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Biomedical subjects

S R Hameroff

Publications and source records attributed to S R Hameroff.

At least 37 records · Page 2Linked to original sources
PubMed1983

Hemodynamic effects of high-frequency jet ventilation.

The hemodynamic effects of high-frequency jet ventilation (HFJV) and conventional ventilation were compared in normovolemic and functionally hypovolemic dogs. In normovolemic animals, no differences in hemodynamic function were found among spontaneous ventilation, conventional ventilation, and HFJV. When venous return was impaired by 15 cm H2O PEEP, cardiac index and stroke index were 25% higher with HFJV than with conventional ventilation (P less than 0.05). In another study with PEEP, conventional ventilation was compared to spontaneous ventilation, HFJV synchronized to five different parts of the cardiac cycle, and asynchronous HFJV. Heart rate was 15% lower and mean arterial pressure was 26% lower with conventional ventilation than with HFJV modes (P less than 0.05). There were no differences between synchronous and asynchronous HFJV. These results indicate that hemodynamic dysfunction may be less likely with HFJV than conventional ventilation. No advantage of synchronizing jet pulsations to a specific part of the cardiac cycle could be demonstrated.

Airway Resistance↗
PubMed1982

Doxepin effects on chronic pain, depression and plasma opioids.

Thirty patients with chronic low back or cervical pain combined with clinical depression were studied in a six-week, randomized, double-blind comparison of doxepin and placebo. Dependent variables included Hamilton Depression Scores, the Clinical Global Assessment Scale, and Profile of Mood States (POMS), and subjective ratings (visual analogue scales) of pain severity, percent of time pain felt, and effect of pain on activity, muscle tension, sleep, mood, and analgesic drug consumption. Plasma levels of doxepin, desmethyldoxepin, beta-endorphin, and enkephalin-like activity were also measured. Significant improvements in the doxepin-treated group compared to the placebo group were seen in Hamilton scores, Global Assessment Scale, Profile of Mood States, percent of time pain felt, and effect of pain on sleep, muscle tension, and mood. Some improvement was observed after 1 week, although most improvement occurred at 6 weeks, when the mean doxepin dose was 2.5 mg/kg and plasma doxepin and desmethyldoxepin averaged 70 ng/ml. Nonspecific enkephalin-like activity (but not beta-endorphins) increased for the treatment group and decreased for the placebo group. The efficacy of doxepin compared with that of placebo was thus documented in several depressive and pain parameters, indicating that doxepin is a valuable treatment for patients with chronic pain and depression.

Adult↗
PubMed1982

General anesthetics directly inhibit electron mobility: dipole dispersion theory of anesthetic action.

A model system of gaseous electron mobility, excitation, and plasma activity was used to study direct effects of six gases, including four general anesthetics, in oxygen. Helium increased, and nitrogen had minimal effects on gaseous excitation. Nitrous oxide, as well as the potent anesthetics halothane, enflurane, and isoflurane, inhibited gaseous excitation, nitrous oxide having the weakest anesthetic effect. The data are compatible with the view that anesthetic inhibition is mediated by Van der Waals dipole dispersion interactions among anesthetic molecules (e.g., halogenated hydrocarbons) and electrons accelerated by the applied field. Dipole dispersion interactions may also mediate anesthetic effects on synaptic protein conformational control.

Anesthesia, General↗
PubMed1981

High-frequency alternating lung ventilation.

A new mode, high-frequency alternating lung ventilation (HFALV) is described and demonstrated in which the lungs are alternately pulsed. A fluidic oscillator may be used to deliver two pulsed gas streams, 180 degrees out of phase, to bronchial catheters placed via a double lumen endobronchial tube. Inspiratory phase of one lung thus coincides with expiratory phase in the other, and characteristic lateral rocking chest movements is observed. In six dogs, HFALV was compared to simultaneous pulsing of both lungs with comparable flow (18.5 l/min), frequency (144 min-1), and pulse wave shape. Arterial PCO2 was significantly lower (P less than 0.001) with HFALV. Arterial PCO2 was also found to increase linearly (r = -0.862, P less than 0.001) with distance of the catheters' distal tips from the dogs' carinae. Theoretical mechanisms and possible applications of HFALV are discussed.

Animals↗
PubMed1981

Acute cardiovascular effects of dimethylsulfoxide.

Dimethylsulfoxide (DMSO) has been advocated as a central nervous system (CNS) protectant against ischemia and trauma. The present study was performed to evaluate acute cardiovascular effects of DMSO which might complicate the clinical treatment of CNS compromised patients. Intravenously administered DMSO in doses which reportedly provide CNS protection, 2 g/kg, were infused in 6 dogs; hemodynamic variables were measured and compared to infusion of equal volumes of 0.9% sodium chloride. Immediately after infusion, DMSO caused increases in cardiac index, heart rate, pulmonary capillary wedge pressures (WP), and pulmonary arterial (systolic, mean, and diastolic) pressures which were significantly greater than changes induced by saline. DMSO decreased systematic diastolic pressure and systemic vascular resistance at the end of infusion. Most DMSO induced changes returned toward pre-infusion values 10 min after the end of infusion. These results suggest transient DMSO effects different from equal volumes of saline, possibly due to hyperosmotic expansion of plasma volume. A decrease in systemic vascular resistances was also observed. Although neither CNS production, intracranial pressure or blood flow were studied, these data suggest that DMSO used for CNS protection would not have adverse acute hemodynamic consequences. This may be particularly relevant in traumatized, hypovolemic patients.

Animals↗
PubMed1981

Comparison of bupivacaine, etidocaine, and saline for trigger-point therapy.

Injections of local anesthetics, saline, "dry needling," or other stimuli at specific, tender loci (trigger or acupuncture points) are reportedly efficacious in treatment of chronic pain syndromes. In a randomized, double-blind crossover study, subjective responses of 15 patients with myofascial syndrome to trigger-point injections of either bupivacaine 0.5%, etidocaine 1%, or physiologic saline without preservative were compared. Responses in six pain-related categories were determined before treatment and 15 minutes, 24 hours, and 7 days after treatment. Trigger-point injections with bupivacaine and etidocaine were generally preferred over saline in several pain-tested categories. Implications and possible mechanisms are discussed.

Acetanilides↗