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Biomedical subjects

S Rodriguez

Publications and source records attributed to S Rodriguez.

12 recordsLinked to original sources
PubMed1992

Lack of relationship between the true airway pressure and the pressure displayed with an infant ventilator.

OBJECTIVE: To establish if the pressure indicated in the manometer of an infant ventilator (IV 100B, Sechrist, Anaheim, CA) reflects the true pressure delivered to the proximal airway during mechanical ventilation in the neonatal ICU. DESIGN: With approval of our Institutional Research Board, data were collected prospectively. Peak inspiratory pressure and end-expiratory pressure were measured at the "Y" piece of the breathing tubing. Pressure readings from the conventional ventilator's manometer were compared with simultaneously obtained measurements using an electronic monitor. SETTING: This study was conducted in a 45-bed neonatal ICU, admitting 700 to 750 newborns per year. PATIENTS: Twelve neonates who required mechanical ventilation were included in the study. INTERVENTIONS: Specific interventions were not made by study design. Measurements routinely obtained were compared. MEASUREMENTS AND MAIN RESULTS: Two hundred seventy-five simultaneous measurements of peak inspiratory pressure and positive end-expiratory pressure were compared. Peak inspiratory pressure values were higher with the electronic monitor in 273 (99%) of 275 measurements and the mean of the differences between the electronic monitor and ventilator's manometer was statistically significant (p less than .001). For positive end-expiratory pressure measurements, values indicated by the electronic monitor were lower in 152 (55%) of 275 determinations, equal in 65 (23%), and higher in 58 (21%) determinations. Percent variations between methods ranged from 0% to 140% for peak inspiratory pressures and from 0% to 500% for positive end-expiratory pressure. CONCLUSIONS: These data demonstrate that it is impossible to know the true pressure delivered to the proximal airway of a neonate during mechanical ventilation by observing the ventilator pressure manometer. The manometer readings consistently underestimate the true peak inspiratory pressure values and are very unpredictable regarding positive end-expiratory pressure values. These findings support the use of other methods to monitor the proximal airway pressure besides the ventilator's manometer in the neonatal ICU. Furthermore, mean airway pressure should not be calculated from the pressure readings obtained from the tested ventilator's manometer.

Airway Resistance↗
PubMed1992

Fibrinogen Lima: a homozygous dysfibrinogen with an A alpha-arginine-141 to serine substitution associated with extra N-glycosylation at A alpha-asparagine-139. Impaired fibrin gel formation but normal fibrin-facilitated plasminogen activation catalyzed by tissue-type plasminogen activator.

An A alpha-arginine-141 to serine substitution has been identified in a homozygous dysfibrinogen, fibrinogen Lima, associated with impaired fibrin polymerization. The point mutation created an asparagine-X-serine-type glycosylation sequence, and indeed, extra, mainly disialylated biantennary oligosaccharides have been isolated from A alpha asparagine-139 of the patient's fibrinogen. This type of glycosylation sequence is unique for human fibrinogen, because the sequences shown for normal and abnormal fibrinogens are all asparagine-X-threonine types. The terminal sialic acids of the extra oligosaccharides seem to have largely contributed to the impaired fibrin gel formation, as evidenced by its correction to a near normal level by desialylation. Nevertheless, the polymerizing fibrin facilitated tissue-type plasminogen activator-catalyzed plasmin formation in a normal fashion, indicating that the initial two-stranded fibrin protofibrils had been constructed normally. Thus the impaired fibrin gel formation could be attributed to the delay in their subsequent lateral association, most probably because of the repulsive forces generated by the negative electric charge of the extra sialic acids. The substitution of a basic residue arginine to a noncharged residue serine may also have contributed to the impaired function in a similar manner or by steric hindrance in association with bulky extra oligosaccharide chains.

Amino Acids↗
PubMed1979

Electrophysiological effects of desipramine on guinea pig papillary muscles.

The effects of desipramine (DMI) in concentrations between 1 x 10(-7) M and 1 x 10(-4) M on various electrophysiological parameters were evaluated in ventricular papillary muscles of guinea pig. At concentrations less than 5 x 10(-5) M, DMI produced a significant shortening in the action potential duration (APD) measured at both 50% and 100% of repolarization. At 1 x 10(-4) M, the terminal portion of repolarization was so prolonged that the total APD was not significantly different from control values. DMI (greater than 1 X 10(-5) M) did not change the resting potential but significantly, decreased the overshoot potential, the amplitude, and the maximum rate of rise of phase O depolarization (Vmax) and shifted the membrane responsiveness and membrane reactivation curves downward and to the right. The effective refractory period (ERP) was shortened or lengthened, the effect being dependent on the concentration, but always made the ERP long relative to APD. DMI, (1 X 10(-5) M and 5 x 10(-5) M), attenuated and abolished the spontaneous activity and the Ca-mediated action potentials induced in ventricular muscle fibers. The mechanisms responsible for DMI's in vivo arrhythmogenic or antiarrhythmic effects are discussed. In terms of changes in ion conductance most effects can be explained by a reduction in sodium and calcium conductance.

Action Potentials↗
PubMed1979

Electrophysiological actions of chlorimipramine on guinea-pig ventricular fibres.

Chlorimipramine (CMI, 1 x 10(-5)M to 7 X 10(-5)M) decreased the amplitude, overshoot and rate of rise of ventricular action potentials and abolished the Ca-mediated action potentials elicited in guinea-pig papillary muscles. These results indicates that CMI inhibits the rise in sodium and calcium conductances during the cardiac action potential.

Action Potentials↗
PubMed1975

Levator ani as substitute puborectalis sling in treatment of anal incontinence.

For anal incontinence caused by destroyed or absent sphincter mechanism, a levator sling serving as a substitute puborectalis sling was used in five patients with incontinence of varied causes with good to excellent results. This sling was constructed bu freeing the insertion of the pubococcygeus and the ileococcygeus muscles from the coccyx. By further freeing the arcus tendineus from the lateral wall of the pelvis, the sling is made to arise from the pubis, thus theoretically giving the sling the potential of greater traction.

Fecal Incontinence↗
PubMedDate not supplied

The Warren operation for anal incontinence caused by disruption of the anterior segment of the anal sphincter, perineal body, and rectovaginal septum: report of five cases.

The use of the Warren vaginal flap operation for repair of a traumatic deformity consisting of disruption of the perineal body, anterior segment of the external anal sphincter, and lower half of the rectovaginal septum is described. Modifications described in this article include use of the jackknife position to give better exposure and epinephrine infiltration to give a bloodless field. The incidences of infection and recurrence appear lower than with the layer technique.

Adult↗