摘要:

The measurements of transcutaneous PO2relies on maximum dilation of the local vasculature in the upper dermis. In maximum hyperemia which is only possible with normal circulation, tissue PO2mirrors the PaO2, since it could be shown that under this condition the PO2becomes independent of smaller flow changes (flow independency), but there remains always a PO2difference between PaO2and PtcO2. Maximum vasodilation could only be achieved by heating up the skin surface to a temperature of about 43°C. By the application of heat, the O2dissociation curve of blood is displaced so that the PO2increases above the PaO2at body temperature. This heat induced PO2increase can be used to overcome the just mentioned remaining PO2decrease. However, the PO2increase by temperature is larger; thus, additionally, an O2consuming method was applied to obtain a PtcO2which is close to the PaO2at body temperature. As a rule, this compensation works well with newborn infants, fairly well with normal adults, but since there are large variations of anatomical and physiological data of the skin, such a compensation can never hold for all conditions.The elements which determine the relation between PaO2and PtcO2are highly nonlinear, but they cancel each other in a certain degree, so that up to about 150 torr (20 kPa) a quasilinear relationship exists. This holds only for a large hyperemia (flow independency). Thus, attempts to measure PaO2should only be made, if the state of flow independency is simultaneously measured. PtcO2measurements without knowing the state of flow should not be made. Unfortunately, the commercially available electrodes, as far as the author knows, do not fulfill this presupposition in a proper way. Only if the measurement of the state of flow is improved in the future, this method can be safely applied and used. It is not supposed to replace the single blood gas analysis but its strength is that it allows a quantitative continuous monitoring if properly used.

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Blood was applied directly to the electrode surface of a transcutaneous oxygen sensor (PtcO2) and the oxygen tension value obtained was compared to oxygen tension value from a conventional blood gas machine. Three hundred and seventeen blood samples were analyzed at four PtcO2electrode temperatures: 37, 40, 42, and 45°C. A linear regression of PO2vs. PtcO2blood drop (PbdO2) produced correlation coefficients (r) from 0.99 to 0.93 and standard errors from 3.2 to 4.7 torr at these temperatures.The mean time for stabilization was 51 sec. The PO2ranged from 4–150 torr. The authors conclude that an accurate PO2of blood can be obtained within 1 min by placing a drop of blood on the surface of a PtcO2electrode.

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Clinical usefulness and factors affecting transcutaneous CO2(PtcCO2) monitoring were studied in 22 critically ill neonates. In 10 of 22 infants, both tissue pH (pHt) and PtcCO2were monitored simultaneously using Roche pHtand CO2electrodes. Arterial blood gases were obtained from umbilical artery catheter. The effect of variations in blood pressure, oxygenation, arterial pH (pHa) pHt, and medications on PtcCO2were studied.There was a linear correlation between pHtand pHa(n = 108, r = 0.85, slope 1.08), PtcCO2and PaCO2(n = 188, r = 0.85, slope 1.49). The pHtchanges correlated better with PtcCO2than with arterial CO2(r = 0.78, slope 1.35).The major factors affecting the PtcCO2relationship were (a) hypoxia and (b) acidosis. When PaO2< 40 torr, PtcCO2correlated poorly to PaCO2(n = 23, r = 0.48, slope 0.72) whereas, during normoxia (PaO2> 40 torr), it correlated well, r = 0.85, slope 1.51 similarly. When pHtwas > 7.30, PtcCO2correlated better with PaCO2(r = 0.88, slope 1.37) than during tissue acidosis (r = 0.71, slope 1.51). Mean blood pressure down to 30 mm Hg and administration of dopamine and tolazoline did not affect the PtcCO2to PaCO2relationship (n = 69, r = 0.86, slope 1.6).Clinically, both continuous pHtand PtcCO2were found to be very useful in the management of critically ill neonates.

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Studies were performed on 44 patients who were monitored continuously with transcutaneous carbon dioxide (PtcCO2) sensors. The patients were monitored intermittently with arterial and mixed venous blood gases and full hemodynamic and oxygen transport data. Twenty of the studies were performed intraoperatively. A total of 411 data sets revealed a correlation coefficient, r, between arterial and transcutaneous PCO2of 0.80 when the patients were not in low flow shock, i.e., cardiac index (CI) > 1.5 L/min μ M2. On the basis of these data, the authors have found the normal arterial-transcutaneous carbon dioxide gradient, ΔCO2, (ΔCO2= PtcCO2– PaCO2) to be 23 ± 11 torr. The PtcCO2monitor was found to be a valuable trend monitor of arterial CO2tensions of adults during adequate cardiac function in the ICU and the operating room.Twenty-four data sets were collected while 3 patients were monitored during severe shock (CI < 1.5 L/min μ M2). PtcCO2trended inversely with changes in CI during shock and did not follow PaCO2(r = −0.85). During shock, ΔCO2= 61 ± 25 torr. The severity of shock could be roughly determined by comparing the PtcCO2values with arterial CO2tensions.

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

The authors measured the partial pressure of carbon dioxide transcutaneously (PtcCO2) in 15 sick newborns and compared the PtcCO2to simultaneously measured partial pressure of arterial carbon dioxide (PaCO2). The PtcCO2values reflected changes in the PaCO2values. A linear regression on 106 paired PtcCO2and PaCO2values produced a correlation coefficient ofr= 0.91 with a slope of 1.89 and a y-intercept of –9.4. The authors found the measurement of PtcCO2to be a clinically useful method of continuously following the trend of PaCO2.

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

One hundred ninety-one simultaneous PtcCO2and PaCO2values were recorded from 20 neonates using a heated CO2sensor. Gestational age and birth weight ranged from 30–44 weeks and 1.22–3.4 kg, respectively. An overestimation of PaCO2was consistently found. Regression analysis revealed a slope of 1.29, an intercept of 18 mm Hg and a correlation coefficient of 0.85 (p< 0.001). The PtcCO2sensor has multiple potential uses in the sick neonate but further experience is necessary to provide adequate correction factors.

ISSN:0090-3493    

出版商:OVID    

年代:1981

数据来源: OVID