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Biomedical subjects

M Croci

Publications and source records attributed to M Croci.

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

A new device for mechanical ventilation of infants and small children.

A new device for use with adult ventilators to allow neonatal and paediatric mechanical ventilation is described. It met International Standards Organisation standards during in vitro evaluation and gave good results when applied in vivo to ten children undergoing elective surgery. The device provided a safe and cost-effective means of delivering mechanical ventilation by an adult ventilator to neonatal and paediatric patients receiving general anaesthesia.

Anesthesia, Inhalation↗
PubMed1995

[Assisted ventilation: experimental evaluation in vitro].

OBJECTIVE: During assist-control mode ventilation (AMV), patients perform external excess work (Wex) to activate the mechanical ventilator itself. Aim of the study was to quantitate such a Wex and evaluate the best ventilator setting in order to minimize it. SETTING: In vitro study, connecting several commercially available mechanical ventilators, with different settings, to an active model lung, developed in our department. METHODS: Gas flow and volume, and airway pressure were measured and digitally recorded; Wex was computed by pressure-volume loops. The maximum negative pressure attained in the circuit (delta Pmax), before the endotracheal tube, the time necessary to reach such a pressure [t(delta Pmax)], from the start of the model lung inspiration, and the time to return to atmospheric pressure [t(P = 0)] after mechanical ventilator activation were also recorded. Different inspiratory flow waveforms (sinusoidal, square and inverted ramp) were tested. RESULTS: Wex was not different between ventilators. However, it was significantly (F8,24 = 2.697, p < 0.05) affected by different flow waveforms: Wex was markedly higher (p < 0.01) with sinusoidal (16.50 +/- 12.12 mJ) than with either square (1.17 +/- 0.96 mJ) or inverted ramp (0.60 +/- 0.70 mJ) inspiratory flow curve. Furthermore, Wex was significantly correlated (p < 0.001) with delta Pmax, t(delta Pmax) and t(p = 0). Those variables are dependent, although not uniquely, upon the trigger mechanism's sensitivity and the ventilator's response time; thus, Wex can be loosely correlated to them as well. CONCLUSIONS: Since AMV is targeted at farily critical patients, whose oxygen consumption might be marginal, every excess work has to be minimized, in order to avoid respiratory fatigue appearance, and worsening of respiratory failure. Prerequisites of a correct AMV application are thus sensitive trigger mechanism, rapid ventilator response to patient's inspiratory effort, and high initial inspiratory flow (inverted ramp or square waveform).

Air Pressure↗
PubMed1993

Performance of a hydrophobic heat and moisture exchanger at different ambient temperatures.

OBJECTIVE: To evaluate the effect of different room temperatures on hydrophobic heat and moisture exchangers (HME) humidifying capability and efficiency. METHODS: Stock HMEs were tested in vitro using an already described test model, with separation of inspiratory and expiratory gas. Absolute humidity (AH) was measured by means of dry-wet dual thermocouple, and HME efficiency was computed as the ratio between expired to inspired AH, at room temperature of 20 and 26 degrees C. RESULTS: Inspired gas temperature and AH were significantly higher at 26 than at 20 degrees C; since expired AH remained substantially unchanged, HME efficiency was also higher in warmer environment. CONCLUSIONS: Hydrophobic HMEs appear to be affected by room temperature, increasing their humidifying ability and their efficiency with its rise.

Cold Temperature↗
PubMed1993

[Practical device to reduce the tidal volume in mechanical ventilation, for neonatal and pediatric anesthesia].

The authors propose a new device for controlled mechanical ventilation during general anaesthesia in pediatric and neonatal patients. This device can reduce TV delivered by an adult ventilator to small values. The device consists of: a small volume box (about 1.3 1); a disposable breathing circuit composed of a bag to put in the box, connecting tubes, a non rebreathing duckbill valve placed at the endotracheal tube; a monitoring system for pressure and expired volume. The authors tested the device according to ISO Standards. Performance during waveform tests and expiratory resistance agree with ISO request. During volume performance tests the device was able to deliver a minimum TV of 10 ml in all ISO Standard requested sets.

Anesthesia, General↗
PubMed1988

Perioperative changes in functional residual capacity in morbidly obese patients.

Functional residual capacity (FRC) was measured before and after induction of anaesthesia for jejunoileal bypass surgery in 30 morbidly obese patients. The onset of anaesthesia was associated with a 51% reduction in FRC from 2.2 litre to 1.0 litre. Eighteen of the patients were investigated more extensively; in these subjects FRC was reduced below the control values of residual volume (RV) with the onset of anaesthesia, but recovered towards baseline after laparotomy incision. Reduction in FRC is related to baseline vital capacity (VC) and FRC and is much greater than that reported for patients of normal weight.

Adult↗
PubMed1978

Ergoline derivatives with oral, prolonged, alpha-adrenolytic activity.

The alpha-adrenolytic activity of 1-methyl-10-methoxydihydrolysergol 2-(3,5-dimethyl)pyrrolcarboxylate (XV, formula II) is, both in vitro and parenterally, quite similar to that of dihydroergotamine. By oral route the new compound is more active, and longer lasting than dihydroergotamine.

Administration, Oral↗
PubMedDate not supplied

Clinical and pharmacological characterization of anomalous metoclopramide-induced growth hormone secretion in insulin-dependent diabetes mellitus.

An abnormal growth hormone (GH) increase after non-specific stimuli (such as TRH, LHRH and, in a few cases, metoclopramide), has been described in insulin-dependent diabetes. Sixty-nine non-hypogonadic male insulin-dependent diabetic patients (mean age 38.6 years, range 18-54; mean duration of diabetes 11.1 years, range 1.3-28, in different degree of metabolic control, some of them with retinopathy, nephropathy and peripheral and/or autonomic neuropathy) were tested twice with 10 mg i.v. metoclopramide (MCP), an antidopaminergic agent with weak serotoninergic activity. Anomalous GH response (i.e. GH increment equal to or higher than 5 ng/ml from basal level) occurred in 33 patients (47.8%). Mean (+/- SE) MCP-induced GH release in these 'responder' patients peaked up to 17.2 +/- 1.7 ng/ml in comparison with no variation found in 'non-responders' and in 25 healthy control men. Abnormal GH secretion appeared to be unrelated to age, metabolic control, basal GH values and duration of diabetes. Moreover, it remained unmodified by pretreatments with placebo, cimetidine, meclastine, propranolol, acetylsalicylic acid and naloxone, while it was enhanced by metergoline, significantly reduced by bromocriptine and almost completely blunted by pirenzepine, a cholinergic muscarinic receptor antagonist. Neuropathy and nephropathy were equally distributed in the two groups, while retinopathy was more frequent in 'responders'. In conclusion, the exact mechanism(s) by which MCP may induce a paradoxical GH release in many insulin-dependent diabetic patients, is still unclear; it might be dependent, at least in part, on the activation of cholinergic pathways. Indeed, it seems to indicate the presence, in diabetes, of a rather complex derangement in the regulatory mechanisms of GH secretion.

Adult↗
PubMedDate not supplied

Estrogen receptor profiles: changes in mouse and rat mammary tumors by treatment with selective estrogen receptor modifiers.

OBJECTIVE: The aim of this work was to analyze the effect of estradiol (E(2)), medroxyprogesterone and the two selective estrogen receptor modulators (SERMs) (tamoxifen (Tam) and raloxifene (Ral)) on the estrogen receptor (ER) conformers profile performed by size exclusion HPLC in relation to hormone dependence of mammary tumors. MATERIALS AND METHODS: Two types of mammary tumors were studied: tumors transplanted in BALB/c mice that are medroxyprogesterone acetate (MPA)-dependent for growth, and tumors induced in Sprague-Dawley rats by intraperitoneal injection of N-nitroso-N-methylurea (NMU). Tumors from mice treated with MPA, E(2), Tam or Ral and NMU-treated rats were analyzed and compared to that of control. RESULTS: The tumor conformer profiles were as follows: control and MPA-treated mice showed only one peak (oligomeric form); E(2)-treated mice also showed only one peak (dimer); Tam-treated mice showed one peak corresponding to a possible proteolytic fragment, and Ral-treated mice showed two peaks (oligomeric and a possible proteolytic fragment). On the other hand, NMU-induced mammary tumors from rats showed three peaks (oligomeric, monomeric and proteolytic). CONCLUSION: Our findings may indicate that SERMs affect the aggregation state of ER and thereby its ability to modulate genomic transcription mechanisms related to growth rate.

Animals↗
PubMedDate not supplied

[Video laparoscopic cholecystectomy in a female patient with cholelithiasis in Steinert's myotonic dystrophy].

Steinert's disease (SD) is a rare (3-5/100000) myotonic myopathy responsible for chronic restrictive respiratory insufficiency and dilatative myocardiopathy. The authors report the case of a 52-years-old female patient with SD who underwent laparoscopic cholecystectomy for cholelithiasis. Postoperative course was uneventful and the patient was discharged after 4 days. Laparoscopic surgery was effective and safe in the treatment of this pathology.

Anesthesia, General↗
PubMedDate not supplied

[Changes in ventilation during use of heat and humidity exchangers].

The Authors studied in 10 patients during mechanical ventilation the effects of the application of heat and moisture exchanger (HME) in the presence of constant TV and frequency. They observed an increase of PaCO2 and PE, CO2 during the use of HME; this is due to Vd/Vt increase. The Authors conclude that it is mandatory to increase the total ventilation when using HME to avoid dangerous levels of hypercapnia.

Adult↗