Biomedical subjects

J Stephanazzi

Publications and source records attributed to J Stephanazzi.

6 recordsLinked to original sources

PubMed1999

Effects of low flow on pulmonary vascular flow-pressure curves and pulmonary vascular impedance.

OBJECTIVE: Flow-pressure curves and vascular impedance are commonly used to investigate pulmonary circulation, but they may be affected at low flow by reflex neurohumoral activation. We therefore investigated the mechanical effects and the reflex effects of decreased flow on pulmonary vascular resistance and impedance. METHODS: In ten anaesthetized dogs, we compared flow-pressure curves generated in less than 10 s to prevent sympathetic activation (fast curves), or generated over 20-30 min to allow neurohumoral equilibration (slow curves), in hyperoxia (inspired oxygen, 40%) and in hypoxia (inspired oxygen, 10%), before and after adrenergic blockade by phentolamine and propranolol. Resistance was assessed from the flow-pressure relationship. Impedance was computed from instantaneous flow and pressure obtained with an ultrasonic flowmeter and a micromanometer-tipped catheter. RESULTS: At baseline, fast flow-pressure curves were steeper and had a lower pressure intercept. Transient low flow did not affect heart rate or pulmonary arterial elastance. Sustained low flow increased heart rate, resistance and elastance, suggesting baroreceptor-induced sympathetic stimulation. After adrenergic blockade, no difference persisted between effects of transient and sustained low flow. In hypoxia, slow and fast flow-pressure curves were similar. Hypoxia increased heart rate and resistance but did not decrease elastance, suggesting chemoreceptor-induced sympathetic stimulation. In hypoxia, differences between transient and sustained low flow were no longer significant, and were completely suppressed by adrenergic blockade. In two additional dogs, epinephrine infusion increased pulmonary vascular resistance and elastance. CONCLUSIONS: We conclude that (1) compared to transient low flow, sustained low flow is associated with increases in distal resistance and proximal elastance due to sympathetic stimulation and (2) these differences between the effects of transient and sustained low flow do not persist in hypoxia, because of an already present chemoreceptor-induced sympathetic stimulation.

Adrenergic alpha-Antagonists↗

PubMed1999

Initial general management and surgery of six extensively burned children treated with cultured epidermal autografts.

PURPOSE: The aim of this study was to document the surgical and intensive care methods used in six extensively burned children (EBC), ie, total body surface area (TBSA) burned over 70% or TBSA with deep burns over 60%, treated with cultured epidermal autografts (CEA). METHODS: Six EBC, with a mean age of 7.5 years (range, 2.5 to 12) received CEA. Their mean TBSA burned was 82% (range, 70-94) with 74% (range, 60-90) of TBSA with deep burns. All sustained flame burns and inhalation injuries. RESULTS: The survival rate was six of six. The average initial and final engraftment rates of CEA were, respectively, 79% (range, 70 to 95) and 84% (range, 72 to 100). CEA definitively covered 45% (range, 18 to 57) of TBSA for a mean cost per child of $80,000 (range, 55,000 to 110,000). CONCLUSION: Even if CEA are expensive, such engraftment rates and survival ratio results make them an excellent alternative wound covering method for EBC when donor sites for widely meshed autografts are exhausted.

Animals↗

PubMed1999

[Ambulatory treatment of burns in children].

A majority of burns in children may have an ambulatory management for which the paediatrician has an important role. He must assess the severity of the burn by quoting extent, depth and localization of the burn injuries and then send the most severe to a specialized burn centre. The circumstances and the social situation are important in the decision of either hospitalization or ambulatory care, remembering that the burn may correspond to child abuse. The treatment consists of initially refreshing the burn to limit the extension, then washing the lesions using topical antiseptic soap, finally applying standard silver sulfadiazine cream. Local care is accomplished daily the first few days, then every three days to follow the healing and to keep a watch on possible complications such as infections or failure to heal, which must be treated in burn units. Pain relief treatment is an important part of the management.

Acetaminophen↗

PubMed1997

[Right ventricular function: physiological and physiopathological features].

Sinus and conus constitute the two cavities of the right ventricle. They are anatomically and functionally different. The sinus is a flow-generator and the conus a pressure-regulator. The coronary circulation of the right ventricle is provided by the right coronary artery and the left anterior descending artery. The right ventricle is perfused during systole and diastole. When oxygen demand increases, coronary arteries dilate and oxygen extraction rises. As for the left ventricle, right ventricular performance depends upon heart rate, rhythm, contractility and loading conditions. Ventricular interactions are very important for right ventricular function. Loading conditions and contractility of the left ventricle are of major significance for right ventricular performance. For the right ventricle, the end of the ejection is different from the end of the active contraction. The time between them allows to achieve ventricular emptying. This duration is linked to afterload. Presently, it is impossible to accurately and simply assess these conditions. Pressure and volume overloadings result in right ventricular failure. They are responsible for ventricular dilation and ischaemia with a decrease in cardiac output, generating a vicious circle. Treatment includes the removal of the cause, and the maintenance of systemic arterial pressure and biventricular contractility. It is difficult to assess the effects of intravenous vasodilators on right ventricular afterload.

Coronary Circulation↗

PubMed1997

[Objectives, results and future prospects of burn treatment in 1997].

When burn injuries to the skin are extensive, delays in wound closure contribute to multiple organ failure because the availability of donor sites does not allow early and permanent coverage of excised wounds. From 1991 to 1996, 30 patients with a mean burn size of 78% total body surface area (65% full-thickness) underwent skin grafting with autologous cultured epidermis (AEC) performed in the labs of Genzyme Tissue Repair Company. Twenty three were adults and seven children under 15 (mean age 29, range 2.5 to 70); 27 suffered inhalation injury; 3 presented with multiple trauma and 2 with blast injury. As soon as possible wound beds were excised and temporarily covered with allografts or with sandwich or meshed autografts; the mean surface covered with autografts was 28 +/- 12%. Keratinocytes grafts were applied to a mean of 37 +/- 16.5%, an average of 210 grafts of 25 to 30 cm2. Three patients died respectively at day 67, 81 and 90. At time of gaze backing removal, the mean percentage of culture engraftment was 69% (range 25 to 95); this engraftment was higher for children (74%) and very bad above 60 (25%). The mean length of hospitalisation was 114 +/- 30 days. The definitive coverage by AEC was evaluated through the percentage of secondary autografted area: 10 +/- 9.5% (range 0 to 46). The average cost by patient was 98,500$ or 16$ by cm2 of culture. The weakness of epithelialisation makes essential a dermal support to the keratinocytes cultures, allodermis is now currently used, perhaps the new skin substitutes will give the ideal missing piece.

Adolescent↗

PubMed1993

[Subxiphoid pericardiostomy and pericardioscopy. Value and indications apropos of a series of 25 cases].

An experience of 25 subxiphoid pericardial windows with pericardioscopy in eleven cases is reviewed and presented. The operative indications in pericardial effusions result from hemodynamic compromise or from the need for etiologic criteria. Validated in its technical simplicity, its safety, its etiologic findings, its efficacy on immediate and delayed no recurrence of pericardial effusion, the low rate of late constrictive changes, this operative procedure is worth listing in the therapeutic know-how of a general surgeon. Indications in patients with suspected traumatic pericardial tamponade by chest wound are related.

Adult↗