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Biomedical subjects

L Vachon

Publications and source records attributed to L Vachon.

47 records · Page 3Linked to original sources

Indications for routine cranial ultrasound scanning in the nursery.

Cranial ultrasonography provides important diagnostic information in neonates. The clinical indications for routine scanning in newborn infants, however, are not established. The purpose of this study is to determine the incidence of cranial pathology detectable by ultrasound in certain clinical states in the neonate. We reviewed the scans and clinical states of 1,031 neonates born between April 1981 and February 1985. We found term infants with dysmorphic features to have the highest incidence of neuropathology (46%), followed by term infants born with macrocephaly (33%), preterm infants (26%), term infants with seizures (26%), and term infants with 1- and 5-min Apgar scores less than 7 (13%). We found a lower incidence (less than 5%) of abnormal CNS findings in the nonasphyxiated term infants with split sutures, cephalohematoma, abnormal neurologic examination, and idiopathic jitteriness. Based on our findings we have concluded that it is important to scan routinely all premature infants, term infants with dysmorphic features, macrocephaly, or seizure disorder, and infants with 1- and 5-min Apgar scores less than 7; routine scanning of term infants with split sutures, cephalohematoma, abnormal neurological examination, or idiopathic jitteriness is not indicated.

Apgar Score↗

Development of noninvasive and quantitative methodologies for the assessment of chronic ulcers and scars in humans.

Chronic ulcers are a significant and common cause of morbidity and mortality worldwide. They disrupt the epidermis and dermis, resulting in a loss of barrier function. Keloids and hypertrophic scars (benign cutaneous tumors) represent an abnormal healing response. These fibroproliferative disorders are characterized by an overabundance of collagen and accumulation of extracellular matrix due to an imbalance between synthesis and degradation, culminating in excessive scarring. The objectives of this study were to evaluate and compare noninvasive biophysical methods for the measurement of outstanding quantitative parameters of scars and chronic ulcers, and to establish correlations between the parameters measured and the results of conventional subjective clinical evaluations. The development of new technologies, based on ultrasonography and laser Doppler, makes possible new dermatological evaluation methods. Fifteen patients (6 females and 9 males) with 15 chronic ulcers (4 diabetic ulcers, 10 venous ulcers and 1 pressure ulcer) and 30 patients (19 females and 11 males) with 30 scars (25 hypertrophic and 5 keloids) were included in this study. Clinical evaluation was performed by a dermatologist, an aesthetic surgeon and an endocrinologist. Biophysical measurements were used to assess local blood flow by laser Doppler flowmetry (Moor DRT4), thickness and echogenicity by high frequency ultrasonography (20 MHz, Dermascan C) and ulcer linear dimensions by image analysis. Our results show that blood flow within the ulcers and scars was higher than within normal skin. Also, skin thickness of chronic ulcers was decreased when compared to normal skin; the thickness of hypertrophic scars, but not of keloids, was increased in comparison to normal skin, and presented the possibility of measuring wound and scar surfaces with precision. In summary, this pilot study established the feasibility of measuring various biophysical parameters and adapted their potential utility to research on wounds.

Adult↗

Long-term external catheter biliary drainage for recurrent cholangitis after hepatoportoenterostomy.

An infant developed relapsing cholangitis following hepatoportoenterostomy for extrahepatic biliary atresia. The source of recurrent infection seemed to be an intrahepatic cyst. Short-term percutaneous cholangio-drainage of such cysts, resulting in eradication of infection, has been described. However, this child required continuous drainage because of persistence of infection in the reaccumulating bile. The insertion of a nephrostomy catheter and use of enterostomal appliances have allowed continuous uneventful biliary drainage for 15 months.

Biliary Tract Diseases↗

Visceral learning in asthma.

The hypothesis of visceral learning has opened a new avenue in the search for a pathway between psychosocial stimuli and physiological changes. To apply this approach to asthma required a technique for the measurement of the airways' patency, which could be interfaced with the strategy of visceral learning. The method of forced oscillations was shown to correlate highly with whole body plethysmography. The rapid output of the instrument was used on line to control a visual reinforcement signal. Forty-six mild asthmatics, blind to the effect sought in order to minimize the role of suggestion, were tested in a series of evolving experiments. In the first series, two groups of subjects (N=15,13) were able, with this sensory feedback, to decrease (p less than 0.01) their total respiratory resistance; subsequently a smaller group of subjects (N=5), who received reinforcement signals unrelated to the state of their airways, showed no such change. Similar results were obtained in the second series of tests; in A-B-B-A order, the subjects (N=13) received either contingent or noncontingent reinforcement; furthermore, the reinforcement was available only if their lung volume was within the range observed during baseline.

Adolescent↗