Mean tcpCO2 Research Articles

Nocturnal Hypoventilation in the Patients Submitted to Thoracic Surgery.

Nocturnal hypoventilation may occur due to obesity, concomitant chronic obstructive pulmonary disease (COPD), obstructive sleep apnea, and/or the use of narcotic analgesics. The aim of the study was to evaluate the risk and severity of nocturnal hypoventilation as assessed by transcutaneous continuous capnography in the patients submitted to thoracic surgery. The material of the study consisted of 45 obese (BMI 34.8 ± 3.7 kg/m2) and 23 nonobese (25.5 ± 3.6 kg/m2) patients, who underwent thoracic surgery because of malignant (57 patients) and nonmalignant tumors. All the patients received routine analgesic treatment after surgery including intravenous morphine sulfate. Overnight transcutaneous measurements of CO2 partial pressure (tcpCO2) were performed before and after surgery in search of nocturnal hypoventilation, i.e., the periods lasting at least 10 minutes with tcpCO2 above 55 mmHg. Nocturnal hypoventilation during the first night after thoracic surgery was detected in 10 patients (15%), all obese, three of them with COPD, four with high suspicion of moderate-to-severe OSA syndrome, and one with chronic daytime hypercapnia. In the patients with nocturnal hypoventilation, the mean tcpCO2 was 53.4 ± 6.1 mmHg, maximal tcpCO2 was 59.9 ± 8.4 mmHg, and minimal tcpCO2 was 46.4 ± 6.7 mmHg during the first night after surgery. In these patients, there were higher values of minimal, mean, and maximal tcpCO2 in the preoperative period. Nocturnal hypoventilation in the postoperative period did not influence the duration of hospitalization. Among 12 patients with primary lung cancer who died during the first two years of observation, there were 11 patients without nocturnal hypoventilation in the early postoperative period. Nocturnal hypoventilation may occur in the patients after thoracic surgery, especially in obese patients with bronchial obstruction, obstructive sleep apnea, or chronic daytime hypercapnia, and does not influence the duration of hospitalization.

Physiological Impacts of Surgical Mask Coverage of Elastomeric Half-mask Respirator Exhalation Valves in Healthcare Workers.

ObjectivesElastomeric half-mask respirator (EHMR) use in healthcare increased significantly during the COVID-19 pandemic. Concern for potential release of infectious aerosols from EHMR exhalation valves prompted recommendations to cover them with surgical masks (SMs), thereby improving source control. The physiological and subjective effects of wearing a SM over the exhalation valve of an EHMR, however, are unknown.MethodsTwelve healthy healthcare worker volunteers completed a 30-min series of simulated healthcare-related tasks, including resting, talking, walking, and bending, proning and supinating a weighted manikin, and performing cardiopulmonary resuscitation. This series recurred three times with different mask configurations—SM only, EHMR only, or EHMR with SM covering the exhalation valve. A transcutaneous sensor continuously measured carbon dioxide (tcPCO2), oxygen saturation (SpO2), and heart rate (HR) from each subject. Subjects scored their rates of perceived exertion (RPE) and levels of discomfort after each round. Physiological parameters and subjective scores were analyzed using mixed linear models with a fixed effect for mask type, activity, age, body mass index (BMI), and gender. Analysis also tested for interaction between mask type and activity.ResultsPhysiological parameters remained within normal ranges for all mask configurations but varied by task. Statistically significant but small decreases in mean tcPCO2 (37.17 versus 37.88 mmHg, P < 0.001) and SpO2 (97.74 versus 97.94%, P < 0.001) were associated with wearing EHMR with SM over the exhalation valve compared with EHMR alone. Mean HR did not differ between these mask configurations. Wearing SM only was associated with lower RPE and level of discomfort compared with EHMR, but these subjective scores did not differ when comparing EHMR with SM to EHMR only. Age, BMI, and gender had no significant effect on any outcomes.ConclusionsWearing a SM over an EHMR did not produce clinically significant changes in tcPCO2, SpO2, or HR compared with uncovered EHMR during healthcare-related tasks. Covered EHMR use also did not affect perceived exertion or discomfort compared with uncovered EHMR use. Covering the exhalation valve of an EHMR with a SM for source control purposes can be done safely.

Ventilation Adjustment in ECT During COVID-19: Voluntary Hyperventilation is an Effective Strategy.

PurposeAirway management is a key objective in adapted electroconvulsive therapy (ECT) protocols during the COVID-19 pandemic to prevent infection. The objective of this study was to describe the effectiveness of a modified ventilation procedure designed to reduce aerosol-generating bag-mask ventilation (BMV) and isolate possible droplets while maintaining adequate respiratory gas values in ECT sessions.Materials and MethodsThis prospective study analyzed the results of the modified protocol applied over a month. Adaptations entailed preoxygenation and extension of the voluntary hyperventilation (VHV) time for two minutes before anesthesia induction, asking patients to hyperventilate with oxygen therapy via nasal cannula and while wearing a face mask. Thereafter, vigorous hyperventilation was avoided, and patients were only assisted with tightly sealed BMV until emergence from anesthesia, isolating the ventilation by using a single-use plastic device. Oxygen saturation (SpO2) and transcutaneous partial pressure of carbon dioxide (TcPCO2) were recorded throughout the session.ResultsThe study included 74 sessions of bilateral ECT with the modified ventilation protocol in 15 subjects. After VHV, the mean SpO2 increase was 2.12±2.14%, and the mean TcPCO2 decrease was 4.05±2.98 mmHg. TcPCO2 values at the moment of stimulus administration were 2.22±3.07 mmHg below pre-ECT values. The mean EEG seizure was 38.70±17.03 s, and postictal suppression was 68.31± 34.58% and 2.13±0.75 on a 0–3 scale. Brief desaturation (SpO2 <90) of 4–5 seconds duration was observed in 4 sessions.ConclusionThis modified ventilation protocol was effective during COVID-19, and it did not elicit significant side effects. In addition to avoiding vigorous BMV, it induced moderate hypocapnia, which has been tied to seizure optimization and less hypercapnia during the apnea period.

Transcutaneous CO2 Monitoring in Children Undergoing Tonsillectomy for Sleep Disordered Breathing.

Children undergoing tonsillectomy for sleep-disordered breathing are at risk for respiratory compromise when narcotics are administered. Severe complications resulting from hypoxia can include neuro-devastation and death. The objective of this prospective study was to evaluate the feasibility, accuracy, and utility of transcutaneous carbon dioxide (tcPCO2) monitoring during and after adenotonsillectomy. Prospective, Observational study. Twenty-nine children with sleep-disordered breathing scheduled for adenotonsillectomy were included in the study. Peri-operative measurements of tcPCO2 were compared against a single venous blood sample (PaCO2) and end-tidal (ET) CO2. The differences between ETCO2, tcPCO2 measures, and PaCO2 were examined using non-paired t-tests and linear regression. Parameters from PSG were recorded and associations with tcPCO2 values were performed using linear regression analysis. Group comparisons were made between pre-, intra-, and post-operative tcPCO2 measurements. Similar to ETCO2, there was good correlation of tcPCO2 to PaCO2. Children with lower oxygen (O2) saturation nadirs had higher peak CO2 levels during surgery and spent a greater proportion of time with CO2 > 50 mmHg in the recovery room (P < .01 and P < .08). Other PSG measures (apnea-hypopnea index, O2 desaturation index, and peak CO2) did not have any significant correlation. Frequent episodes of hypercapnia were noted intra- and post-operatively and mean tcPCO2 values during both periods were significantly higher than baseline (P < .001). tcPCO2 monitoring is viable in children undergoing adenotonsillectomy and can provide a good estimate of hypoventilation. tcPCO2 measurements may have particular benefit in the post-operative setting and may assist in identifying children at greater risk for respiratory complications. 4 Laryngoscope, 131:1410-1415, 2021.

Feasibilty of Transcutaneous pCO2 Monitoring During Immediate Transition After Birth-A Prospective Observational Study.

Background: According to recommendations, non-invasive monitoring during neonatal resuscitation after birth includes heart rate (HR) and oxygen saturation (SpO2). Continuous transcutaneous monitoring of carbon dioxide partial pressure (tcpCO2) may further offer quantitative information on neonatal respiratory status.Objective: We aimed to investigate feasibility of tcpCO2 measurements in the delivery room during immediate neonatal transition and to compare the course of tcpCO2 between stable term and preterm infants.Methods: Neonates without need for cardio-respiratory intervention during immediate transition after birth were enrolled in a prospective observational study. In these term and preterm neonates, we measured HR and SpO2 by pulse oximetry on the right wrist and tcpCO2 with the sensor applied on the left hemithorax during the first 15 min after birth. Courses of tcpCO2 were analyzed in term and preterm neonates and groups were compared.Results: Fifty-three term (gestational age: 38.8 ± 0.9 weeks) and 13 preterm neonates (gestational age: 34.1 ± 1.5 weeks) were included. First tcpCO2 values were achieved in both groups at minute 4 after birth, which reached a stable plateau after the equilibration phase at minute 9. Mean tcpCO2 values 15 min after birth were 46.2 (95% CI 34.5–57.8) mmHg in term neonates and 48.5 (95%CI 43.0–54.1) mmHg in preterm neonates. Preterm and term infants did not show significant differences in the tcpCO2 values at any time point.Conclusion: This study demonstrates that tcpCO2 measurement is feasible during immediate neonatal transition after birth and that tcpCO2 values were comparable in stable term and preterm neonates.

Apnoeic oxygenation with nasal cannula oxygen at different flow rates in anaesthetised patients: a study protocol for a non-inferiority randomised controlled trial

IntroductionApnoeic oxygenation using nasal high-flow oxygen delivery systems with heated and humidified oxygen has recently gained popularity in the anaesthesia community. It has been shown to allow a prolonged apnoea...

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.

Noninvasive Ventilation in Children with Spinal Muscular Atrophy Types 1 and 2

Our aim was to assess the efficacy of noninvasive ventilation (NIV) for the treatment of thoracoabdominal asynchrony during sleep in children with spinal muscular atrophy (SMA) types 1 and 2. Nine subjects underwent assessment for sleep apnea/hypopnea index (AHI), mean oxyhemoglobin saturation (SpO2), oxygen desaturation index, transcutaneous carbon dioxide tension (tcpCO2), and mean phase angle during sleep as a measure of thoracoabdominal coordination. A second sleep study was performed with use of NIV. The nine patients (7 mos of age, range 2-33) had a baseline AHI of 2.1 events per hour (range 0.5-55.8), oxygen desaturation index of 3.7 events per hour (range 1.6-46.1), mean tcpCO2 of 46 mm Hg (range 37-60), and phase angle of 127 degrees (range 72.7-151.7). Comparing baseline and NIV sleep studies, we found significant improvement in oxygen desaturation index (P < 0.010), mean tcpCO2 (P < 0.001), and phase angle (P < 0.001). For five patients, phase-angle improvement became significant when using high-span bilevel positive airway pressure (PAP). NIV improved sleep breathing parameters and thoracoabdominal coordination during sleep in SMA types 1 and 2. Phase-angle improvement correlated with bilevel PAP pressures. Phase angle may be useful for the evaluation and monitoring of therapeutic interventions such as NIV.

Transcutaneous CO2 tension effects of clonidine in paediatric caudal analgesia

In adults, clonidine when added to bupivacaine, results in no detectable respiratory depressant effect except when carbon dioxide challenge is performed. However, to date no investigations have quantified this in children. Twenty-four children (nine months to seven years) were randomized in a double-blind study into two groups. After induction, a caudal block was performed with 1 ml.kg-1 0.25% bupivacaine. Clonidine 1 microgram.kg-1 was added in the clonidine group, and 1 ml normal saline in the placebo group. Patients were monitored in the recovery room for three h from arrival to discharge with continuous pulse oximetry, respiratory rate, a transcutaneous CO2 tension (tcPCO2) every 15 min, and a four point sedation score every 30 min. Mean tcPCO2 and respiratory rate values were not different between the two groups. Apnoea and desaturation less than 97% were not observed. The sedation score decreased with time in both groups, and the score time interval was significantly higher in the clonidine group (P < 0.05). All the patients left the recovery room with a sedation score of 1, excepting four in the clonidine group with a sedation score of 2. Clonidine 1 microgram.kg-1 with 0.25% bupivacaine mixture in caudal analgesia in children did not induce an increase in tcPCO2 despite prolonged sedation.

Noninvasive Nasal Mask-Assisted Ventilation in Respiratory Failure of Duchenne Muscular Dystrophy

The effects of noninvasive nasal mask-assisted ventilation were studied in two patients with chronic respiratory failure due to Duchenne's muscular dystrophy. Observations were made with continuous recordings of transcutaneous CO2 and O2 and ear oximetry. In one case, the mean tcPCO2 fell from 72 mm Hg to 43 mm Hg. The tcPO2 increased from 38 mm Hg to 62 mm Hg without supplementary oxygen. In the second case, hypercapnia associated with supplementary oxygen was corrected, and at five months' follow-up, hypoxemia was corrected without supplementary oxygen. Prolonged therapy during sleep has resulted in sustained clinical improvement for more than 18 months.

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.