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Biomedical subjects

M F Hellot

Publications and source records attributed to M F Hellot.

52 records · Page 3Linked to original sources
PubMed1978

Pulmonary gas exchange, diffusing capacity in natives and newcomers at high altitude.

At high altitude, in resting conditions, no differences have been observed between High Altitude Natives (HAN) and acclimatized Sea Level Natives (SLN) in AaDO2, aADCO2 or venous admixture. In acclimatized SLN, AaDO2 is smaller than at sea level because of: (1) The minor effect on arterial oxygenation of the probably constant venous admixture. (2) The reduction of VA/Q inequality as shown by a smaller aADCO2. In HAN, DLCO is greater than in SLN; the contribution of DM or VC in this difference remains unsettled, mainly because of the difficulties of measurement of DM and VC in HAN suddenly exposed to acute hyperoxia. In SLN, in acute hypoxia, DLCO increased transitorily. Asynchronous mechanisms of adaptation to high altitude are evoked.

Acclimatization↗
PubMed1978

[Influence of blood hemoglobin concentration on pulmonary diffusing capacity in man].

CO transfer factor for lungs (TLCO) was measured by a steady state method in 83 subjects (haemoglobin concentration from 60 to 270 g.l-1). TLCO was related with height (T), age (A) and with logarithm of haemoglobin concentration for a non negligeable part : TLCO = 15.45 log Hb + 33.1 T -- 0.06 A -- 51.8. The interest of this relation is discussed.

Adult↗
PubMed1975

[Changes in ventilatory patterns before and after vagotomy in rabbits].

Ventilatory pattern have been investigated during rebreathing experiments. Before vagotomy, a linear relation has been found between increasing tidal volume and decreasing inspiratory and expiratory durations. After vagotomy, these relations existed but expiratory duration remained almost constant.

Animals↗
PubMedDate not supplied

Comparison of the effects of continuous and cyclic nocturnal parenteral nutrition on energy expenditure and protein metabolism.

Although cyclic nocturnal total parenteral nutrition is a widely used technique, its metabolic consequences have not been fully investigated. During two successive 7-day periods, 12 patients received randomly either standard continuous (infusion 24 hr/day) or cyclic (infusion between 5 pm and 9 am) total parenteral nutrition (TPN). Calorie and nitrogen intakes were identical during both periods. Energy expenditure was investigated by indirect calorimetry and showed practically no difference between continuous standard (1383 +/- 41 kcal/day-1) and cyclic total parenteral nutrition (1428 +/- 46 kcal/day-1). However, in the cyclic regimen, when compared with continuous infusion, energy expenditure was higher between 5 pm and 9 am and lower between 9 am and 5 pm. At the end of the noninfusion period, the 24-hr profile of the nonprotein respiratory quotient showed a slight decrease in patients receiving the cyclic infusion, in contrast with the stability of the quotient in the standard regimen. However, the nitrogen balance and variations in nutritional status did not differ significantly. In conclusion cyclic TPN is efficient for achieving a positive energy and nitrogen balance and in addition it induces a metabolic profile closer to physiological conditions.

Adult↗
PubMedDate not supplied

[Reference values of pulmonary compliance (author's transl)].

Pulmonary compliance has been measured, using a classical method in 156 healthy subjects aged between 18 and 74 years, breathing spontaneously. Pulmonary compliance (ml-cmH2O-1) was related to height in meters (H) by an allometric relationship such as C = aHb. As b was not significantly different from three, than C/H3 ratio was studied. This ratio was not dependent on age so that it was possible to establish that, in men, C (ml-cmH2O-1) = 36.6 H3 (m) and in women, C (ml-cmH2O-1) = 33.3 H3 (m). These two relationships were significantly different. From these relationships and from reference values of pulmonary volumes, specific pulmonary compliance could be calculated but since confidence limits were very wide, their utilization is limited. Furthermore, it is difficult to apply specific compliance in respiratory impairment.

Adolescent↗
PubMedDate not supplied

[Evaluation of the diagnosis of pigmented tumors of the skin and factors leading to a decision to excise. Dermatologists of the Postgraduate Association of Haute-Normandie].

INTRODUCTION: The necessity of excising melanomas characterized by a slight thickness at an early stage, leads dermatologists to remove pigmented lesions which do not correspond to melanomas. The aims of this study were: a) to prospectively assess the accuracy of melanoma diagnosis, b) to quantify the number of excisions performed according to the degree of melanoma suspicion, c) to determine the specific clinical sign or signs of relevant diagnostic value. PATIENTS AND METHODS: This study was conducted prospectively from January 1996 to August 1997 by dermatologists in private practice and dermatologists from a University Hospital staff. When it was decided to excise a pigmented lesion, a form was filled out choosing the most appropriate clinical diagnosis, the degree of melanoma suspicion, and clinical signs which lead to surgery. Based on histological findings as the reference, the sensitivity, specificity, accuracy of melanoma diagnosis and the kappa test that evaluates the concordance between clinical and histological diagnosis, were performed. The diagnostic value of clinical signs was assessed by variance analysis. RESULTS: Of the 353 excised lesions, 38 (10.7 p. 100) were identified as melanoma on histologic examination. The sensitivity, the specificity and diagnostic accuracy were: 79 p. 100, 94 p. 100 and 53 p. 100 respectively. The kappa test concordance between clinical and histological diagnosis was 0.66. Two hundred and two lesions (57 p. 100) were excised even though the clinical suspicion of melanoma was poorly considered. Only one of these 202 lesions was identified histologically as a true melanoma. Thirty seven (24.5 p. 100) of the 151 remaining excised lesions with an "average" or "strong" suspicion were true melanomas. The clinical signs considered, alone or associated, had a poor predictive positive value (< 38 p. 100). An analytical approach performed with a logistic model permitted the identification of two associated signs suggesting a best diagnostic value. DISCUSSION: This is the only study, to our knowledge, reported in the literature which prospectively assesses the sensitivity, specificity and concordance between clinical and histological diagnosis of melanoma. Results were considered from average to good. The originality of this study was to assess the number of pigmented lesions excised according to the degree of melanoma suspicion, suggesting the possibility of reducing the number of nevi removed when the melanoma risk was considered clinically poor. Finally, this study emphasizes the limits of clinical semiology and the need for future diagnostic methods in the assessment of melanoma.

Adult↗
PubMedDate not supplied

The value of clinical characteristics from a standard questionnaire to discriminate cardiac from neurological syncope in the elderly.

OBJECTIVES: To identify signs and symptoms to differentiate cardiac from neurological syncope in patients over 70 using a standardized questionnaire. DESIGN: Prospective cohort study. SETTING: Five short-stay units in a French university hospital. PARTICIPANTS: One hundred thirty-one in-patients with syncope aged 70 and older. MEASUREMENTS: Patients were interviewed about the signs and symptoms that had been present before, during or after syncope. When possible, a witness who had been present during syncope was also interviewed to compare theirs and the patients' answers. The sensitivity and specificity of 35 questions were calculated among 3 groups defined according to the cause of syncope: cardiac (n = 58), neurological (n = 31) and syncope of unknown origin (n = 42). Statistical analyses were performed to determine discriminating signs and symptoms among the causes and crude agreement was calculated for answers from patients and witnesses. RESULTS: Only 8 and 3 of 35 questions had a sensitivity of at least 0.5 for cardiac and neurological causes respectively. A feeling of impending syncope, thoracic oppression, recall of events preceding syncope and a history of arrhythmia were independently and significantly discriminant among groups. Recall of events preceding syncope (Odds Ratio (OR) = 7.5; 95% confidence interval (CI) = 2.2-25.3) and a personal history of arrhythmia (OR = 4.8; 95% CI = 1.6-14.2) were discriminant between cardiac and neurological causes suggesting mostly a cardiac cause. Agreement between patients and witnesses was only found for questions on the patient's medical history or the circumstances surrounding the onset of syncope. CONCLUSIONS: Recall of events preceding syncope and a history of arrhythmia are strongly suggestive of a cardiac rather than a neurological cause of syncope. Interviews of witnesses are not helpful in suggesting a cause for syncope.

Aged↗
PubMedDate not supplied

[Contribution of functional respiratory exploration to the etiological study of spontaneous pneumothorax (author's transl)].

In order to specify the etiology of primary spontaneous pneumothorax, lung function studies were performed on 14 patients after one pneumothorax without any set. All the patients showed at least one disturbance. 4 patients revealed a decrease of maximal expiratory flow, a decrease of lung recoil, a hyperinflation and a reduction of lung transfer factor. In 6 other patients decrease of elasticity, hyperinflation and decrease of transfer factor were observed, but maximal expiratory flow was normal. One patient showed an obstructive syndrome. It is difficult indeed to connect physiological findings and anatomy, but these disturbances are often observed in lung dystrophy. Perhaps, these disturbances are in connexion with the proximity of accident; so, a long term study is required in order to know the etiopathogeny of this disease.

Adolescent↗