Transcutaneous Partial Pressure Of Carbon Dioxide Research Articles

Morphine in the management of dyspnoea in ALS. A pilot study

The study aimed to verify the efficacy and safety of morphine in the management of dyspnoea in patients with terminal amyotrophic lateral sclerosis (ALS). A further aim was to assess the effect of morphine on ventilation and the potential diminishing effect of nasal O(2)-insufflation preceding morphine administration on the intensity of dyspnoea. Six dyspnoeic ALS patients were included in a prospective, non-randomized study. The intensity of dyspnoea was measured with a Numeric Rating Scale (NRS 0-10). Transcutaneous carbon dioxide partial pressure (tcpaCO(2)), oxygen saturation (SaO(2)) and pulse frequency were continuously monitored during the nasal insufflation of O(2) preceding the first morphine dose and also afterwards. A significant decrease was seen in both respiratory rate (from 42.0 +/- 6.0/min to 29.0 +/- 4.0) (P = 0.027) and the intensity of dyspnoea (from 7.5 +/- 1.9 to 1.8 +/- 0.8) (P = 0.027) 120 min after the morphine administration. Neither a significant tcpaCO(2) increase nor a SaO(2) decrease were seen. O(2)-insufflation did not significantly decrease the intensity of dyspnoea. The anxiety of choking correlated highly significantly with the intensity of dyspnoea (r = 0.861, P = 0.028) in all patients. There were no cases of respiratory depression. Therapeutic doses of morphine were effective and safe in the management of dyspnoea in ALS patients.

The accuracy of non‐invasive carbon dioxide monitoring: A clinical evaluation of two transcutaneous systems

We determined the accuracy of two transcutaneous carbon dioxide monitoring systems (SenTec Digital Monitor with V-Sign Sensor and TOSCA 500 with TOSCA Sensor 92) for the measurement of single values and trends in the arterial partial pressure of carbon dioxide in 122 adult patients during major surgery and in 50 adult patients in the intensive care unit. One or several paired measurements were performed in each patient. The first measurement was used to determine the accuracy of a single value of transcutaneous carbon dioxide; the difference between the first and the last measurements was used to analyse the accuracy and to track trends. We defined a 95% limit of agreement of <or=1 kPa as being clinically useful. There was insufficient agreement between transcutaneous carbon dioxide partial pressure values derived from the two systems and arterial carbon dioxide values for both single values and trends as defined by our suggested limit of agreement. We conclude that these systems cannot replace conventional blood gas analysis in the clinical setting studied.

An Evaluation of Transcutaneous Carbon Dioxide Partial Pressure Monitoring during Apnea Testing in Brain-dead Patients

Diagnosis of brain death usually requires an arterial carbon dioxide partial pressure (Paco2) of 60 mmHg during the apnea test, but the increase in Paco2 is unpredictable. The authors evaluated whether transcutaneous carbon dioxide partial pressure (Ptcco2) monitoring during apnea test can predict that a Paco2 of 60 mmHg has been reached. The authors compared Ptcco2 measured with a transcutaneous ear sensor (V-Sign Sensor, Sentec Digital Monitoring System; SENTEC-AG, Therwil, Switzerland) and Paco2 obtained from arterial blood gas measurements in 32 clinically brain-dead patients. In the first 20 patients, the mean Paco2-Ptcco2 gradient was 0.7 +/- 3.6 mmHg at baseline and 8.7 +/- 7.1 mmHg after 20 min of apnea. Using receiver operating characteristic curve analysis (area under the curve: 0.983 +/- 0.013), the best threshold value of Ptcco2 to predict that a Paco2 of 60 mmHg had been reached was 60 mmHg (positive predictive value: 1.00 [0.93-1.00]). In the following 12 patients investigated with use of this Ptcco2 target value of 60 mmHg, the mean duration of the apnea test (11 +/- 4 vs. 20 +/- 0 min; P < 0.001), hypercapnia (74.0 +/- 4.9 vs. 98.3 +/- 20.0 mmHg; P < 0.001), acidosis (pH: 7.18 +/- 0.06 vs. 7.11 +/- 0.08; P < 0.001), and decrease in arterial oxygen partial pressure (-47 +/- 44 vs. -95 +/- 89; P < 0.05) at the end of the test were reduced as compared with the 20-min apnea test group. During the apnea test in brain-dead patients, a Ptcco2 of 60 mmHg accurately predicts that a Paco2 of 60 mmHg has been reached. This may allow a reduction in the duration of the apnea test and consecutively limit occurrence of complications.

Simultaneous measurements of end-expiratory and transcutaneous carbon dioxide partial pressure in ventilated premature and newborn infants

The aim of the present trial was to study the relationship between end-tidal pCO2 (p(et)CO2) and transcutaneous pCO2 (ptcCO2) after in-vivo calibration in ventilated newborns. 61 end-tidal and transcutaneous pCO2 measurements were simultaneously performed in 30 ventilated preterm and term newborn infants (weight at birth 1862.6 +/- 981.9 g). End-tidal pCO2 was measured in mainstream mode at the end of the endotracheal tubus (Novametrix 7000 Medical Systems Inc., USA, dead volume of the chamber 0.6 ml). Transcutaneous pCO2 was measured by means of a Servomed (SMK 365 Hellige, FRG) analyser. The statistical analysis demonstrated a good correlation (r = 0.72, p < 0.001) between ptcCO2 (mean +/- SD, 44.3 +/- 11.2 mmHg) and p(et)CO2 (32.4 +/- 10.4 mmHg). A considerable difference between transcutaneous and end-tidal pCO2 values was observed (p(tc-et)CO2 = +11.9 +/- 8.7 mmHg). This phenomenon was probably caused by ventilation-perfusion disturbances in the studied critically ill neonates. The statistical analysis revealed that the absolute magnitude of the P(tc-et)CO2 difference was independent from disease, episodes of spontaneous respiration or of respiratory frequency. Capnographic determination of P(et)CO2 provides informations about alveolar ventilation-perfusion-disturbances. Capnography enables the on-line control of end-tidal pCO2 in neonates with respiratory failure. It cannot replace transcutaneous pCO2 measurements or blood gas analysis but it can reduce its frequency in clinically stable patients. The analysis of the capnogram can be used to optimise artificial ventilation. A quantitative evaluation of the capnogram by calculation of Murányi's-CO2-Index was possible only in 28% of the ventilated newborns which limits its value in such patients.

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)

Transcutaneously measured carbon dioxide partial pressure in non-hypoxic fetuses during labor

Using the newly developed Severinghaus electrode we performed measurements of the transcutaneous carbon dioxide partial pressure (tcPco2) in 81 non-hypoxic fetuses during labor. The calibration and measuring temperature was 39 degrees C. After a correction with a factor of 13% the transcutaneous Pco2 values corresponded well with the blood values of the Pco2 from FBA respectively the umbilical artery. While during the first stage of labor we found only a gradual rise in the tcPco2 level, we observed a rapid rise at the end of the second stage. Analysing the influence of clinical factors on the fetal tcPco2 level we found statistically significant higher levels during the first stage of labor in primipara compared with multipara. However there was no significant difference dependent on gestational age, the age of the mother and the birthweight.

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.