Transcutaneous Capnography Research Articles

Effects of Double Filtration Plasmapheresis on Nocturnal Respiratory Function in Myasthenic Patients

Assessment of respiratory function using combined oximetry-cutaneous capnography has never been evaluated in patients with myasthenia gravis (MG). We investigated the effects of double filtration plasmapheresis (DFPP) on respiratory status in 18 MG patients. Results of combined oximetry and transcutaneous capnography, MG scores, and acetylcholine receptor antibody titers before and after DFPP treatment were compared. The respiratory monitoring was performed at three time periods (morning, afternoon, and sleep). Mean MG score was markedly lower after DFPP treatment (5.7) than before treatment (7.9). Before DFPP, the minimum pulse oximetric saturation (SpO2 ) level obtained during the night session was significantly lower (P = 0.0513 and P = 0.0199) than the levels obtained during the two daytime sessions. A similar phenomenon was noted for maximum transcutaneous carbon dioxide tension (PtcCO2 ). After DFPP treatment, the maximum and mean PtcCO2 levels were significantly higher (P = 0.0056) in the morning than in the afternoon. Of all the respiratory function parameters measured, only minimum SpO2 levels obtained during morning sessions before DFP treatment differed significantly from those obtained after DFPP treatment (P = 0.0322). Overall, however, minimum SpO2 levels as well as mean and maximum PtcCO2 levels improved significantly during sleep after DFPP. In conclusion, we found that respiratory function abnormalities were common in myasthenic patients without clinical respiratory symptoms. DFPP treatment resulted in minimal improvement of respiratory parameters.

Impact of Different Backup Respiratory Rates on the Efficacy of Noninvasive Positive Pressure Ventilation in Obesity Hypoventilation Syndrome: A Randomized Trial

Unintentional leaks, patient-ventilatory asynchrony, and obstructive or central events (either residual or induced by noninvasive positive pressure ventilation [NPPV]) occur in patients treated with NPPV, but the impact of ventilator settings on these disturbances has been little explored. The objective of this study was to investigate the impact of backup respiratory rate (BURR) settings on the efficacy of ventilation, sleep structure, subjective sleep quality, and respiratory events in a group of patients with obesity hypoventilation syndrome (OHS). Ten stable patients with OHS treated with long-term nocturnal NPPV underwent polysomnographic recordings and transcutaneous capnography on 3 consecutive nights with three different settings for BURR in random order: spontaneous (S) mode, low BURR, and high BURR. No other ventilator parameter was modified. The S mode was associated with the occurrence of a highly significant increase in respiratory events, mainly of central and mixed origin, when compared with both spontaneous/timed (S/T) modes. Accordingly, the oxygen desaturation index was significantly higher in the S mode than in either of the S/T modes. The results of nocturnal transcutaneous P(CO(2)) (Ptc(CO(2))) (mean value and time spent with Ptc(CO(2)) > 50 mm Hg) were similar over the three consecutive nocturnal recordings. The quality of sleep was perceived as slightly better, and the number of perceived arousals as lower with the low- vs high-BURR (S/T) mode. In a homogenous group of patients treated with long-term NPPV for obesity-hypoventilation, changing BURR from an S/T mode with a high or low BURR to an S mode was associated with the occurrence of a highly significant increase in respiratory events, of mainly central and mixed origin. ClinicalTrials.gov; No.: NCT01130090; URL: www.clinicaltrials.gov

Significant hypercapnia either in CO 2-insufflated or air-insufflated colonoscopy under deep sedation

Background Previous reports showed that CO 2-insufflated colonoscopy is safe and less discomfortable. However, hypercapnia remains a vital concernment if deep sedation is necessary for difficult colonoscopy with prolonged CO 2 insufflation. This observational study is to measure bodily CO 2 subjected to colonoscopy facilitated by CO 2- and air- or air-insufflation in conscious-sedation, deep-sedation and awake patients. Objective To investigate if CO 2-insufflated colonoscopy could increase the risk of hypercapnia in awake, conscious-sedation and deep-sedation patients. Methods 104 patients in our health center undergoing sequential esophagogastroscopy and colonoscopy screening were included. At patients’ request, incremental intravenous sedatives were given in order that the air-insufflated esophagogastroscopy could be carried out without the molestation of gag and cough reflexes. The sedation levels were re-evaluated before proceeding colonoscopy and the patients were divided into conscious-sedation (respond purposefully to verbal commands) and deep-sedation groups and randomly allocated for air or CO 2 insufflation. Transcutaneous capnography (TcCO 2) was recorded every minute throughout the colonoscopy procedure. Results The baseline TcCO 2 in the air- (50.9 ± 5.7 mmHg) and CO 2-insufflated (53.1 ± 6.5 mmHg) groups under deep sedation was significantly higher than the groups under conscious-sedation and the awake groups ( p < 0.01). In both air- and CO 2-insufflation groups there were also a statistically significant ( p < 0.01) correlation in TcCO 2 between the start, the peak and the end of colonoscopy. TcCO 2 did not significantly change throughout the colonoscopy in awake and conscious-sedation groups, either with air or CO 2 insufflation. With deep sedation, TcCO 2 significantly increased and peaked around the time when the scope touching the cecum, and then returned to original state with suction and withdrawl of the colonoscope without significant interaction of CO 2 insufflation and deep sedation. Conclusion The TcCO 2 during colonoscopy was correlated to the data before inserting colonoscope but significantly different within awake, conscious-sedation and deep-sedation groups. TcCO 2 did not change significantly either with CO 2 insufflation or air insufflations in awake and conscious-sedation groups. However, in deep-sedation groups with significantly higher baseline TcCO 2, further increase of TcCO 2 were significant without interaction with CO 2 insufflation. We concluded that when patients need deep sedation for colonoscopic procedures facilitated by gas insufflation, hypercapnia is still considerably present, not only with CO 2 insufflation but also with air insufflation colonoscopy.

Combined oximetry and transcutaneous capnography is a reliable non-invasive monitoring in patients after cardiac surgery

The aim of this study was to validate the revised V-Sign™ 2 ear lobe sensor for combined assessment of pulse rate (PR), pulse oximetry (SpO2) and transcutaneous carbon dioxide tension (PtcCO2) in adults after cardiac surgery.

Temazepam 10 mg does not affect breathing and gas exchange in patients with severe normocapnic COPD

Benzodiazepines can improve sleep quality, but are also thought to cause respiratory depression in patients with chronic obstructive pulmonary disease (COPD). The aims of this study were to assess the effects of temazepam on indices of circadian respiratory function, dyspnea, sleep quality, and sleepiness in patients with severe COPD and insomnia. In a double-blind, randomized, placebo-controlled, cross-over study in 14 stable patients with COPD (mean FEV(1) 0.99+/-0.3L) with insomnia, polysomnography with continuous transcutaneous capnography and oximetry, arterial gas sampling, hypercapnic ventilatory response, multiple sleep latency test, Epworth Sleepiness Scale, dyspnea and sleep visual analogue scales (VAS) were performed at baseline, after one week of temazepam 10mg at bedtime and after one week of placebo. Temazepam did not cause statistically significant changes in mean transcutaneous carbon dioxide tension during sleep compared to placebo (5.9+/-1.0 kPa vs. 6.3+/-1.4 kPa, p-value 0.27), nor in mean oxygen saturation (92+/-3% vs. 92+/-2%, p-value 0.31), nor in any of the other investigated variables, except for the total sleep time and sleep latency VAS, which improved with temazepam. One week usage of temazepam 10mg does not influence circadian respiratory function, dyspnea, and sleepiness in patients with stable, severe, normocapnic COPD and insomnia and it improves total sleep time and subjective sleep latency. However, this is a preliminary explorative study for assessing the feasibility to perform a larger study on this topic. The clinical implications of this study are very limited.

Impact of volume targeting on efficacy of bi-level non-invasive ventilation and sleep in obesity-hypoventilation

Volume targeting by bi-level positive pressure ventilation (BPPV) has recently been made available by several manufacturers for home care ventilators. Although it may improve nocturnal ventilation, we hypothesized that increased pressure swings related to volume targeting may have a deleterious effect on sleep structure and patient comfort. Patients in stable clinical condition (n=12) treated by BPPV for obesity-hypoventilation (BMI: 44+/-8 kg/m(2)) for a median of 30 months (range: 2-138), underwent nocturnal polysomnography with transcutaneous capnography on 2 consecutive nights with either BPPV and usual ventilator settings or BPPV with volume targeting, in randomized sequence. Subjective quality of sleep (St. Mary's Hospital Questionnaire) and comfort of ventilation (VAS scales) were also assessed. Mean IPAP, mean tidal volume, and total ventilation increased significantly with volume targeting. Control of nocturnal hypoventilation was slightly improved with volume targeting (nocturnal TcPCO(2): 42+/-9 vs. 45+/-5 mmHg, p=0.04). However, total sleep time and stage 2 sleep were greater without volume targeting, and wake after sleep onset and awakenings >20s increased with volume targeting. Subjectively, patients described a lighter sleep, of lesser quality and more frequent awakenings with volume targeting; ventilation was perceived as less comfortable, with an increased perception of leaks and of "too much air". In stable patients treated by BPPV for obesity-hypoventilation, volume targeting improved control of nocturnal hypoventilation at the expense of a slight decrease in objective and subjective sleep quality, and comfort of ventilation.

Noninvasive Assessment of Gas Exchange in the Critically Ill Patient

A variety of technologies is available to noninvasively evaluate arterial oxygen saturation and partial pressure of serum oxygen (PaO2) and carbon dioxide (PaCO2) in the critically ill patient. These include pulse oximeters, transcutaneous monitoring devices, capnometry, and capnography. Understanding the technology, the clinical significance of the data, and the associated limitations is fundamental in optimizing patient assessment and management. Accordingly, critical care nurses have increasing responsibilities related to these aspects of patient care.