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Biomedical subjects

D Pestaña

Publications and source records attributed to D Pestaña.

8 recordsLinked to original sources
PubMed2003

Adjusting positive end-expiratory pressure and tidal volume in acute respiratory distress syndrome according to the pressure-volume curve.

BACKGROUND: Management of acute respiratory distress syndrome (ARDS) patients implies the selection of the adequate ventilatory parameters, essentially PEEP and tidal volume (Vt), to prevent ventilator-induced lung injury. These parameters should be reset as the lung injury evolves. Among the different methods proposed for the adjustment of the ventilator, the measurement of the P-V curve has emerged as a useful, although debated, tool. Our aim has been to study the relationship between the different inflection points of the P-V curve in ARDS patients, and to assess the changes in the empiric PEEP and Vt (PEEP(emp), V(temp) following its use. METHODS: P-V curves were measured in 27 patients (lung injury score [LIS] >or= 2, 69 measurements) by means of the low-flow continuous inflation method. RESULTS: A lower inflection point (LIP) was found in all patients and, although it correlated with the PEEP(emp), there was only a fair concordance, so the PEEP was modified in 80% of the cases. The expiratory inflection point (EIP) was significantly lower than the LIP (6.3 +/- 1.7 vs. 8.1 +/- 3.2, P = 0.008). An upper inflection point was observed in 16 measurements (23%) and the Vt was reset in 20% of the cases. Both PEEP and Vt were readjusted on 10 occasions (14%). Only the EIP was significantly higher on the first 3 days of mechanical ventilation. The LIS was correlated with all the inflection points. There were no differences for any parameter independent of the cause of the ARDS (pulmonary/extrapulmonary). CONCLUSIONS: The quasi-static measurement of the P-V curve is a simple method, easy to interpret, for objective adjustment of the ventilatory parameters in ARDS patients as the lung injury evolves. The implementation of this strategy may vary the empiric clinical practice. The role of the EIP for the evaluation of the severity of lung injury deserves further investigation.

Acute Disease↗
PubMed2001

[Anesthesia in a case of Holt-Oram syndrome].

A 19-year-old man with Holt-Oram syndrome (HOS) underwent emergency surgical treatment of an occipital abscess. He presented total aplasia of the radius and first and second finger of the left hand, asymmetric thorax and complex cyanotic cardiopathy with double output of the right ventricle that had been treated on several occasions, malpositioning of the large vessels and interventricular conduction. He had been treated with digoxin for episodes of supraventricular tachycardia. After premedication with 0.4 mg of atropine, balanced general anesthesia was induced with etomidate and remifentanil and maintained with O2/air/desflurane and infused remifentanil. The patient remained hemodynamically stable during surgery and tubes were removed in the operating room with no complications. HOS, a hereditary disease characterized by congenital malformations of the upper extremities and the heart, is often associated with rhythm disorders. Problems that may develop in such patients during anesthesia include difficulty catheterizing vessels, difficult orotracheal intubation and ventilation, hemodynamic instability, and the presentation of arrhythmias and cardiac arrest.

Adult↗
PubMed1998

[Relationship between mixed venous saturation and cardiac index, hemoglobin and oxygen consumption in aortic surgery].

OBJECTIVE: Mixed venous oxygen saturation (SvO2) depends mainly on four variables: cardiac index (CI), hemoglobin concentration (Hb), arterial oxygen saturation (SpO2) and oxygen consumption (VO2). Our aim was to study the correlation between each of these variables and SvO2 during abdominal aortic surgery, a situation which is of special interest because of associated hemodynamic and metabolic variations and the high risk of cardiovascular events. PATIENTS AND METHODS: Twelve patients undergoing intrarenal aortic surgery were monitored by pulmonary artery catheter (Opticath), pulse oximetry and indirect calorimetry (Deltatrac Metabolic Monitor). SvO2, CI (measured by thermodilution), SpO2 and VO2 at six moments: post-induction (baseline), 1 min before and 1 min after clamping (pre-C, post-C), 1 min (post-D) and 10 min after declamping and at the end of the surgery. Hemoglobin concentration was measured at all moments except 10 min after declamping. RESULTS: All variables except SpO2 varied significantly (p < 0.001) during the study. SvO2 was associated with CI at all moments except post-D and at the end of surgery. Hemoglobin concentration was related to SvO2 at baseline and post-C. We found no correlation between SvO2 and VO2 or SpO2 at any moment. CONCLUSION: Monitoring SvO2 in patients undergoing aortic surgery is useful for detecting potentially prejudicial variations in cardiac output or hemoglobin concentration.

Aged↗
PubMed1996

Metabolic pattern and lipid oxidation during abdominal surgery: midazolam versus propofol.

Propofol is formulated in an emulsion similar to 10% Intralipid, and several authors have suggested that fat accumulates during its infusion. In this study we used indirect calorimetry to measure lipid metabolism during abdominal surgery in patients anesthetized with propofol, using midazolam as a control. Thirty patients were randomly divided into three groups: Group P (propofol 2 mg/kg + 5 mg.kg-1.h-1, n = 13); Group M (midazolam, n = 9), and Group I (midazolam + 10% Intralipid at rates similar to those infused in Group P, n = 8). They were monitored with an indirect calorimeter for 90 min. Data including oxygen consumption (VO2), CO2 production (VCO2), energy expenditure (EE), respiratory quotient (RQ), and lipid utilization were obtained every 15 min. VO2 increased in all groups at 45 min in respect to basal measurements with no differences between them. VCO2 decreased significantly only in Groups P and I, although no differences between the three groups were observed. EE did not vary in any of the groups. RQ decreased in all groups at 30 min, being significantly higher in Group M than in Groups P and I. Lipid oxidation increased in all groups from the beginning of the study reaching a plateau at 45 min. The lipid oxidation was higher in Groups P and I than in Group M, and coincided (80-100 g/24 h) with the amount of fat administered exogenously (85.4 g/ 24 h for a patient of 70 kg). Compared to VO2, VCO2, and EE, propofol behaves as other anesthetics. The fat administered in its formulation is metabolized in a preferential way, although it is likely that larger doses than those studied in our patients partially accumulate.

Abdomen↗
PubMed1994

Calculated versus measured oxygen consumption during aortic surgery: reliability of the Fick method.

Oxygen consumption (VO2) can be obtained by the Fick method as the product of cardiac index (CI) by the arteriovenous oxygen content difference (D[a-v]O2) or by indirect calorimetry (IC) based on gas exchange measurements. IC is considered the "gold standard" but is not widely available in clinical practice. Our objective was to test the reliability of the reversed Fick method compared with IC under conditions of hemodynamic changes. For this purpose we chose aortic clamping and unclamping as a model. Twelve patients undergoing abdominal aortic surgery were monitored with a fiberoptic pulmonary artery catheter (Opticath). Calculated oxygen consumption (cVO2) was obtained from hemodynamic and analytic data according to the Fick method at six stages: postinduction, before cross-clamping (Pre-C), postclamping (Post-C), before unclamping (Pre-U), after unclamping (Post-U), and the end of surgery. cVO2 was compared with measured oxygen consumption (mVO2) obtained by IC. CI and mixed venous oxygen saturation (SVO2) varied significantly (P < 0.0001) during the interventions. Although mVO2 did not vary, cVO2 varied significantly (P = 0.0001), reaching a maximum at Post-U coinciding with a sudden decrease in SVO2. There was good concordance between mVO2 and cVO2 except at Post-U (P = 0.005). We conclude that cVO2 is a reliable indicator of VO2 in this hemodynamic model except at Post-U. This lack of correlation seems to be due to a mathematical artifact, because the low value of SVO2 registered at this stage and introduced into the Fick formula reflects a sudden venous return of desaturated blood and not an increase in VO2.

Aged↗
PubMed1984

Arsenic mononucleotides. Separation by high-performance liquid chromatography and identification with myokinase and adenylate deaminase.

The spontaneous formation of arsenic mononucleotides has been detected in mixtures of arsenate and inosine or adenosine or its deoxy analogues. These compounds have been separated by high-performance liquid chromatography and identified by their behavior in the presence of myokinase and adenylate deaminase. The nucleoside 5'-arsenates are formed preferentially to the 2'- and 3'-arsenate analogues. All arsenic nucleotides detected showed similar kinetic and equilibrium constants of formation: about 8 X 10(-4) M-1 S-1 and 2 X 10(-3) M-1, respectively. These values are several orders of magnitude greater than those of their phosphoric analogues. The adenosine 5'-arsenate was able to substitute for 5'AMP in the reaction of myokinase and adenylate deaminase. The substitutions of the 2'- or 3'-hydrogen for hydroxyl groups in the ribose moiety of this compound slightly affected its suitability as substrate for myokinase but had drastic effect in the case of adenylate deaminase. The half-life of the arsenic nucleotides, at pH 7.0 and 25 degrees C, ranged from 30 to 45 min. The lability of these compounds is increased during catalysis with myokinase. Results on the reaction mechanism of myokinase with adenosine 5'-arsenate indicate that the mixed-anhydride analogue to ADP, adenosine 5'-(arsenate phosphate), is not detected either because it is not formed in the reaction with this enzyme or because it is rapidly hydrolyzed.

AMP Deaminase↗