Transcutaneous Carbon Dioxide Pressure Research Articles

The relation of lactate level and carbon dioxide pressure discrepancies between transcutaneous and arterial measurements.

Partial carbondioxide pressure of the arterial blood (PaCO2) is used to evaluate alveolar ventilation. Transcutaneous carbon dioxide pressure (TcCO2) monitoring has been developed as a non-invasive (NIV) alternative to arterial blood gas analysis (ABG). Studies have shown that decreased tissue perfusion leads to increased carbondioxide (CO2). The use of transcutaneous capnometry may be unreliable in patients with perfusion abnormalities. In this study, we aimed to evaluate the relation between TcCO2-PaCO2 and lactate level which is recognized as a marker of hypoperfusion. In this prospective cohort study in critical care patients with hypercapnic respiratory failure (PaCO2 ≥45 mmHg) who received NIV between April 2019 and January 2020 in the intensive care unit were enrolled in the study. Patients' simultaneously measured TcCO2 and PaCO2 values of hypercapnic patients were recorded. Each paired measurement was categorized into two groups; normal lactate (<2 mmol/L) and increased lactate (≥2 mmol/L). A total of 116 paired TcCO2 and PaCO2 measurements of 29 patients were recorded. Bland-Altman analysis showed the mean bias between the TcCO2 and PaCO2 and 95% limits of agreement (LOA) in all measurements (1.75 mmHg 95% LOA -3.67 to 7.17); in the normal lactate group (0.66 mmHg 95% LOA -1.71 to 3.03); and in the increased lactate group (5.17 mmHg 95% LOA -1.63 to 11.97). The analysis showed a correlation between lactate level and the difference between TcCO2 and PaCO2 (r= 0.79, p< 0.001) and a negative correlation between mean blood pressure and the difference between TcCO2 and PaCO2 (r= -0.54, p= 0.001). Multiple regression analysis results showed that lactate level was independently associated with increased differences between TcCO2 and PaCO2 (Beta= 0.875, p< 0.001). TcCO2 monitoring may not be reliable in patients with increased lactate levels. TcCO2 levels should be checked by ABG analysis in these patients.

Transcutaneous oximetry of angiosomes of maxillary and facial arteries

Aim. To qualitatively predict and control the quality of periodontal diseases treatment, to determine changes in the transcutaneous pressure of oxygen and carbon dioxide in angiosomes of maxillary and facial arteries in healthy adults. Materials and methods. 17 healthy people participated in this study. There were 10 (58 %) men aged 24 (22–27), weight 66 (62–80) kg and height 175 (169–182) cm and 7 (42 %) women, whose average age was 23 (20–26) years old, weight 58 (47–72) kg, height 165 (160–178) cm. Results. The highest values of tissue perfusion with oxygen were observed in the angiosomes of the upper jaw compared to the angiosomes of the lower jaw, where this indicator ranged from 105 to 153 mm Hg. On the lower jaw, the maximum value of the regional perfusion index (RPI) of 1.70 ± 0.04 was observed at the point of measurement where a. mentalis exits through the homonymous chin orifice, anastomosing with the branches of a. facialis. The highest values of tissue perfusion with carbon dioxide were observed in angiosomes of the lower jaw (28–36 mm Hg). In general, non-invasive measurements of oxygen and carbon dioxide pressure in tissues allow more accurate and direct visualization and control of microcirculation in the tissues of the corresponding angiosomes. Conclusions. The index of regional perfusion on the upper jaw is normally in the range of 2.2 to 2.6 (р &lt; 0.0001). In the angiosome of the lower jaw, the RPI value is within 1.3–1.7, respectively (p &lt; 0.0001). The tension of carbon dioxide in the tissues of the upper and lower jaw averages 31–34 mm Hg (р &lt; 0.05), reaches its maximum in the zones of the lowest oxygen perfusion.

Hypoventilation in patients with Prader-Willi syndrome across the pediatric age.

Few data on alveolar hypoventilation in Prader-Willi syndrome (PWS) are available and the respiratory follow-up of these patients is not standardized. The objectives of this study were to evaluate the prevalence of alveolar hypoventilation in children with PWS and identify potential risk factors. This retrospective study included children with PWS recorded by polysomnography (PSG) with transcutaneous carbon dioxide pressure (PtcCO2) or end-tidal CO2 (ETCO2) measurements, between 2007 and 2021, in a tertiary hospital center. The primary outcome was the presence of alveolar hypoventilation defined as partial pressure of carbon dioxide (pCO2) ≥ 50 mmHg during ≥2% of total sleep time (TST) or more than five consecutive minutes. Among the 57 included children (38 boys, median age 4.8 years, range 0.1-15.6, 60% treated with growth hormone [GH], 37% obese), 19 (33%) had moderate-to-severe obstructive sleep apnea syndrome (defined as obstructive apnea-hypopnea index ≥5/h) and 20 (35%) had hypoventilation. The median (range) pCO2 max was 49 mmHg (38-69). Among the children with hypoventilation, 25% were asymptomatic. Median age and GH treatment were significantly higher in children with hypoventilation compared to those without. There was no significant difference in terms of sex, BMI, obstructive or central apnea-hypopnea index between both groups. The frequency of alveolar hypoventilation in children and adolescents with PWS is of concern and may increase with age and GH treatment. A regular screening by oximetry-capnography appears to be indicated whatever the sex, BMI, and rate of obstructive or central apneas.

Intra-Observer and Inter-Observer Reliability of Ankle Circumference Measurement in Patients with Diabetic Foot: A Prospective Observational Study.

Inflammation, being a typical response to vascular tissue alterations, induces variations in tissue oxygen diffusion pressure. Diabetic microangiopathy, an inflammatory process, is characterized by an increase in vascular flow at rest, reduced venous and arteriolar responses, and increased capillary permeability, resulting in oedema development, decreased transcutaneous oxygen pressure, and increased transcutaneous carbon dioxide pressure. This phenomenon potentially hampers ulcer healing. Although the figure-of-eight method has proven to be a reliable, valid, quick, and efficient test for assessing foot and ankle measurements in patients with oedema and compromised skin integrity, it has not been studied in patients with diabetic foot. The aim of this study was to determine and compare the intra- and inter-observer variabilities of the figure-of-eight method in patients with diabetic foot. A prospective observational and cross-sectional study was undertaken, involving sixty-one subjects from a specialized Diabetic Foot Unit. Three investigators with varying levels of experience independently measured the subjects to assess both intra-observer and inter-observer variability. The evaluation was conducted using the Intraclass Correlation Coefficient (ICC). In the statistical analysis, an ICC of 0.93, adjusted using a 95% confidence interval (CI), was obtained for inter-observer reliability ICC, indicating excellent reliability among observers. Furthermore, an ICC of 0.98 with a 95% CI was obtained for the intra-observer reliability analysis, indicating excellent reliability. The results support using this test during the clinical management of oedema in patients with diabetic foot. The absence of an objective, fast, and readily available diagnostic method for oedema in diabetic foot patients in clinical practice might pose a limitation. Subsequent research should tackle this issue and explore the correlation between ankle perimeter measurements and other clinical outcomes in diabetic foot patients, including wound healing and quality of life.

Linear versus Quadratic Detrending in Analyzing Simultaneous Changes in DC-EEG and Transcutaneous pCO2.

Physiological direct current (DC) potential shifts in electroencephalography (EEG) can be masked by artifacts such as slow electrode drifts. To reduce the influence of these artifacts, linear detrending has been proposed as a pre-processing step. We considered quadratic detrending, which has hardly been addressed for ultralow frequency components in EEG. We compared the performance of linear and quadratic detrending in simultaneously acquired DC-EEG and transcutaneous partial pressure of carbon dioxide during two activation methods: hyperventilation (HV) and apnea (AP). Quadratic detrending performed significantly better than linear detrending in HV, while for AP, our analysis was inconclusive with no statistical significance. We conclude that quadratic detrending should be considered for DC-EEG preprocessing.

Detection of episodic nocturnal hypercapnia in patients with neurodegenerative disorders.

Episodic nocturnal hypercapnia (eNH) in transcutaneous carbon dioxide pressure (PtcCO2) corresponding to rapid eye movement sleep hypoventilation is a useful biomarker for detecting nocturnal hypoventilation. However, the relationship between eNH and neurodegenerative diseases with sleep-related breathing disorders (SRBDs) is unknown. The aim of this study was to evaluate the relationship between eNH and nocturnal hypoventilation in neurodegenerative diseases. Patients with neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), multiple system atrophy (MSA), Parkinson's disease, progressive supranuclear palsy, corticobasal syndrome, and idiopathic normal pressure hydrocephalus, were enrolled and received overnight PtcCO2 monitoring. The patients were divided into groups for eNH and sleep-associated hypoventilation (SH) prevalence analysis: A (ALS), B (MSA), and C (others). Among 110 patients, twenty-three (21%) and 10 (9%) of the patients met eNH and SH criteria, respectively. eNH and SH were significantly more frequent in groups A and B than in C. The prevalence of SH in the patients with eNH was 39% whereas most of patients with SH (90%) presented with eNH. Among patients withdaytime carbon dioxide pressure in arterial blood ≤ 45mmHg, eNH frequency was 13%, whereas none of the patients met SH criteria. The frequency of noninvasive positive pressure ventilation after PtcCO2 monitoring was significantly higher in those with than without eNH. eNH is common in patients with MSA and ALS who present with SRBD. eNH with overnight PtcCO2 monitoring is a useful biomarker to detect hypoventilation among neurodegenerative diseases with different SRBD mechanisms.

The Effect of High Flow Nasal Oxygen Cannula Versus Conventional Oxygen Therapy in COPD Patients with Indication for Long-term Oxygen Therapy: A Pilot Randomized Crossover Study

Background: Long-term oxygen therapy (LTOT) is recommended to be used in stable chronic obstructive pulmonary disease (COPD) patients with severe resting hypoxemia. High-flow nasal oxygen cannula (HFNC) demonstrated benefits in acute hypoxemic respiratory failure. The mechanisms of HFNC by washing out dead space and decreasing work of breathing may be also beneficial in COPD patient who has an indication for LTOT. Objective: To compare the effect of HFNC versus conventional oxygen therapy (COT) in terms of respiratory rate, gas exchange, and health-related quality of life. Materials and Methods: A pilot randomized crossover study was conducted in eleven stable COPD patients. Subjects were randomly assigned to HFNC at a flow rate of 30 L/minute or simple nasal cannula at 2 to 4 L/minute for two weeks in a cross-over fashion. The primary outcome was respiratory rate. The secondary outcomes included blood pressure, heart rate, oxygen saturation (SpO₂), transcutaneous carbon dioxide pressure (PtcCO₂), and St.George’s Respiratory Questionnaire (SGRQ) score. Results: The duration of HFNC and COT use was 8 (IQR 3 to 13) and 14 (IQR 10 to 20) hours/day, respectively (p=0.039). Respiratory rate was significantly lower with HFNC compared to COT at 18 breaths/minute (IQR 16 to 20) versus 22 breaths/minute (IQR 20 to 25) , respectively (p=0.018). SpO₂ was significantly higher with HFNC compared to COT (p=0.046). No differences in blood pressure, heart rate, PtcCO₂, and SGRQ score were observed between the two groups. No serious adverse event from HFNC was observed. Conclusion: The present pilot study demonstrated that HFNC was tolerable in patients with stable COPD who had an indication for LTOT. Respiratory rate was significantly lower and SpO₂ was significantly higher with HFNC compared to COT. Another study with larger sample size is needed to further clarify the efficacy of HFNC in stable COPD patients. Keywords: Chronic obstructive pulmonary disease; Dyspnea; High-flow nasal cannula; Oxygen therapy; Respiratory rate

Limitations of the apnea-hypopnea index in children and young adults with neuromuscular disorders

There are no validated criteria to initiate noninvasive ventilation (NIV) in children and young adults with neuromuscular disease (NMD). In order to analyze NIV initiation criteria, we reviewed the polysomnography (PSG) criteria that led to the initiation of NIV in 61 consecutive patients with NMD, median age 4.1 (0.8–21) years, who had a PSG during their routine care. NIV was initiated on abnormal PSG data (apnea-hypopnea index (AHI) > 10 events/h and/or a transcutaneous carbon dioxide pressure > 50 mmHg and/or a pulse oximetry 〈 90%, both during at least 2% sleep time or 〉 5 consecutive minutes) in 11 (18%) patients. Six of these 11 patients had an AHI ≤ 10 events/h and would not have been ventilated if only AHI was retained. However, one of these 6 patients had isolated nocturnal hypoxemia, 3 isolated nocturnal hypercapnia and 2 abnormal respiratory events. Six (10%) patients with a normal PSG were started on NIV on clinical criteria. Our results show the limitation of the AHI when taken as the unique PSG criterion for NIV initiation in young patients with NMD and underline the need to include also abnormalities of overnight gas exchange into the NIV decision-making process.

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

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. 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. 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. 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.

BIOMICROSCOPY HIGHLIGHTS THE EFFICACY OF SKIN GRAFT ON MICROVASCULAR PARAMETERS IN NON-DIABETIC ULCERS

Objective. Laser Doppler owmetry (LDF), transcutaneous partial pressure of oxygen (pO2) and carbon dioxide (pCO2), and Biomicroscopy (BM) are exams used in daily clinical practice to assess capillary and microvascular functionality. Skin graft (SG) is a well-established intervention for the treatment of chronic lower leg ulcers. The sequence of improvements at the microvascular and macrovascular level, letting to a successful outcome after SG, is not yet been determined. This observation aims to determine which parameters of capillary functionality could show how SG takes to a positive outcome. Methods. In this trial, cutaneous perfusion, district microcirculatory reserve, and variation of cutaneous perfusion induced by the postural vasoconstriction reex (VAR) were measured with LDF as the number and diameter of capillary loops at 1 cm, 2 cm, and 4 cm from the big toe nailfold and the ulcer edge. Cutaneous gas exchanges were detected through pO2 and pCO2, and capillary density and average diameter loops were recorded with BM. Because of the exploratory nature of this study, consecutive patients' afferent to our structure receiving SG for the treatment of non-diabetic chronic non-relapsing ulcers on the lower limb, were assessed before and 5 days after SG. All measures were collected by the same operator and SG was performed in a standardized manner. Paired non-parametric statistical tests were performed to compare basal with after SG measurements. Results. All 13 patients observed had a clinically successful outcome after SG in terms of pain reduction, absence of SG complications, and absence of secretion. The median number of capillary loops changed at the different evaluation points (e.g. from 19 vs 21 (P=.004) at the big toe nailfold and 16 vs. 22 (P&lt;.001) at 2 cm from the ulcer edge). The median diameter of capillary loops changed at the different evaluation points (e.g. at the big toe nailfold decreased from 24mm to 19mm (P=.004) and from 16mm to 22mm (P=.031) at 2 cm from the ulcer). The median values of pO2 increased from 10 mmHg to 36 mmHg (P=.005) on supine and from 28 mmHg to 3 mmHg (P=.006) at the dependent lower limb None of the LDF measures, or pCO2.Conclusion.In this exploratory evaluation, BM measurements reveal, for the rst time, a successful outcome after SG for the treatment of chronic lower limb skin ulcers, especially on the big toe nailfold, 1 and 2 cm from the ulcer. The improvement observed at the capillary level seems parallel with the improvement of tissue oxygenation

INFLUENCE OF THE AMOUNT OF COMPRESSION ON VENOUS AND ARTERIAL BLOOD FLOW VELOCITY AND SKIN MICROCIRCULATION OF THE LOWER EXTREMITY.

The aim: To determine the effect of compression on the venous and arterial velocity of the main blood flow of the lower limb and the skin microcirculation of the rear part of the foot. Materials and methods: 20 healthy subjects participated in this study: 11 men 11 (55%) men and 9 (45%) girls. The ankle brachial index (ABI), femoropop¬liteal index, femoral arterial blood flow velocity (AFV), venous blood flow velocity (VFV), transcutaneous oxygen pressure (tcPO2) and carbon dioxide pressure (tcPCO2) were measured. After the general measurements were taken, the tire was inflated to 10 mm Hg under general basic conditions and kept for three minutes. The experiment ended when no decrease in tcPO2 was observed between two consecutive pressure levels. Results: The average tire pressure to reach physiological zero was 80 mm Hg. for all participants. At 10 mmHg significant changes in indicators were found by 19% (p=0.0001). tcPCO2 values increased significantly at 10 mmHg (p=0.0319) and continued to increase until the end of the study. It was established that its values increased by 14% compared to the input data (p=0.0005). Conclusions: At the maximum compression of 60 mmHg the arterial blood flow rate decreased by 5.5 times (p=0.0001). TcPCO2 increases significantly when compressed by 10 mm Hg also in parallel with the decrease in the regional perfusion index, which begins at an external compression of 40 mm Hg, which is evidence of the deterioration of the perfusion of the skin of the anterior part of the foot in healthy subjects.

Non-invasive high frequency oscillatory ventilation inhibiting respiratory motion in healthy volunteers

Precision radiotherapy needs to manage organ movements to prevent critical organ injury. The purpose of this study is to examine the feasibility of motion control of the lung by suppressing respiratory motion. The non-invasive high frequency oscillatory ventilation (NIHFOV) is a technique commonly used in the protection of lung for patients with acute lung disease. By using a very high respiratory frequency and a low tidal volume, NIHFOV allows gas exchange, maintains a constant mean airway pressure and minimizes the respiratory movements. We tested healthy volunteers NIHFOV to explore the optimal operational parameter setting and the best possible motion suppression achievable. This study was conducted with the approval of Institutional Review Boards of the Wuwei Cancer hospital (approval number: 2021-39) and carried out in accordance with Declaration of Helsinki. The study comprises two parts. Twenty three healthy volunteers participated in the first part of the study. They had 7 sessions of training with the NIHFOV. The duration of uninterrupted, continuous breathing under the NIHFOV and the optimal operational machine settings were defined. Eight healthy volunteers took part in the second part of the study and underwent 4-dimensional CT (4DCT) scanning with and without NIHFOV. Their respiratory waveform under free breathing (FB) and NIHFOV were recorded. The maximum range of motion of the diaphragm from the two scannings was compared, and the variation of bilateral lung volume was obtained to evaluate the impact of NIHFOV technique on lung volume. The following data were collected: comfort score, transcutaneous partial pressure of oxygen (PtcO2), transcutaneous partial pressure of carbon dioxide (PtcCO2), and pulse rate. Data with and without NIHFOV were compared to evaluate its safety, physiological impacts and effect of lung movement suppression. All the volunteers completed the training sessions eventlessly, demonstrating a good tolerability of the procedure. The median NIHFOV-on time was 32 min (22–45 min), and the maximum range of motion in the cephalic-caudal direction was significantly reduced on NIHFOV compared with FB (1.8 ± 0.8 cm vs 0.3 ± 0.1 cm, t = − 3.650, P = 0.003); the median range of motion was only 0.3 ± 0.1 cm on NIHFOV with a good reproducibility. The variation coefficient under NIHFOV of the right lung volume was 2.4% and the left lung volume was 9.2%. The PtcO2 and PtcCO2 were constantly monitored during NIHFOV. The medium PtcCO2 under NIHFOV increased lightly by 4.1 mmHg (interquartile range [IQR], 4–6 mmHg) compared with FB (t = 17.676, P < 0.001). No hypercapnia was found, PtcO2 increased significantly in all volunteers during NIHFOV (t = 25.453, P < 0.001). There was no significant difference in pulse rate between the two data sets (t = 1.257, P = 0.233). NIHFOV is easy to master in healthy volunteers to minimize respiratory movement with good tolerability and reproducibility. It is a feasible approach for lung motion control and could potentially be applied in accurate radiotherapy including carbon-ion radiotherapy through suppression of respiratory movement.

Evolution of Ultrasound-Assessed Lung Aeration and Gas Exchange in Respiratory Distress Syndrome and Transient Tachypnea of the Neonate

To use clinical, lung ultrasound, and gas exchange data to clarify the evolution of lung aeration and function in neonates with respiratory distress syndrome (RDS) and transient tachypnea of the neonate (TTN), the most common types of neonatal respiratory failure. In this prospective observational cohort study, lung aeration and function were measured with a semiquantitative lung ultrasound score (LUS) and transcutaneous blood gas measurement performed at 1hour (time point 0), 6hours (time point 1), 12hours (time point 2), 24hours (time point 3) and 72hours (time point 4) of life. Endogenous surfactant was estimated using lamellar body count (LBC). LUS, oxygenation index (OI), oxygen saturation index (OSI), and transcutaneous pressure of carbon dioxide (PtcCO2) were the primary outcomes. All results were adjusted for gestational age. Sixty-nine neonates were enrolled in the RDS cohort, and 58 neonates were enrolled in the TTN cohort. LUS improved over time (within-subjects, P<.001) but was worse for the RDS cohort than for the TTN cohort at all time points (between-subjects, P<.001). Oxygenation improved over time (within-subjects, P=.011 for OI, P<.001 for OSI) but was worse for the RDS cohort than for the TTN cohort at all time points (between-subjects, P<.001 for OI and OSI). PtcCO2 improved over time (within-subjects, P<.001) and was similar in the RDS and TTN cohorts at all time points. Results were unchanged after adjustment for gestational age. LBC was associated with RDS (β=-0.2 [95% CI, -0.004 to -0.0001]; P=.037) and LUS (β=-3 [95% CI, -5.5 to -0.5]; P=.019). For the first 72hours of life, the RDS cohort had worse lung aeration and oxygenation compared with the TTN cohort at all time points. CO2 clearance did not differ between the cohorts, whereas both lung aeration and function improved in the first 72hours of life.

Transcutaneous CO2 Pressure Monitoring Increases Salvage Rates after Free Tissue Transplantation for Extremity Reconstruction.

Background:Although free tissue transplantation (FTT) is an essential technique in extremity functional reconstruction, postoperative blood flow disturbance is one of the critical complications leading to transplanted tissue necrosis. Early detection of this complication may prevent tissue failure by prompt improvement of blood flow. The aim of this study was to determine whether transcutaneous carbon dioxide pressure (TcPCO2) monitoring increases the salvage rates after FTT.Methods:We retrospectively reviewed 75 consecutive patients who underwent FTT for extremity reconstruction with TcPCO2 monitoring postoperatively between December 2016 and September 2021.Results:Extremity reconstruction was performed in 53 cases due to trauma, 20 cases due to infection, and two cases due to tumor resection for tissue defects. The overall success rate of the FTT was 98.7%, with 13 complications. Of the 11 patients who underwent reoperation, nine had thrombosis and two had vascular strangulation. However, when reoperation was decided, none of the reoperation cases still exhibited any deterioration in the Doppler or clinical assessment. All reoperated cases were salvaged. Of the two patients who did not undergo reoperation, one had failed flaps and one had partial skin necrosis. With a TcPCO2 cutoff value of 70 mm Hg, the sensitivity and specificity for detecting complications due to impaired blood flow were 100% and 93.5%, respectively.Conclusions:TcPCO2 monitoring was performed after FTT for extremity reconstruction, and all cases of reoperation were salvaged. TcPCO2 monitoring can detect impaired postoperative blood flow critically earlier than clinical assessments and may increase salvage rates of transplanted tissue.

Relationship Between Episodic Nocturnal Hypercapnia and History of Exacerbations in Patients with Advanced Chronic Obstructive Pulmonary Disease

PurposeAn episodic increase in transcutaneous carbon dioxide pressure (PtcCO2) is often recognized in patients with advanced chronic obstructive pulmonary disease (COPD) by overnight PtcCO2 monitoring. This phenomenon, called episodic nocturnal hypercapnia (eNH), mainly corresponds to rapid eye movement (REM) sleep-related hypoventilation. However, it is unclear whether eNH is associated with the frequency of COPD exacerbation. We aimed to investigate whether a relationship exists between COPD exacerbation and eNH.Patients and MethodsWe enrolled consecutive patients with stable, severe, or very severe COPD with a daytime arterial carbon dioxide pressure (PaCO2) <55.0 mmHg who underwent overnight PtcCO2 monitoring from April 2013 to January 2017. We retrospectively analyzed the prevalence of eNH and sleep-associated hypoventilation (SH) as defined by the American Academy of Sleep Medicine. Moreover, we compared the relationship between the frequency of COPD exacerbations in the previous year and eNH or SH.ResultsTwenty-four patients were included in this study. The study patients had a mean daytime PaCO2 and nocturnal PtcCO2 of 43.3 ± 6.8 mmHg and 42.9 ± 9.6 mmHg, respectively. Six (25.0%) and 11 (45.9%) of the 24 patients met the SH and eNH criteria, respectively. The odds ratios of SH and eNH for at least one annual exacerbation were 1.0 [95% confidence interval (CI): 0.16–6.00] and 11.1 [95% CI: 1.39–87.7], respectively. The odds ratios of SH and eNH for at least two annual exacerbations were 0.3 [95% CI: 0.04–2.64] and 6.6 [95% CI: 1.06–39.4], respectively.ConclusionIn patients with advanced COPD and a daytime PaCO2 <55.0 mmHg, eNH may be associated with a history of more frequent exacerbations than SH. Further studies are required to validate these findings.

High-flow nasal cannula improves respiratory impedance evaluated by impulse oscillometry in chronic obstructive pulmonary disease patients: a randomised controlled trial

Non-pharmacological treatment with high-flow nasal cannula (HFNC) may play a vital role in treatment of patients with chronic obstructive pulmonary disease (COPD). To evaluate the efficacy of HFNC, impulse oscillation system (IOS) is a new noninvasive technique in measuring the impedance of different portions of lungs. It shows higher sensitivity in contrast to conventional pulmonary function tests (PFT). However, whether IOS is an appropriate technique to evaluate the efficacy of HFNC in improving the impedance of small airways or peripheral lung in patients with COPD is still unclear. We enrolled 26 stable COPD participants randomised into two groups receiving HFNC or nasal cannula (NC) for 10 min followed by a 4-week washout period and crossover alternatively. IOS was used to detect the difference of respiratory impedance after HFNC or NC interventions. IOS parameters, PFT results, transcutaneous partial pressure of carbon dioxide, peripheral oxygen saturation, body temperature, respiratory rate, pulse rate, and blood pressure at the time of pre-HFNC, post-HFNC, pre-NC, and post-NC, were collected and analysed using SPSS (version 25.0, IBM, Armonk, NY, USA). The IOS measurement indicated that HFNC significantly improved R5, R5% predicted, R5–R20, X5-predicted, and Fres compared with NC, whereas no significant difference was observed through the PFT measurement. The beneficial effect of HFNC in improving small airway resistance and peripheral lung reactance compared with that of NC in patients with stable COPD was confirmed through IOS measurement.Trial registration: ClinicalTrials.gov NCT05130112 22/11/2021.

Feasibility of Transcutaneous Method for Carbon Dioxide Monitoring in an Intensive Care Unit

Background: Transcutaneous partial pressure of carbon dioxide (PtCO2) monitorization provides a continuous and non-invasive measurement of partial pressure of carbon dioxide (pCO2). In addition, peripheral oxygen saturation (SpO2) can also be measured and followed by this method. However, data regarding the correlation between PtCO2 and arterial pCO2 (PaCO2) measurements acquired from peripheric arterial blood gas is controversial. Objective: We aimed to determine the reliability of PtCO2 with PaCO2 based on its advantages, like non-invasiveness and continuous applicability. Methods: Thirty-five adult patients with hypercapnic respiratory failure admitted to our tertiary medical intensive care unit (ICU) were included. Then we compared PtCO2 and PaCO2 and both SpO2 measurements simultaneously. Thirty measurements from the deltoid zone and 26 measurements from the cheek zone were applied. Results: PtCO2 could not be measured from the deltoid region in 5 (14%) patients. SpO2 and pulse rate could not be detected at 8 (26.7%) of the deltoid zone measurements. Correlation coefficients between PtCO2 and PaCO2 from deltoid and the cheek region were r: 0,915 and r: 0,946 (p = 0,0001). In comparison with the Bland-Altman test, difference in deltoid measurements was -1,38 ± 1,18 mmHg (p = 0.252) and in cheek measurements it was -5,12 ± 0,92 mmHg (p = 0,0001). There was no statistically significant difference between SpO2 measurements in each region. Conclusion: Our results suggest that PtCO2 and SpO2 measurements from the deltoid region are reliable compared to the arterial blood gas analysis in hypercapnic ICU patients. More randomized controlled studies investigating the effects of different measurement areas, hemodynamic parameters, and hemoglobin levels are needed.

Sleep-related hypoventilation and hypercapnia in multiple system atrophy detected by polysomnography with transcutaneous carbon dioxide monitoring.

PurposeWe aimed to evaluate sleep-related hypoventilation in multiple system atrophy (MSA) using polysomnography (PSG) with transcutaneous partial pressure of carbon dioxide (PtcCO2) monitoring.MethodsThis prospective study included 34 patients with MSA. Motor and autonomic function, neuropsychological tests, PSG with PtcCO2 monitoring, and pulmonary function tests were performed. Sleep-related hypoventilation disorder (SRHD) was defined according to the International Classification of Sleep Disorders, third edition.ResultsNine (27%) of the 34 patients met the diagnostic criteria of SRHD. Twenty-nine (85%) patients had sleep-related breathing disorders based on an Apnea–Hypopnea Index of ≥ 5/h. The patients with MSA and SRHD had a higher arousal index (p = 0.017) and obstructive apnea index (p = 0.041) than those without SRHD. There was no difference in the daytime partial pressure of carbon dioxide in arterial blood or respiratory function between MSA patients with and without SRHD.ConclusionSleep-related hypoventilation may occur in patients with MSA even with a normal daytime partial pressure of carbon dioxide. This can be noninvasively detected by PSG with PtcCO2 monitoring. SRBD and sleep-related hypoventilation are common among patients with MSA, and clinicians should take this into consideration while evaluating and treating this population.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11325-022-02568-4.

Efficacy of high-flow nasal cannula therapy in bedridden patients.

A growing number of studies have demonstrated the efficacy of high-flow nasal cannula therapy (HFNC) for treating children with acute respiratory distress. However, it remains unknown whether HFNC is effective in bedridden patients with acute respiratory distress. We retrospectively reviewed the medical records of bedridden patients with acute respiratory distress who were treated with HFNC using a home ventilator in continuous positive airway pressure mode at our center between March 2014 and August 2016. We assessed heart rate, respiratory rate, oxygen saturation measured using a pulse oximeter, the partial pressure of venous carbon dioxide, or the transcutaneous partial pressure of carbon dioxide, and symptoms of respiratory distress before and after the initiation of HFNC. During the 2-year-study period, 25 patients were treated with HFNC. The patients' mean heart rate, respiratory rate, oxygen saturation measured using a pulse oximeter, and pressure of venous carbon dioxide/the transcutaneous partial pressure of carbon dioxide values improved significantly (P < 0.05). Symptoms of respiratory distress were considerably ameliorated at 1-3 h after the HFNC initiation, except in two patients. In these two patients, the HFNC was replaced with non-invasive positive pressure ventilation. Non-invasive positive pressure was also required at 16 to 168 h after the initiation of HFNC in five of the 28 episodes in which the patient was initially responsive to HFNC, as the patients' respiratory symptoms gradually deteriorated. Performing HFNC with a home ventilator in continuous positive airway pressure mode is effective at treating bedridden patients with acute respiratory distress. However, it is essential that the HFNC can be switched to non-invasive positive pressure if needed.

Sleep-disordered breathing in school-aged children with Prader-Willi syndrome.

Studies of sleep-disordered breathing (SDB) in children with Prader-Willi syndrome (PWS) have focused on early childhood and growth hormone (GH)-naïve children, but little is known about older children, including those on long-term GH therapy. This study aimed to describe the nature and prevalence of SDB in school-aged children with PWS in the growth hormone era. This retrospective single-center chart review included children aged 6-18 years with PWS who had overnight polysomnography not involving respiratory support over 5 years (2012-2017). The main outcome measures were the presence of obstructive sleep apnea, central sleep apnea, or hypoventilation defined by an elevated transcutaneous partial pressure of carbon dioxide (TcPCO2) as per standard pediatric criteria. Seventeen children (8 males; median age 11.6 years, range 6.6-16.1 years) were included. Fifteen demonstrated SDB of different types: central sleep apnea (18%), obstructive sleep apnea (24%), both obstructive and central sleep apnea (29%), or hypoventilation without obstructive or central sleep apnea (18%). Twelve (71%) children had evidence of hypoventilation. Those with hypoventilation had a higher central apnea-hypopnea index but no difference in the obstructive apnea-hypopnea index, age, sex, growth parameters, or the presence of scoliosis or sleep-related symptoms compared with those without hypoventilation. Sleep-related hypoventilation is common in school-aged children with PWS. The presence of central sleep apnea, including the quantification of central hypopneas, but not obstructive sleep apnea or clinical factors, predicted the presence of hypoventilation. Long-term polysomnography surveillance in children with PWS should include identification of central hypopneas and measurement of continuous pCO2. Schaefer J, Davey MJ, Nixon GM. Sleep-disordered breathing in school-aged children with Prader-Willi syndrome. J Clin Sleep Med. 2022;18(4):1055-1061.