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Biomedical subjects

P Navalesi

Publications and source records attributed to P Navalesi.

17 recordsLinked to original sources
PubMed2003

Orthopnea and inspiratory effort in chronic heart failure patients.

STUDY OBJECTIVE: Orthopnea is a typical feature of patients with chronic heart failure (CHF), the factors contributing to it are not completely understood. We investigated changes in dyspnea and other respiratory variables, induced by altering posture (from sitting to supine) in 11 CHF patients (NYHA classes II-IV) and 10 control subjects. METHODS AND RESULTS: We measured dyspnea (Borg scale) the diaphragm pressure time product per minute (PTPdi/m, index of metabolic consumption), and mechanical properties of the lung (lung compliance (C,L) and resistances (R,L). CHF patients also underwent a trial of non-invasive mechanical ventilation (NIMV) in the supine position in order to ascertain whether unloading the inspiratory muscles could somehow relieve dyspnea. While sitting the PTPdi/min was significantly higher in CHF patients than in controls (181 +/- 54 cm H2O x s/min vs. 96 +/- 32; P<0.05). Assuming a supine position caused no major changes in controls, whereas CHF patients showed a significant worsening in dyspnea, a rise in PTPdi/min (243 +/- 97 p<0.01) and R,L (4.7 +/- 1.2 cm H2O/L x s sitting vs. 7.9 +/- 2.5 supine; P<0.01) and a decrease in C,L (0.08 +/- 0.02 L/cm H2O sitting vs. 0.07 +/- 0.01 supine; P<0.05). Applying NIMV to supine CHF patients significantly reduced the PTPdi/min to 81 +/- 42 (P<0.001). Changes in dyspnea, produced by varying position or applying NIMV, were significantly correlated with PTPdi/min (r=0.80, P<0.005 and r=0.58, P<0.01, respectively). CONCLUSIONS: CHF patients had a higher PTPdi/min than controls when sitting, and assuming a supine position induced severe dyspnea, a large rise in R,L, and a reduction in C,L so that PTPdi/min increased further. Orthopnea was strongly correlated with the increased diaphragmatic effort.

Cardiac Output, Low↗
PubMed2002

Noninvasive vs. conventional mechanical ventilation in patients with chronic obstructive pulmonary disease after failure of medical treatment in the ward: a randomized trial.

OBJECTIVE: We conducted a randomized prospective study comparing noninvasive positive pressure ventilation (NPPV) with conventional mechanical ventilation via endotracheal intubation (ETI) in a group of patients with chronic obstructive pulmonary disease who failed standard medical treatment in the emergency ward after initial improvement and met predetermined criteria for ventilatory support. DESIGN AND SETTING: Prospective randomized study in a university hospital 13-bed general ICU. PATIENTS: Forty-nine patients were randomly assigned to receive NPPV (n=23) or conventional ventilation (n=26). RESULTS: both NPPV and conventional ventilation significantly improved gas exchanges. The two groups had similar length of ICU stay, number of days on mechanical ventilation, overall complications, ICU mortality, and hospital mortality. In the NPPV group 11 (48%) patients avoided intubation, survived, and had a shorter duration of ICU stay than intubated patients. One year following hospital discharge the NPPV group had fewer patients readmitted to the hospital (65% vs. 100%) or requiring de novo permanent oxygen supplementation (0% vs. 36%). CONCLUSIONS: The use of NPPV in patients with chronic obstructive pulmonary disease and acute respiratory failure requiring ventilatory support after failure of medical treatment avoided ETI in 48% of the patients, had the same ICU mortality as conventional treatment and, at 1-year follow-up was associated with fewer patients readmitted to the hospital or requiring for long-term oxygen supplementation. An editorial regarding this article can be found in the same issue (http://dx.doi.org/10.1007/s00134-002-1503-3).

Aged↗
PubMed2001

Electrical activity of the diaphragm during pressure support ventilation in acute respiratory failure.

We compared crural diaphragm electrical activity (EAdi) with transdiaphragmatic pressure (Pdi) during varying levels of pressure support ventilation (PS) in 13 intubated patients. With changing PS, we found no evidence for changes in neuromechanical coupling of the diaphragm. From lowest to highest PS (2 cm H(2)O +/- 4 to 20 cm H(2)O +/- 7), tidal volume increased from 430 ml +/- 180 to 527 ml +/- 180 (p < 0.001). The inspiratory volume calculated during the period when EAdi increased to its peak did not change from 276 +/- 147 to 277 +/- 162 ml, p = 0.976. Respiratory rate decreased from 23.9 (+/- 7) to 21.3 (+/- 7) breaths/min (p = 0.015). EAdi and Pdi decreased proportionally by adding PS (r = 0.84 and r = 0.90, for mean and peak values, respectively). Mean and peak EAdi decreased (p < 0.001) by 33 +/- 21% (mean +/- SD) and 37 +/- 23% with the addition of 10 cm H(2)O of PS, similar to the decrease in the mean and peak Pdi (p < 0.001) observed (34 +/- 36 and 35 +/- 23%). We also found that ventilator assist continued during the diaphragm deactivation period, a phenomenon that was further exaggerated at higher PS levels. We conclude that EAdi is a valid measurement of neural drive to the diaphragm in acute respiratory failure.

Acute Disease↗
PubMed2001

Physiologic evaluation of 4 weeks of nocturnal nasal positive pressure ventilation in stable hypercapnic patients with chronic obstructive pulmonary disease.

BACKGROUND: The long-term daily use of noninvasive mechanical ventilation (NIMV) to treat chronic respiratory failure in chronic obstructive pulmonary disease (COPD) patients is not widely recommended, partly because of a lack of clear clinical results and partly because the physiological mechanisms by which the daily application of NIMV would be helpful in these patients have not yet been clarified. OBJECTIVES: We designed a physiological study in order to assess the effects of supervised long-term NIMV on gas exchange, respiratory muscle function, pulmonary mechanics and to ascertain the possible effect of the treatment in responders and nonresponders. METHODS: Fourteen consecutive inpatients with stable hypercapnic COPD (pH = 7.37 +/- 0.01; PaCO(2) = 56.73 +/- 6.48 mm Hg) underwent 4 weeks of nocturnal NIMV delivered with a bilevel ventilator 'physiologically' set to reduce tidal transdiaphragmatic pressure (Pdi) by at least 50% and the amount of dynamic intrinsic positive end-expiratory pressure by 70%. Various measurements were compared with those obtained in a control group of consecutive patients with comparable baseline characteristics who refused NIMV and underwent breathing exercises for the same period of time. RESULTS: By the end of the 4 weeks NIMV had induced a slight but significant (p < 0.01) reduction in resting PaCO(2) (53.78 +/- 5.64 mm Hg) associated with a decrease in the pressure time product of the diaphragm per minute (from 172 +/- 60 to 136 +/- 61 cm H(2)O/l/s; p < 0.05). This latter value was primarily due to a significant shortening of the inspiratory duty cycle, while Pdi and lung mechanics were not modified. Eight of the 13 NIMV-treated patients (1 dropped out for nonmedical reasons) had a clear reduction in PaCO(2) (>3 mm Hg or >5% from enrollment) and were classified as responders. The acute reduction in PaCO(2) during the first trial with NIMV resulted to be a strong index of the final response. The subgroup of responders had a significantly increased maximal Pdi (from 41 +/- 19 to 49 +/- 23 cm H(2)O, p < 0.05) and an enhanced ability of the ventilatory pump to clear CO(2) (9.7 +/- 3.4 vs. 7.2 +/- 2.9 cm H(2)O x s/min; p < 0.01). No significant changes were observed in the control group. CONCLUSIONS: These results suggest that in a remarkable and identifyable proportion of patients with stable hypercapnic COPD, nocturnal NIMV may decrease resting PaCO(2), reraising the role of chronically supporting the respiratory pump.

Aged↗
PubMed2000

Physiologic evaluation of noninvasive mechanical ventilation delivered with three types of masks in patients with chronic hypercapnic respiratory failure.

OBJECTIVE: The efficacy of noninvasive mechanical ventilation (NIMV) in improving breathing pattern and arterial blood gases (ABG) in hypercapnic patients has been well documented; however, little attention has been given to the choice of the interface and the ventilatory mode. We evaluated the effects of three types of masks and two modes of ventilation on patients' ABG, breathing pattern, and tolerance to ventilation. DESIGN: Prospective randomized study. SETTING: Two respiratory weaning centers. PATIENTS: A total of 26 stable hypercapnic patients (pH, 7.38 +/- 0.04; PaCO2, 59.2. +/- 10.9 torr) had not received NIMV and were affected by restrictive thoracic disease or obstructive pulmonary disease. INTERVENTIONS: Three 30-min runs of NIMV, delivered using volume-assisted (n = 13) or pressure-assisted modes of partial mechanical support (n = 13), were performed in random order with a full-face mask, a nasal mask, and nasal plugs. MEASUREMENTS: ABG, breathing pattern, and patients' tolerance to ventilation. MAIN RESULTS: Compared with spontaneous breathing, the application of NIMV significantly improved ABG and minute ventilation, irrespective of the ventilatory mode, the underlying pathology or the type of mask. Overall, a nasal mask was better tolerated than the other two interfaces (p < .005 vs. nasal plugs and full-face mask). PaCO2 was significantly lower (p < .01) with a full-face mask or nasal plugs than with a nasal mask (49.5 +/- 9.4 torr, 49.7 +/- 8 torr, and 52.4 +/- 11 torr, respectively). Minute ventilation was significantly higher with a full-face mask than with a nasal mask because of an increase in tidal volume. No differences were observed in tolerance to ventilation, ABG, or breathing pattern, using assist control or pressure-assisted modes. CONCLUSIONS: In this physiologic study, we have shown that in patients with hypercapnic respiratory failure, irrespective of the underlying pathology, the type of interface affects the NIMV outcome more than the ventilatory mode.

Chronic Disease↗
PubMed1996

Proportional assist ventilation in acute respiratory failure: effects on breathing pattern and inspiratory effort.

Proportional assist ventilation (PAV) is a new mode of assisted ventilation which, by applying pressure in proportion to volume (volume assist, VA) and flow (flow assist, FA), should specifically reduce the inspiratory effort needed to overcome respiratory system elastance (Ers) and resistance (Rrs), respectively. The aims of this study were to determine (1) the effects of varying the level of VA on breathing pattern, inspiratory effort, and work of breathing, and (2) the interaction between VA and FA. In eight intubated patients with acute respiratory failure, four levels of VA (20 to 80% Ers) with and without a fixed amount of FA (approximately 50% Rrs) were evaluated. Compared with spontaneous breathing, VA increased tidal volume (VT) while respiratory rate (RR) was unchanged or fell slightly. The increase in minute ventilation (VE) was small and not significant. The addition of FA further increased VT while RR was significantly reduced so that VE remained unchanged. Increasing VA produced a graded reduction in inspiratory effort, reflected by decreases in the pressure-time integral of the diaphragm and the inspiratory muscles. These were further reduced when FA was added. VA decreased the elastic work of breathing (Wel) whereas resistive work (Wres) tended to increase so that the fall in total work (W/tot) was less than expected. At each VA setting, the addition of FA significantly reduced Wres and, as a result, Wtot. These results demonstrate that PAV can improve breathing pattern while reducing inspiratory effort by specifically decreasing Wel and Wres, and that VA and FA should be used together to optimize reductions in Wtot and the efficacy of assistance provided.

Acute Disease↗
PubMed1994

Comparison of static and dynamic measurements of intrinsic PEEP in anesthetized cats.

Dynamic measurements of intrinsic positive end-expiratory pressure (PEEPi,dyn) considerably underestimate values obtained under static conditions (PEEPi,stat) in patients with severe airway obstruction. This may be related to regional differences in respiratory system mechanical properties and/or viscoelastic behavior. To evaluate this concept, PEEPi,stat and PEEPi,dyn were compared in six anesthetized paralyzed cats during dynamic hyperinflation produced by inverse ratio ventilation (IRV) and aerosolized methacholine (MCh). PEEPi,stat did not differ between IRV and MCh, averaging 2.70 +/- 0.33 (SE) and 2.70 +/- 0.25 cmH2O, respectively. PEEPi,dyn was significantly less with MCh (0.25 +/- 0.05 cmH2O) than IRV (2.05 +/- 0.28 cmH2O) (P < 0.0001), resulting in a lower PEEPi,dyn/PEEPi,stat ratio for MCh (0.10 +/- 0.02) than for IRV (0.76 +/- 0.03) (P < 0.0001). Compared with control values (33.5 +/- 3.7 cmH2O.l-1.s), maximum resistance (Rmax) was unchanged during IRV (29.1 +/- 2.1 cmH2O.l-1.s) but increased considerably with MCh (288.8 +/- 18.4 cmH2O.l-1.s) (P < 0.0001). Similar changes in minimum resistance (Rmin) and delta R (Rmax-Rmin) were noted. There was a strong inverse relationship between delta P, an index of time constant inequalities and viscoelastic pressure losses and PEEPi,dyn/PEEPi,stat ratio. No correlation was found between this ratio and Rmax, Rmin, delta R, or compliance. In conclusion, PEEPi,dyn considerably underestimates PEEPi,stat in acute nonhomogeneous airway obstruction with MCh in contrast to IRV, where the magnitude and distribution of mechanical properties remain unaltered. These findings support the concept that the difference between PEEPi,dyn and PEEPi,stat is related to regional time constant inequalities and/or increased viscoelastic pressure losses.

Airway Obstruction↗
PubMed1994

Influence of site of tracheal pressure measurement on in situ estimation of endotracheal tube resistance.

In situ measurement of distal tracheal pressure (Ptr) via an intraluminal side-hole catheter (IC) has been used to determine endotracheal tube (Rett) and intrinsic patient (Rpt) resistances in intubated subjects. Because of differences in cross-sectional area between the endotracheal tube (ETT) and trachea, fluid dynamic principles predict that IC position should critically influence these results. Accordingly, the aim of this study was to determine the effect of IC position on Rett. Ptr was recorded in vitro through an IC from 2 cm inside, at the tip of, or 2 cm outside an ETT (7, 8, and 9 mm ID) situated within an artificial trachea (13, 18, and 22 mm ID). A reference value of Rett was also obtained. Results were unaffected by IC position during inspiration, overestimating Rett by 7.9 +/- 0.7% (SE). In contrast, during expiration, Rett fell as IC position changed from outside to inside the ETT and was underestimated by 41.3 +/- 3.6% with Ptr recorded inside the ETT. Varying ETT or tracheal size had little effect on the relative error in Rett. The IC itself did increase Rett due to a reduction in effective cross-sectional area, the change varying directly with IC size and inversely with ETT caliber. In vivo values in 11 intubated patients were comparable to in vitro results. In summary, IC position and size can have important consequences on in situ measurements of Ptr and should be considered when clinically monitoring Rett or Rpt.

Aged↗
PubMed1994

Comparison of static and dynamic measurements of intrinsic PEEP in mechanically ventilated patients.

Intrinsic positive end-expiratory pressure (PEEPi) is routinely determined under static conditions by occluding the airway at end-expiration (PEEPi,stat), the resulting plateau pressure representing the average PEEPi present within a nonhomogeneous lung. In contrast, PEEPi can also be evaluated dynamically (PEEPi,dyn) by recording the change in pressure required to initiate lung inflation. It has been suggested that PEEPi,dyn reflects the lowest regional PEEPi, and therefore underestimates PEEPi,stat in the presence of heterogenous mechanical properties. The purposes of this study were (1) to compare PEEPi obtained with these two methods in mechanically ventilated patients with significant airway obstruction (AWO) and those without (non-AWO), and (2) to relate any discrepancies observed with other indices of respiratory mechanics. PEEPi,stat, PEEPi,dyn, and respiratory mechanics were measured during controlled mechanical ventilation in 22 sedated, paralyzed patients. PEEPi,dyn was significantly less than PEEPi,stat in AWO, averaging 3.0 +/- 0.5 (SEM) and 9.3 +/- 1.1 (SEM) cm H2O, respectively (p < 0.0001). In contrast, these values were more comparable in non-AWO, averaging 4.6 +/- 0.8 and 5.4 +/- 1.0 cm H2O (p > 0.05). As a result, the ratio of PEEPi,dyn to PEEPi,stat amounted to 0.36 +/- 0.06 for AWO compared with 0.87 +/- 0.05 in non-AWO (p < 0.005). Maximal (Rmax) and minimal (Rmin) respiratory resistance were greater in AWO whereas respiratory compliance (Crs) was no different between groups. PEEPi,dyn/PEEPi,stat was inversely related to delta P, the pressure losses attributable to time constant inequalities and viscoelastic tissue properties (r = 0.64, p < 0.005). No correlation was found between this ratio and Rmax, Rmin, or Crs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

["ARCHIDIA": a system for patients' data collection and computerized filing. Part I. Methodology].

This report describes a computer based program of patient clinical data collection: the ARCHIDIA system. The project relies on descriptive analysis of clinical events according to well defined methodological criteria. This allows the formulation of a concise diagnosis which is, at the same time, exhaustive of all essential information. Two are the basis principles of this methodology: To define, as accurately as possible, the logical steps necessary to elaborate the diagnosis, that is construed by a sequence of codes. To define all the conditions that must be followed so to use any code in a controlled and independent way. These criteria were derived from literature. The major claim of the system is likely to be the introduction of a "common language" between different ICUs. Uniformed diagnostic and clinical criteria are the main source of large data collection for descriptive, analytic and prospective studies. After a one year pilot study performed by 4 ICUs, ARCHIDIA was used, in 1991, by 20 centers from the area of Milan, Pavia, Como, Varese (70% of total) and 4148 patient data were collected. A descriptive analysis will be reported in the following paper.

Electronic Data Processing↗
PubMed1994

["ARCHIDIA": a system for patients' data collection and computerized filing. Part II. General description of a caseload].

OBJECTIVE: To describe a population of patients admitted in ICU in an homogeneous urban area by means of a computed system. EXPERIMENTAL DESIGN: Observational study. SETTING: 20 general intensive care units of general and university hospitals. PATIENTS: Patients admitted in ICU from 1-1-1991 to 31-12-1991. 3 centers collected patients only for 6 months, starting on 1-6-1991. MEASUREMENTS: For each patient demographic data, hospitalization data, outcome, diagnosis and diagnostic procedures used during hospitalization according to defined criteria previously described, were collected. Data have been collected on PC using dedicated software. RESULTS: All centers concluded data collection, none abandoned the study. General characteristics of 4148 valuable patients were reported. Age was 52.9 years, SAPS 12.4 and mortality 21.7%. The patients spent 8.7 days in ICU and, when transferred to a general ward, the following hospitalization was 21.5 days. CONCLUSIONS: Data collection demonstrated the project feasibility. It realizes a continue up to date system inside each unit and allows the use of a "common language" and homogeneous methodology between centers.

Adolescent↗
PubMedDate not supplied

Use of bronchodilators during non-invasive mechanical ventilation.

Bronchodilators represent one of the most important therapeutic weapons for the treatment of airway obstructive diseases and the inhaled route of administration is very often employed due to the greater drug availability and reduced magnitude of side effects. During acute exhacerbations, it is not unfrequent that the elastic and resistive loads imposed on the ventilatory pump overcome the force sustainable by the respiratory muscles and the patient requires ventilatory assistance, in order to relieve fatigue and to optimize alveolar gas exchange. During these episodes, inhaled bronchodilators, far from being discontinued, sometime must be administered during mechanical ventilation, that, in hypercapnic ventilatory failure can be frequently applied noninvasively with a good rate of success. While in the current literature there are a lot of data about inhaled drug administration during invasive mechanical ventilation, very few data are available on the topic of aerosol therapy during noninvasive mechanical ventilation. With the present paper we want to analyze the rationale, the feasibility and the current data dealing with the administration of inhaled drugs during noninvasive mechanical ventilation.

Asthma↗