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Biomedical subjects

R W Arnold

Publications and source records attributed to R W Arnold.

At least 37 records · Page 2Linked to original sources
PubMed1985

Extremes in human breath hold, facial immersion bradycardia.

Although the average human response to apneic facial immersion in ice water is a reduction in heart rate from 70 to 45 beats/min, a small proportion of healthy subjects develop diving bradycardia to less than 20 beats/min. Twenty-seven healthy subjects performed resting, seated, 30-s mid-inspiratory breath hold, facial immersion in a basin of water. Heart rate dropped more when the water temperature was 1 degree C than at 24 degrees C. Five subjects developed asymptomatic diving bradycardia to less than 15 beats/min. One physically active individual consistently had dive heart rates as low as 5.6 beats/min.

Adult↗
PubMed1981

Spinal analgesia using bupivacaine 0.5% plain. Variation in the extent of the block with patient age.

Bupivacaine 0.5% plain solution was used to produce spinal analgesia on 63 occasions. In 33 patients a fixed dose of 4 ml injected at the L2/3 interspace at 0.5 ml/second produced an extent of analgesia which was directly related to patient age (p les than 0.005). The latency was 17.3 minutes (SD 8 . 4) and duration of action was 286 minutes (SD 62). A second group receiving only 1 ml of solution had a much shorter duration of action (mean 154 minutes, SD 30). In 90% of patients the analgesia obtained was fully sufficient for surgery to be performed and no form of analgesic supplementation was given. On two occasions no analgesia occurred at all. Bupivacaine 0.5% plain proved to be an effective agent for subarachnoid block. The extent of analgesia was, however, poorly predictable, and even with low doses unacceptably high level of block were sometimes achieved.

Adult↗
PubMed1975

Comparison of 99mTc complexes for renal imaging.

The distribution of 17 different agents for renal imaging was compared in the rabbit by organ radioassay at 1 hr. Similarly, 99mTc complexes of iron-ascorbate, glucoheptonate (GHA) and 2,3-dimercaptosuccinic acid (DMS), and 203Hg-chlormerodrin were compared in the dog. The distribution of 99mTc-GHA and DMS was assessed in the human by blood and urinary clearance, external renal measurements, and scintillation camera imaging, and compared with older renal radiopharmaceuticals. Radiation dose estimates, based chiefly on human data, were calculated. Technetium-99m-DMS reaches a high concentration in the renal cortex and its urinary excretion rate and blood clearance are slow. It is excellent for imaging the renal parenchyma without activity in pelvocalyceal collecting system. However, it readily oxidizes and must be used within 30 min of preparation. The biologic distribution of 99mTc-GHA is similar to gluconate and iron-ascorbate complex. Its renal concentration is not as great as that of DMS but its blood and urinary clearances are much faster, resulting in lower radiation doses to most organs. Early camera images with this agent usually demonstrate both the renal parenchyma and collecting system. In later images, ther is excellent demonstration of the parenchyma alone, superior to that obtained with 99mTc-Sn-DTPA. It is a very stable complex and may be used for at least 5 hr after preparation. All radioactive renal agents examined to date have a significant concentration in the liver, making an accurate quantitative comparison between the two kidneys difficult.

Albumins↗
PubMedDate not supplied

Corneal crystals, myopathy and nephropathy: a new syndrome?

A case with ocular (corneal crystals and retinal pigment epithelial mottling), muscle (oropharyngeal and hand weakness and atrophy), and renal (proteinuria and hypertension) abnormalities is described. We believe that this represents a previously unrecognized syndrome.

Adolescent↗
PubMedDate not supplied

Acquired divergent strabismus: presumed metastatic gastric carcinoma to the medial rectus muscle.

A patient with rapidly progressive metastatic gastric carcinoma developed diplopia and diminished adduction of the right eye. The right medial rectus muscle belly was enlarged, as shown by computed tomography. This case is unusual, because gastric carcinoma comprises only 1% of orbital metastases and less than 5% of all orbital metastases localize to extraocular muscle.

Carcinoma↗
PubMedDate not supplied

Susceptibility to retinopathy of prematurity in Alaskan Natives.

Threshold retinopathy of prematurity occurred in 11 of 34 Alaskan natives compared with 10 of 93 non-natives. Natives constitute 16% of the state population. This significant Alaskan native preponderance was not explained by differences in prenatal or intensive care unit morbidity except that the intervals from birth to extubation and birth to cryotherapy were shorter for natives.

Alaska↗
PubMedDate not supplied

Bilateral monocanalicular silicone loop: predictable home removal of nasolacrimal stents.

Premature dislocation, a potential disadvantage of conventional, unilateral silicone intubation for lacrimal disease, can be alleviated with a firmly-tied, bilateral, superior canaliculus intubation. Since the looped silicone stent can be removed easily at home by parents, this technique is particularly beneficial for remote patients for whom postoperative, clinic removal is a financial burden.

Dacryocystorhinostomy↗
PubMedDate not supplied

Palinopsia with bacterial brain abscess and Noonan syndrome.

Though positive visual symptoms can be psychological in nature, or can result from a perceptive or anxious patients recognizing optical principals in the eye itself, this case illustrates how a thorough history is required to delineate those rarer signs which accompany serious macular or neuro-ophthalmic pathology.

Adult↗
PubMedDate not supplied

The human heart rate response profiles to five vagal maneuvers.

Healthy teens and adults performed four vagotonic maneuvers. A large series of strabismus surgery patients had deliberately quantified tension on extraocular rectus muscles during general anesthesia. The mean bradycardia was greatest for diving response (apneic facial exposure to cold) and Valsalva maneuver and least for pressure on the globe and carotid sinus massage. Bradycardia occurred for every subject for the non-surgical maneuvers, however, extraocular muscle tension frequently caused no change in heart rate or even tachycardia. The inter-subject variance in percent heart rate change was greatest for surgical oculocardiac reflex. Of the rectus muscles, the inferior caused the most bradycardia while the lateral caused the least. The percent oculocardiac reflex was not age dependent. Occasional patients demonstrated profound bradycardia with strabismus surgery. Of these maneuvers, diving response has theoretical advantage in treating paroxysmal atrial tachycardia. The human cardiac vagal efferent was stimulated by several carefully controlled maneuvers resulting in wide inter-maneuver differences in bradycardia magnitude. The greatest intra-maneuver variability occurred with surgical oculocardiac reflex.

Adolescent↗
PubMedDate not supplied

The Alaska Blind Child Discovery project: rationale, methods and results of 4000 screenings.

BACKGROUND: Photoscreening allows lay persons to adapt the Enhanced Brückner Test to preschoolers in an attempt to identify refractive amblyopia. The Alaska Blind Child Discovery (ABCD) project is charitably funded and administered. METHODS: MTI photoscreening was offered to children in rural and urban communities in southern Alaska from 1996 through June 1999. Parents answered questions concerning the child's health, family ocular history and whether the child had any eye "Warning Signs." The MTI images were interpreted by two eye doctors using a modification in MTI published guidelines. RESULTS: Out of 4000 screenings performed on 3930 children, there was an overall "not normal" interpretation of 9% and an inconclusive rate of 1%. The mean S.D. age was 3.9 2 years. Only 6% had had a prior eye exam. The average number of Polaroid pictures per screening was 1.16. Follow-up data on "not normal" results was obtained on just over 50%. The positive predictive value during the first two years was 77% but improved to 92% from 1998-1999. Affirmative answers to the questions concerning previous eye exam, child's health, siblings eye health and positive "Warning Signs" were significantly associated with "not normal" interpretations but affirmative answers about eye health of mother, father and relatives were not. Community penetrance of photoscreening to the target age-group ranged from only 5% for Anchorage to almost 100% for the Bristol Bay public health nurses. Five percent of parents of "positive" results surveyed would not have recommended screening for their friends. Equipment functioned dependably even in remote Alaska. CONCLUSION: Charitable volunteer Polaroid photoscreening detected amblyopia and significant pediatric eye disease in over 300 children during the first 3.5 years of ABCD.

Alaska↗
PubMedDate not supplied

The detection of congenital glaucoma by photoscreen interpretation.

Photoscreening is designed to detect abnormalities in children's eye, particularly abnormal refractive errors, which can lead to amblyopia. An Alaska Bind Child Discovery MTI Polaroid photoscreen in one girl resulted in diagnosis and treatment of congenital glaucoma. Patients with known pediatric eye disease underwent photoscreening. Subtle non-refractive changes in photoscreen images may reveal eye disease even more serious than amblyopia. We suggest that human or computer interpretation of photoscreening images, particularly when retained, be done conscientiously with respect to the refractive state and alignment of the eyes, but also regarding other potentially serious ocular pathology.

Child, Preschool↗
PubMedDate not supplied

An emergency corneal ulcer kit.

Bacterial corneal ulcer is a potentially blinding emergency which should ideally be treated by an ophthalmologist aided by slit lamp biomicroscopy, microbial stain and cultures, and then selected fortified topical antibiotics. We suggest an emergency corneal ulcer kit for the initial treatment of patients with suspected corneal ulcers who are unable to readily travel to an ophthalmologist.

Aminoglycosides↗