Search PubMed⌕ Search

Biomedical subjects

M S Albin

Publications and source records attributed to M S Albin.

At least 37 records · Page 2Linked to original sources
PubMed1989

Incidence of venous air embolism during cesarean section is unchanged by the use of a 5 to 10 degree head-up tilt.

One hundred healthy parturients were divided at random into two demographically similar groups and were positioned for cesarean section either horizontally or flexed 5 to 10 degrees head up, with a 15 degrees lateral tilt. A Doppler ultrasound transducer was positioned over the fourth intercostal space parasternally. Initially, two patients received spinal, three general, and 95 epidural anesthesia. Two patients subsequently needed general for failed epidural anesthesia. Changes in Doppler heart tones (greater than 15 sec duration) indicative of venous air embolism (VAE) were identified 15 times in 11 patients--seven in supine and four in head-up patients (no statistically significant difference). Six awake patients (three horizontal, three head-up) developed chest tightness or pain during surgery, but only one episode correlated with VAE. No patient developed breathlessness. Moderate hypotension (greater than 10% decrease in systolic arterial pressure [SAP]) occurred in seven of 11 (63.6%) patients with, and in 26 (29.2%) of 89 patients without, VAE (P less than 0.001). More severe hypotension (SAP less than 90 mm Hg) due to bleeding occurred once. We conclude that a modest (5-10 degrees) head-up position does not influence the occurrence of VAE in patients having cesarean section. An 11% incidence of clinically insignificant VAE, although low, is still worrisome, as even small air bubbles in the circulation are potentially harmful, especially if the foramen ovale is patent. VAE during cesarean section should be anticipated and the anesthetic management planned accordingly.

Adult↗
PubMed1987

Intracranial pressure measurement from the anterior fontanelle utilizing a pneumoelectronic switch.

A newly developed infant cranial model shows that accurate, reproducible, and noninvasive measurements of intracranial pressure (ICP) can be made from the anterior fontanelle when fontanelle pressure is referenced from the bony margins adjacent to the fontanelle opening. Also, this model provides insight into the elastic properties of the fontanelle membrane and the pressure/volume relationships governing ICP transmission through the fontanelle window. An anterior fontanelle pressure monitor design based on data from the infant cranial model was used to monitor anterior fontanelle pressure in three infants with elevated ICP and previously inserted ventricular catheters. Measured anterior fontanelle pressure was highly correlated to ICP (r = 0.962) with high reproducibility after blind application and reapplication. Base line adjustment and in situ recalibration were easily achieved, with the monitor showing no sensitivity to patient movement and excellent frequency response.

Humans↗
PubMed1987

Epidemiology, physiopathology, and experimental therapeutics of acute spinal cord injury.

This article analyzes the epidemiological factors relating to acute spinal cord injury. It also delineates the anatomical and rheological characteristics of the spinal cord and denotes the latest concepts in autoregulation of spinal cord blood flow. The physiopathology of spinal cord injury is examined in terms of existing animal models, responses of the white and grey matter, and biochemical and biomechanical correlates. Experimental and clinical therapeutic modalities ranging from hypothermia to opioid antagonists, and adrenergic blockers to free radical scavengers are evaluated.

Acute Disease↗
PubMed1986

An experimental study of craniocerebral trauma during ethanol intoxication.

This study evaluates the effects of ethanol (blood levels of 200 mg/dl for one hour) and dimethyl sulfoxide (DMSO) on cerebral lesion volumes after pressure-induced focal ischemia during normotension and induced hypotension in the canine. This experimental design simulates the situation where an individual imbibes two to four alcoholic drinks over a one-hour period, then drives a motor vehicle, and suffers a head injury either without significant blood loss or where the cerebral perfusion pressure is reduced to the lower limits of autoregulation (mean arterial pressure of 50 mm Hg). Ethanol was shown to increase brain lesion volumes in both the normotensive (4.5 +/- 0.7 cm3) and hypotensive (14.9 +/- 2.2 cm3) groups when compared to controls (0.8 +/- 0.3 and 2.9 +/- 0.4 cm3, respectively). DMSO markedly attenuated this response in the normotensive and hypotensive ethanol groups. It is thought that the intermediate metabolites of ethanol provide a large source of hydroxyl-free radicals in the presence of neuronal tissue damage and that these free radicals are effectively scavenged by DMSO.

Alcoholic Intoxication↗
PubMed1985

Brain and lungs at risk after cervical spinal cord transection: intracranial pressure, brain water, blood-brain barrier permeability, cerebral blood flow, and extravascular lung water changes.

The early physiopathologic responses to transection of the cervical spinal cord (C-4) were studied in the experimental animal. After transection, increases were seen in the mean arterial pressure, pulmonary capillary wedge pressure, intracranial pressure, brain water, blood--brain barrier permeability, and extravascular lung water with a marked decrease occurring in cerebral blood flow. Pretreatment with an alpha-adrenergic blocker, phentolamine (Regitine Ciba-Geigy Corp.), followed by transection blocked the rise in mean arterial blood pressure and pulmonary capillary wedge pressure but did not affect the increases in intracranial pressure, brain water, blood--brain barrier permeability, and extravascular lung water and decreases in cerebral blood flow. Transection of the cervical spinal cord initiates a complex series of events involving intracranial compliance and pulmonary permeability, placing both brain and lungs at risk.

Animals↗
PubMed1985

Spinal cord and cerebral blood flow responses to subarachnoid injection of local anesthetics with and without epinephrine.

Subarachnoid anesthesia with lidocaine, mepivacaine, or tetracaine with and without added epinephrine (1:100 000) produced no demonstrable changes in average cerebral (CBF) or segmental spinal cord blood flow (SCBF) in 38 cats anesthetized with pentobarbital. Blood flow was measured by the injection of radioactive microspheres. Seven groups of cats received either lidocaine 15 mg, lidocaine 15 mg with epinephrine, mepivacaine 10 mg, mepivacaine 10 mg with epinephrine, tetracaine 5 mg, tetracaine 5 mg with epinephrine, or saline with epinephrine 1:100 000. Mean arterial pressure (MAP) decreased significantly (P less than 0.05) in Groups I-VI. Added epinephrine had no effect on the decrease in MAP. Amplitude of the somatosensory cortical evoked response decreased significantly in Groups I-VI, but did not change from control in Group VII. No significant change in CBF or SCBF was demonstrated in any group at any time. Plasma lidocaine and mepivacaine levels were significantly less at 5 min after subarachnoid injection in the groups receiving epinephrine compared to those not receiving epinephrine (P less than 0.05). The data appear to support the hypothesis of a vasoconstrictive reduction in systemic absorption of intrathecal local anesthetics, but suggest that significant segmental spinal cord ischemia does not occur. Maintenance of total flow in the face of a decrease in MAP suggests that autoregulation in brain and spinal cord may be maintained. Changes in regional SCBF or CBF may have been present but were not examined in this study. Further studies of brain and spinal cord blood flow dynamics, regional flow changes, and regulation of flow after intrathecal agents are necessary.

Anesthesia, Spinal↗
PubMed1985

Acute cervical spinal injury.

The epidemiology, biomechanics, physiopathology, emergency medical systems, diagnostic criteria, and therapy related to acute cervical spinal cord injury are discussed in this article.

Acute Disease↗
PubMed1984

Venous air embolism in a child undergoing posterior fossa craniotomy: a case report.

The incidence of venous air embolism in children undergoing neurosurgical procedures in the sitting position may be as high as 33 per cent. It may be more serious in children because smaller total volumes of air can produce serious physiologic disturbances or fatalities, and the risk of systemic air embolism through a patent foramen ovale or patent ductus arteriosus may be greater than in adults. The case of a six-year-old child who sustained four separate episodes of air embolism while undergoing posterior fossa exploration is presented. Early episodes were well tolerated, but later episodes produced clinical instability. A total of 11 cc of air was recovered from an indwelling right atrial catheter, and the patient recovered uneventfully. This case report illustrates the physiologic changes produced by venous air embolism and reviews the importance of adequate monitoring techniques and early treatment.

Astrocytoma↗
PubMed1984

Verification of global cerebral ischaemia using scintigraphy.

The induction of global cerebral ischaemia in laboratory animals is difficult to accomplish and has been even more difficult to verify. Most reported verification methods suffer from lack of sensitivity or from being traumatic and highly invasive. We describe a non-traumatic global cerebral ischaemia verification technique which is quantitative, simple, and highly sensitive. Radioactive technetium-99m pertechnetate is injected intravenously during the ischaemic phase of an experiment and the appearance of radioactivity within the animal's head is quantitated using a gamma camera and nuclear medicine computer. Radioactivity levels below the visual perception threshold are readily measured, thus providing a high degree of confidence in assessing the partial or total nature of cerebral ischaemia.

Animals↗