Application Of Transcutaneous Carbon Dioxide Monitoring In Chronic Obstructive Pulmonary Disease With Type Ⅱ Respiratory Failure

Background:Chronic obstructive pulmonary disease（COPD）is one of the common diseases in respiratory department.Acute exacerbations of COPD are often associated with type II respiratory failure（RF）.Non invasive positive pressure ventilation（NIPPV）is required during the treatment.It is particularly important to monitor carbon dioxide（CO₂）retention levels during NIPPV.Arterial blood gas text（ABG）is the internationally accepted gold standard for assessing hypoxia and CO₂retention.However,due to its invasiveness,discontinuity,and other shortcomings,it limits clinical application.Transcutaneous CO₂（PtcCO₂）can provide an overall trend of changes in CO₂ retention of the body,it is an effective non-invasive,continuous monitoring technology,could also monitor the extent of CO₂ retention in real time for clinicians to evaluate treatment effectiveness,early adjustment of treatment options and non-invasive ventilator related parameters.Objective:To observe the changes of Transcutaneous carbon dioxide（PtcCO₂）and arterial carbon dioxide（PaCO₂）through noninvasive ventilation in COPD with typeⅡrespiratory failure patients,we explore the correlation between PtcCO₂ and PaCO₂ and evaluate the value of early changes of PtcCO₂ on the prognosis.It will provide scientific basis for discovering the retention of carbon dioxide,delaying the occurrence and development of complications,improving the prognosis of patients,reducing the economic expenditure and improving the patients’life quality.Methods:COPD with typeⅡrespiratory failure patients that treated by NIPPV and hospitalized at the Department of respiratory and sleep-related disease in the first affiliated Hospital of Zhengzhou University were recruited in the study.Patients in group A monitored PaCO₂ by ABG and others in group B monitored CO₂ by both ABG and PtcCO₂.The age,sex,BMI,smoking,times of exacerbations in the past year,percentage of predicted FEV₁ and CAT scores were recorded for every patient.Of group A,Pa CO₂ was measured by ABG at beginning of NIPPV（T₀）,and at after NIPPV 8±2h（T₁）,24±2h（T₂）,and 72±2h（T₃）.Patients in group B were recorded PaCO₂ and PtcCO₂ at T₀,T₁,T₂,T₃.The IPAP,EPAP,tidal volume at each moment,endotracheal intubation,and the time PaCO₂ reached discharge standard were also recorded.The statistical analysis was performed by SPSS 22.0 for Windows.P<0.05（α=0.05）was considered statistically significant.Results:184 patients were included in this study,including 98 patients in group A and 86 patients in group B.There were no significant difference in age,sex,BMI,smoking,times of exacerbations in the past year,percentage of predicted FEV₁,body temperature and CAT scores between the two groups（P>0.05）.The correlation coefficient between PtcCO₂ and PaCO₂（r=0.9512,P=0.039）.In group A,PaCO₂ at T₀ was（76.63±10.12）mmHg,PaCO₂ at T₁ was（71.28±8.60）mmHg,PaCO₂ at T₂ was（64.12±7.32）mmHg,PaCO₂ at T₃ was（55.48±4.08）mmHg;In group B,PaCO₂ at T₀ was（75.92±8.60）mmHg,PaCO₂ at T₁ was（68.13±9.35）mmHg,Pa CO₂ at T₂ was（57.12±6.61）mmHg,PaCO₂ at T₃ was（48.66±5.17）mmHg,there was a statistically significant difference in PaCO₂ between two groups at T₁,T₂,and T₃.There was no significant difference in IPAP,EPAP,and tidal volume at T₀ between group A and B（P>0.05）.However,the difference between IPAP and tidal volume in group B at T1,T2,and T3 was higher than that in group A（P<0.05）.In Group A,10 patients had tracheal intubation,and the time PaCO₂reached discharge standard was（6.17±2.21）days,these in Group B were 2 patients and（4.62±2.82）days,the differences were statistically significant（P<0.05）.Conclusion:（1）There is high relationship between PtcCO₂ and PaCO₂,and it can be used as a non-invasive indicator for assessing carbon dioxide retention.（2）PtcCO₂ used in COPD patients with type II respiratory failure,can help doctors adjust NIPPV treatment parameters instantly,improve hypoventilation more effectively,reduce carbon dioxide retention and tracheal intubation rate.