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Biomedical subjects

Franco Cavaliere

Publications and source records attributed to Franco Cavaliere.

15 recordsLinked to original sources
PubMed2005

Comparison of two methods to assess blood CO2 equilibration curve in mechanically ventilated patients.

In order to compare two mathematical methods to assess the blood CO2 equilibration curve from a single blood gas analysis [Loeppky, J.A., Luft, U.C., Fletcher, E.R., 1983. Quantitative description of whole blood CO2 dissociation curve and Haldane effect. Resp. Physiol. 51, 167-181; Giovannini, I., Chiarla, C., Boldrini, G., Castagneto, M., 1993. Calculation of venoarterial CO2 concentration difference. J. Appl. Physiol. 74, 959-964], arterial and central venous blood gas analyses and oximetry were performed before and after ventilatory resetting, at constant arterial O2 saturation, in 12 mechanically ventilated patients. CO2 equilibration curves obtained from basal arterial blood gas analyses were used to predict arterial CO2 content after ventilatory resetting and vice versa. Internal consistency was very good for both methods and comparable. Method 2 also yielded excellent predictions of changes of arterial pH associated with ventilatory resetting. In determining Haldane effect, method 2 yielded very stable results within the expected range of values, while method 1 yielded a wider spread of results. Method 2 appeared more suitable to determine the Haldane effect in the conditions of the study, probably due to an approach minimizing the effect of potential sources of inaccuracy.

Adolescent↗
PubMed2005

Physiologic evaluation of different levels of assistance during noninvasive ventilation delivered through a helmet.

OBJECTIVE: To evaluate the effects of various levels of pressure support (PS) during noninvasive ventilation delivered through a helmet on breathing pattern, inspiratory effort, CO2 rebreathing, and comfort. DESIGN: Physiologic study. SETTING: University-affiliated hospital. PATIENTS AND PARTICIPANTS: Eight healthy volunteers. INTERVENTIONS: Volunteers received ventilation through a helmet with four different PS/positive end-expiratory pressure combinations (5/5 cm H2O, 10/5 cm H2O, 15/5 cm H2O, and 10/10 cm H2O) applied in random order. MEASUREMENTS AND RESULTS: The ventilatory respiratory rate, esophageal respiratory rate (RRpes), airway pressure, esophageal pressure tracings, esophageal swing, and pressure-time product (PTP) [PTP per breath, PTP per minute, and PTP per liter] were evaluated. We also measured the partial pressure of inspired CO2 (Pi(CO2)) at the airway opening, mean partial pressure of expired CO2 (Pe(CO2)), CO2 production (V(CO2)), minute ventilation (V(E)) delivered to the helmet (V(E)h), and the true inspired V(E). By subtracting V(E) from V(E)h, we obtained the Ve washing the helmet (V(E)wh). A visual analog scale (from 0 to 10) was used to evaluate comfort. Compared to spontaneous breathing, different levels of PS progressively increased tidal volume (V(T)) and decreased RRpes, reducing inspiratory effort. The increased levels of assistance did not produce significant changes in Pi(CO2), end-tidal CO2, and V(CO2). Pe(CO2) had a slight decrease when increasing the level of PS from 5 to 10 cm H2O (p < 0.05). Despite the presence of constant values of Ve, the increase of PS produced an increase in V(E)wh, without significant differences comparing 10 cm H2O and 15 cm H2O of PS. The subjects had a slight but not significant increase in discomfort by augmenting the level of assistance. At the highest level of PS (15 cm H2O), the discomfort was significantly higher (p < 0.001) than at the other levels of assistance. CONCLUSION: In volunteers, the helmet is efficient in ventilation, allowing a Vt increase and RRpes reduction. A significant discomfort was present only at the highest level of assistance; however, it did not affect patient/ventilator interaction.

Adult↗
PubMed2005

The potential dangers of treating head injury patients with corticosteroids.

In the past, corticosteroids were given to head-injured patients in order to prevent secondary brain damage, even if clinical trials had been inconclusive and potential risks of complications were of concern. Recently, CRASH, a large, multi-centre study on short-term, high-dose corticosteroid treatment in head trauma, was interrupted after enrolling > 10,000 patients because corticosteroid treatment was associated with significantly higher mortality within two weeks. Participating clinicians were not requested to judge the causes of death, but rates of infections and gastrointestinal haemorrhages did not differ between treated patients and controls. Other potential corticosteroid complications include metabolic derangements (particularly hyperglycaemia), adrenal insufficiency and critical illness myopathy. Furthermore, experimental data suggest that corticosteroids may have some harmful effects on neural tissue. In this review, the potential risks of treating head-injured patients with corticosteroids are examined.

Adrenal Cortex Hormones↗
PubMed2005

Analgesia in PACU: intravenous opioids.

Critically ill patients, particularly those under mechanical ventilation, require analgo-sedation to control noxious stimuli and enhance comfort. Despite their harmful side effects, such as respiratory depression, physical dependence and difficult arousal, opioids are effective in providing a good level of analgesia and comfort. Traditional opioids (morphine and fentanyl) have been shown effective in providing analgesia; however, the respiratory adverse effects and their pharmacokinetics, with an high risk of accumulation, limits their use, especially for a long-term sedation. In the last decade, new synthetic opioids with limited side effects and favourable pharmacokinetics profile, such as Sufentanil and Remifentanil, have been investigated to evaluate their efficacy in mitigating pain and enhancing comfort in critically ill patients.

Analgesics, Opioid↗
PubMed2005

Postoperative delirium.

Delirium is a global impairment of upper brain functions caused by an organic substrate. It is frequently observed in the postoperative period, particularly in elderly people. Vascular and orthopedic surgery and long-duration surgery are associated with a higher incidence of postoperative delirium. When it occurs, postoperative delirium makes patient management much more difficult, increases costs, and, above all, causes severe discomfort to the patient. Delirium is also associated with higher postoperative mortality and morbidity, and with delayed functional recovery, but it is still unclear whether worse prognosis is directly caused by delirium or results from the neurological damage of which delirium is simply a symptom. Drug therapy should be part of a complex approach to prevent and treat this complication. Neuroleptics like haloperidol and droperidol, and benzodiazepines are usually employed in order to control symptoms like agitation, restlessness, and altered perceptions. Atypical neuroleptics, like risperidone, have not yet been studied in postoperative delirium, although some case reports in which they were successfully used have been published. Physiostigmine is effective in delirium caused by anticholinergic syndrome; vitamins may be useful in alcoholics; melatonin use has been suggested in order to prevent and treat delirium by normalizing sleep-wake cycle alterations. Environmental interventions are often costless and may be very useful to prevent and treat postoperative delirium in patients at risk.

Anti-Anxiety Agents↗
PubMed2004

Noise exposure during noninvasive ventilation with a helmet, a nasal mask, and a facial mask.

OBJECTIVE: To assess noise exposure during noninvasive ventilation (NIV) with different types of interface (helmet, nasal, and facial masks). SUBJECTS AND METHODS: Ten "naive" healthy volunteers underwent NIV at pressure support levels of 10 and 15 cmH2O with: (a) helmet, (b) helmet equipped with HME filters at the junctions between the helmet and the inspiratory and expiratory branches of the respiratory circuit, (c) nasal mask, and (d) facial mask. Noise intensity was assessed with a sound level meter by placing a microphone near the right ear. Noise intensity and degree of discomfort were also assessed subjectively with a visual analogue scale. RESULTS: Inside the helmet noise exceeded 100 dB. Noise intensity was poorly affected by pressure support level and unaffected by the presence of HME filters. During NIV with nasal or facial masks the noise did not exceed 70 dB (i.e., noise was not louder than the usual noise background in ICU). Subjective evaluation of noise intensity mirrored objective measurements; however, the presence of HME filters was associated with the feeling of less noise inside the helmet. The discomfort associated with the helmet did not significantly differ from that associated with the masks. CONCLUSIONS: NIV helmet is associated with significantly greater noise than nasal and facial masks, but is as comfortable as masks, at least in the short term. Medium- and long-term exposure to loud noise may potentially impair ear function and increase the patient's discomfort.

Adult↗
PubMed2004

A prospective, blinded evaluation of indexes proposed to predict weaning from mechanical ventilation.

OBJECTIVE: To conduct a blinded evaluation of the predictors of weaning from mechanical ventilation. DESIGN: A prospective clinical study. SETTING: A 23-bed general intensive care unit. PATIENTS: Ninety-three non-selected patients, ventilated for more than 48 h. METHODS: The study had two steps: at first, patients' data were used to select the cut-off value for weaning predictors (the minimal false classification). The cut-off value for each index was prospectively assessed in a group of 52 patients. The predictive performance of these indexes was evaluated by calculating the area under the receiver operating characteristic curve. In the prospective-validation set we used Bayes' theorem to assess the probability of each test in predicting weaning. The physicians making decisions about the weaning process were always unaware of the predictive values. Weaning was considered successful if spontaneous breathing was sustained for more than 48 h after extubation. MEASUREMENTS AND RESULTS: During the first 2 min after discontinuation of mechanical ventilation the following tests were performed: vital capacity, tidal volume, airway occlusion pressure (P(0.1)), minute ventilation, respiratory rate, maximal inspiratory pressure (MIP), respiratory frequency to tidal volume (f/V(T)), P(0.1)/MIP and P(0.1) x f/V(T). The areas under the curve showed that the tests had not the ability to distinguish between successful and unsuccessful weaning. CONCLUSION: Our results show that all the evaluated indexes are poor predictors of weaning outcome in a general intensive care unit population.

Aged↗
PubMed2004

Sedation with sufentanil in patients receiving pressure support ventilation has no effects on respiration: a pilot study.

PURPOSE: To evaluate the effects of sedation with sufentanil on respiratory drive, respiratory pattern, and gas exchange of critically ill patients during pressure support ventilation. METHODS: In this prospective observational cohort study, we observed 12 adult patients receiving partial ventilatory support for acute respiratory failure. Each subject received a continuous infusion of sufentanil at 0.2 to 0.3 micro g x kg(-1) x hr(-1) to obtain a modified Ramsay sedation score between 2 and 3. In basal conditions and at variable distance from the beginning of the sufentanil infusion (10', 30', 60', 120', 24 hr) we evaluated gas exchange, hemodynamic variables, respiratory rate (RR), tidal volume (TV), respiratory pattern, respiratory drive (P0.1) and inspiratory impedance of the respiratory system [P0.1/TV/inspiratory time (Ti)]. RESULTS: The continuous iv administration of 0.2 to 0.3 micro g x kg(-1) x hr(-1) of sufentanil resulted in the desired level of sedation. No significant heart rate, heart rhythm and blood pressure changes were observed. Sufentanil infusion did not affect TV, minute volume, Ti/inspiratory duty cycle, RR, P0.1, P0.1/TV/Ti and gas exchange did not change significantly over the study period. CONCLUSION: A continuous infusion of sufentanil induces "awake" sedation with no detectable effects on respiratory variables in critically ill patients during partial ventilatory support.

Adult↗
PubMed2004

New indications for corticosteroids in intensive care units.

In last years an increasing number of evidences has been gained that inflammatory response plays a major role in critical illness. The acronym SIRS (Systemic Inflammatory Response Syndrome) has been introduced to define the condition in which the inflammatory reaction exceeds local mechanisms of containment and inflammatory mediators invade the bloodstream causing systemic disturbances. Theoretically, the use of corticosteroids offers a potent tool to control the excess of inflammatory reaction, but initial trials on Adult Respiratory Distress Syndrome (ARDS), head trauma, and septic shock showed not only that mortality was unaffected, but also that morbidity could increase. Recently, however, some new studies have suggested that corticosteroids given at dosages lower than those initially tested, could positively affect late stages of ARDS by preventing pulmonary fibrosis, and septic shock by improving hemodynamics and facilitating the weaning from catecholamines. To date, it is not clear whether these effects are related to the correction of an adrenocortical dysfunction.

Adrenal Cortex Hormones↗
PubMed2003

Effects of non-invasive ventilation on middle ear function in healthy volunteers.

OBJECTIVES: To evaluate the effects of non-invasive ventilation (NIV) with facial mask or helmet on middle ear (ME). DESIGN. Prospective, randomised study. SETTING: University hospital. PARTICIPANTS: Ten healthy subjects randomly allocated in two groups of five subjects each. INTERVENTIONS: NIV for 1 h, with helmet (group H) or facial mask (group M). Flow-triggered pressure support was 10 cmH(2)O, PEEP 5 cmH(2)O, FiO(2) 0.21. MEASUREMENTS AND RESULTS: Impedenzometry was performed before NIV and 5 min after NIV ended; it was repeated 60 min later. In group H the acoustic compliance increased after NIV from 2.0+/-.6 ml to 2.3+/-.6 ml ( P<.01), suggesting that the tympanic membrane became less stiff; 1 h later the compliance returned to basal values (2.0+/-.7 ml); in group M the compliance was unaffected (from 2.0+/-.5 ml to 2.0+/-.4 ml; 1.9+/-.4 ml 1 h later). The acoustic reflex, i.e., the contraction of the stapedial muscle in response to an auditory stimulus, involving the acoustic and facial nerves, was also evaluated during impedenzometry at 250 Hz, 500 Hz, 1,000 Hz, and 4,000 Hz; no significant change of the threshold was observed. CONCLUSIONS: The tympanic membrane is tighten by the tensor tympani and a reversible loosening suggests muscle fatigue in response to the application of intermittent positive pressure applied to the external ear during NIV with helmet. The loss of tensor tympani protective action could theoretically predispose the middle and inner ear to mechanical damage during NIV with helmet, suggesting the use of protective devices (ear plugs) in selective cases requiring long-term, high-pressure treatment.

Adult↗
PubMed2002

Fiberoptic bronchoscopy during noninvasive positive pressure ventilation delivered by helmet.

OBJECTIVE: To evaluate the feasibility and safety of fiberoptic bronchoscopy (FOB) with bronchoalveolar lavage (BAL) during noninvasive positive pressure ventilation (NPPV) delivered by helmet in patients with acute respiratory failure (ARF) and suspected pneumonia. DESIGN AND SETTING: Prospective, clinical investigation in a general intensive care unit (ICU) of a university hospital. PATIENTS AND PARTICIPANTS: Four adult patients with ARF who underwent NPPV via the helmet and required fiberoptic BAL for suspected pneumonia. INTERVENTIONS: NPPV was delivered through the helmet in the pressure support ventilation mode. The specific seal connector placed in the plastic ring of the helmet allowed the passage of the bronchoscope, maintaining assisted ventilation. Arterial blood gas levels, pH, oxygen saturation, respiratory rate, heart rate, and mean arterial blood pressure were monitored during the study. RESULTS: Helmet NPPV avoided gas exchanges deterioration during FOB and BAL, with good tolerance. During the procedure heart rate increased by 5% and mean arterial blood pressure by 7% over baseline; these levels returned to prebronchoscopic values immediately after the withdrawal of the bronchoscope. Endotracheal intubation was never required during the 24 h after the procedure. BAL yielded diagnostic information in three of four patients. CONCLUSIONS: NPPV through the helmet allows a safe diagnostic FOB with BAL in patients with hypoxemic ARF, avoiding gas exchange deterioration, and endotracheal intubation. ELECTRONIC SUPPLEMENTARY MATERIAL: is available if you access this article at http://dx.doi.org/10.1007/s00134-002-1554-5. On that page (frame on the left side), a link takes you directly to the supplementary materials.

Adult↗
PubMed2002

A low-dose remifentanil infusion is well tolerated for sedation in mechanically ventilated, critically-ill patients.

PURPOSE: To study the analgesic and sedative effects of remifentanil in critically-ill patients. METHODS: Remifentanil infusion was started at 0.02 microg x kg(-1) x min(-1) in ten mechanically ventilated critically-ill patients, and the infusion rate was increased to 0.05, 0.10, 0.15, 0.20, and 0.25 microg x kg(-1) x min(-1) every 30 min. Basally and 25 min after each increase we measured: the Ramsey sedation score (RSS) and the respiratory response subscore of comfort scale (CSRR); the bispectral index (BIS) before and after lightly touching tracheal mucosa; heart rate and systemic arterial pressure; respiratory variables; plasma epinephrine and norepinephrine levels. RESULTS: Infusion rates up to 0.05 microg x kg(-1) x min(-1) were effective against agitation and achieved a good degree of adaption to the respirator in all patients (RSS 2 or more and CSRR 3 or less); BIS decreased significantly; respiratory and circulatory variables were unaffected; mean plasma epinephrine levels decreased. At infusion rates higher than 0.05 microg x kg(-1) x min(-1) RSS but not BIS decreased further and patient arousability caused by noxious stimuli was not prevented; respiratory drive suppression occurred at the infusion rates higher than 0.05 microg x kg(-1) x min(-1) in four patients; bradycardia and arterial hypotension was observed in three patients; plasma epinephrine levels decreased significantly, while norepinephrine was unaffected; severe itching was experienced by one patient. CONCLUSIONS: Low doses of remifentanil (up to 0.05 microg x kg(-1) x min(-1)) can be useful in critically-ill patients in order to achieve calm and sedation. Higher doses can inhibit respiratory drive and require controlled mechanical ventilation.

Aged↗
PubMed2002

Noninvasive positive-pressure ventilation vs. conventional oxygen supplementation in hypoxemic patients undergoing diagnostic bronchoscopy.

OBJECTIVE: We have reported previously on the use of noninvasive positive-pressure ventilation (NPPV) to assist spontaneous breathing in high-risk hypoxemic patients (i.e., PaO(2)/fraction of inspired oxygen [FIO(2)] ratio, < or = 100) who are undergoing diagnostic fiberoptic bronchoscopy (FOB). The efficacy of this intervention in patients with less severe forms of hypoxemia (i.e., PaO(2)/FIO(2) ratio, < 200) is unknown. PATIENTS AND METHODS: Twenty-six patients with PaO(2)/FIO(2) ratios < or = 200 who required bronchoscopic BAL for suspected nosocomial pneumonia were entered into the study. Thirteen patients were randomized during FOB to receive NPPV, and 13 patients were randomized to receive conventional oxygen supplementation by Venturi mask. The primary end points were changes in the PaO(2)/FIO(2) ratio during FOB and within 60 min of terminating the procedure. RESULTS AND OUTCOME: At study entry, the two groups were similar in terms of age, simplified acute physiologic score II values, and cardiorespiratory parameters. During FOB, the mean (+/- SD) PaO(2)/FIO(2) ratio increased by 82% in the NPPV group (261 +/- 100 vs 139 +/- 38; p < 0.001) and decreased by 10% in the conventional oxygen supplementation group (155 +/- 24 to 139 +/- 38; p = 0.23). Sixty minutes after undergoing FOB, the NPPV group had a higher mean PaO(2)/FIO(2) ratio (176 +/- 62 vs 140 +/- 38; p = 0.09), a lower mean heart rate (91 +/- 18 vs. 108 +/- 15 beats/min; p = 0.02), and no reduction in mean arterial pressure in comparison to a 15% decrease from the baseline in the control group. One patient in the NPPV group and two patients in the control group required nonemergent intubation. Major bacterial isolates included Staphylococcus aureus (7 of 30 isolates; 23%) and Pseudomonas aeruginosa (12 of 30 isolates; 40%). CONCLUSION: In patients with severe hypoxemia, NPPV is superior to conventional oxygen supplementation in preventing gas-exchange deterioration during FOB with better hemodynamic tolerance.

Adult↗
PubMed2002

Furosemide protective effect against airway obstruction.

Furosemide (frusemide) is mainly employed as a powerful diuretic that inhibits Na and K reabsorption in renal tubules. However other valuable pharmacological effects have been discovered that include a protective action from bronchospasm. The effects of furosemide on airways have been recognized to be more and more complex as far as an increasing amount of studies have been produced on this subject. The drug shows no acute bronchodilator effect, but prevents or attenuates bronchospasm caused by many factors, such as hyperpnea, drugs (metabisulphite, bradykinin, AMP), physical agents (hypo- and hypertonic aerosols), and allergen challenge in asthmatic patients. Furosemide is also active on upper airway mucosa, on which the drug decreases nasal resistance in patients affected by non-allergic rhinitis and exhibits a protective effect on nasal mucosa reactivity to the specific allergen in atopic subjects. The mechanism of action of furosemide on airways has not yet been fully cleared and interference with electrolyte epithelial transport, prostaglandins, inflammatory cell activity, vascular and neural regulation has been hypothesized. The interest for clinical application of inhaled furosemide has grown in last years. Some Authors have investigated whether the drug is effective in acute asthma attacks or not. Furosemide is one of the drugs currently used to prevent exercise-induced asthma. More recently, inhaled furosemide has been observed to decrease the sensation of experimentally-induced dyspnea. Apart from possible therapeutic application, studies about furosemide effects on respiratory mucosa can contribute to better understand the physiology of upper and lower airways.

Administration, Inhalation↗