sara ponce - Academia.edu (original) (raw)

Papers by sara ponce

Biomaterials, 2002

The biocompatibility of alginate-PLL-alginate (APA) microcapsules has been evaluated with respect... more The biocompatibility of alginate-PLL-alginate (APA) microcapsules has been evaluated with respect to impurity levels. The impurity content of three different alginates (a raw high M-alginate, a raw high G-alginate and a purified high G-alginate) has been determined and the in vivo antigenic response of APA beads made with each alginate assessed. Results show that purification of the alginate not only reduces the total amount of impurities (63% less in polyphenols, 91.45% less in endotoxins and 68.5% less in protein in relation to raw high M-alginate), but also avoids an antibody response when microcapsules of this material are implanted in mice. In contrast, raw alginates produced a detectable antibody response though the differences in their impurity content. Consequently, this work revealed that purity of the alginate rather than their chemical composition, is probably of greater importance in determining microcapsule biocompatibility.

Molecular Therapy, 2005

The present paper investigates the long-term functionality of an ex vivo gene therapy approach ba... more The present paper investigates the long-term functionality of an ex vivo gene therapy approach based on cell microencapsulation for the continuous delivery of erythropoietin (EPO) without implementation of immunosuppressive protocols. Polymer microcapsules (0.5 ml) loaded with EPOsecreting C 2 C 12 myoblasts and releasing 15,490 F 600 IU EPO/24 h were implanted in the peritoneum and subcutaneous tissue of syngeneic and allogeneic mice. High and constant hematocrit levels were maintained for more than 100 days in all implanted mice. Capsules retrieved from the peritoneum were free-floating or forming small capsule clusters, and we detected only a weak fibroblast outgrowth in capsules adhered to organs, whereas capsules explanted from the subcutaneous region appeared altogether as a richly vascularized structure with no signs of major host reaction. Interestingly, the functionality of capsules implanted in the allogeneic mice persisted until day 210 after implantation. These results highlight the feasibility of cell encapsulation technology for the long-term delivery of EPO independent of the method of administration and the mouse strain.

Journal of Controlled Release, 2006

Alginates are the most employed biomaterials for cell encapsulation due to their abundance, easy ... more Alginates are the most employed biomaterials for cell encapsulation due to their abundance, easy gelling properties and apparent biocompatibility. However, as natural polymers different impurities including endotoxins, proteins and polyphenols can be found in their composition. Several purification protocols as well as different batteries of assays to prove the biocompatibility of the alginates in vitro have been recently developed. However, little is known about how the use of alginates with different purity grade may affect the host immune response after their implantation in vivo. The present paper investigates the long-term functionality and biocompatibility of murine erythropoietin (EPO) secreting C2C12 cells entrapped in microcapsules elaborated with alginates with different properties (purity, composition and viscosity). Results showed that independently of the alginate type employed, the animals presented elevated hematocrit levels until day 130, remaining at values between 70-87%. However, histological analysis of the explanted devices showed higher overgrowth around non-biomedical grade alginate microcapsules which could be directly related with higher impurity content of this type of alginate. Although EPO delivery may be limited by the formation of a fibrotic layer around non-biomedical grade alginate microcapsules, the high EPO secretion of the encapsulated cells together with the pharmacodynamic behaviour and the angiogenic and immune-modulatory properties of EPO result in no direct correlation between the biocompatibility of the alginate and the therapeutic response obtained.

International Journal of Pharmaceutics, 2007

Several findings suggest that glial cell line-derived neurotrophic factor (GDNF) may be a useful ... more Several findings suggest that glial cell line-derived neurotrophic factor (GDNF) may be a useful tool to treat parkinsonism by acting as a neuroprotective and neurotrophic factor for dopaminergic neurotransmission systems. In the present study, we implanted alginate-poly-L-lysine-alginate microcapsules containing immobilized Fischer rat 3T3 fibroblasts transfected to produce GDNF in vitro into the striatum of 6-hydroxydopamine (6-OHDA) lesioned rats. Microencapsulated GDNF secreting cells were stable for at least 3 weeks in vitro. Intrastriatal implantation of microencapsulated GDNF secreting cells into 6-OHDA lesioned rats resulted in a decrease in apomorphine-induced rotations by 84%, 64%, 84%, 60% and 52% (2, 5, 8, 16 and 24 weeks, respectively) with respect to the value before implantation and with respect to the value obtained from the empty microcapsule implanted-group at each time point. Six months after transplantation, immunohistochemical detection of GDNF revealed strong immunoreactivity in the striatal tissue surrounding the microcapsules in the absence of tissue damage due to microcapsule implantation. No changes in the levels of dopamine and its metabolites or of tyrosine hydroxylase immunoreactivity were detected in the striatum. In summary, the implantation of microencapsulated GDNF secreting cells allows the delivery of this molecule into the rat striatum for at least 6 months and results in substantial behavioral improvement.

Biomaterials, 2006

Implantation of microencapsulated cells has been proposed as a therapy for a wide variety of dise... more Implantation of microencapsulated cells has been proposed as a therapy for a wide variety of diseases. An absolute requirement is that the applied microcapsules have an optimal biocompatibility. The alginate-poly-L-lysine system is the most commonly applied system but is still suffering from tissue responses provoked by the capsule materials. In the present study, we investigate the biocompatibility of microcapsules elaborated with two commonly applied alginates, i.e. an intermediate-G alginate and a high-G alginate. These alginates were coated with poly-L-lysine (PLL), poly-D-lysine (PDL) and poly-L-ornithine (PLO). The main objective of this study is to determine the interaction of each alginate matrix with the different polycations and the potential impact of these interactions in the modulation of the host's immune response. To address these issues the different types of microcapsules were implanted into the peritoneal cavity of rats for I month. After this period the microcapsules were recovered and they were evaluated by different techniques. Monochromatised X-ray photoelectron spectroscopy (XPS) was performance and the degree of capsular recovery, overgrowth on each capsule, and the cellular composition of the overgrowth were evaluated by histology. Our results illustrate that the different observed immune responses are the consequence of the variations in the interactions between the polycations and alginates rather than to the alginates themselves. Our results suggest that PLL is the best option available and that we should avoid using PLO and PDL in its present form since it is our goals to produce capsules that lack overgrowth and do not induce an immunological response as such.

Journal of Controlled Release, 2009

Improvement of long-term drug release and design of mechanically more stable encapsulation device... more Improvement of long-term drug release and design of mechanically more stable encapsulation devices are still major challenges in the field of cell encapsulation. This may be in part due to the weak in vivo stability of calcium-alginate beads and to the use of inactive biomaterials and inert scaffolds that do not mimic the physiological situation of the normal cell milieu. We hypothesized that designing biomimetic cell-hydrogel capsules might promote the in vivo long-term functionality of the enclosed drug-secreting cells and improve the mechanical stability of the capsules. Biomimetic capsules were fabricated by coupling the adhesion peptide arginine glycine aspartic acid (RGD) to alginate polymer chains and by using an alginate-mixture providing a bimodal molecular weight distribution. The biomimetic capsules provide cell adhesion for the enclosed cells, potentially also leading to mechanical stabilization of the cell-polymer system. Strikingly, the novel cell-hydrogel system significantly prolonged the in vivo long-term functionality and drug release, providing a sustained erythropoietin delivery during 300 days without immunosuppressive protocols. Additionally, controlling the cell-dose within the biomimetic capsules enables a controlled in vitro and in vivo drug delivery. Biomimetic cell-hydrogel capsules provide a unique microenvironment for the in vivo long-term de novo delivery of drugs from immobilized cells.

International Journal of Pharmaceutics, 2005

Cell microencapsulation represents a promising tool for the treatment of many central nervous sys... more Cell microencapsulation represents a promising tool for the treatment of many central nervous system (CNS) diseases such as Parkinson's disease. In this technology, cells are surrounded by a semipermeable membrane which protects them from mechanical stress and isolates them from host's immune response. However, if the future clinical application of this strategy is wanted, many challenges remain including the improvement of the mechanical resistance of the microcapsules and the optimization of the intracapsular microenvironment conditions. In this way, the selection of the matrix is essential because the morphological and the physiological behavior of the cells depend on the interactions between the matrix and the enclosed cells. Assuming these considerations, three types of microcapsules elaborated with four different polymers: alginate, cellulose sulfate, agarose and pectin have been fabricated and compared in order to evaluate some key properties such as morphology, size and mechanical stability. Furthermore, GDNF secreting Fischer rat 3T3 fibroblasts were immobilized in each type of capsule and the viability and neurotrophic factor release was determinated. Results showed that the alginate and pectin microcapsules were the most resistant devices, maintaining an adequate microenvironment for the enclosed cells. In contrast, cells entrapped in alginate-cellulose sulfate matrices presented the lowest mechanical resistance, cell viability and GDNF production.

Many of the implementation guidelines and network planning tools of DVB-H rely on the existence o... more Many of the implementation guidelines and network planning tools of DVB-H rely on the existence of an Single Frequency Network (SFN) gain due to the co-existence of several rays within the guard interval. This presents three experiments performed in some field trials which results lead to some conclusions that are not aligned with the existence of the SFN gain.

Archivos De Bronconeumologia, 2006

OBJECTIVE: To evaluate the usefulness of transcutaneous carbon dioxide pressure (TcPCO 2 ) monito... more OBJECTIVE: To evaluate the usefulness of transcutaneous carbon dioxide pressure (TcPCO 2 ) monitoring in patients hospitalized for respiratory disease. PATIENTS AND METHODS: We used a SenTec TcPCO 2 monitor that also determines transcutaneous oxygen saturation (SpO 2 ) by means of a sensor placed behind the ear lobe at a temperature of 42 degrees C. We compared arterial blood gas measurements--PaCO 2 and arterial oxygen saturation (SaO 2 )-with transcutaneous measurements and analyzed the correlation, regression line, and agreement between the 2 methods.

Chest, 2009

Increased concentrations of exhaled nitric oxide (ENO) are identified predominantly in subjects w... more Increased concentrations of exhaled nitric oxide (ENO) are identified predominantly in subjects with chronic cough due to conditions that habitually respond well to therapy with inhaled corticosteroids (ICSs). The aim of this study was to assess the usefulness of ENO in predicting the response to ICS therapy in subjects with chronic cough and to determine the relationship between either methacholine or adenosine 5'-monophosphate (AMP) responsiveness and the response to ICS therapy. A total of 43 patients with chronic cough were studied. During the baseline period, ENO measurement, spirometry, and concentration-response studies with both methacholine and AMP were performed. For the next 4 weeks, the patients were treated with inhaled fluticasone propionate, 100 microg twice daily. At baseline (1 week) and during the 4-week treatment period, patients twice daily completed entries in a diary, in which they recorded daytime and nighttime cough symptom scores. Nineteen patients (44%) responded well to fluticasone therapy. The receiver operating characteristic curve analysis showed that the accuracy of identifying the response to ICS therapy for ENO at baseline was poor. The sensitivity and specificity of ENO for predicting the response to ICS therapy, using 20 parts per billion as the ENO cutoff point, were 53% and 63%, respectively. Differences in both prevalence and degree of airway responsiveness to either methacholine or AMP between fluticasone-responsive subjects and nonresponsive subjects were also not significant. Although a significant proportion of subjects with chronic cough respond well to ICS therapy, these patients cannot be identified by ENO levels or AMP responsiveness at baseline.

Archivos De Bronconeumologia, 2006

La valoración clínica de los pacientes con enfermedad respiratoria agudizada puede precisar la re... more La valoración clínica de los pacientes con enfermedad respiratoria agudizada puede precisar la realización de ga-sometrías arteriales repetidas para el control evolutivo de la enfermedad. Ello requiere la repetición de punciones arteriales, que son molestas y en ocasiones dificultosas. Para obviar este problema se ha generalizado el uso de pulsioxímetros que analizan la saturación arterial de oxígeno (SaO 2 ) y orientan sobre los valores de presión arterial de oxígeno (PaO 2 ). La pulsioximetría, aunque está sujeta a errores que dependen de factores hemodinámicos, problemas técnicos o alteraciones de la curva de disocia-OBJETIVO: Estudiar la utilidad de la medida de la presión transcutánea de anhídrido carbónico (PtcCO 2 ) en pacientes con enfermedad respiratoria hospitalizados. PACIENTES Y MÉTODOS: Utilizamos el analizador de PtcCO 2 SenTec ® , que también determina la saturación transcutánea de oxígeno (SpO 2 ), mediante un sensor colocado en el lóbulo de la oreja a una temperatura de 42 °C. Se compararon los valores gasométricos -presión arterial de anhídrido carbónico (PaCO 2 ) y saturación arterial de oxígeno (SaO 2 )-con los transcutáneos, analizando la correlación, recta de regresión y la concordancia entre ambos métodos.

Biomaterials, 2002

The biocompatibility of alginate-PLL-alginate (APA) microcapsules has been evaluated with respect... more The biocompatibility of alginate-PLL-alginate (APA) microcapsules has been evaluated with respect to impurity levels. The impurity content of three different alginates (a raw high M-alginate, a raw high G-alginate and a purified high G-alginate) has been determined and the in vivo antigenic response of APA beads made with each alginate assessed. Results show that purification of the alginate not only reduces the total amount of impurities (63% less in polyphenols, 91.45% less in endotoxins and 68.5% less in protein in relation to raw high M-alginate), but also avoids an antibody response when microcapsules of this material are implanted in mice. In contrast, raw alginates produced a detectable antibody response though the differences in their impurity content. Consequently, this work revealed that purity of the alginate rather than their chemical composition, is probably of greater importance in determining microcapsule biocompatibility.

Molecular Therapy, 2005

The present paper investigates the long-term functionality of an ex vivo gene therapy approach ba... more The present paper investigates the long-term functionality of an ex vivo gene therapy approach based on cell microencapsulation for the continuous delivery of erythropoietin (EPO) without implementation of immunosuppressive protocols. Polymer microcapsules (0.5 ml) loaded with EPOsecreting C 2 C 12 myoblasts and releasing 15,490 F 600 IU EPO/24 h were implanted in the peritoneum and subcutaneous tissue of syngeneic and allogeneic mice. High and constant hematocrit levels were maintained for more than 100 days in all implanted mice. Capsules retrieved from the peritoneum were free-floating or forming small capsule clusters, and we detected only a weak fibroblast outgrowth in capsules adhered to organs, whereas capsules explanted from the subcutaneous region appeared altogether as a richly vascularized structure with no signs of major host reaction. Interestingly, the functionality of capsules implanted in the allogeneic mice persisted until day 210 after implantation. These results highlight the feasibility of cell encapsulation technology for the long-term delivery of EPO independent of the method of administration and the mouse strain.

Journal of Controlled Release, 2006

Alginates are the most employed biomaterials for cell encapsulation due to their abundance, easy ... more Alginates are the most employed biomaterials for cell encapsulation due to their abundance, easy gelling properties and apparent biocompatibility. However, as natural polymers different impurities including endotoxins, proteins and polyphenols can be found in their composition. Several purification protocols as well as different batteries of assays to prove the biocompatibility of the alginates in vitro have been recently developed. However, little is known about how the use of alginates with different purity grade may affect the host immune response after their implantation in vivo. The present paper investigates the long-term functionality and biocompatibility of murine erythropoietin (EPO) secreting C2C12 cells entrapped in microcapsules elaborated with alginates with different properties (purity, composition and viscosity). Results showed that independently of the alginate type employed, the animals presented elevated hematocrit levels until day 130, remaining at values between 70-87%. However, histological analysis of the explanted devices showed higher overgrowth around non-biomedical grade alginate microcapsules which could be directly related with higher impurity content of this type of alginate. Although EPO delivery may be limited by the formation of a fibrotic layer around non-biomedical grade alginate microcapsules, the high EPO secretion of the encapsulated cells together with the pharmacodynamic behaviour and the angiogenic and immune-modulatory properties of EPO result in no direct correlation between the biocompatibility of the alginate and the therapeutic response obtained.

International Journal of Pharmaceutics, 2007

Several findings suggest that glial cell line-derived neurotrophic factor (GDNF) may be a useful ... more Several findings suggest that glial cell line-derived neurotrophic factor (GDNF) may be a useful tool to treat parkinsonism by acting as a neuroprotective and neurotrophic factor for dopaminergic neurotransmission systems. In the present study, we implanted alginate-poly-L-lysine-alginate microcapsules containing immobilized Fischer rat 3T3 fibroblasts transfected to produce GDNF in vitro into the striatum of 6-hydroxydopamine (6-OHDA) lesioned rats. Microencapsulated GDNF secreting cells were stable for at least 3 weeks in vitro. Intrastriatal implantation of microencapsulated GDNF secreting cells into 6-OHDA lesioned rats resulted in a decrease in apomorphine-induced rotations by 84%, 64%, 84%, 60% and 52% (2, 5, 8, 16 and 24 weeks, respectively) with respect to the value before implantation and with respect to the value obtained from the empty microcapsule implanted-group at each time point. Six months after transplantation, immunohistochemical detection of GDNF revealed strong immunoreactivity in the striatal tissue surrounding the microcapsules in the absence of tissue damage due to microcapsule implantation. No changes in the levels of dopamine and its metabolites or of tyrosine hydroxylase immunoreactivity were detected in the striatum. In summary, the implantation of microencapsulated GDNF secreting cells allows the delivery of this molecule into the rat striatum for at least 6 months and results in substantial behavioral improvement.

Biomaterials, 2006

Implantation of microencapsulated cells has been proposed as a therapy for a wide variety of dise... more Implantation of microencapsulated cells has been proposed as a therapy for a wide variety of diseases. An absolute requirement is that the applied microcapsules have an optimal biocompatibility. The alginate-poly-L-lysine system is the most commonly applied system but is still suffering from tissue responses provoked by the capsule materials. In the present study, we investigate the biocompatibility of microcapsules elaborated with two commonly applied alginates, i.e. an intermediate-G alginate and a high-G alginate. These alginates were coated with poly-L-lysine (PLL), poly-D-lysine (PDL) and poly-L-ornithine (PLO). The main objective of this study is to determine the interaction of each alginate matrix with the different polycations and the potential impact of these interactions in the modulation of the host's immune response. To address these issues the different types of microcapsules were implanted into the peritoneal cavity of rats for I month. After this period the microcapsules were recovered and they were evaluated by different techniques. Monochromatised X-ray photoelectron spectroscopy (XPS) was performance and the degree of capsular recovery, overgrowth on each capsule, and the cellular composition of the overgrowth were evaluated by histology. Our results illustrate that the different observed immune responses are the consequence of the variations in the interactions between the polycations and alginates rather than to the alginates themselves. Our results suggest that PLL is the best option available and that we should avoid using PLO and PDL in its present form since it is our goals to produce capsules that lack overgrowth and do not induce an immunological response as such.

Journal of Controlled Release, 2009

Improvement of long-term drug release and design of mechanically more stable encapsulation device... more Improvement of long-term drug release and design of mechanically more stable encapsulation devices are still major challenges in the field of cell encapsulation. This may be in part due to the weak in vivo stability of calcium-alginate beads and to the use of inactive biomaterials and inert scaffolds that do not mimic the physiological situation of the normal cell milieu. We hypothesized that designing biomimetic cell-hydrogel capsules might promote the in vivo long-term functionality of the enclosed drug-secreting cells and improve the mechanical stability of the capsules. Biomimetic capsules were fabricated by coupling the adhesion peptide arginine glycine aspartic acid (RGD) to alginate polymer chains and by using an alginate-mixture providing a bimodal molecular weight distribution. The biomimetic capsules provide cell adhesion for the enclosed cells, potentially also leading to mechanical stabilization of the cell-polymer system. Strikingly, the novel cell-hydrogel system significantly prolonged the in vivo long-term functionality and drug release, providing a sustained erythropoietin delivery during 300 days without immunosuppressive protocols. Additionally, controlling the cell-dose within the biomimetic capsules enables a controlled in vitro and in vivo drug delivery. Biomimetic cell-hydrogel capsules provide a unique microenvironment for the in vivo long-term de novo delivery of drugs from immobilized cells.

International Journal of Pharmaceutics, 2005

Cell microencapsulation represents a promising tool for the treatment of many central nervous sys... more Cell microencapsulation represents a promising tool for the treatment of many central nervous system (CNS) diseases such as Parkinson's disease. In this technology, cells are surrounded by a semipermeable membrane which protects them from mechanical stress and isolates them from host's immune response. However, if the future clinical application of this strategy is wanted, many challenges remain including the improvement of the mechanical resistance of the microcapsules and the optimization of the intracapsular microenvironment conditions. In this way, the selection of the matrix is essential because the morphological and the physiological behavior of the cells depend on the interactions between the matrix and the enclosed cells. Assuming these considerations, three types of microcapsules elaborated with four different polymers: alginate, cellulose sulfate, agarose and pectin have been fabricated and compared in order to evaluate some key properties such as morphology, size and mechanical stability. Furthermore, GDNF secreting Fischer rat 3T3 fibroblasts were immobilized in each type of capsule and the viability and neurotrophic factor release was determinated. Results showed that the alginate and pectin microcapsules were the most resistant devices, maintaining an adequate microenvironment for the enclosed cells. In contrast, cells entrapped in alginate-cellulose sulfate matrices presented the lowest mechanical resistance, cell viability and GDNF production.

Many of the implementation guidelines and network planning tools of DVB-H rely on the existence o... more Many of the implementation guidelines and network planning tools of DVB-H rely on the existence of an Single Frequency Network (SFN) gain due to the co-existence of several rays within the guard interval. This presents three experiments performed in some field trials which results lead to some conclusions that are not aligned with the existence of the SFN gain.

Archivos De Bronconeumologia, 2006

OBJECTIVE: To evaluate the usefulness of transcutaneous carbon dioxide pressure (TcPCO 2 ) monito... more OBJECTIVE: To evaluate the usefulness of transcutaneous carbon dioxide pressure (TcPCO 2 ) monitoring in patients hospitalized for respiratory disease. PATIENTS AND METHODS: We used a SenTec TcPCO 2 monitor that also determines transcutaneous oxygen saturation (SpO 2 ) by means of a sensor placed behind the ear lobe at a temperature of 42 degrees C. We compared arterial blood gas measurements--PaCO 2 and arterial oxygen saturation (SaO 2 )-with transcutaneous measurements and analyzed the correlation, regression line, and agreement between the 2 methods.

Chest, 2009

Increased concentrations of exhaled nitric oxide (ENO) are identified predominantly in subjects w... more Increased concentrations of exhaled nitric oxide (ENO) are identified predominantly in subjects with chronic cough due to conditions that habitually respond well to therapy with inhaled corticosteroids (ICSs). The aim of this study was to assess the usefulness of ENO in predicting the response to ICS therapy in subjects with chronic cough and to determine the relationship between either methacholine or adenosine 5'-monophosphate (AMP) responsiveness and the response to ICS therapy. A total of 43 patients with chronic cough were studied. During the baseline period, ENO measurement, spirometry, and concentration-response studies with both methacholine and AMP were performed. For the next 4 weeks, the patients were treated with inhaled fluticasone propionate, 100 microg twice daily. At baseline (1 week) and during the 4-week treatment period, patients twice daily completed entries in a diary, in which they recorded daytime and nighttime cough symptom scores. Nineteen patients (44%) responded well to fluticasone therapy. The receiver operating characteristic curve analysis showed that the accuracy of identifying the response to ICS therapy for ENO at baseline was poor. The sensitivity and specificity of ENO for predicting the response to ICS therapy, using 20 parts per billion as the ENO cutoff point, were 53% and 63%, respectively. Differences in both prevalence and degree of airway responsiveness to either methacholine or AMP between fluticasone-responsive subjects and nonresponsive subjects were also not significant. Although a significant proportion of subjects with chronic cough respond well to ICS therapy, these patients cannot be identified by ENO levels or AMP responsiveness at baseline.

Archivos De Bronconeumologia, 2006

La valoración clínica de los pacientes con enfermedad respiratoria agudizada puede precisar la re... more La valoración clínica de los pacientes con enfermedad respiratoria agudizada puede precisar la realización de ga-sometrías arteriales repetidas para el control evolutivo de la enfermedad. Ello requiere la repetición de punciones arteriales, que son molestas y en ocasiones dificultosas. Para obviar este problema se ha generalizado el uso de pulsioxímetros que analizan la saturación arterial de oxígeno (SaO 2 ) y orientan sobre los valores de presión arterial de oxígeno (PaO 2 ). La pulsioximetría, aunque está sujeta a errores que dependen de factores hemodinámicos, problemas técnicos o alteraciones de la curva de disocia-OBJETIVO: Estudiar la utilidad de la medida de la presión transcutánea de anhídrido carbónico (PtcCO 2 ) en pacientes con enfermedad respiratoria hospitalizados. PACIENTES Y MÉTODOS: Utilizamos el analizador de PtcCO 2 SenTec ® , que también determina la saturación transcutánea de oxígeno (SpO 2 ), mediante un sensor colocado en el lóbulo de la oreja a una temperatura de 42 °C. Se compararon los valores gasométricos -presión arterial de anhídrido carbónico (PaCO 2 ) y saturación arterial de oxígeno (SaO 2 )-con los transcutáneos, analizando la correlación, recta de regresión y la concordancia entre ambos métodos.