services for home care are essential. The current review describes various important practical aspects of HMV that remain frontiers in the implementation of the current knowledge in clinical practice and may help in providing effective HMV to all those in need.

High-intensity non-invasive ventilation in stable hypercapnic COPD: Evidence of efficacy and practical advice

Patients with end-stage chronic obstructive pulmonary disease (COPD) frequently develop chronic hypercapnic respiratory failure (CHRF), with disabling symptoms and poor survival. The use of long-term nocturnal non-invasive ventilation (NIV) to treat CHRF in COPD has long been subject of debate due to conflicting evidence. However, since the introduction of high-intensity NIV (HI-NIV) in COPD, physiological and clinical benefits have been shown. HI-NIV refers to specific ventilator settings used for NIV aimed at achieving normocapnia or the lowest partial arterial carbon dioxide pressure (PaCO₂ ) values as possible. This review will provide an overview of existing evidence of the efficacy of HI-NIV stable COPD patients with CHRF. Secondly, we will discuss hypotheses underlying NIV benefit in stable hypercapnic COPD, providing insight into better patient selection and hopefully more individually titrated HI-NIV. Finally, we will provide practical advice on how to initiate and follow-up patients on HI-NIV, with special emphasis on monitoring that should be available during the initiation and follow-up of HI-NIV, and will discuss more extended monitoring techniques that could improve HI-NIV treatment in the future.

The Pathophysiology of Respiratory Failure: Control of Breathing, Respiratory Load, and Muscle Capacity

The purpose of this review is to provide an overview on how interactions between control of breathing, respiratory load, and muscle function may lead to respiratory failure. The mechanisms involved vary according to the underlying pathology, but respiratory failure is most often the result of an imbalance between the muscular pump and the mechanical load placed upon it. Changes in respiratory drive and response to CO2 seem to be important contributors to the pathophysiology of respiratory failure. Inspiratory muscle dysfunction is also frequent but is not a mandatory prerequisite to respiratory failure since increased load may also be sufficient to precipitate it. It is crucial to recognize these interactions to be able to timeously establish patients on mechanical ventilation and adapt the ventilator settings to their respiratory system physiology.

Prevalence of sleep apnoea and capnographic detection of nocturnal hypoventilation in amyotrophic lateral sclerosis

OBJECTIVE

This retrospective study aimed to investigate whether overnight oxymetry and early morning blood gas analysis predict nocturnal hypoventilation (NH) as reflected by night-time hypercapnia in patients with amyotrophic lateral sclerosis (ALS). In addition, prevalence and clinical determinants of sleep apnoea in ALS were evaluated.

METHODS

In 250 patients with non-ventilated ALS, transcutaneous capnometry was performed along with polysomnography or polygraphy and early morning blood gases.

RESULTS

123 patients were female, and 84 patients had bulbar-onset ALS. 40.0% showed NH, and an apnoea-hypopnoea index (AHI) >5/hour was found in 45.6%. In 22.3%, sleep apnoea and NH coincided. The obstructive apnoea index was significantly higher than the central apnoea index (p<0.0001). Both NH and sleep apnoea were significantly more common in male than in female patients. Sleep apnoea and AHI were associated with better bulbar function. Desaturation time (t_<90%) and transcutaneous CO₂ were negatively correlated with upright vital capacity. Early morning base excess (EMBE), bicarbonate and t_<90% were independent predictors of NH. However, among 100 patients with NH, 31 were missed by t_<90% >5 min and 17 were not identified when EMBE >3 mmol/L and t_<90% >5 min were combined.

CONCLUSION

In ALS, sleep apnoea is common and often accompanies NH. It is mainly obstructive, and central apnoea appears to be clinically irrelevant. Polygraphy or oxymetry alone are not sufficient to uncover NH. Combination of EMBE and t_<90% may increase sensitivity, but transcutaneous capnography is strongly recommended for reliable detection of NH in patients with ALS.

Non-invasive ventilation in the ED: Whom, When, How?

As emergency physicians, we encounter patients suffering from either hypoxemic and/or hypercarbic respiratory problems on a daily basis. A stepwise approach to solving this problem seems logical from an emergency medicine perspective. Current literature supports the notion that NIV decreases endotracheal intubation rates and, mortality in select patient populations. The key to the success of NIV is patient cooperation and support for the care givers. In this narrative review, non-invasive ventilation (NIV) is discussed in terms of modes of delivery, interface and patient selection, as well as practical considerations.

Continuous non-invasive PCO2 monitoring in weaning patients: Transcutaneous is advantageous over end-tidal PCO2

BACKGROUND AND OBJECTIVE

Continuous partial pressure of carbon dioxide (PCO₂ ) assessment is essential for the success of mechanical ventilation (MV). Non-invasive end-tidal PCO₂ (PetCO₂ ) and transcutaneous PCO₂ (PtcCO₂ ) measurements serve as alternatives to the gold standard arterial PCO₂ (PaCO₂ ) method, but their eligibility in critical care is unclear.

METHODS

The present study therefore performed methodological comparisons of PaCO₂ versus PetCO₂ and PtcCO₂ , respectively, in weaning patients receiving invasive MV via tracheal cannulas. PetCO₂ and PtcCO₂ were recorded continuously, while PaCO₂ was analysed at baseline, and after 30 and 60 min. Using the Bland-Altman analysis, a clinically acceptable range was defined as a mean difference of ±4 mm Hg between PaCO₂ and non-invasive strategies.

RESULTS

A total of 60 patients (COPD (n = 30) and non-COPD (n = 30)) completed the protocol. Mean PCO₂ values were 42.4 ± 8.6 mm Hg (PaCO₂ ), 36.5 ± 7.5 mm Hg (PetCO₂ ) and 41.7 ± 8.7 mm Hg (PtcCO₂ ). Mean differences between PtcCO₂ and PaCO₂ were -0.7 ± 3.6 mm Hg (95% CI: -1.6/0.3 mm Hg; 95% limits of agreement: -7.8 to 6.4 mm Hg), and between PetCO₂ and PaCO₂ -5.9 ± 5.3 mm Hg (95% CI: -7.2/-4.5 mm Hg; 95% limits of agreement: -16.2 to 4.5 mm Hg). Underestimation of PaCO₂ by PetCO₂ was most pronounced in COPD patients.

CONCLUSION

Our data therefore support PtcCO₂ as a suitable means for monitoring PCO₂ in patients undergoing invasive MV. This is in contrast to PetCO₂ , which clearly underestimated PaCO₂ , especially in patients with COPD.

Practical Insight to Monitor Home NIV in COPD Patients

Home noninvasive ventilation (NIV) is used in COPD patients with concomitant chronic hypercapnic respiratory failure in order to correct nocturnal hypoventilation and improve sleep quality, quality of life, and survival. Monitoring of home NIV is needed to assess the effectiveness of ventilation and adherence to therapy, resolve potential adverse effects, reinforce patient knowledge, provide maintenance of the equipment, and readjust the ventilator settings according to the changing condition of the patient. Clinical monitoring is very informative. Anamnesis focuses on the improvement of nocturnal hypoventilation symptoms, sleep quality, and side effects of NIV. Side effects are major cause of intolerance. Screening side effects leads to modification of interface, gas humidification, or ventilator settings. Home care providers maintain ventilator and interface and educate patients for correct use. However, patient's education should be supervised by specialized clinicians. Blood gas measurement shows a significant decrease in PaCO₂ when NIV is efficient. Analysis of ventilator data is very useful to assess daily use, unintentional leaks, upper airway obstruction, and patient ventilator synchrony. Nocturnal oximetry and capnography are additional monitoring tools to assess the impact of NIV on gas exchanges. In the near future, telemonitoring will reinforce and change the organization of home NIV for COPD patients.

Utility of Transcutaneous Capnography for Optimization of Non-Invasive Ventilation Pressures

INTRODUCTION

Nocturnal Non-invasive Positive Pressure Ventilation (NPPV) is the treatment of choice in patients with chronic hypercapnic respiratory failure due to hypoventilation. Continuous oxygen saturation measured with a pulse oximeter provides a surrogate measure of arterial oxygen saturation but does not completely reflect ventilation. Currently, Partial Pressure of Arterial (PaCO2) measured by arterial blood analysis is used for estimating the adequacy of ventilatory support and serves as the gold standard.

AIM

To examine the safety, feasibility and utility of cutaneous capnography to re-titrate the non-invasive positive pressure ventilation settings in patients with chronic hypercapnic respiratory failure due to hypoventilation.

MATERIALS AND METHODS

Twelve patients with chronic hypercapnic respiratory failure prospectively underwent complete polysomnography and cutaneous capnography measurement on the ear lobe. Non-invasive ventilation pressures were adjusted with the aim of normalizing cutaneous carbon dioxide or at least reducing it by 10 to 15 mmHg. Sensor drift for cutaneous carbon dioxide of 0.7 mmHg per hour was integrated in the analysis.

RESULTS

Mean baseline cutaneous carbon dioxide was 45.4 ± 6.5 mmHg and drift corrected awake value was 45.1 ± 8.3 mmHg. The correlation of baseline cutaneous carbon dioxide and the corrected awake cutaneous carbon dioxide with arterial blood gas values were 0.91 and 0.85 respectively. Inspiratory positive airway pressures were changed in nine patients (75%) and expiratory positive airway pressures in eight patients (66%). Epworth sleepiness score before and after the study showed no change in five patients, improvement in six patients and deterioration in one patient.

CONCLUSION

Cutaneous capnography is feasible and permits the optimization of non-invasive ventilation pressure settings in patients with chronic hypercapnic respiratory failure due to hypoventilation. Continuous cutaneous capnography might serve as an important additional tool to complement diurnal arterial carbon dioxide tension values.

Prognostic Value of Initial Assessment of Residual Hypoventilation Using Nocturnal Capnography in Mechanically Ventilated Neuromuscular Patients: A 5-Year Follow-up Study

Background

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, and its efficiency is mostly assessed by daytime blood gases or nocturnal oxygen saturation monitoring (SpO₂). Non-invasive transcutaneous measure of CO₂ (TcCO₂) allows to directly assess nocturnal hypercapnia and to detect residual hypoventilation with a higher sensitivity than SpO₂. We aimed to compare the prognostic value of nocturnal SpO₂ and TcCO₂ in ventilated adult NMD patients.

Methods

All consecutive capno-oximetries performed between 2010 and 2011 in ventilated adult NMD patients were analyzed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Nocturnal hypoxemia and hypercapnia (using four different definitions) at baseline were compared in their ability to predict mortality and respiratory events requiring ICU admission during follow-up.

Results

Data from 55 patients were analyzed (median age 28 [interquartile range: 25–36.5] years; 71% Duchenne muscular dystrophy; vital capacity 12 [7–27]% of predicted; 51% tracheostomy). Capno-oxymetry showed hypoxemia in 14.5% and hypercapnia in 12.7–41.8%, according to the used definition. Over a follow-up lasting up to 5 years (median 4.0 [3.6–4.5] years), we observed 12 deaths and 20 respiratory events requiring ICU admission. Hypercapnia was significantly associated with the study outcomes, with TcCO₂ > 49 mmHg during ≥10% of the time being the best definition, while hypoxemia was not.

Conclusion

Our data show for the first time that residual hypoventilation, assessed by capnometry, is significantly associated with negative outcomes in adult ventilated NMD patients, while oximetry is not. Accordingly, we suggest capnometry to be included in the systematic assessment of HMV efficiency in NMD patients.

ClinicalTrials.gov Identifier

NCT02551406.