A Case of Nemaline Myopathy With Sleep-Related Hypoventilation Diagnosed Using Polysomnography During Daytime Napping.

This is the case of a 49-year-old woman who was admitted to the hospital for a close examination of pulmonary hypertension; however, the next morning, she developed carbon dioxide (CO2) narcosis and was started on artificial ventilation. As pulmonary arterial hypertension was ruled out, the patient was extubated, and 24-hour transcutaneous partial pressure of carbon dioxide (PCO2)(transcutaneous carbon dioxide (TcPCO2)) monitoring was performed to diagnose sleep-related hypoventilation. Polysomnography (PSG) during daytime napping revealed markedly decreased chest motion and a "pseudo-central event," which was neither central nor obstructive hypopnea. Based on the PSG results and physical examination findings, a neuromuscular disorder was suspected, and a muscle biopsy was performed to diagnose nemaline myopathy. Neuromuscular diseases are widely recognized for their association with sleep-disordered breathing; thus, sleep-related hypoventilation should also be considered. Monitoring of TcPCO2 and PSG are useful tools in identifying the cause of hypoventilation; however, overnight PSG may cause CO2 narcosis in some diseases. In such cases, PSG may be beneficial during daytime napping.

Contribution of Transcutaneous PCO2 in Obesity Hypoventilation Syndrome.

BACKGROUND: More and more patients have obesity-hypoventilation syndrome (OHS) because of the increasing prevalence of obesity. The accuracy of transcutaneous PCO2 (PtcCO2 ) has recently been validated. However, no study evaluated the interest of measuring systematically nocturnal PtcCO2 in the follow-up of patients with OHS and home mechanical ventilation to detect residual nocturnal hypoventilation. We aimed to evaluate the contribution of nocturnal PtcCO2 to assess nocturnal hypoventilation compared with current routine examinations, that is, daytime arterial blood gases and nocturnal pulse oximetry. METHODS: A prospective monocentric pilot study was conducted from August 2018 to November 2019. Patients with stable OHS and who were treated with home noninvasive ventilation for at least 6 months were eligible to participate. After oral consent, we performed both diurnal arterial blood gases and combined home oximetry and capnography. The primary end point was the presence of residual nocturnal hypoventilation, defined as PaCO2 > 45 mm Hg or bicarbonate ≥ 27 mmol/L, SpO2 < 90% for ≥ 10% of the night, or PtcCO2 > 49 mm Hg for ≥ 10% of the night. RESULTS: A total of 32 subjects were included. Twenty-nine subjects with nocturnal PtcCO2 were analyzed. Eighteen of the 29 subjects showed residual nocturnal hypoventilation. The association of diurnal arterial blood gases and nocturnal pulse oximetry revealed nocturnal hypoventilation in only 9 subjects. Among the 19 subjects with both normal blood gases and normal nocturnal pulse oximetry, 11 had nocturnal hypoventilation with transcutaneous capnography. Only one subject presented with hypoventilation symptoms (asthenia). CONCLUSIONS: The assessment of PtcCO2 in comparison with nocturnal pulse oximetry and arterial blood gases provides important information for the diagnosis of residual nocturnal hypoventilation in the subjects with OHS who were ventilated at home.

Uso de la determinación transcutánea de co2 en pacientes con déficit de timidina quinasa 2 y costes de su uso en una consulta de ventilación mecánica no invasiva / Use of transcutaneous co2 determination in patients with thymidine kinase 2 deficit and costs of its use in a noninvasive mechanical ventilation consultation

Objetivo: Describir el uso de la capnografía transcutánea en una población adulta y pediátrica de pacientes con déficit de timidina quinasa 2 y hacer un estudio comparativo de costes de una determinación de gasometría arterial y capnografía en la población de nuestra consulta de VMNI. Metodología: Se realizó una anamnesis y unas pruebas funcionales respiratorias para valorar afectación de la musculatura respiratoria y calidad del sueño. Para determinar la hipoventilación, se midió la pCO2 transcutánea en vigilia y/o durante el sueño. Se realizó un estudio económico para comparar el coste de una determinación de ptcCO2 frente a la determinación mediante GSA. El estudio económico se realizó estimando la población total de pacientes que se valoraba en la consulta de VMNI de manera anual. Resultados: 9 pacientes con déficit de TK2 (4 adultos y 5 niños). A 4 pacientes se les realizó una poligrafía respiratoria basal. A la población pediátrica se les realizó un registro continuo de ptcCO2 con pulsioximetria anual. Se realizaron 4 registros con ptcCO2 y VMNI. Elcoste de la determinación de ptCO2 en comparación con la GSA fue de 6,29 euros frente a 5,37 euros. Conclusiones: La medición de la ptcCO2 es útil en la consulta de VMNI para la realización de medidas puntuales en la consulta como para monitorización continua durante el sueño. Con el uso que realizamos en nuestra consulta de la capnografía transcutánea, la determinación puntual de la pCO2 transcutánea es más económica que la realización de la GSA. (AU)

Objective: to describe the use of transcutaneous capnography in an adult and pediatric population of patients with Thymidine inase 2 deficiency and to compare the costs between blood gases by arterial gasometry (BGA) and capnography in our population. Material and methods: an anamnesis, and respiratory functional tests to assess respiratory muscle involvement, sleep quality were performed.To assess the presence of alveolar hypoventilation the determination of transcutaneous pCO2while awake and/or during sleepwas performed. An economic study has been done to compare the cost of a determination of ptcCO2 versus the determination by BGA. Results: 9 patients with TK2 deficiency (4 adults and 5 children). 4 patients underwent baseline respiratory polygraphy. The pediatric patients underwent at least one continuous recording of ptcCO2 with pulse oximetry each year.4 studies of ptcCO2 duringNIV were performed. The cost in the adult population of a punctual determination of pCO2 by BGA was 6,29 euros while for capnography was 5,37 euros. Conclusions: the measurement of ptcCO2 is useful in the consultation of NIV for the realization of specific measurements in the consultation as for continuous monitoring of this parameter. In our practice of transcutaneous capnography, the punctual determination of transcutaneous pCO2 is cheaper than the BGA. (AU)

Comparison between PtCO2 and PaCO2 and Derived Parameters in Heart Failure Patients during Exercise: A Preliminary Study.

Evaluation of arterial carbon dioxide pressure (PaCO2) and dead space to tidal volume ratio (VD/VT) during exercise is important for the identification of exercise limitation causes in heart failure (HF). However, repeated sampling of arterial or arterialized ear lobe capillary blood may be clumsy. The aim of our study was to estimate PaCO2 by means of a non-invasive technique, transcutaneous PCO2 (PtCO2), and to verify the correlation between PtCO2 and PaCO2 and between their derived parameters, such as VD/VT, during exercise in HF patients. 29 cardiopulmonary exercise tests (CPET) performed on a bike with a ramp protocol aimed at achieving maximal effort in ≈10 min were analyzed. PaCO2 and PtCO2 values were collected at rest and every 2 min during active pedaling. The uncertainty of PCO2 and VD/VT measurements were determined by analyzing the error between the two methods. The accuracy of PtCO2 measurements vs. PaCO2 decreases towards the end of exercise. Therefore, a correction to PtCO2 that keeps into account the time of the measurement was implemented with a multiple regression model. PtCO2 and VD/VT changes at 6, 8 and 10 min vs. 2 min data were evaluated before and after PtCO2 correction. PtCO2 overestimates PaCO2 for high timestamps (median error 2.45, IQR -0.635-5.405, at 10 min vs. 2 min, p-value = 0.011), while the error is negligible after correction (median error 0.50, IQR = -2.21-3.19, p-value > 0.05). The correction allows removing differences also in PCO2 and VD/VT changes. In HF patients PtCO2 is a reliable PaCO2 estimation at rest and at low exercise intensity. At high exercise intensity the overall response appears delayed but reproducible and the error can be overcome by mathematical modeling allowing an accurate estimation by PtCO2 of PaCO2 and VD/VT.

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.

Respiratory acidosis during bronchoscopy-guided percutaneous dilatational tracheostomy: impact of ventilator settings and endotracheal tube size.

BACKGROUND: The current study investigates the effect of bronchoscopy-guided percutaneous dilatational tracheostomy (PDT) on the evolution of respiratory acidosis depending on endotracheal tube (ET) sizes. In addition, the impact of increasing tidal volumes during the intervention was investigated. METHODS: Two groups of ICU-patients undergoing bronchoscopy-guided PDT with varying tidal volumes and tube sizes were consecutively investigated: 6 ml/kg (N = 29, mean age 57.4 ± 14.5 years) and 12 ml/kg predicted body weight (N = 34, mean age 59.5 ± 12.8 years). RESULTS: The mean intervention time during all procedures was 10 ± 3 min. The combination of low tidal volumes and ETs of 7.5 mm internal diameter resulted in the most profound increase in PaCO2 (32.2 ± 11.6 mmHg) and decrease in pH-value (- 0.18 ± 0.05). In contrast, the combination of high tidal volumes and ETs of 8.5 mm internal diameter resulted in the least profound increase in PaCO2 (8.8 ± 9.0 mmHg) and decrease of pH (- 0.05 ± 0.04). The intervention-related increase in PaCO2 was significantly lower when using higher tidal volumes for larger ET: internal diameter 7.5, 8.0 and 8.5: P > 0.05, =0.006 and = 0.002, respectively. Transcutaneous PCO2 monitoring revealed steadily worsening hypercapnia during the intervention with a high correlation of 0.87 and a low bias of 0.7 ± 9.4 mmHg according to the Bland-Altman analysis when compared to PaCO2 measurements. CONCLUSIONS: Profound respiratory acidosis following bronchoscopy-guided PDT evolves in a rapid and dynamic process. Increasing the tidal volume from 6 to 12 ml/kg PBW was capable of attenuating the evolution of respiratory acidosis, but this effect was only evident when using larger ETs. TRIAL REGISTRATION: DRKS00011004 . Registered 20th September 2016.

[Significance of monitoring the gradients between transcutaneous PCO(2) and end-tidal PCO(2) in patients with septic shock].

Objective: To investigate the significance of monitoring the gradients between transcutaneous PCO(2) and end-tidal PCO(2) [P(c-et)CO(2)] in patients with septic shock. Method: Thirty-five mechanically ventilated patients with early septic shock were enrolled as the study group and 18 non-septic shock patients with stable hemodynamics as the control group between May 2014 and October 2016. The patients with septic shock were treated by early goal-directed therapy (EGDT) within 6 hours since hospitalization. The differences of baseline level of P(c-et)CO(2) and arterial lactate concentration (LAC) between the two groups and the variations of these indexes after EGDT in the study group were compared respectively. Results: The baseline levels of P(c-et)CO(2) and LAC in patients with septic shock were significantly higher than those of the control group [(26.0±16.2) mmHg vs (11.0±5.6) mmHg (1 mmHg=0.133 kPa) and (4.0±1.7) mmol/L vs (1.6±0.6)mmol/L, all P=0.000]. The area under receiver operator characteristic (ROC) curve (AUC) for baseline P(c-et)CO(2) and LAC was 0.924 (95%CI: 0.851-0.996) and 0.931 (95%CI: 0.872-1.000), respectively. P(c-et)CO(2) >12.6 mmHg and LAC >2.5 mmol/L could discriminate septic shock patients from those without shock with the same sensibility of 97% and the specificity of 83% and 78% respectively. With regard to the prognosis (Day 28) of the patients with septic shock, AUC for baseline P(c-et)CO(2) and LAC was 0.709 (95%CI: 0.533-0.886) and 0.714 (95%CI: 0.545-0.883), respectively. P(c-et)CO(2) >20.0 mmHg and LAC>3.6 mmol/L could discriminate survivors from non-survivors with the same sensibility of 92% and the same specificity of 76%. All the patients in the study group completed EGDT within 6 hours after admission, 20 (57.1%) passed EGDT and 17 (85.0%) survived, 15 (42.9%) failed EGDT and 4 (26.7%) survived, and the survival rates were significantly different (F=9.844, P=0.001). After EGDT, P(c-et)CO(2) (21.0±9.5 mmHg) and LAC(3.3±2.5 mmol/L)reduced significantly compared with the baselines (P=0.008 and P=0.046), and the associated AUC was 0.905(95%CI: 0.792-1.000) and 0.747 (95%CI: 0.576-0.917)respectively. P(c-et)CO(2) > 16.5 mmHg and LAC > 3.1 mmol/L could discriminate survivors from non-survivors with the sensibility of 97% and 91%, and the specificity of 78% and 69%, respectively. Conclusions: P(c-et)CO(2) >12.6 mmHg could play the same role as LAC in recognizing early septic shock. EGDT was an effective therapy for the septic shock and P(c-et)CO(2) reflected efficacy. P(c-et)CO(2)>20 mmHg before EGDT and >16.5 mmHg after EGDT both could predict the 28 d prognosis of patients with septic shock, and the effect of the former was equal to that of LAC, but the latter was better than LAC.

Estimating Arterial Partial Pressure of Carbon Dioxide in Ventilated Patients: How Valid Are Surrogate Measures?

The arterial partial pressure of carbon dioxide (PaCO2) is an important parameter in critically ill, mechanically ventilated patients. To limit invasive procedures or for more continuous monitoring of PaCO2, clinicians often rely on venous blood gases, capnography, or transcutaneous monitoring. Each of these has advantages and limitations. Central venous Pco2 allows accurate estimation of PaCO2, differing from it by an amount described by the Fick principle. As long as cardiac output is relatively normal, central venous Pco2 exceeds the arterial value by approximately 4 mm Hg. In contrast, peripheral venous Pco2 is a poor predictor of PaCO2, and we do not recommend using peripheral venous Pco2 in this manner. Capnography offers measurement of the end-tidal Pco2 (PetCO2), a value that is close to PaCO2 when the lung is healthy. It has the advantage of being noninvasive and continuously available. In mechanically ventilated patients with lung disease, however, PetCO2 often differs from PaCO2, sometimes by a large degree, often seriously underestimating the arterial value. Dependence of PetCO2 on alveolar dead space and ventilator expiratory time limits its value to predict PaCO2. When lung function or ventilator settings change, PetCO2 and PaCO2 can vary in different directions, producing further uncertainty. Transcutaneous Pco2 measurement has become practical and reliable. It is promising for judging steady state values for PaCO2 unless there is overt vasoconstriction of the skin. Moreover, it can be useful in conditions where capnography fails (high-frequency ventilation) or where arterial blood gas analysis is burdensome (clinic or home management of mechanical ventilation).

Overnight Transcutaneous Carbon Dioxide Monitoring in Eucapnic Patients with Obstructive Sleep Apnea Syndrome.

OBJECTIVES: We monitored increases in CO2 levels during sleep by measuring transcutaneous pCO2 (PtcCO2) to determine its relationship with polysomnographic data in normocapnic patients with obstructive sleep apnea syndrome (OSAS). MATERIAL AND METHODS: Between October 2011 and December 2012, 139 patients underwent PtcCO2 monitoring with polysomnography. All patients were evaluated with arterial blood gas (ABG) measurements and pulmonary function tests (PFTs). We excluded 13 patients with COPD and/or daytime hypercapnia and 29 patients whose PtcCO2 records could not be evaluated. RESULTS: The patients' mean age was 46.8±10.3 years. Fifty-nine patients (60.8%) were male, and 38 (39.2%) patients were female. The mean overnight PtcCO2 was ≤45 mm Hg in 84 (86.6%) patients and >45 mm Hg in 13 (13.4%) patients. In the group with PtcCO2>45 mm Hg, 10 patients had an apnea-hypopnea index (AHI) >15, and 3 patients had an AHI<15, without a statistically significant difference (p=0.078). The mean apnea and apnea/interapnea periods were similar. The mean PtcCO2 values correlated with time spent when the SpO2 was <90% (r=0.220, p<0.031). When we grouped the patients by AHI, 60 (61.8%) patients had an AHI>15 (moderate to severe OSAS), and 37 (37.2%) had an AHI<15 (mild OSAS). Of the former group, 16.7% had a mean PtcCO2 >45 mm Hg, whereas this ratio was 8.1% in the latter group. The difference was not statistically significant (p=0.359). In the group with an AHI>15, the highest PtcCO2 levels were significantly higher (p<0.05). CONCLUSION: We conclude that seemingly eucapnic OSAS patients may experience hypercapnia when sleeping, and PtcCO2 monitoring may be useful in the early diagnosis of hypercapnia.

The significance of monitoring the gradients between transcutaneous PCO2 and arterial PCO2 in patients with septic shock / 中华急诊医学杂志

Objective To investigate the significance of monitoring P(c-a)CO2 (the gradients between transcutaneous PCO2 and arterial PCO2) in patients with septic shock.Method 31 patients with early septic shock were enrolled as the study group and 20 patients with stable hemodynamics as the control group from Fab.2013 to Sept.2014 in our Intensive Care Unit (ICU).The patients with septic shock were treated guided by early goal directed therapy (EGDT) within 6 hours since hospitalization.The differences of baseline P(c-a) CO2 levels and other index as arterial lactate (LAC) concentration between two groups and the variations of these indexes after EGDT in the study group were compared respectively.Results The baseline levels of P(c-a)CO2 and LAC in patients with septic shock were significantly higher than in patients of control group: (21.2 ± 10.1) mmHg vs.(7.5 ±4.6), P =0.000, and (4.0±2.4) mmol/ Lvs.(1.6 ± 0.5), P =0.000.The areas under receiver operator characteristic (ROC) curve (AUC) for baselineP(c-a)CO2 and LAC were 0.918 (95％ CI: 0.843-0.992) and 0.840 (95％ CI: 0.719-0.962) respectively.A threshold of 14.0 mmHg for P(c-a)CO2 and 2.1 mmol/L for LAC discriminated patients with septic shock from without shock with the same sensibility of 83.9％ and the same specificity of 90.0％, respectively.With regard to prognosis (Day 28), AUC for baseline P(c-a)CO2 and LAC were 0.739 (95％ CI: 0.562-0.917) and0.702 (95％ CI: 0.514-0.889) respectively.A threshold of 21.5 mmHg for P(c-a) CO2 and 3.9 mmol/L for LAC discriminated survivors from nonsurvivors with the same sensibility of 71.4％ and the same specificity of 70.6％ respectively.31 patients in the study group completed EGDT within 6 hours after the admission, 16 (51.6％) passed EGDT and 13 (81.3％) survived, 15 (48.4％) failed EGDT and 4 (26.7％) survived, and survival rates were significantly different, F =9.314, P =0.004.After EGDT, P(c-a) CO2 (18.8 ± 9.4) mmHg and LAC (3.3 ± 2.4) mmol/Lreduced significantly compared with the baselines, all P =0.000.AUC then for P(c-a) CO2 and LAC were 0.742 (95％ CI: 0.562-0.921) and 0.769 (95％ CI: 0.593-0.945), respectively.A threshold of 18.3 mmHg for P(c-a)CO2 and 3.1 mmol/L for LAC discriminated survivors from nonsurvivors with the same sensibility of 71.4％ and the specificity of 71.4％ and of 76.5％ respectively.P(c-a) CO2 and LAC of patients passed EGDT reduced significantly compared with those failed EGDT: (14.8 ± 7.5) mmHgvs.(23.6±9.6) mmHg (P=0.012)、 (2.5±1.5) mmol/L vs.(4.3±2.9) mmol/L (P=0.038), and so did with their baseline : (14.8±7.5) mmHgvs.(18.0±8.1) mmHg, (P=0.042)、 (2.5±1.5) mmol/Lvs.(3.2±1.8) mmol/L, P=0.043.In patients failed EGDT, P(c-a)CO2 and LAC changed little after EGDT, from (24.6 ± 9.2) to (23.6 ± 9.6) mmHg (P =0.238) and from (4.8 ± 2.5) mmol/L to (4.3 ± 2.9) mmol/L (P =0.629).When baseline levels were compared between patients passed EGDT with those failed EGDT, P(c-a) CO2 was (18.0 ±8.1) mmHg vs.(24.6 ± 9.2) mmHg (P =0.042), LAC was (3.2 ± 1.8) mmol/L vs.(4.8 ± 2.5) mmol/L (P =0.050).Conclusions P(c-a) CO2 ＞ 14.0 mmHg could play a role in recognizing early septic shock.EGDT was an effective therapy for the disease and P(c-a)CO2 level could reflect the efficacy of EGDT.P(c-a)CO2 ＞ 21.5mmHg before EGDT and P(c-a) CO2 ＞ 19.3 mmHg after EGDT both could predict the prognosis of patients with septic shock.All above correlated well with LAC and represented a new efficient technique to assess tissue microperfusion.

The accuracy of transcutaneous PCO2 in subjects with severe brain injury: a comparison with end-tidal PCO2.

BACKGROUND: In patients suffering from brain injury, end-tidal PCO2 (PETCO2 ) monitoring is controversial, but transcutaneous PCO2 (PtcCO2 ), which is noninvasive and utilizes immediate display, may be an alternative method. We hypothesized that PtcCO2 would be more accurate than PETCO2 for monitoring PaCO2 in patients with severe brain injury. METHODS: A prospective observational study included consecutive mechanically ventilated adult subjects who had acute brain injury and an arterial catheter in place. When an arterial blood gas analysis was required, the PETCO2 and PtcCO2 values were simultaneously recorded. The agreement between the PETCO2 , PtcCO2 , and PaCO2 measurements (reference) was determined using the Bland-Altman method. The number of outliers defined by the formula ([PETCO2 or PtcCO2 ] - PaCO2 ) > ± 4 mm Hg indicated the proportion of measurements that were considered clinically unacceptable. RESULTS: A total of 25 subjects were included in the study, and 85 simultaneous measurements of PaCO2 , PtcCO2 , and PETCO2 were obtained. The bias and precision between PaCO2 and PtcCO2 were -0.75 and 6.23 mm Hg, respectively. The limits of agreement ranged from -12.97 to 11.47 mm Hg. The bias and precision between PaCO2 and PETCO2 were 0.68 and 5.82 mm Hg, respectively. The limits of agreement ranged from -10.72 to 12.08 mm Hg. There were 34 (40%) outliers for the PtcCO2 sensor and 34 (40%) outliers for the PETCO2 sensor (P > .99). CONCLUSIONS: The accuracy of PtcCO2 was not superior to that of PETCO2 for assessing PCO2 levels and should not be used to monitor these levels in subjects with severe brain injury.