Transcutaneous Carbon Dioxide Tension Research Articles

Physiological effects of standard oxygen therapy, high-flow nasal cannula, and helmet CPAP in acute bronchiolitis: a randomized cross-over study

ObjectivesAcute viral bronchiolitis (AVB) is a major cause of hospitalization for children in developed and developing countries. Nasal high flow (NHF) therapy improves oxygenation and reduces respiratory drive by enhancing carbon dioxide wash-out. However, little is known about the physiological effects of non-invasive helmet continuous positive airway pressure (h-CPAP) and NHF on respiratory work of breathing (WOB) in pediatric patients with AVB. The present study measured esophageal pressure time product over 1 min (PTPes*min−1), as a close surrogate for WOB during standard oxygen therapy (SOT), NHF delivered at incremental flow rates, and h-CPAP in hospitalized patients with AVB.MethodsThis is a physiological randomized crossover study with four 20-min steps: SOT delivered by a Venturi mask; NHF2 set at 2L/kg*min−1PBW; NHF3 set at 3L/kg*min−1PBW; and h-CPAP with PEEP 7 cmH2O. PTPes *min−1, pressure rate product (PRP), respiratory and other physiological parameters were collected towards the end of each step.ResultsTen hypoxemic children with AVB were enrolled. PTPes*min−1, respiratory rate (RR), PRP, and heart rate (HR) decreased progressively from h-CPAP to NHF3, NHF2, and SOT (p < 0.01). Transcutaneous carbon dioxide tension (tcCO2) was lower during h-CPAP, NHF3, and NHF2 than during SOT (p < 0.001). SpO2:FiO2 was higher during h-CPAP than with all other support (p < 0.01).ConclusionsIn pediatric patients with AVB, h-CPAP was associated with lower WOB, better oxygenation, and lower tcCO2 than with SOT and NHF trials.Trial registrationClinicaltrials.gov NCT03689686 Registered 1 August 2018.

Pain-related changes in crSO2 among premature infants undergoing PICC insertion

Objective To evaluate the effectiveness of cerebral regional oxygen saturation (crSO2) values, measured using near-infrared spectroscopy (NIRS), in assessing pain associated with the peripherally inserted central catheter (PICC) in premature infants. Methods NIRS was used to measure the crSO2 levels of 48 premature infants with gestational age (GA) of < 32 weeks or a birth weight of < 1500 g. Premature infant pain profile (PIPP) scores, vital signs, transcutaneous oxygen tension (TcpO2), transcutaneous carbon dioxide tension (TcpCO2), and crSO2 values were monitored. One-way repeated measure analysis of variance was used to compare heart rate (HR), respiratory rate (RR), blood pressure (BP), peripheral oxygen saturation (SpO2), TcpO2, TcpCO2, and crSO2 values before (Time 1), during (Time 2), and after (Time 3) PICC insertion. The correlation between the PIPP scores at Time 2 and the fluctuations (values detected at Time 2 minus those at Time 1) of SpO2, TcpO2, and crSO2 were also analyzed. Results The PIPP score at Time 2 was significantly higher than those at Times 1 and 3. HR, RR, and BP values increased (p < .05), and SpO2 and crSO2 levels decreased at Time 2 (p < .05) compared with those at Time 1. Stratified analysis based on GA revealed significant differences in HR, RR, and crSO2 values between Times 1 and 2 in infants with a GA of ≥ 32 weeks. In infants with a GA < 32 weeks, significant differences were observed in HR, RR, SpO2, BP, and crSO2 values between Times 1 and 2. The fluctuation of the crSO2 level was strongly correlated with the PIPP score at Time 2 (r = −0.829, p < .001). A weak correlation was observed between the PIPP score at Time 2 and TcpO2 level fluctuation (r = 0.375, p = .009). No correlation was observed between the PIPP score at Time 2 and SpO2 level fluctuation (r = 0.242, p = .097). Conclusion The fluctuation of crSO2 levels strongly correlates with PICC procedural pain. Hence, crSO2 levels measured using NIRS may be used as an indicator for pain assessment in premature infants.

Effects of high-flow nasal cannula with oxygen on self-paced exercise performance in COPD: A randomized cross-over trial.

Introduction:Studies have demonstrated that noninvasive ventilation improves exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). The role of heated humidified high-flow nasal cannula (HFNC) therapy in patients with COPD on self-paced exercise performance remains unclear. Therefore, the purpose of the present study was to determine whether HFNC-aided supplemental oxygen during a 6-minute walk test (6MWT) would change self-paced exercise performance and cardiopulmonary outcomes in patients with stable COPD.Methods:A single-site, cross-over trial was conducted in a pulmonary rehabilitation outpatient department. This study enrolled 30 stable COPD patients without disability. The participants with and without HFNC performed 6MWTs on 2 consecutive days. Outcomes were the distance walked in the 6MWT, physiological, and cardiopulmonary parameters.Results:Those performing HFNC-aided walking exhibited a longer walking distance than those performing unaided walking. The mean difference in meters walked between the HFNC-aided and unaided walking scenarios was 27.3 ± 35.6 m (95% CI: 14.4–40.5 m). The energy expenditure index was significantly lower when walking was aided by HHHNFC rather than unaided (median: 1.21 beats/m walked vs median: 1.37 beats/m walked, P < .001). However, there were no differences in transcutaneous carbon dioxide tension between HHHNFC and non-HHHNFC patients.Conclusion:Walking distance and arterial oxygen saturation improved in stable COPD patients receiving HFNC with additional oxygen support. However, HFNC did not affect transcutaneous carbon dioxide tension and the self-reported dyspnea score during the walking test. The present study demonstrated the feasibility and safety of using HFNC in self-paced exercise.Trial registration:NCT03863821

Effect of high-flow nasal cannula oxygen therapy in patients with chronic obstructive pulmonary disease: A meta-analysis.

High-flow nasal cannula oxygen therapy reduces the arterial partial pressure of carbon dioxide and acute exacerbation but does not increase exercise capacity or decrease hospitalisation or mortality. The study aimed to test the hypothesis that in chronic obstructive pulmonary disease patients, the use of high-flow nasal cannula decreases arterial partial pressure of carbon dioxide and increases the partial pressure of oxygen and 6-min walking distance. PubMed, Embase and the Cochrane library were searched for eligible studies published from database inception to November 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist). The primary outcomes were partial pressure of carbon dioxide and partial pressure of oxygen, and the secondary outcomes were transcutaneous partial pressure of carbon dioxide and 6-min walking distance. Nine studies (680 patients) were included. high-flow nasal cannula did not decrease partial pressure of carbon dioxide compared with the control interventions (mean difference=-0.81, 95% confidence interval: -2.68 to 1.06, p=.395; I2 =42.9%, pheterogeneity =.105). high-flow nasal cannula decreased partial pressure of carbon dioxide compared with long-term oxygen therapy (mean difference=-3.25, 95% confidence interval: -5.65 to -0.85, p=.008; I2 =0%, pheterogeneity =.375); no difference was observed for the control modalities. high-flow nasal cannula resulted in better partial pressure of carbon dioxide compared with control interventions in hypoxemic patients (mean difference=-2.59, 95% confidence interval: -4.82 to -0.35, p=.023; I2 =32.5%, pheterogeneity =.224), but not in other types of patients. high-flow nasal cannula did not increase partial pressure of oxygen compared with the control interventions (mean difference=1.17, 95% confidence interval: -1.50 to 3.83, p=.390; I2 =0%, pheterogeneity =.660). high-flow nasal cannula decreased transcutaneous carbon dioxide tension (transcutaneous partial pressure of carbon dioxide) compared with the control interventions (mean difference=2.37, 95% confidence interval: 0.07-4.68, p=.044; I2 =8.7%, pheterogeneity =.295). high-flow nasal cannula increased 6-min walking distance compared with the control interventions (mean difference=18.22, 95% confidence interval: 0.86-,35.57, p=.040; I2 =0%, pheterogeneity =.918). The sensitivity analyses showed that the results were robust. High-flow nasal cannula did not significantly decrease partial pressure of carbon dioxide or increase partial pressure of oxygen in chronic obstructive pulmonary disease patients, which is different from the previous meta-analysis, but it decreases transcutaneous partial pressure of carbon dioxide and increased 6-min walking distance. This meta-analysis shows that in patients with chronic obstructive pulmonary disease, high-flow nasal cannula improves both transcutaneous partial pressure of carbon dioxide and 6-min walking distance, suggesting the high-flow nasal cannula has benefits in the management of chronic obstructive pulmonary disease. Considering that the literature suggests no impact of high-flow nasal cannula on hospitalisation and mortality, the benefits of high-flow nasal cannula might be limited to the patients who survive the chronic obstructive pulmonary disease events. Still, the global impact of high-flow nasal cannula on the quality of life of patients with chronic obstructive pulmonary disease should be examined.

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.

Preference of neuromuscular patients regarding equipment for daytime mouthpiece ventilation: A randomized crossover study.

Patients with neuromuscular disorders (NMDs) are likely to develop respiratory failure which requires noninvasive ventilation (NIV). Ventilation via a mouthpiece (MPV) is an option to offer daytime NIV. To determine the preferred equipment for MPV by patients with NMDs. Two MPV equipment sets were compared in 20 patients with NMDs. Set 1, consisted of a non-dedicated ventilator for MPV (PB560, Covidien) with a plastic angled mouthpiece. Set 2, consisted of a dedicated MPV ventilator (Trilogy 100, Philips Respironics) without backup rate and kiss trigger combined with a silicone straw mouthpiece. The Borg dyspnea score, ventilator free time, transcutaneous oxygen saturation (SpO2) and carbon dioxide tension (TcCO2 ) were recorded with and without MPV. Patient perception was assessed by a 17-items list. Carbon dioxide tension measurements and total perception score were not different between the two MPV sets. Dyspnea score was lower with the non-dedicated versus dedicated equipment, 1 (0.5) versus 3 (1-6), P<0.01. All patients with a ventilator free time lower than 6hours preferred a set backup rate rather than a kiss trigger. Sixty five percent of patients preferred the commercial arm support and 55% preferred the plastic angled mouthpiece. Dedicated and non-dedicated MPV equipment are deemed effective and comfortable. Individualization of arm support and mouthpiece is advised to ensure success of MPV. A ventilator free time lower than 6hours seems to be a useful indicator to a priori set a backup rate rather than a rate at zero associated to the kiss trigger.

Demonstrating the Potential of Using Transcutaneous Oxygen and Carbon Dioxide Tensions to Assess the Risk of Pressure Injuries.

Pressure injuries have a high incidence in elderly and critically ill patients, and can endanger lives in severe cases. The key to reducing the incidence of pressure injuries is to find an objective, noninvasive, automatic and consistent scientific method for assessing pressure injuries. To serve this need, we conducted a clinical study to investigate the potential of using transcutaneous oxygen tension (TcPO2) and transcutaneous carbon dioxide tension (TcPCO2) for assessing pressure injuries. From the results of the study we found that first, the values of TcPO2 and TcPCO2 are sensitive to the change of pressure imposed on the measured region and to the risk status of a pressure injury when a pressure is imposed. Second, the magnitude of change in TcPO2 and TcPCO2 is higher in patients with a high risk of a pressure injury compared with those who have a low risk. Third, TcPO2 and TcPCO2 are both significantly correlated with the Braden score, the widely used score for assessing the risk of a pressure injury. Therefore, TcPO2 and TcPCO2 have a potential to be an effective and convenient scientific tool for assessing the risk of pressure injuries.

High flow or titrated oxygen for obese medical inpatients: a randomised crossover trial.

To compare the effects on transcutaneous carbon dioxide tension (Ptco2) of high concentration and titrated oxygen therapy in medical inpatients with morbid obesity who were not selected for a pre-existing diagnosis of obesity hypoventilation syndrome. A randomised, crossover trial undertaken between February and September 2015. Internal medicine service, Wellington Regional Hospital, New Zealand. 22 adult inpatients, aged 16 years or more, with a body mass index exceeding 40 kg/m2. Participants received in random order two 60-minute interventions, with a minimum 30-minute washout period between treatments: titrated oxygen therapy (oxygen delivered, if required, via nasal prongs to achieve peripheral oxygen saturation [Spo2] of 88-92%), and high concentration oxygen therapy (delivered via Hudson mask at 8 L/min, without regard to Spo2). Ptco2 and Spo2 were recorded at 10-minute intervals. Ptco2 at 60 minutes, adjusted for baseline. Baseline Ptco2 was 45 mmHg or lower for 16 participants with full data (73%). The mean difference in Ptco2 between high concentration and titrated oxygen therapy at 60 minutes was 3.2 mmHg (95% CI, 1.3-5.2 mmHg; P = 0.002). High concentration oxygen therapy increases Ptco2 in morbidly obese patients. Our findings support guidelines that advocate oxygen therapy, if required in patients with morbid obesity, be titrated to achieve a target Spo2 of 88-92%. Australian New Zealand Clinical Trials Registry, ACTRN12610000522011.

Physiological effects of titrated oxygen via nasal high-flow cannulae in COPD exacerbations: A randomized controlled cross-over trial.

Increased arterial carbon dioxide tension (PaCO2 ) is an important complication of acute exacerbations of COPD. The effects of nasal high-flow cannulae (NHF) on PaCO2 in patients with COPD exacerbations, and whether this therapy should be used in this clinical situation, are less certain. We aimed to investigate the effect of NHF on PaCO2 in patients admitted to hospital with a COPD exacerbation. We performed a single-centre randomized controlled cross-over trial in 24 hospital inpatients with acute exacerbations of COPD receiving oxygen via standard nasal prongs (SNPs). Patients received both supplemental oxygen via NHF (35 L/min) and SNP for 30 min each, with oxygen titrated to maintain the patient's baseline oxygen saturation, measured by pulse oximetry (SpO2 ). Interventions were administered in random order with a minimum 15-min washout between interventions. The primary outcome was difference in transcutaneous carbon dioxide tension (PtCO2 ) at 30 min adjusted for time zero. The difference in PtCO2 adjusted for time zero was lower after 30 min for NHF compared with SNP (-1.4 mm Hg (95% CI: -2.2 to -0.6), P = 0.001). There was no difference in SpO2 at 30 min (-0.02% (95% CI: -0.8 to 0.7), P = 0.96). The reduction in respiratory rate for NHF at 30 min was not statistically significant (-2.0 breaths/min (95% CI: -4.5 to 0.4), P = 0.099). Short-term use of NHF results in a small reduction in PtCO2 compared with SNP in patients with acute exacerbations of COPD, but whether this is clinically significant is uncertain.

Short term general anesthesia for retro-bulbar block in ophthalmic surgery generates no significant hypercapnia.

To assess the impact of short time hypnosis for retro-bulbar anesthesia on ventilation in patients undergoing ophthalmic surgery of the anterior eye chamber. In all patients, a combined continuous transcutaneous carbon dioxide tension (PtcCO2) and partial oxygen saturation (SpO2) measurement was applied in addition to routine monitoring. To enable unconscious application of retro-bulbar anesthesia, intravenous thiopental was given in one to multiple bolus doses. Transient breathing support included chin lift, Esmarch maneuver and manual hand-bag ventilation via face mask. Main endpoints were apnea time, recovery time according to the Richmond Agitation Sedation Scale, as well as SpO2 and PtcCO2 readings at predefined time points. Fifty-two patients with a mean age of 68 ± 13years were included. Average thiopental dose was 2.7 ± 0.6mg/kg. In seven (13.5%) patients repeated doses of thiopental were necessary to a total of 3.3 ± 1.1mg/kg. Except one patient, no severe, significant or clinical relevant hypercapnia or desaturation periods were observed, and the occurring elevation of PtcCO2 values did not correlate with the application of repeated doses of thiopental or the need for the Esmarch maneuver. Higher PtcCO2 values were associated with the presence of hypertension and smoking. Apnea (p < 0.001) and recovery (p = 0.003) time were significantly prolonged in the patients needing the Esmarch maneuver. Short term anesthesia with thiopental in ophthalmic surgery is associated with a mild but not clinically relevant hypercapnia.

The Effectiveness of Mechanical Insufflator/Exsufflator in Sputum Discharge Among Intensive Care Unit Admitted Patients

Background: Mechanical insufflator/exsufflator has been introduced in relevant fields during the recent decades and provides intermittent negative and positive pressures to simulate an effective cough in patients. The current study attempted to assess the effectiveness of mechanical insufflator/exsufflator in secretion evacuation from patients’ airways in an ICU setting. Methods: Through a randomized clinical trial study at a university referral center for pulmonary diseases, patients with neuromuscular disorders causing face sputum discharge problems, were recruited. Patients with chest tube and positive cases for human immunodeficiency virus (HIV) in addition to people with predisposing problems, who confounded the study, were excluded. Physical examination and the consequent findings, such as chest auscultation, peak cough flow, the color of sputum, and patient’s general condition were recorded before dividing the participants to two groups of cases and controls. The control group only experienced traditional techniques of physiotherapy, such as respiratory exercises, chest massage and percussion against the other group, who used mechanical insufflator/exsufflator under the brand “Cough Assist ®” in coping mode (SYNC) beside the mentioned traditional methods, available for the controls. Visual analog scale (VAS) was used for the two former items with scores between 0 and 10, considering higher scores for more critical or worse conditions. Results: In total, the 40 cases enrolled in the trial were divided to 20 cases and 20 controls. The mean age ± standard deviation was 32.3 ± 4 years in controls and 31.8 ± 3.4 years in others. The results showed statistically significant differences between the groups. Heart rate, O2 saturation, and Ptcco2 (transcutaneous carbon dioxide tension) were the only parameters, which were not different comparing cases and controls. Chest auscultation and sputum growth had the most improvement in cases. Concerning the peak cough flow, an absolute rise was found in mechanical insufflator/exsufflator when compared with traditional methods (43 cmH2O in cases versus 8 cmH2O in controls). Sputum transparence was the other parameter, which differed absolutely after using the machine in the case group (56% versus 44% in controls). Conclusions: To conclude, MIE deserves greater focus in a wide area to assist patients with impaired cough expectorate and their secretions using a device with no serious complications like barotrauma, pneumothorax, cardiovascular consequences or even postoperative wound dehiscence in relevant surgery cases.

Flexible bronchoscopy with moderate sedation in COPD: a case-control study.

BackgroundFlexible bronchoscopy is increasingly used for diagnostic and therapeutic purposes. We aimed to examine the safety of flexible bronchoscopy with moderate sedation in patients with COPD.MethodsThis study is a prospective, longitudinal, case–control, single-center study including 1,400 consecutive patients. After clinical and lung function assessments, patients were dichotomized in COPD or non-COPD groups. The primary end point was the combined incidence of complications.ResultsThe incidence of complications was similar in patients with and without COPD and independent of forced expiratory volume in the first second % predicted. Patients with COPD more frequently required insertion of a naso- or oropharyngeal airway; however, this difference was no longer significant after adjustment for age, gender, and duration of the procedure. Hypotension was significantly more common among patients with COPD. The number of episodes of hypoxemia ≤90% did not differ between the groups. However, patients with COPD had a lower mean and nadir transcutaneous oxygen saturation. Transcutaneous carbon dioxide tension (PtcCO2) change over the time course was similar in both groups, but both peak PtcCO2 and time on PtcCO2 >45 mmHg were higher in the COPD group. There were no differences in patient-reported outcomes.ConclusionThe safety of flexible bronchoscopy is similar in patients with and without COPD. This finding confirms the suitability of the procedure for both clinical and research indications.

EEG maturation and stability of cerebral oxygen extraction in very low birth weight infants.

Fractional cerebral tissue oxygen extraction (FTOE) can be continuously monitored by simultaneous near-infrared spectroscopy (NIRS) and pulse oximetry. The objective of this study is to test the hypothesis that in very low birth weight (VLBW) infants, the more mature EEG activity is, the less variable FTOE is. A prospective study was conducted on VLBW infants (< 1500 g and ⩽ 34 weeks gestation) without significant brain injury. Simultaneous continuous two-channel electroencephalography (EEG), NIRS and pulse oximetry were recorded. Absolute and relative powers of EEG in the delta, theta, alpha, beta and total frequency bands have been calculated. FTOE variability was calculated on two scales: short scales (3 to 20 s) and long scales (20 to 150 s). FTOE variability was examined against changes in relative spectral power of different EEG bands. We evaluated 67 studies performed on 46 VLBW infants. Average study duration was 21.3 ± 5.5 h. Relative power of delta band positively correlated with FTOE short- and long-scale variability (r=0.45, P<0.001; r=0.44, P<0.001, respectively). Relative power of alpha bands negatively correlated with FTOE short- and long-scale variability (r=-0.38, P=0.002; r=-0.42, P<0.001, respectively). These correlations continued to be significant when controlling for sex, small for gestational age, postmenstrual age, being on respiratory support, hemoglobin concentration, systemic oxygen saturation and transcutaneous carbon dioxide tension. Increased maturation of EEG activity is associated with decreased variability in cerebral oxygen extraction. The implications of increased variability in FTOE on brain injury in premature infants need further exploration.

P94. Effects of non-invasive ventilation on sleep and nocturnal ventilation in patients with amyotrophic lateral sclerosis

The majority of patients with amyotrophic lateral sclerosis (ALS) develop chronic ventilatory failure which substantially adds to disease burden and massively affects prognosis. Both quality of life and life expectancy can be influenced by non-invasive ventilation (NIV). Initiation of NIV is indicated in case of sleep-disordered breathing (SDB), daytime hypercapnia, or significant diaphragmatic weakness. Since nocturnal hypercapnia and sleep apnea substantially reduce sleep quality we investigated the effects of NIV on objective measures of both sleep quality and ventilation in patients with ALS. We retrospectively analysed polysomnography (PSG) and oxycapnometry (OC) data obtained from patients with ALS in whom NIV was initiated based on the presence of SDB. PSG and OC were used in all patients for establishing the diagnosis of SDB (t0), for treatment initiation (t1) and for follow-up examination at 3, 9, and 15 months (t2, t3, and t4, respectively). As outcome parameters we chose sleep efficiency (SE), slow wave sleep percentage (N3), REM sleep percentage (REM), apnea hypopnea index (AHI), oxygen desaturation index (ODI), desaturation time (T < 90), respiratory rate (RR) and maximal nocturnal transcutaneous carbon dioxide tension (tc-CO2). Records from 62 patients were analysed. Mean age was 63.2 years, and mean disease duration was 23.1 months. 28 patients were female, and 22 patients reported bulbar onset of ALS symptoms. All patients were started on pressure and volume-controlled bilevel ventilation via a nasal or oronasal interface. Comparison of the above parameters at t0 and t1 showed significant improvement of AHI and ODI, oxygenation, CO2 elimination, and sleep stage duration (N3, REM) in the first night on NIV. Sleep efficiency was neither improved nor reduced by NIV. At t2, t3 and t4 the number of PSG records available became smaller because in many patients, follow-up studies included rather polygraphy than PSG (t2, 33 patients, t3, 15 patients, t4, 11 patients with PSG data). ANOVA for repeated measures revealed stable normoxia and eucapnia under bilevel ventilatory support. Objective measures of sleep quality did not show any significant change over time. Increasing duration of NIV per day was found in all patients in the course of the disease, reflecting disease progression. In patients with ALS, NIV initiation significantly improves objective sleep quality, oxygenation and CO2 elimination in the first night of treatment. Over time, NIV is able to warrant nocturnal normoventilation with only minor changes to ventilator settings. Objective sleep quality does not significantly change in the first 15 months after onset of NIV.

Effects of non-invasive ventilation on objective sleep and nocturnal respiration in patients with amyotrophic lateral sclerosis.

In amyotrophic lateral sclerosis (ALS), non-invasive ventilation (NIV) is indicated if sleep-disordered breathing (SDB), daytime hypercapnia, or significant diaphragmatic weakness is present. We investigated both short-term and long-term effects of NIV on objective measures of sleep and nocturnal respiration in patients with ALS. Polysomnography (PSG) and transcutaneous capnography were conducted for diagnosis of SDB (T0), for treatment initiation (T1), and follow-up 3, 9, and 15months later (T2, T3, and T4, respectively). Records from 65 patients were retrospectively analyzed at T0 and T1. At subsequent timepoints, the number of full data sets decreased since follow-up sleep studies frequently included polygraphy rather than PSG (T2, 38 patients, T3, 17 patients, T4, 11 patients). At T0, mean age was 63.2years, 29 patients were female, and 22 patients had bulbar ALS. Immediate sequelae of NIV initiation included significant increases of slow wave sleep, rapid eye movement sleep, and oxygen saturation. Mean apnea-hypopnea index, respiratory rate, and the maximum transcutaneous carbon dioxide tension were reduced. At T2-T4, normoxia and normocapnia were preserved. Sleep quality measures showed no alteration as diurnal use of NIV gradually increased reflecting disease progression. In contrast to previous reports, improvement of sleep and respiratory outcomes was found in both non-bulbar and bulbar patients. NIV significantly improves objective sleep quality and SDB in the first night of treatment in patients with bulbar and non-bulbar ALS. NIV warrants nocturnal normoventilation without deterioration of sleep quality in the long run with only minor changes to ventilator settings.

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.

Determinants of Transcutaneous Ear Lobe CO2 Tension (PtCO2) at 37°C During On-Pump Cardiac Surgery.

There are no available criteria for determining the optimal flow rate and mean arterial pressure level in patients undergoing cardiopulmonary bypass (CPB). Transcutaneous carbon dioxide tension (PtCO2) has been proposed for microcirculation monitoring and it could be useful for guiding hemodynamic optimization under CPB. The goal of this exploratory study was to determine the factors that influence PtCO2 variations during CPB. Cutaneous ear lobe CO2 tension was monitored along with hemodynamic parameters every 10 minutes during CPB, until aortic unclamping. French university teaching hospital. Patients scheduled for cardiac surgery requiring CPB were prospectively included. None. A total of 41 patients were included (520 observations). There was a statistically significant association between PaCO2 and PtCO2 (beta = 0.493 [0.154-0.832], p = 0.043), mostly when PaCO2 was outside the normal range. When PaCO2 was normal, PtCO2 was inversely correlated with mean arterial pressure (after adjustment for PaCO2 and body temperature: Beta -0.245, SE = 0.037, p<0.001) but not with CPB flow rate (p = 0.11). The factors that influence PtCO2 during CPB cardiac surgery are PaCO2, body temperature, and mean arterial pressure. When PaCO2 is normal, a PtCO2 elevation might be explained by insufficient mean arterial pressure. Whether low PtCO2 values during CPB should trigger the administration of vasoconstrictors remains to be evaluated.

Transcutaneous continuous carbon dioxide tension monitoring reduced incidence, degree and duration of hypercapnia during combined regional anaesthesia and monitored anaesthesia care in shoulder surgery patients

We studied the impact of transcutaneous continuous carbon dioxide tension (PtcCO2) monitoring on ventilation and oxygenation during monitored anaesthesia care (MAC) in patients scheduled for shoulder surgery with continuous interscalene block. 50 patients were randomised either to the intervention (I-group) or the control (C-group) group. In both groups MAC was performed using target controlled infusion of propofol and remifentanil. MAC regimen was adapted to PtcCO2 values in the I-group, whereas the C-group was blinded for these values. Primary outcome was the incidence, degree and duration of hypoventilation stages. In the I-group and the C-group the mean ± SD [range] of PtcCO2 and PaCO2 was 5.79 ± 0.84 [4.37] and 5.44 ± 0.59 [2.78] kPa, as well as 6.41 ± 1.17 [6.29] and 6.01 ± 0.96 [7.15] kPa. Periods of PtcCO2/PaCO2 > 6.5 kPa were 21.0 ± 35.7/1.2 ± 4.2 min in the I-group and 45.6 ± 40.0/18.6 ± 26.8 min in the C-group. Severe hypercapnia (PtcCO2 and/or PaCO2 > 7.5 kPa) was dected in 3/0 patients of the I-group and in 10/3 patients of the C-group. PtcCO2 and PaCO2 showed a strong correlation (r = 0.78), but only moderate agreement with a mean bias (LOA) of -0.37 (-1.69; +0.95) kPa showing an overestimation of the PaCO2. Sensitivity and specificity of PtcCO2 to detect changes of PaCO2 was 0.94 and 0.56, respectively. In no patient SpO2 or SaO2 values lower than 90% were measured. Despite a moderate agreement between PaCO2 and PtcCO2 the PtcCO2 monitoring significantly reduced incidence, degree and duration of hypercapnia in shoulder surgery patients with MAC.

Disordered breathing during sleep and exercise in idiopathic pulmonary fibrosis and the role of biomarkers.

Idiopathic pulmonary fibrosis (IPF) patients report fatigue, possibly reflecting sleep disturbance, but little is known about sleep-related changes. We compared ventilation and gas exchange during sleep and exercise in a cohort of IPF patients, and evaluated associations with selected biological markers. Twenty stable IPF patients (aged 67.9 ± 12.3 [SD]) underwent overnight polysomnography following an acclimatization night. Cardiopulmonary exercise testing was performed and inflammatory markers measured including TNF-α, IL-6, CXCL8, C-C motif ligand 18 (CCL-18) and C-reactive protein (CRP) RESULTS: Nine patients had sleep-disordered breathing (SDB) with an apnea-hypopnea frequency (AHI) ≥ 5/h, but only two had Epworth sleepiness score ≥ 10, thus having an obstructive sleep apnea syndrome. Sleep quality was poor. Transcutaneous carbon dioxide tension (PtcCO2) rose by 2.56 ± 1.59 kPa overnight (P = 0.001), suggesting hypoventilation. Oxygen saturation (SaO2) was lower during sleep than exercise (P < 0.01), and exercise variables correlated with resting pulmonary function. CCL-18 and CRP levels were elevated and correlated with PtcCO2 rise during sleep (P < 0.05). CCL-18 negatively correlated with diffusion capacity of carbon monoxide (DLCO), arterial oxygen (PaO2) and mean arterial carbon dioxide (PaCO2) (P < 0.05) and CRP negatively correlated with DLCO, PaO2, sleep SaO2 and oxygen uptake (VO2) during exercise (P < 0.05). IPF patients desaturate more during sleep than exercise; thus, nocturnal pulse oxymetry could be included in clinical assessment. CCL-18 and CRP levels correlate with physiological markers of fibrosis.

Analysis of mean transcutaneous carbon dioxide tension during polysomnographic extended monitoring in Sarah Network Hospital patients

Introduction Transcutaneous CO2 (PtcCO2) monitoring is a good non-invasive method of analysis to understand the PtcCO2 behavioral tendency during sleep in a great variety of respiratory sleep disorders (RDB). When a patient is under investigation for sleep disorders like Sleep Apnea or Obesity/Hypoventilation Syndrome, this method can help the physician both in the diagnostic criteria and in the follow up of therapeutic responses. Objective: To analyze the PtcCO2 in 179 consecutive patients submitted to a polysomnographic research at Sarah's Neurophysiology Department and to identify the normal variety of mean PtcCO2 during the record of those patients that are considered normal ( N =53). The normality distribution trend was also studied. Materials and methods 179 patients were submitted to a polysomnographic record (PSGR) with concomitant measure of PtcCO2 using a TCM4 monitor (Radiometer, Switzerland). The group was classified into normal and non-normal patients. The normal group (N53) had an Apnea/hypopnea index 5events/hour of sleep. The exclusion criteria were: existence of respiratory comorbidities, smoking history, existence of neurologic diseases that could be responsible for dynamic respiratory commitment and/or central PCO2 deregulation. The age ranged from 7 to 76years old. Results The age ranged from 7 to 76years old in the normal group (mean of 43.13 and SD of 16.46); 32 patients were female and 21 were male. .The Shapiro-Wilk test with Liliefors correction was accomplished to analyze the tendency to normality of data (sig 0.379). The mean of mean PtcCO2 was 41.325 (confidence interval of 95% ranging from 40.122 to 42.325). The standard deviation was 4.363 and a 2 ∣ O reference was used for this appraisal. The normal values ranged from > 33.0 to > 50.0mmHg of PtcCO2. Conclusion The mean PtcCO2 values in the normal group showed a Gaussian distribution and in 98.7% of them, the PtcCO2 ranged from 33.1 to 50.0mmHg (SD 4.363 with 2 ∣ O of interval). Those results allowed the establishment of mean PtcCO2 normative values to normal subjects. Acknowledgements Sarah Network Hospital.