The Application Of Transcutaneous Blood Gas Monitoring In ICU Patients After General Anesthesia

BackgroundFor patients who transferred to ICU after general anesthesia surgery, during mechanical ventilation, continuous observation of the level changes of PaCO2,PaO2, lactic acid and other mesures is very important to observe the operation effect and timely adjust the parameters of the ventilator and ensure the therapeutic effect. At present the most widely used method is arterial blood gas analysis, but frequent sampling of arterial blood samples is painful for patients, and may increase the chance of infection.Present study has confirmed that transcutaneous oxygen and carbon dioxide has a good agreement to arterial oxygen and carbon dioxide partial pressure in adults.And it has been widely used in the children, especially in the NICU(neonatal intensive care unit).Caused by many factors such as the surgical trauma, inappropriate respiratory or circulatory treatment during the operation,systemic or local effective circulating blood volume reduction can occur early after surgery, followed by inadequate tissue perfusion and tissue hypoxia,cellular metabolic disorder, lactate acid production.And the lactic acid level has beed incresed before the changes of the normal hemodynamic indexes.Early detection and effective treatment are important to improve the prognosis of patients.Previous studies have shown that percutaneous index (PtcO2/PaO2) can eliminate the influence of arterial blood gas and oxygen concentration.Pertutaneous index can reflex the degree of shock of patients with hemodynamic instability,PtcO2/PaO2>0.7 suggests good tissue perfusion and stable hemodynamics.ObjectiveBy studing the correlation between transcutaneous carbon dioxide partial pressure (PtcCO2) and oxygen partial pressure (PtcO2) monitoring and arterial blood carbon dioxide partial pressure (PaCO2) and oxygen partial pressure (PaO2) in ICU patients with mechanical ventilation after general anesthesia surgeries, to confirm the predictive value of PtcCO2/PtcO2 to PaCO2/PaO2. Meanwhile to analyse the results of percutaneous index(PtcO2/PaO2) to discuss whether it can reflex the tissue perfusion of patients after surgery.Method1.Study subjects1.1 Inclusion criteriaGeneral-anesthesia-surgery patients transferred to ICU of Shandong Provincial Hospital during December 2015 to March 2016.1.2Exclusion criteriaAnterior chest skin with ulceration, transcutaneous oxygen monitoring is unable.2.Study protocal:After the patient transferred to ICU, in addition to basic monitoring such as blood pressure, heart rate, pulse oxygen saturation, transcutaneous oxygen pressure and carbon dioxide partial pressure was continuously monitoring.2.1 Data collection:Clerk electrode was placed immediately once the patient was transferred to ICU, initial value(TO) was defined as When the PtcO2 and PtcCO2 values are stable(10-15min), arterial blood samples were collected in the same time for gas analysis, record PaO2,PaCO2,SaO2,LacPtcO2,cPCO2,SpO2 and patient’s vital signs and hemodynamic parameters.2.2Monitoring of transcutaneous oxygen and carbon dioxide:Use TCM4 transdermal detector of Radiometer. Strictly according to the operating rules, fristly do standard gas calibration, disinfect the skin with alcohol, then place the electrodes. The anterior chest thin skin was selected for measurements, electrode temperature was 44 ℃, exchange position every 4 hours to prevent skin burn.2.3 Statistical method:Use SPSS22.0 for analysis, P<0.05 was statistically significant. Descriptive data are presented as means±SDs and as number and proportions, the concordance between PtcCO2/PaCO2 and PtcO2/PaO2 was evaluated by Paired-sample T tests,groups were compared by one-way ANOVA,relations between the two groups were analyzed using relevant indicators bivariate correlation analysis (Pearson-related).Results1 General characteristics:65 patients were inclued,male 35,female 30;aged 18-75 years, mean age 54±16 years.(Demographic statistics and vital signs of patients are shown in Table 1)2 Correlation test of PtcCO2/PtcO2 and PaCO2/PaO2:There was an excellent correlation between PtcCO2 and PaCO2 (r=0.820, p<0.01).There was also excellent correlation between PtcO2 and PaO2(r=0.923, p<0.01),all PaO2 are greater than PtcO2 (147.88±76.33mmHg,94.76±29.10mmHg)(p<0.01). Statistical results shown in Table 2, the correlation analysis results shown in Figure 1, Figure 2.3 Correlation test of PtcCO2/PtcO2 and PaCO2/PaO2 at different stages after surgeries(TO:when transferred in, before T1:before extubation,T2:before back to general wards):There were excellent correlations between PtcCO2/PaCO2 and PtcO2/PaO2 at different time points after operation (p<0.05).Statistical results in Table 3, correlation analysis shown in Figure 6-11.4 Correlation test of PtcCO2/PtcO2 at different oxygen concentration:Select part of the data were divided into three groups according to oxygen concentration(21%,40% and50%),bivariate correlation and linear regression analysis showed TcP02 and PaO2 had good linear correlation at different oxygen concentration(p<0.05).Statistical results in Table 4, correlation analysis shown in Figure 3-5.5 Analysis of percutaneous index(PtcO2/PaO2):The overall value of PtcO2/PaO2 was 0.74± 0.13, the value of PtcO2/PaO2 were 0.76±0.10,0.73±0.13,0.72±0.14,when FIO2 were 21%,40%,50% respectively. Statistical analysis showed that F= 1.754, P=0.176, the difference between the groups was not statistically significant. (Statistical results in Table 5)Conclusion:There are excellent correlations between both PtcO2/PaO2 and PtcCO2/PaCO2, and no significant differences between different stages after surgery and different oxygen concentration, confirmed that PtcCO2/PtcO2 can accurately predict PaCO2/PaO2.Thus transcutaneous blood gas monitoring may play an important role in observe patients’oxygenation and timely adjust the parameters of the ventilator and ensure the therapeutic effect.