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Biomedical subjects

J Sprung

Publications and source records attributed to J Sprung.

At least 73 records · Page 4Linked to original sources
PubMed1995

Oxygen transport and cardiovascular effects of resuscitation from severe hemorrhagic shock using hemoglobin solutions.

OBJECTIVE: To test the short-term efficacy of three hemoglobin solutions in restoring cardiac output, intravascular pressures, oxygen transport (DO2), and oxygen consumption (VO2) after resuscitation from severe hemorrhagic shock. DESIGN: Prospective study. SETTING: Research laboratory. SUBJECTS: Beagle dogs. INTERVENTIONS: After anesthesia and instrumentation, hemorrhagic shock was induced for 2 hrs by blood withdrawal to maintain systolic blood pressure at 50 mm Hg. Resuscitation then occurred with one of four different resuscitation fluids. One group of dogs was not resuscitated. Survival rate was monitored for 8 days. MEASUREMENTS AND MAIN RESULTS: In 33 beagle dogs, cardiovascular variables (DO2 and VO2) were compared after resuscitation with 8% stroma-free hemoglobin, 4% or 8% pyridoxalated-hemoglobin-polyoxyethylene conjugate (PHP44 and PHP88, respectively), or autologous whole blood. The dogs were anesthetized, paralyzed, mechanically ventilated (FIO2 of 0.21), and instrumented with arterial and pulmonary artery catheters. An average of 63% of estimated blood volume was removed to maintain systolic blood pressure at 50 mm Hg for 2 hrs. The dogs then were either not resuscitated (n = 4) or resuscitated with 8% stroma-free hemoglobin (n = 7), PHP44 (n = 6), PHP88 (n = 8), or whole blood (n = 8), with a volume equivalent to the withdrawn blood. Cardiovascular variables, DO2, VO2, oxygen extraction ratios, and blood concentrations of lactic acid and catecholamines were determined before, and for < or = 6 hrs after, resuscitation from hemorrhagic shock. Blood smears were microscopically examined. In addition, the survival rate was monitored for 8 days after resuscitation. By 2 hrs of hemorrhagic shock, there was a large decrease in DO2 (p < .05) and an increase in oxygen extraction ratio from 0.27 to 0.70 (p < .05). There was a 3.5-fold increase in lactate concentrations and a 25-fold increase in catecholamine concentrations as compared with preshock values. All dogs not resuscitated died within 1.75 hrs after 2 hrs of shock. After resuscitation with whole blood, all cardiovascular and oxygen transport variables returned to approximately prehemorrhage values and remained so throughout the measurement period. After resuscitation with any hemoglobin solution, DO2 returned transiently to control values. However, recovery of DO2 was short-lived in all hemoglobin solution groups, and, by 4 hrs postresuscitation in all groups, DO2 was less than the DO2 of the dogs receiving whole blood (p < .05). These changes were associated with decreases in total hemoglobin concentrations compared with the values immediately before resuscitation (p < .05). In addition, with resuscitation using the PHP solutions, blood smears demonstrated aggregation of red blood cells and platelets. On day 8 after hemorrhagic shock, the survival rate was 100% for whole blood and PHP44, 86% for 8% stroma-free hemoglobin, and 33% for PHP88. CONCLUSIONS: Resuscitation from severe hemorrhagic shock with 8% stroma-free hemoglobin, PHP44, or PHP88 is equally effective in restoring cardiac index and vascular pressures as using whole blood. However, resuscitation with the three hemoglobin solutions only transiently restored DO2 after hemorrhagic shock. The subsequent reduction of DO2 compared with the DO2 value using whole blood was due mostly to hemodilution. With the two PHP solutions, formation of red blood cell aggregates probably resulted in sequestration of red cell mass and additional loss of oxygen carrying capacity.

Animals↗
PubMed1995

Lung tissue and airway impedances during pulmonary edema in normal range of breathing.

How pulmonary edema affects lung tissue and airway properties is not clear. From measurements of airway pressure and flow, we measured lung elastance (EL) and resistance (RL) in 5 anesthetized-paralyzed open-chested dogs during sinusoidal forcing in the frequency (f) and tidal volume (VT) ranges of normal breathing. RL was divided into its tissue (Rti) and airway (Raw) components from measurements of alveolar pressure through capsules glued to the lung surface. After induction of severe pulmonary edema by injection of oleic acid into the right atrium, forcing was repeated at the same mean airway pressure (Paw) as in control animals (11 cmH2O) and at a higher Paw (14 cmH2O), as would occur in closed-chested dogs during edema (G. M. Barnas, D. Stamenovic, and K. R. Lutchen. J. Appl. Physiol. 73: 1040-1046, 1992). Edema increased EL, and this increase was greater at Paw = 14 cmH2O (P < 0.05). The f dependences of EL and Rti were increased by edema (P < 0.05), and there was a large negative dependence of EL on VT at Paw = 14 cmH2O. Edema increased RL (P < 0.05), but this increase depended on f, VT, and Paw. The increase in RL was due largely to increases in Rti at Paw = 14 cmH2O and to increases in Raw at Paw = 11 cmH2O. We conclude that the functional effects of oleic acid-induced pulmonary edema on RL are due mostly to changes in lung tissue.

Airway Resistance↗
PubMed1994

Chronic methemoglobinemia: improving hemoglobin saturation monitoring during anesthesia.

Methemoglobin interferes with the accuracy of pulse oximetry data. Methemoglobinemia is caused by many factors, both congenital and acquired. However, the increasing usage of dapsone, which converts hemoglobin to methemoglobin, is increasing the number of patients with methemoglobinemia. We present the case of a patient with dapsone-induced methemoglobinemia who was successfully treated with methylene blue, which converts methemoglobin back to hemoglobin.

Aged↗
PubMed1994

Differential effects of halothane and isoflurane on contractile force and calcium transients in cardiac Purkinje fibers.

BACKGROUND: Halothane and isoflurane have been shown to differentially effect mechanisms of contraction in working myocardial fibers. The aim of this study was to compare effects of halothane and isoflurane on contractile force (CF) and Ca2+ transients in canine cardiac Purkinje fiber preparations. METHODS: Fiber preparations (n = 29) were superfused with Krebs-Ringer solution and stimulated at 40-60 pulses/min at 30 degrees C in the absence and presence of 0.55% and 1.01% isoflurane or 0.27% and 0.78% halothane. Isometric tension (CF), and intracellular Ca2+ transients (luminescence, L) were measured after microinjecting the Ca2+ sensitive photoprotein aequorin into Purkinje fibers. Peak CF and peak L, rate of rise (slope) of CF and L, time to attain peak CF and L, and duration of CF and L at half-peak CF and L, were measured at 5 mM extracellular CaCl2. Changes in peak CF and peak L also were measured during incremental increases in CaCl2 from 3.6 to 9.0 mM. RESULTS: Both anesthetics depressed peak CF and peak L and the rate of increase in peak CF and L in a concentration-dependent fashion, and effects of halothane were greater than those of isoflurane. Time to attain peak L and duration of L at half-peak L was decreased or unchanged by isoflurane and was increased by halothane, whereas time to attain peak CF and duration of CF at half-peak CF was shortened by both. The change in peak CF response as a function of the change in peak L with increasing extracellular CaCl2 was attenuated similarly by both halothane and isoflurane. CONCLUSIONS: Halothane depresses peak CF and Ca2+ transients and prolongs Ca2+ transients more than does isoflurane at equivalent minimum alveolar concentration in Purkinje fibers. This suggests Ca2+ concentration is differentially altered by anesthetics in this tissue. Peak CF at equivalent peak Ca2+ transients, however, appears to be attenuated similarly by both anesthetics. These differences in anesthetic effect are qualitatively similar to those found in cardiac tissue of other species. These findings add to our understanding of effects of volatile anesthetics on contractile properties and myoplasmic Ca2+ in cardiac Purkinje fibers.

Animals↗
PubMed1994

Hypothermia modifies anesthetic effect on contractile force and Ca2+ transients in cardiac Purkinje fibers.

Mild hypothermia enhances cardiac contractility, and volatile anesthetics depress contractility. Contractile force (tension) and Ca2+ transients were measured in canine Purkinje fibers at 35 and 25 degrees C with and without halothane and isoflurane to examine how anesthetics attenuate the positive inotropic effect of mild hypothermia. Isometric tension and light emitted from the photoprotein aequorin were used to assess contractility and intracellular Ca2+ transients in fibers stimulated at 40-60 pulses/min. At 35 degrees C, each anesthetic depressed peak tension and peak Ca2+ transients and decreased contractile force duration but, for halothane, increased Ca2+ transient duration. Decreases in tension by both anesthetics at 35 degrees C were converted to marked increases in tension at 25 degrees C, whereas Ca2+ transients were little changed. Removal of anesthetics at 25 degrees C greatly increased tension with a small increase in Ca2+ transients that was much lower than that at 35 degrees C. The curve relating peak contractile force as a function of Ca2+ transients at 25 degrees C during stepwise increases in extracellular CaCl2 was shifted steeper and leftward of the curve at 35 degrees C. These studies suggest that the positive inotropic effect of mild hypothermia is due primarily to increased myofibrillar Ca2+ sensitivity and that anesthetics decrease tension during hypothermia by decreasing myofibrillar Ca2+ sensitivity. Reduced influx of transsarcolemmal or sarcoplasmic reticular Ca2+ may also play a role during mild hypothermia.

Aequorin↗
PubMed1994

Endotracheal tube and tracheobronchial obstruction as causes of hypoventilation with high inspiratory pressures.

Two cases of difficult ventilation are presented, the first caused by endotracheal tube obstruction with nasal turbinate, and the second caused by tracheobronchial obstruction with blood clots. The clinical presentation in each case was characterized by extreme difficulty in ventilating and severe hypercapnia despite vigorous ventilatory efforts with either a mechanical ventilator or resuscitator bag. A simple manipulation of the endotracheal tube cuff helped to differentiate between increased impedance caused by endotracheal tube obstruction as opposed to increased respiratory system impedance beyond the tip of tube. In the second patient, in whom even a short interruption of ventilation was poorly tolerated, simultaneous rigid bronchoscopy (for removal of intratracheal masses) and ventilation via endotracheal tube were successfully performed.

Adult↗
PubMed1994

Treatment of a bronchopleural fistula with a Fogarty catheter and oxidized regenerated cellulose (surgicel).

A patient with bronchopleural fistula was successfully treated by occluding the fistula with an inflated Fogarty catheter balloon packed with oxidized regenerated cellulose (Surgicel) using a fiberoptic bronchoscope. After 48 h, the balloon was deflated, the fistula had sealed, and the patient did well. This simple and relatively noninvasive therapy was effective in this patient who was not a surgical candidate.

Aged↗
PubMed1993

Effect of lung volume on lung resistance and elastance in awake subjects measured during sinusoidal forcing.

BACKGROUND: Although lung volume may be changed by certain procedures during anesthesia and mechanical ventilation, dependence of the dynamic mechanical properties of the lungs on lung volume are not clear. Based on studies in dogs, the authors hypothesized that changes in lung mechanics caused by anesthesia in healthy humans could be accounted for by immediate changes in lung volume and that lung resistance will not be decreased by positive end-expiratory airway pressure if tidal volume and respiratory frequency are in the normal ranges. METHODS: Lung resistance and dynamic lung elastance were measured in six healthy, relaxed, seated subjects during sinusoidal volume oscillations at the mouth (5 mL/kg; 0.4 Hz) delivered at mean airway pressure from -9 to +25 cmH2O. Changes in lung volume from functional residual capacity were measured with inductance plethysmographic belts. RESULTS: Decreases in mean mean airway pressure that caused decreases in lung volume from functional residual capacity comparable to those typically observed during anesthesia were associated with significant increases in both dynamic lung elastance and lung resistance. Increases in mean mean airway pressure that caused increases in lung volume from functional residual capacity did not increase lung resistance and increased dynamic lung elastance only above about 15 cmH2O. CONCLUSIONS: Increases in dynamic lung elastance and lung resistance with anesthesia can be explained by the accompanying, acute decreases in lung volume, although other factors may be involved. Increasing lung volume by increasing mean airway pressure with positive end-expiratory pressure will decrease lung resistance only if the original lung volume is low compared to awake, seated functional residual capacity.

Adult↗
PubMed1993

Effects of mean airway pressure and tidal volume on lung and chest wall mechanics in the dog.

Dependencies of the dynamic mechanical properties of the respiratory system on mean airway pressure (Paw) and the effects of tidal volume (VT) are not completely clear. We measured resistance and dynamic elastance of the total respiratory system (Rrs and Ers), lungs (RL and EL), and chest wall (Rcw and Ecw) in six healthy anesthetized paralyzed dogs during sinusoidal volume oscillations at the trachea (50-300 ml; 0.4 Hz) delivered at mean Paw from -9 to +23 cmH2O. Changes in end-expiratory lung volume, estimated with inductance plethysmographic belts, showed a typical sigmoidal relationship to mean Paw. Each dog showed the same dependencies of mechanical properties on mean Paw and VT. All elastances and resistances were minimal between 5 and 10 cmH2O mean Paw. All elastances, Rrs, and RL increased greatly with decreasing Paw below 5 cmH2O. Ers and EL increased above 10 cmH2O. Ecw, Ers, Rcw, and Rrs decreased slightly with increasing VT, but RL and EL were independent of VT. We conclude that 1) respiratory system impedance is minimal at the normal mean lung volume of supine anesthetized paralyzed dogs; 2) the dependency of RL on lung volume above functional residual capacity is dependent on VT and respiratory frequency; and 3) chest wall, but not lung, mechanical behavior is nonlinear (i.e., VT dependent) at any given lung volume.

Air Pressure↗