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Biomedical subjects

L S Berman

Publications and source records attributed to L S Berman.

11 recordsLinked to original sources
PubMed1988

Capnographic detection of anaesthesia circle valve malfunctions.

To determine whether capnographic waveforms can characterize valve malfunction of the anaesthesia circle, which would enable such problems to be identified and rectified immediately, we monitored capnographic respiratory waveforms during anaesthesia with simulated circle valve malfunctions. Ten mongrel dogs were anaesthetized with pentobarbitone, 25 mg.kg-1 IV, and halothane, 0.5 to 1 per cent. Respiratory gas was sampled from the elbow of the circle system for capnographic monitoring. At fresh gas flow rates of 2.5 or 5 L.min-1 during consecutive periods of controlled and spontaneous ventilation, the inspiratory valve, the expiratory valve, or both valves of the circle system were opened for 15 min. Inspired CO2 concentration increased significantly every time a valve was opened, except during spontaneous breathing at 5 L.min-1. At 2.5 L.min-1, inspired CO2 increased from baseline to 0.41 +/- 0.28 per cent with the inspiratory valve opened and to 2.22 +/- 1.72 per cent with the expiratory valve opened during controlled ventilation and to 0.43 +/- 0.20 per cent and 2.02 +/- 1.28 per cent, respectively, during spontaneous ventilation. Inspired CO2 increased to almost 1 per cent when the inspiratory valve was open and to greater than or equal to 1.89 per cent when the expiratory valve was open. The effects with the expiratory valve open and with both valves open were similar. Capnograms were affected in characteristic ways by the valve malfunctions.

Anesthesiology↗
PubMed1988

Kerosene aspiration: immediate and early pulmonary and cardiovascular effects.

Hydrocarbon aspiration is responsible for substantial morbidity and mortality in both children and domestic animals. To better understand the pathogenesis of hydrocarbon poisoning, we evaluated the effects of aspiration of 0.5 ml/kg of kerosene on various pulmonary and cardiovascular variables over a 4-hr period in a canine model. Heart rate and blood pressure decreased immediately after kerosene aspiration but returned to control values within 60 min. Respiratory rate and intrapulmonary shunting were increased and PaO2 was decreased for up to 4 hr after kerosene aspiration. PaCO2 increased and pH decreased immediately after aspiration but returned to baseline within 45 and 90 min, respectively. Intrapleural pressure became more negative after kerosene was aspirated, which suggests that total lung compliance was diminished. Kerosene aspiration resulted in severe and persistent intrapulmonary physiologic shunting, hypoxemia, bradycardia, and hypotension.

Administration, Inhalation↗
PubMed1986

Wakefulness during cesarean section after anesthetic induction with ketamine, thiopental, or ketamine and thiopental combined.

Thirty-six pregnant women (ASA class I or II) at term who underwent general anesthesia and cesarean section received either ketamine, 1 mg/kg (n = 12); thiopental, 4 mg/kg (n = 13); or a combination of ketamine, 0.5 mg/kg, and thiopental, 2 mg/kg (n = 11). A blood pressure cuff inflated to 250 mm Hg isolated one arm from the effects of succinylcholine so that awareness during anesthesia could be assessed by asking the patient to move her hand. Although only one patient receiving ketamine responded to commands during anesthesia, 46% of patients receiving either thiopental or the combination responded to commands intraoperatively. No patient hallucinated, the incidence of dreams was low (11%), and no postoperative dysphoria was noted. Three patients (8%) had postoperative recall of intraoperative awareness; one had received thiopental and two the combination. Maternal intraoperative cardiovascular responses among the groups were similar, as were umbilical blood gas values, newborn Apgar scores, and neonatal neurobehavioral test scores at 4 and 24 hr. Ketamine more effectively blocked maternal responsiveness to commands and strong stimuli during the first few minutes after anesthetic induction for cesarean section than did thiopental or a combination of thiopental and ketamine, each at a lower dose.

Adult↗
PubMed1985

Prolonged use of high-frequency jet ventilation for a pediatric patient.

A 10-yr-old boy who developed postoperative respiratory failure with evidence of significant barotrauma was treated with high-frequency jet ventilation (HFJV). HFJV reduced peak inflation pressure, enhanced oxygenation, and improved ventilation. The patient could not be weaned from HFJV by decreasing drive pressure. Instead, he was successfully weaned by decreasing the HFJV rate to 80 cycle/min and then switching to conventional intermittent mandatory ventilation at initially similar rate and pressure levels.

Barotrauma↗
PubMed1981

Inspiration: expiration ratio. Is mean airway pressure the difference?

Mechanical ventilation with different ratios of inspiratory to expiratory times (I:E ratio) and levels of positive end-expiratory pressure (PEEP) were applied to 9 dogs after the aspiration of fresh water and then were compared. The dogs were ventilated with an I:E ratio of 2:1 with 0 PEEP; an I:E ratio of 2:1 with 5 torr PEEP; and an I:E ratio of 1:2 with 5 torr PEEP. Peak airway pressures were regulated to maintain a mean airway pressure of 13 mm Hg. Arterial oxygenation was better with an I:E ratio of 1:2 with PEEP than with an I:E ratio of 2:1 either with or without PEEP (60 +/- 15 torr as compared with 42 +/- 11 torr and 43 +/- 10 torr). Cardiac index was depressed with all ventilatory modes, but oxygen delivery did not significantly differ among all the modes of ventilation. A ratio of prolonged I:E was not seen to benefit blood gas tension.

Airway Resistance↗
PubMed1977

Tracheal extubation of the neonate at 2 to 3 cm H2O continuous positive airway pressure.

To investigate the efficacy of extubation at higher levels of continuous positive airway pressure (CPAP), 49 newborns (0.95 to 4.0 kg) were extubated at 2 to 3 cm H2O following 1 to 47 days of CPAP therapy. Pre- and postextubation measurements of Po2, PCO2, pH, FiO2, and CPAP were made in all infants. No significant differences (P less than.05) were found between pre- and post-extubation arterial blood gas values for all patients. Comparison of pre- and post-extubation blood gas data with respect to birthweight (less than 2.0 kg vs greater than 2.0 kg) and intubation time (less than 8 days vs. greater than 8 days) also indicated no statistical differences. Mean alveolar-arterial oxygen differences and FiO2 for 41 infants showed progressive decreases following extubation. Six of the 49 infants required reintubation within 72 hours following extubation. The results of this study indicate that newborns with respiratory disease requiring CPAP may be extubated at 2 to 3 cm H2O with no significant changes in arterial blood gas values, thus preventing prolonged intubation associated with weaning to 0 cm H2O CPAP.

Birth Weight↗
PubMed1976

Optimum levels of CPAP for tracheal extubation of newborn infants.

Arterial oxygen tension and functional residual capacity were studied in 16 intubated, spontaneously breathing newborn infants recovering from respiratory disease. Studies were made at 2 cm H2O continuous positive airway pressure, at zero end expiratory pressure, and following extubation. The study showed that PaO2 and FRC at 2 cm H2O CPAP were the same as observed following extubation, but that both values were significantly lower at ZEEP.

Humans↗
PubMed1975

The therapeutic application of end-expiratory pressure in the meconium aspiration syndrome.

The effectiveness of end-expiratory pressure (EEP) in relieving hypoxemia in the meconium aspiration syndrome (MAS) was studied in 14 patients with the disorder. These infants demonstrated a direct, mean PO2 response of 12 torr/cm H2O EEP. A maximum PO2 response was observed in an EEP range of 4 to 7 cm H2O. EEP was equally effective whether patients were breathing spontaneously or were being mechanically ventilated. EEP is useful in the treatment of hypoxemia in the infants with meconium aspiration syndrome.

Blood Gas Analysis↗
PubMedDate not supplied

The PaO2 response to changes in end expiratory pressure in the newborn respiratory distress syndrome.

To quantitate the effect of changes in end-expiratory pressure (EEP) upon PaO2 in infants with the respiratory distress syndrome, arterial blood gas (ABG) data was reviewed in 28 neonates. A total of 94 ABG specimen pairs were analyzed (specimen I taken before EEP adjustment; specimen II taken after EEP change). An overall change in PaO2 of 15 torr was noted per cm H2O change in EEP. Patients in whom the level of EEP was low (0-3 cm H2O) at the time of Sample I had a greater change in PaO2 (p less than 0.01) than infants whose Sample I ABG was taken at mid-range of EEP (4-6 cm H2O) or at high ranges (7-12 cm H2O). At the high ranges of EEP a minimal and variable PaO2 response was observed. The PaO2 response was not statistically different between neonates on controlled ventilation and those breathing spontaneously. Survivors had a greater PaO2 response than did nonsurvivors, but because of the variables affecting respiratory distress syndrome (RDS) patients, it could not be determined if this PaO2 response had a prognostic value. From this data, the clinician is provided with a guide to the expected PaO2 response when a change in EEP is made.

Humans↗