Biomedical subjects
J H Modell
Publications and source records attributed to J H Modell.
Megaloblastic anemia and brief exposure to nitrous oxide--a causal relationship.
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Pulmonary embolism: high-frequency jet ventilation offers advantages over conventional mechanical ventilation.
After injecting autologous muscle to induce massive pulmonary embolism, the effects of high-frequency jet ventilation (HFJV) were compared with those of controlled mechanical ventilation (CMV) in anesthetized, paralyzed dogs. HFJV better maintained both alveolar ventilation and oxygenation than did CMV. Moreover, PaO2, cardiac index, and oxygen delivery were greater with HFJV than with CMV when the two modes of ventilation were compared at the same PaCO2.
Who is captain of the anesthesia ship?
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Minimal requirements for monitoring--1986.
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Treatment of near-drowning: is there a role for H.Y.P.E.R. therapy?
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Continuous positive airway pressure and expiratory positive airway pressure increase functional residual capacity equivalently.
The effect of continuous positive airway pressure (CPAP) and expiratory positive airway pressure (EPAP) on functional residual capacity (FRC) of ten healthy, spontaneously breathing, lightly anesthetized intubated mongrel dogs was studied. The CPAP and EPAP at 5, 10, 15, and 20 cm H2O were alternately applied to all animals. Total (lung and chest wall) compliance, esophageal pressure, airway pressure, transpulmonary pressure, control FRC, and the change in FRC (delta FRC) were measured before and after each application of CPAP and EPAP. Neither expiratory transpulmonary pressure nor delta FRC with CPAP differed significantly from that with EPAP at all levels (p greater than 0.05). These data suggest that CPAP and EPAP, when applied at the same expiratory pressure, result in an equivalent increase in FRC due to passive mechanical distention of the lungs.
Near drowning.
Several conditions that contribute to drowning and near drowning must be considered in the treatment of near-drowned victims. Regardless of the cause, mechanical ventilation should begin as soon as possible and closed-chest cardiac massage should be administered when there is any question about the adequacy of cardiac output. After aspiration of either fresh or seawater, a large intrapulmonary physiologic shunt can occur, which requires aggressive mechanical ventilatory support to ensure adequate oxygenation and to return pulmonary function to normal. Near drowning is a multisystem disease and, while abnormalities of the lung and brain have been emphasized, definitive therapy must be tailored to each patient and must address all of the patient's needs.
Serum electrolyte changes in near-drowning victims.
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Titration of PEEP by the arterial minus end-tidal carbon dioxide gradient.
It was shown in dogs that intrapulmonary physiologic shunt (Qsp/Qt), arterial oxygen tension (PaO2), total static respiratory compliance (CT), oxygen delivery (O2AV), cardiac output (Qt), and arterial minus end-tidal carbon dioxide gradient (PaCO2-PetCO2) undergo statistically significant deterioration when oleic acid is injected into the pulmonary artery. Positive end-expiratory pressure (PEEP) therapy reduced Qsp/Qt and PaCO2-PetCO2 gradient and increased PaO2. The CT did not show any consistent pattern of improvement with the application of PEEP. The Qt and the O2AV progressively decreased as PEEP was increased. The application of additional PEEP beyond that which minimized the PaCO2-PetCO2 gradient produced a statistically significant increase in the PaCO2-PetCO2 gradient, but this was not reflected by concomitant changes in Qsp/Qt or PaO2 in spite of a further decrease in Qt. Thus, the PaCO2-PetCO2 gradient may be a more sensitive indicator of excessive PEEP than is Qst/Qt or PaO2, since it should be smallest when there is maximal recruitment of perfused or functional gas units without overdistention of alveolar areas contributing to dead space. Also, the use of the PaCO2-PetCO2 gradient permits the rapid titration of PEEP without the need for a pulmonary artery catheter.
Expiratory valve dysfunction in a semiclosed circle anesthesia circuit--verification by analysis of carbon dioxide waveform.
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Pulmonary aspiration--effects of volume and pH in the rat.
To evaluate the effect of volume of aspirates with different pHs on mortality associated with pulmonary aspiration, hydrochloric acid solutions were injected into the tracheas of 336 Sprague-Dawley rats. The rats were divided randomly into 33 groups, were observed for 96 hr after aspiration, and were not resuscitated. Deaths were divided into two groups: early, less than 30 min after aspiration, and late, greater than 4 hr after aspiration. Late deaths, accounting for 22% of all fatalities, occurred exclusively in animals aspirating solutions with a pH less than 2.5. These late deaths indicated progressive lung damage as opposed to acute cardiorespiratory failure, which early deaths suggested. Low volume pulmonary aspirates (0.3 ml/kg) with extremely low pH (1.0) resulted in a high mortality rate (90%). Conversely, higher volume pulmonary aspirates (1.0-2.0 ml/kg) with a higher pH (greater than or equal to 1.8) resulted in a low mortality rate (14%). These data demonstrate an important interaction between pH and volume of aspirates: even low volumes have a high mortality rate if pH is very low, whereas if gastric fluid is effectively buffered, then much higher volumes than previously thought can be tolerated. This suggests that the routine use of nonparticulate antacids may be indicated in patients at risk from aspiration of stomach contents and should not be withheld because of concern of increasing gastric volume.
Effectiveness of CPAP by mask for pulmonary edema associated with hypercarbia.
We describe continuous positive airway pressure (CPAP) by mask to reduce hypercarbia in two patients who had pulmonary edema due to congestive heart failure. In such patients, beside reducing venous return and filling pressures, CPAP improves compliance and decreases the work of breathing, thereby improving effective ventilation. Hence, CPAP may be useful to combat not only hypoxemia but also hypercarbia that is associated with pulmonary edema.
Early detection of endotracheal tube accidents by monitoring carbon dioxide concentration in respiratory gas.
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Fluid administration increases oxygen delivery during continuous positive pressure ventilation after freshwater near-drowning.
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Continuous positive airway pressure is beneficial in treatment of smoke inhalation.
This study demonstrates that continuous positive airway pressure (CPAP) improves pulmonary function after smoke inhalation by dogs. Sixteen dogs were anesthetized with iv sodium pentobarbital. Arterial and mixed venous blood gas tensions; carboxyhemoglobin concentration (COHgb); mean systemic arterial (MAP), mean pulmonary arterial (MPAP), and pulmonary arterial wedge (WP) pressures; heart (HR) and respiratory (f) rates; cardiac output (CO); and airway pressure (Paw) were measured. Intrapulmonary physiologic shunt (Qsp/Qt) and pulmonary (PVR) and systemic (SVR) vascular resistances were calculated. The animals then breathed an aerosol of smoke and were divided randomly into 2 groups. The treatment group breathed spontaneously on 8-torr CPAP whereas the control group continued to breathe spontaneously at ambient pressure. After inhalation of smoke, Qsp/Qt, MPAP, PVR, COHgb, HR, and f rose, whereas PaO2 and MAP fell in untreated animals. When CPAP was applied, PaO2 and Qsp/Qt returned nearly to baseline values. Mean f also was significantly lower in the treated animals. We found that the early institution of CPAP improves oxygen exchange in the lungs after the inhalation of smoke.
Continuous positive airway pressure improves oxygenation in dogs after the aspiration of blood.
Fourteen dogs were anesthetized, intubated, and breathed room air spontaneously. We then instilled 2 ml/kg of fresh nonheparinized donor blood into their tracheas. Seven dogs received no treatment and served as controls (group A); respiratory rate (RR) increased from 25 +/- 11 (mean +/- SD) to 103 +/- 33 breath/min, HR decreased from 179 +/- 28 to 136 +/- 42 beat/min, PaO2 decreased from 82 +/- 10 to 30 +/- 4 torr, pulmonary venous admixture (Qsp/Qt) increased from 0.14 +/- 0.10 to 0.72 +/- 0.06, and venous oxygen tension (PVO2) decreased from 46 +/- 4 to 22 +/- 5 torr 10 min after the aspiration of blood; all changes were statistically significant (p less than .05). After 4 h, RR and HR returned to control values, but PaO2 was only 58 +/- 10 torr. Cardiac output, oxygen consumption (VO2), and pulmonary and systemic BP and resistances were not significantly affected. Thirty-five min after the other 7 dogs aspirated blood (group B), 10 cm H2O of continuous positive airway pressure (CPAP) was applied while they breathed spontaneously. CPAP reduced Qsp/Qt to 0.31 +/- 0.10 and 0.15 +/- 0.11 30 and 90 min after its application, respectively (p less than .05). By 4 h, the PaO2 of group B dogs was 81 +/- 15 torr (p less than .05 compared with group A). CPAP also increased arteriovenous oxygen content difference (C[a-v]O2) compared with the nontreated dogs. Four hours after the aspiration of blood, all dogs were extubated. Twenty-four hours later, arterial blood gases were normal in all dogs of both groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Intermittent continuous positive airway pressure by mask: its use in the treatment of atelectasis.
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