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Biomedical subjects

A M Cros

Publications and source records attributed to A M Cros.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Value of the monitoring of curarisation during prolonged mivacurium induced neuromuscular block].

A case of neuromuscular blockade of about 200 min of duration, in a 9-year-old boy from mivacurium 0.15 mg.kg-1 is reported. The diagnosis was delayed, after onset of the first signs of recovery, due to the lack of monitoring of neuromuscular transmission. The neuromuscular blockade was reversed with neostigmine 0.04 mg.kg-1. Complete reversal required fifty minutes. The presence of an abnormal genetic variant of pseudocholinesterases was demonstrated by the measurements of pseudocholinesterase activity and dibucaine number. The importance of monitoring of neuromuscular transmission for diagnosis and treatment of mivacurium-induced neuromuscular blockade is underlined.

Anesthesia Recovery Period↗
PubMed1994

Is proximal airway pressure a good reflection of peripheral airspace pressure in infants and children models under HFJV?

This experimental study was carried out to determine if an alveolar positive end-expiratory pressure (PEEP) could occur during high frequency jet ventilation (HFJV) in infants, and if tracheal pressure is a good estimation of alveolar pressure. We used physical models simulating a 1.5 kg premature (P), a 3 kg newborn (N) and a 6 kg child (C) with normal compliance and normal resistance. Moreover, in the N model, we used two different resistances and lung compliance heterogeneity was studied in the P model. Pressure was measured simultaneously in the tube simulating trachea (Paw) and in the bottle simulating the lung (Palv). HFJV was performed either via an endotracheal tube (ETT) or via a long catheter as in laryngoscopy. The ratio of injection time upon cycle duration (Ti/Ttot) was 20% or 30%, jet frequency was altered from 150 to 300 min-1 and the driving pressure was set as in clinical practice (0.5 and 0.6 bar). PEEP occurred mainly in N (1.1 to 3.2 cm H2O) and C models (0 to 3.5 cm H2O). It was inversely related to expiratory time (Te). The end-expiratory pressure drop between Palv and Paw (delta EEP) was higher in N and increased from 0.5 to 2 cm H2O with the shortening of Te and with airway resistances, i.e. the presence of ETT. In the heterogeneous model, PEEP and delta EEP were greater in the higher compliance alveolus. This study shows that the end-expiratory Palv is underestimated by end-expiratory Paw.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pressure↗
PubMed1994

[Ambulatory anesthesia in ORL. Indication, limits and techniques].

Patients undergoing ENT surgery, mainly children, are excellent candidates for outpatient anaesthesia. Most surgical procedures are simple and do not require complicated techniques. Patient selection criteria have been defined by the "Société Française d'Anesthésie et de Réanimation" e.g. ASA I or II patients, age > 50 weeks, ability to understand and follow specific instructions. Operation selection criteria ought to take into account the duration of surgery (< 1 h 30), and risks of bleeding, airway obstruction, pain, nausea and vomiting. Myringotomy and adenoidectomy and simple nasal or otologic surgery can be performed on an outpatient basis. Indications can be extended to other procedures that do not require hypotension and that meet selection criteria. Tonsillectomy and direct laryngoscopy could be performed on an outpatient basis in definite circumstances which have to be discussed for each patient.

Ambulatory Care↗
PubMed1993

Mathematical analysis of the upper respiratory tract from an anthropometric study.

In order to design a new, performed tracheal tube adapted to the shape of the upper respiratory tract, we have undertaken an anthropometric study from lateral x-rays of the neck in 130 patients with the head in a fixed position. In order to assess different clinical situations, we studied three groups of patients: group 1 = sitting, no tracheal tube; group 2 = supine, no tracheal tube; group 3 = supine, trachea intubated. We defined a standard coordinate system and determined mathematical curves for segments of the upper respiratory tract by a polynomial regression method. With these data it was possible to study the effects of physiological variations on the shape of the curves. It was then possible to determine at which region changes occur and the factors influencing these changes. We found that the relative position of the larynx was constant, whereas the hypopharynx exhibited the greatest change with the position of the head. These observations should allow us to construct a new, performed tracheal tube with elastic compliance properties to fit the changes occurring in the region of the hypopharynx.

Adolescent↗
PubMed1993

[Sudden deafness: a randomized comparative study of 2 administration modalities of hyperbaric oxygenotherapy combined with naftidrofuryl].

Hyperbaric oxygen therapy is one of the numerous therapies which have been proposed in the management of sudden deafness. It is presumptuous to claim the efficiency of any treatment in a pathology where both the origin and the actual rate of spontaneous recovery are unknown. The grounds of therapies are therefore empirical but the need of urgent therapy is dictated by ethics. This study compares the effects of hyperbaric oxygen therapy in two groups of patients; according ot their order in randomization the subjects were treated either at a rate of 1 session or 2 sessions per day. Hyperbaric oxygen therapy was associated with infusion of Naftidrofuryl to counteract the vasoconstrictive effect of increased oxygen pressure in blood. Steroids were also administered simultaneously to avoid, for the same reasons, cerebral oedema. Normovolemic hemodilution (Dauman et al. 1983) was systemically performed in all the patients preliminarily to hyperbaric oxygen therapy, in order to reduce the haematocrit and thus facilitate blood supply. The efficiency and the side effects were similar in the two groups, provided that some principles in the selection and the monitoring of the patients were respected. The rate of 2 sessions of hyperbaric oxygen therapy per day has obvious advantages in view of health policy, but it requires the hospitalization of the patient and should be restricted to the younger subjects.

Adult↗
PubMed1993

[Value of the association of normovolemic dilution and hyperbaric oxygenation in the treatment of sudden deafness. A retrospective study].

The multiple treatments of sudden deafness shows how this pathology still remains quite unknown. The authors present a retrospective study of 87 patients treated by normovolemic hemodilution associated to hyperbaric oxygenation. They obtain a total à 60% of significant recovery (ratio between hearing gain and initial hearing loss, above 25%) and in severe hearing loss (threshold between 70 and 90 dB) 60% of good results (ratio above 50%). The importance of the initial form of audiogram and the presence of dizziness as prognostic factors is not confirmed. On the other hand, the evolution of tinnitus is correlated with the deafness and it is a supplementary means to evaluate the therapeutic efficiency. Moreover the persistence of tinnitus represents an important after effect. Sudden deafness still remains a medical emergency and the delay for carrying out any treatment should be as short as possible. On the other hand it is possible to reduce hospital stay by two sessions of hyperbaric oxygenation per day.

Adolescent↗
PubMed1991

High frequency jet ventilation and upper tracheal stenosis: a model study.

A chest-lung model, consisting of a human laryngo-tracheo-bronchial tree cast (4 or 5 bronchial generations) tightly enclosed in a 100 l rigid box was used to assess the potential efficiency of high frequency jet ventilation in patients with upper tracheal stenosis. The elasticity of the air in the box stimulated normal adult chest-lung compliance. Diaphragms (0.5 or 1.5 cm thick) were inserted into the upper trachea to simulate stenoses of 0.7, 1, 1.5 and 1.75 cm inner diameter. A rigid injector-catheter (5 mm outside diameter) was directed in the axis of the trachea with its tip 2.5 cm beneath the stenosis. The end inspiratory alveolar pressure (PA), the end expiratory pressure (PEEP) and the tidal volume (VT) were measured at a rate of 100/min and 30% inspiratory to total periods ratio. Entrained flow, Vem, measured at the start of air insufflation, was compared to that calculated (Vec) from a simple model. For a given setting of the ventilator, PEEP, PA--PEEP and VT were approximately linearly related to the difference in diameters of stenosis and injector. While PEEP decreased, both PA--PEEP and VT increased with increasing diameter of stenosis. When the diameter of the stenosis was higher than 1.5 cm no changes in PA--PEEP and VT were observed, owing to the narrowest section of the larynx. Vec was always higher than Vem. The thickness of the stenosis did not affect the results, and the diameter of the stenosis appeared to be the main factor affecting the ventilatory parameters under our experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

High-Frequency Jet Ventilation↗
PubMed1989

Variations in flow and intraalveolar pressure during jet ventilation: theoretical and experimental analysis.

Alteration in flow and pressure in a chest-lung model during jet ventilation was studied from a theoretical and experimental standpoint. The model consisted of a stiff box, with an inserted cast of the bronchial tree, simulating either normal or low compliance of the human chest-lung. Airway resistances in the model could be altered. A constant driving flow (Vd) was applied through the opening of the trachea at various rates. The driving flow drew in a constant flow (entrained flow = Ve) and increased the box pressure (PA), which in turn induced an increasing back flow (Vr). Vd, Ve-Vr and PA were measured. Theoretical analysis of time variation in box pressure showed a monoexponential pattern which was confirmed experimentally. Tr, the time at which back flow and entrained flow become equal could be predicted taking the physical characteristics of the experimental set-up and the values of Vd and Ve into account. Tr values depended mainly on the compliance of the experimental set-up. Increasing the resistances was found to reduce Ve. In practice, the efficiency of jet ventilation for gas exchange at a frequency below 4 Hz is known to be mainly related to the volume of gas flowing in the trachea towards the alveoli. This efficiency generally depends on the values of Tr and the inspiratory period (TI). A value of TI less than or equal to Tr will thus improve the jet ventilation efficiency.

Adult↗
PubMed1989

[An experimental and clinical study of a new intubation tube with a foam-filled cuff].

An experimental and clinical study of an endotracheal tube with a foam-filled cuff has been carried out. The experimental study showed that, during inspiration, the cuff was insufflated through the "T piece" connecting the cuff in the inspiratory limb of the ventilator circuit, preventing inspiratory leak. The intracuff pressure was equal to airway pressure. During expiration the gas insufflated into cuff leaked out through the "T piece" and intracuff pressure rapidly returned to zero. When N2O in 50% O2 was used for one hour, intracuff pressure did not increase. Twenty patients intubated with a foam-filled cuff tube, for ENT surgery, have been studied. The mean intubating time was 151 min +/- 36 and two patients were intubed, respectively, 26 hours and 28 hours. No complications were noted, 24 hours after extubation, during laryngeal fibroscopic control. Only two patients had light edema of the vocal cords and three of them had a light inflammation of the subglottic mucosa, without sore throat. No tracheal ischaemic damage nor tracheal mucosal inflammation were observed.

Adolescent↗
PubMed1986

[Normovolemic hemodilution in the treatment of sudden deafness].

After the apparition of a sudden deafness, 45 patients (22 men and 23 women, with a mean age of 44 +/- 14.9 years) were treated with normovolaemic haemodilution performed with dextran 60. They were placed into 4 groups depending on their hearing loss: total loss: 10 cases; severe loss: 90 to 70 db. 13 cases; moderates loss: 65 to 40 db, 14 cases, slight loss: less than or equal to 35 db, 8 cases. The mean time between the onset of the hearing loss and treatment was 9.3 +/- 12.4 days. The initial mean haematocrit was 44.8 +/- 3.8% and mean haematocrit after haemodilution was 33.1 +/- 2.8%. For 51% of the patients, an almost total recovery was obtained. In 15.5% of cases, recovery was between 25 to 50% of the hearing loss, and in 33.3% of the patients recovery was negligible. We did not find any relationship between hearing recovery and initial haematocrit. The best results were obtained in the group of patients treated early. Hearing gain was significatively better if delay in starting treatment was less than 7 days. There was a relationship between the initial hearing loss and the final recuperation. These results suggested that haemodilution increased labyrinth microcirculation and oxygenation of the cochlear sensory cells, reversing the ischaemic insult to these cells.

Adult↗