Continuous Transcutaneous Carbon Dioxide Research Articles

Late permissive hypercapnia and respiratory stability among very preterm infants: a pilot randomised trial

ObjectiveDetermine if targeting higher transcutaneous carbon dioxide improves respiratory stability among very preterm infants on ventilatory support.DesignSingle-centre pilot randomised clinical trial.SettingThe University of Alabama at Birmingham.PatientsVery preterm infants on ventilatory...

Contribution of hypercapnia to cognitive impairment in severe sleep-disordered breathing.

Although cognitive impairment in obstructive sleep apnea (OSA) is primarily attributed to intermittent hypoxemia and sleep fragmentation, hypercapnia may also play a role in patients whose OSA is complicated by hypoventilation. This study investigated the impact of hypercapnia on cognitive function in severe sleep-disordered breathing (OSA accompanied by hypoventilation). Patients with severe OSA (apnea-hypopnea index >30 events/h; n = 246) underwent evaluation for accompanying hypoventilation with polysomnography that included continuous transcutaneous carbon dioxide (TcCO2) monitoring and awake arterial blood gas analysis. Patients were categorized as having no hypoventilation (n = 84), isolated sleep hypoventilation (n = 40), or awake hypoventilation (n = 122). Global cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA), memory with the Rey Auditory Verbal Learning Test (RAVLT), and processing speed with the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV), Digit Symbol Coding subtest (DSC). Apnea-hypopnea index was similar across groups (P = .15), but the sleep and awake hypoventilation groups had greater nocturnal hypoxemia compared with the no-hypoventilation group (P < .01). Within all groups, mean MoCA scores were < 26, which is the validated threshold to indicate mild cognitive impairment; RAVLT scores were lower than age-matched norms only in the awake-hypoventilation group (P ≤ .01); and DSC scores were lower than age-matched norms within all groups (P < .01). In multivariable regression analyses, higher arterial partial pressure of carbon dioxide (PaCO2) and TcCO2 during wakefulness were associated with lower MoCA and DSC scores (P ≤ .03), independent of confounders including overlap syndrome (OSA + chronic obstructive pulmonary disease). Awake hypoventilation is associated with greater deficits in cognitive function in patients with severe sleep-disordered breathing. Beaudin AE, Raneri JK, Ayas NT, Skomro RP, Smith EE, Hanly PJ; on behalf of Canadian Sleep and Circadian Network. Contribution of hypercapnia to cognitive impairment in severe sleep-disordered breathing. J Clin Sleep Med. 2022;18(1):245-254.

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

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

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

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

P1386Continuous, transcutaneous carbon-dioxide monitoring in complex electrophysiological procedures in conscious sedation - is there a safer way to sleep?

Abstract Funding Acknowledgements Karolina Weinmann was supported by the Hertha-Nathorff fellowship from Ulm University Background – Ablation of cardiac arrhythmias by complex electrophysiological procedures is a growing field. A moderate to deep sedation is needed to immobilize the patient to warrant a safe and effective intervention. The administrated medication to obtain an adequate sedation has respiratory depressant side effects and could cause respiratory complications, like hypercapnia and hypoxia. Purpose – Our aim was to investigate the feasibility and accuracy of an additional, continuous transcutaneous carbon-dioxide (tpCO2) measurement during moderate to deep sedation in complex electrophysiological catheter ablations. Methods – Consecutive patients received an electrophysiological intervention with need for deep sedation. Routine hemodynamic monitoring was performed by the measurement of non-invasive blood-pressure, oxygen saturation and half-hourly venous blood gas analysis. Additionally, patients received a tpCO2 sensor on the forehead with an automated, continuous documentation of transcutaneous oxygen saturation and carbon-dioxide. A precise sedation protocol was performed and administrated drugs were registered. Results – We included 110 patients to the analysis. Fifty patients received cryoballoon pulmonary vein isolation, 58 patients 3D-mapping procedure and two patients ventricular tachycardia ablation. The mean procedure time was 135.1 ± 63.5 minutes and the fluoroscopy time was 21.5 ± 10.9 minutes. To achieve an adequate sedation a mean of 5.0 ± 0.8 mg midazolam, 583.8 ± 320.4 mg propofol, 72.0 ± 30.3 µg fentanyl and 0.2 ± 0.1 mg remifentanil were administrated. Hypercapnia (pCO2 &amp;gt; 70 mmHg) was detected in five patient by the tpCO2 monitoring and only in two patients using venous carbon-dioxide partial pressure (vpCO2) analysis. Correlation of tpCO2 and vpCO2 were analyzed half-hourly by Pearsons’ correlation coefficient. There was a good correlation during the investigated 120 minutes of procedure time (baseline: r = 0.65, p &amp;lt; 0.0001; 30 minutes: r = 0.75, p &amp;lt; 0.0001; 60 minutes: r = 0.77, p &amp;lt; 0.0001; 90 minutes: r = 0.78, p &amp;lt; 0.0001; 120 minutes: r = 0.85, p &amp;lt; 0.0001). The detected difference between tpCO2 and vpCO2 was at baseline &amp;lt;5 mmHg in 65% (79/110) and &amp;lt;10 mmHg in 96% (103/110), after 30 minutes the difference was &amp;lt;5 mmHg in 71% (78/110) and &amp;lt;10 mmHg in 96% (105/110), after 60 minutes the difference was &amp;lt;5 mmHg in 77% (60/78) and &amp;lt;10 mmHg in 96% (75/78) and after 90 minutes the difference between the two methods was &amp;lt;5 mmHg in 63% (30/48) and &amp;lt;10 mmHg in 98% (47/48) of the cohort. Conclusion – The continuous tpCO2 monitoring is a feasible and precise method with a good correlation to the venous blood gas carbon-dioxide analysis of the standard monitoring during complex catheter ablations in deep sedation. Randomized trials are required to further analyze if tpCO2 monitoring adds further safety to electrophysiological procedures in deep sedation.

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.

Usefulness of transcutaneous PCO2 to assess nocturnal hypoventilation in restrictive lung disorders.

Nocturnal hypoventilation is now an accepted indication for the initiation of non-invasive ventilation. Nocturnal hypoventilation may be an under diagnosed condition in chronic respiratory failure. The most appropriate strategy to identify sleep hypoventilation is not yet clearly defined. In clinical practice, it is indirectly assessed using nocturnal pulse oximetry (NPO) and morning arterial blood gases (mABG). Even though continuous transcutaneous carbon dioxide partial pressure (TcPCO2 ) monitoring is theoretically superior to NPO plus mABG, it is not routinely used. We aimed to prospectively compare NPO plus mABG with nocturnal TcPCO2 for the detection of alveolar hypoventilation in a cohort of patients with chronic restrictive respiratory dysfunction. We assessed 80 recordings of mABG, nocturnal TcPCO2 and NPO in 72 consecutive patients with neuromuscular disease or thoracic cage disorders. Nocturnal hypoventilation was defined as a mean nightime TcPCO2 ≥50 mm Hg, and nocturnal hypoxaemia as ≥30% of the night with transcutaneous pulse oxygen saturation ≤90% and/or >5 consecutive minutes with transcutaneous pulse oxygen saturation ≤88%. Amongst the 80 recordings, 25 of 76 (32.9%) without nocturnal hypoxaemia and 16 of 59 (27.1%) without hypercapnia on mABG showed nocturnal hypoventilation on TcPCO2 . Amongst recordings showing both normal NPO and mABG, 16 of 52 (30.8%) had a mean TcPCO2 ≥50 mm Hg. Nocturnal hypoxaemia was associated with nocturnal hypoventilation in all recordings. However, 5 of 21 (23.8%) recordings that showed an absence of nocturnal hypoventilation at the chosen threshold showed hypercapnia on mABG. Morning arterial blood gases and NPO alone or in combination underestimate nocturnal hypoventilation in patients with chronic restrictive respiratory dysfunction of extrapulmonary origin.

Diagnostic and Therapeutic Strategies for Hypercarbia in Elderly Patients Undergoing Prolonged Retroperitoneoscopic Surgery ——The Role of TcPCO2 and PEEP

Background: Retroperitoneal laparoscopy provides less morbidity and faster recovery period. However, long-term pneumoperitoneum increases the risk of hypercapnia that may induce severe postoperative complications, especially in elderly patients. Our study aims at investigating the sensitivity and reliability of continuous transcutaneous carbon dioxide (TcPCO2) monitoring in diagnosing hypercapnia during retroperitoneoscopic surgery in elderly patients and evaluating the effect of positive end-expiratory pressure (PEEP) against retroperitoneum induced hypercapnia.Methods: Fifty-five patients aged over 65 years who were scheduled for selective retroperitoneoscopic surgery under general anesthesia were enrolled. The correlations between TcPCO2, end-tidal partial pressure of CO2 (PETCO2) and arterial CO2 (PaCO2) were evaluated before pneumoperitoneum as well as 30 and 60 minutes after establishment of pneumoperitoneum (time 0, 1 and 2), respectively. Patients were randomly assigned to 5 groups accepting different levels of PEEP: 0, 4, 6, 8 and 10 cm H2O (group I, II, III, IV and V). PaCO2 and PETCO2 were measured at 80 minutes following pneumoperitoneum (time 3). Heart rate (HR), arterial pressure, airway pressure were evaluated throughout surgery.Results: There was a significant correlation between TcPCO2 and PaCO2 (r=0.87, P<0.01), but the correlation between PETCO2 and PaCO2 was lessened with prolonged pneumoperitoneum. The consistency limit (mean±2SD) between PaCO2 vs. TcPCO2 and PaCO2 vs. PETCO2 was (-2.86, 5.46) and (-1.61, 20.11) mm Hg, respectively. A difference of ≤5 mm Hg happened in 96% results of PaCO2 vs. TcPCO2 and 32% of PaCO2 vs. PETCO2 (P<0.01). After the use of PEEP, the PaCO2 was increased in group I and II, sustained in group III, but decreased in group IV and V (P<0.05). In addition, PEEP restored the correlation between PETCO2 and PaCO2(r=0.6, P<0.01, N=55). The hypercapnia induced enhancement of mean arterial pressure (MAP) and HR was normalized by 10 cm H2O PEEP although the airway plateau pressure (PPLAT) and airway pressure peak (PPEAK) values were elevated.Conclusions: TcPCO2 may be used as an alternative non-invasive monitoring to predict the PaCO2 levels in elderly patients undergoing long-term retroperitoneoscopic surgery. PEEP (10 cm H2O) combined with low tidal volume (VT=7 ml/kg) ventilation provides a therapeutic approach to ameliorate pneumoperitoneum -induced hypercapnia in these patients.

The Significance of Transcutaneous Continuous Overnight CO2Monitoring in Determining Initial Mechanical Ventilator Application for Patients with Neuromuscular Disease

ObjectiveTo reveal the significance of continuous transcutaneous carbon dioxide (CO2) level monitoring through reviewing cases which showed a discrepancy in CO2 levels between arterial blood gas analysis (ABGA) and continuous transcutaneous blood gas monitoring.MethodMedical record review was conducted retrospectively of patients with neuromuscular diseases who had started home mechanical ventilation between June 2008 and May 2010. The 89 patients underwent ABGA at the 1st hospital day, and changes to their CO2 level were continuously monitored overnight with a transcutaneous blood gas analysis device. The number of patients who initially appeared to show normal PaCO2 through ABGA, yet displayed hypercapnea through overnight continuous monitoring, was counted.Results36 patients (40.45%) presented inconsistent CO2 level results between ABGA and continuous overnight monitoring. The mean CO2 level of the 36 patients using ABGA was 37.23±5.11 mmHg. However, the maximum and mean CO2 levels from the continuous monitoring device were 52.25±6.87 mmHg and 46.16±6.08 mmHg, respectively. From the total monitoring period (357.28±150.12 minutes), CO2 retention over 45 mmHg was detected in 198.97 minutes (55.69%).ConclusionAlthough ABGA only reflects ventilatory status at the puncturing moment, ABGA results are commonly used to monitor ventilatory status in most clinical settings. In order to decide the starting point of home mechanical ventilation in neuromuscular patients, continuous overnight monitoring should be considered to assess latent CO2 retention.

Propofol Safety in Bronchoscopy: Prospective Randomized Trial Using Transcutaneous Carbon Dioxide Tension Monitoring

Background: Midazolam is commonly used for sedation during flexible bronchoscopy because of its relatively wide therapeutic window. Recently, sedation with propofol for bronchoscopy has gained popularity, although concern has been raised regarding its potential ability to induce severe respiratory depression. Objectives: The aim of this study was to evaluate the safety of sedation under midazolam + alfentanil compared to propofol. Methods: We conducted a prospective randomized trial using continuous transcutaneous carbon dioxide tension monitoring. The study group included 115 patients undergoing bronchoscopy, prospectively randomized to receive sedation with either midazolam + alfentanil (n = 59) or propofol (n = 56). Results: Intra-procedural carbon dioxide tension values were higher in the midazolam + alfentanil group than in the propofol group (maximum 53.72 vs. 49.49 mm Hg, mean 46.78 vs. 43.78 mm Hg), but the differences did not reach statistical significance (p = 0.149 and 0.193, respectively). Carbon dioxide tension values were significantly higher in the midazolam + alfentanil group than in the propofol group at 5 and 10 min following procedure (51.7 vs. 49.3 mm Hg, p = 0.026, and 50.8 vs. 42.7 mm Hg, p < 0.01, respectively), and significantly more patients in the midazolam + alfentanil group needed oxygen supplementation or airway support (24 vs. 8 patients, respectively). Conclusion: Midazolam + alfentanil and propofol are equally safe for sedation during bronchoscopy. Sedation with propofol, using small boluses at short intervals, does not cause excessive respiratory drive depression and represents an excellent alternative to traditional sedation agents.

Continuous transcutaneous carbon dioxide measurement from the fetal scalp during labor and during first minutes of extrauterine life.

An electrode for continuous transcutaneous carbon dioxide (tcPco2) monitoring was attached to the fetal scalp in 25 consecutive vaginal deliveries. In six patients the electrode fell off or was deliberately removed when the fetal head was on the pelvic floor, while eight patients were delivered with the electrode in situ, making it possible to study changes in the fetal carbon dioxide level when the fetus changed from placental to lung breathing. The mean recording time was 136 minutes (range 10-348). Fifteen patients were recorded until delivery and analysis of cord blood showed a statistically highly significant correlation between tcPco2 in both umbilical venous and arterial blood. The mean fetal tcPco2 during the late first stage of labor was 56 torr (range 40-75; n = 18). The post partum tcPco2 level in newborns was stable 20 minutes after delivery with a mean level of 51 torr (range 40-60). Fetuses with a normal fetal heart rate tracing showed a lower mean tcPco2 level than fetuses with fetal heart rate tracing abnormalities. The experience with the current technique indicates that both Apgar score and fetal heart rate tracing are rather crude methods to judge fetal blood gas status.

Transcutaneous carbon dioxide measurements in the fetus during labor.

Continuous transcutaneous carbon dioxide partial pressure (tcPco2) was monitored in 40 spontaneous labors. The electrode was attached by glue fixation. An interpretable tracing was obtained in 36 cases. All cases but 2 were normal pregnancies. Thirty-two patients had epidural analgesia while the others had no analgesia. All infants had an Apgar score above 7 at five minutes after delivery and only two had a pH of the umbilical artery of less than 7.16. Mean duration of the recordings was 116 minutes (range: 15-300) and mean time for reaching steady-state was 27 minutes (range: 10-45 minutes). Mean value of tcPco2 was 48 mmHg (SD: 6) before 6 cm of dilatation, 47 mmHg (SD: 8) between 6 and 10 cm, and 47 mmHg (SD: 15) at the second stage of labor. Mean umbilical artery Pco2 was 48 mmHg (SD: 14) and mean umbilical artery pH was 7.25 (SD: 0.06). The range of tcPco2 obtained in these normal cases was 20 to 62 mmHg. Comparison of the results with those of other authors and with previous studies of normal labor and epidural analgesia show a higher tcPco2 compared to scalp Pco2. In contrast to other studies in these series no correlation was found in the series between umbilical artery Pco2 and tcPco2 values. This lack of correlation could be explained either by the small number of cases in which both measurements were available (9 cases) and by the small range of variation or by some inaccuracy in the measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous transcutaneous carbon dioxide and transcutaneous oxygen monitoring in neonatal intensive care.

Continuous transcutaneous carbon dioxide partial pressure (tc PCO2) and continuous transcutaneous oxygen partial pressure (tc PO2) was monitored simultaneously in 10 consecutive neonatal intensive care patients treated for respiratory problems or immaturity. During measurement the electrode temperature was 44 degrees C while during the resting periods--with the electrodes left in situ--the electrode temperature was 37 degrees C. Measurements were performed for periods up to 31 hours. It was possible to discover changes in central blood gas partial pressures also at the lower electrode temperature. This was especially true for the tc PCO2 recording which was less influenced by the decrease in electrode temperature than the tc PO2 recording. In six patients an increased frequency of apnoea was diagnosed by the transcutaneous blood gas monitoring equipment previous to other clinical signs. A statistically highly significant correlation was found between transcutaneous and arterial blood gas values, the arterial samples obtained from umbilical artery catheters. tc PCO2 and tc PO2 very sensitively reacts to changes in the breathing pattern and to changes in activity of the neonate emphasizing the drawbacks of previous blood gas monitoring techniques. The technique for continuous transcutaneous carbon dioxide monitoring is ready for clinical use and is a valuable additional tool in all neonatal intensive care patients with the risk of alveolar hypoventilation.

Continuous transcutaneous carbon dioxide monitoring in the fetus during labor.

From the Department of Obstetrics and Gynecology, University of Lund, General Hospital, S-214 01 Malmö, Sweden.