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Biomedical subjects

M S Albin

Publications and source records attributed to M S Albin.

At least 55 records · Page 3Linked to original sources
PubMed1984

Regional organ blood flow during high-frequency positive-pressure ventilation (HFPPV) and intermittent positive-pressure ventilation (IPPV).

The effect of high-frequency ventilation (HFV) on cerebral blood flow (CBF) at normal and elevated intracranial pressure (ICP) was compared with flows measured under the same conditions during intermittent positive pressure ventilation (IPPV). Renal, lung (bronchial artery supply), and cardiac blood flows also were measured during HFV and compared with flows observed during IPPV. Measurements were made in canines with stable hemodynamic variables and arterial CO2 and O2 tensions in the normal range, CBF during HFV was comparable to the CBF during IPPV. Following an increase in ICP to a mean of 44 +/- 18 mmHg (SD), mean CBF decreased to 22.5 +/- 11 ml . 100 g-1 . min-1 (SD) during IPPV and 21.7 +/- 13.2 ml . 100 g-1 . min-1 (SD) during HFV. No statistical differences could be noted in regional or global flow as a function of ventilatory mode. Renal, lung (bronchial artery supply), and cardiac blood flows also showed no statistical variation between HFV and IPPV. Ventilator-synchronous fluctuations in ICP observed during IPPV were reduced during HFV at normal ICP and eliminated by HFV at elevated ICP.

Animals↗
PubMed1983

Rapid selective brain-cooling using head immersion and naso-oral perfusion in dogs.

Utilizing a technique of selective surface head cooling and naso-oral perfusion, rapid profound cooling of the brain to 14-19 degrees C with maintenance of body temperature has been achieved in 24 dogs. Post perfusion, neurological examination of the animals were within normal limits, and neuropathological review of brain specimens demonstrated absence of tissue abnormality.

Animals↗
PubMed1983

Isolated profound cerebral cooling with a bi-carotid heat exchanger shunt in dogs.

Intracerebral temperatures of 15 degrees C have been achieved in 20 canine brains using a simple cannulation of the carotid arteries and interposition of a highly efficient heat exchanger. The appropriate changes in cardiovascular function and cerebral electrical activities have been documented. The extracorporeal system does not require the use of a pump oxygenator unit.

Animals↗
PubMed1982

Mechanical and neurological response of cat spinal cord under static loading.

The force/deformation relationship of the exposed spinal cord of cats was studied when the force was gradually applied posteriorly at T10. A linear elastic behavior was identified for deformation less than 0.5 mm, but it was not observed when the static force was no longer supported by the dural sheath. Nonlinear force/deformation, along with a strong hysteresis during a cycle of compression and decompression. The mechanical behavior remained practically the same in a repeated loading if the deformation was less than 2 mm. The motor function of cats did not recover after the cord had been compressed to 4 mm. The associated static force was about 15% of the dynamic force producing the same deformation.

Animals↗
PubMed1981

Stress-strain relationship and neurological sequelae of uniaxial elongation of the spinal cord of cats.

An in vivo experimental method was developed to measure the mechanical or rheological properties of the spinal cord of anesthetized cats. This novel approach resulted in measurements of the tensile force in the cord and the modulus of the spinal cord tissue under longitudinal elongation. Both sensory and motor function of the cats recovered within a week after a spinal cord segment had been stretched by a 50% elongation.

Animals↗
PubMed1981

Positioning the right atrial catheter: a model for reappraisal.

A flexible Silastic casting of the human right atrium was developed to correspond to some in vivo human right atrium hemodynamic characteristics including chamber pressures, pulsatility, fluid output, and flow velocity. Using an infusion pump, air was introduced (10 ml in 30 s) into the superior vena cava of the model and aspirated via a catheter from different positions within the model atrial chamber. The tests were carried out at atrial inclinations of 60 degrees, 80 degrees, and 90 degrees from the horizontal and compared the aspiration efficiency of a single-orificed 16-gauge catheter to a 16-gauge multiorified (5 aperatures) catheter. Optimal air aspiration occurred with the multiorificed catheter tip positioned within the area 2.0 cm below the junction of the superior vena cava (SVC) and the atrial chamber at an inclination of 80 degrees. As much as 80 per cent of the incoming air could be aspirated under these conditions. At its optimal position the single-orificed catheter gave a maximal yield of 45 to 50 per cent aspiration when the tip was positioned 3.0 cm above the SVC and atrial chamber junction. Aspiration of air from mid right atrium (4.5 cm below the SVC-atrial junction) was poor regardless of the type of catheter used or atrial inclination. These data suggest a need for reappraisal of catheter design and placement.

Cardiac Catheterization↗
PubMed1980

Spontaneous migration of a central venous catheter and its repositioning: technical note.

A right atrial catheter was inserted the night before operation and its position was verified by an X-ray film. Before the performance of the surgical procedure, the catheter was attached to a strain gauge transducer and a wave form indicated catheter migration into the right ventricle. The catheter was withdrawn until atrial pulse contour developed. Verification of catheter position using this pressure pulse contour technique is simple and accurate and avoids the potential hazards of ventricular placement and the inability to aspirate adequately in the event of venous air embolism.

Adult↗
PubMed1980

Analysis and comparison of venous air embolism detection methods.

Changes in precordial ultrasonic Doppler patterns in dogs were compared with changes of end-tidal carbon dioxide (EtCO2) and pulmonary arterial pressure (PAP). Possible mechanisms of pulmonary arterial hypertension after air embolism in dogs are discussed. After the injection of air, an immediate change in the Doppler ultrasonic pattern was detected, including a shift of the base line. The duration of change of Doppler patterns varied depending upon the length of time that trapped air remained in the right heart. There was a delay of 15 to 30 seconds before the EtCO2 and PAP responded. In a group of dogs pretreated with 0.3 mg of propranolol per kg, there was a significant decrease in the PAP response due to induced air embolism compared to the control group (P < 0.05). We found that the Doppler ultrasonic device was the most sensitive for detecting venous air embolism at a level as low as 0.05 ml of air per kg compared to 0.25 ml/kg for the PAP and EtCO2 responses.

Animals↗
PubMed1979

Subdural tension pneumocephalus. Report of two cases.

Two patients developed subdural tension pneumocephalus after undergoing posterior fossa surgery performed in the sitting position. The mechanism for entry of air into the intracranial compartment is analogous to the entry of air into an inverted soda-pop bottle. As the fluid pours out, air bubbles to the top of the container. We have thus referred to this as the "inverted pop-bottle syndrome." Computerized tomography provided prompt diagnosis and confirmed brain displacement. Twist-drill aspiration of the air resulted in improvement in both patients, although one patient subsequently died from an intracerebellar hemorrhage. Tension pneumocephalus appears to be another potential complication of posterior fossa surgery in the sitting position. This condition is easily diagnosed and treated, and should be considered whenever a patient fails to recover as expected following posterior fossa surgery.

Aged↗