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Biomedical subjects

M Gorini

Publications and source records attributed to M Gorini.

At least 37 records · Page 2Linked to original sources
PubMed1999

Chest wall hyperinflation during acute bronchoconstriction in asthma.

The mechanics of the chest wall was studied in seven asthmatic patients before and during histamine-induced bronchoconstriction (B). The volume of the chest wall (VCW) was calculated by three-dimensional tracking of 89 chest wall markers. Pleural (Ppl) and gastric (Pga) pressures were simultaneously recorded. VCW was modeled as the sum of the volumes of the pulmonary-apposed rib cage (VRC,p), diaphragm-apposed rib cage (VRC,a), and abdomen (VAB). During B, hyperinflation was due to the increase in end-expiratory volume of the rib cage (0.63 +/- 0.09 L, p < 0.01), whereas change in VAB was inconsistent (0.09 +/- 0.07 L, NS) because of phasic recruitment of abdominal muscles during expiration. Changes in end-expiratory VRC,p and VRC,a were along the rib cage relaxation configuration, indicating that both compartments shared proportionally the hyperinflation. VRC,p-Ppl plot during B was displaced leftward of the relaxation curve, suggesting persistent activity of rib cage inspiratory muscles throughout expiration. Changes in end-expiratory VCW during B did not relate to changes in FEV(1) or time and volume components of the breathing cycle. We concluded that during B in asthmatic patients: (1) rib cage accounts largely for the volume of hyperinflation, whereas abdominal muscle recruitment during expiration limits the increase in VAB; (2) hyperinflation is influenced by sustained postinspiratory activity of the inspiratory muscles; (3) this pattern of respiratory muscle recruitment seems to minimize volume distortion of the rib cage at end-expiration and to preserve diaphragm length despite hyperinflation.

Abdominal Muscles↗
PubMed1999

Physiological changes during severe airflow obstruction in chronic obstructive pulmonary disease.

Chronic expiratory flow limitation and hyperinflation are the mechanical hallmarks of chronic obstructive pulmonary disease (COPD). Although carbon dioxide retention is dependent on the severity of airflow limitation, there is considerable variability in the relationships between arterial carbon dioxide tension (Pa,CO2) and forced expiratory volume in one second (FEV1) or total lung resistance (RL). In stable COPD patients with severe airflow obstruction, shallow breathing and inspiratory muscle weakness are the main factors associated with CO2 retention. In stable COPD patients, the diaphragm is less effective than in normal subjects and, with increasing airflow obstruction and hyperinflation, the contribution to the generation of ventilatory pressure of the ribcage inspiratory muscles increased. Abdominal muscles are recruited during expiration in severe COPD patients and the expiratory rise in gastric pressure is directly related to intrinsic positive end-expiratory (alveolar) pressure (PEEPi). During acute bronchoconstriction, COPD patients with severe airflow obstruction recruited the rib cage inspiratory muscles proportionally more than the diaphragm. The associated recruitment of abdominal muscles results in a reduction in abdominal volume at end-expiration and contributes to a significant extent to PEEPi. Dynamic hyperinflation can be overestimated during chronic and acute airway obstruction if abdominal muscle function is not evaluated.

Acute Disease↗
PubMed1998

Effects of abdominal strapping on forced expiration in tetraplegic patients.

Patients with traumatic transection of the lower segments of the cervical cord contract the clavicular portion of the pectoralis major during forced expiration and cough, and the rise in intrathoracic pressure resulting from this contraction produces dynamic airway compression in many patients. Because the abdominal muscles are paralyzed, however, there is paradoxical expansion of the abdomen, which may reduce the rise in intrathoracic pressure and the degree of airway collapse. To evaluate the magnitude of this effect, we measured expiratory flow rate (Vexp) and esophageal pressure (Pes) during a series of forced expiratory vital capacity maneuvers and constructed isovolume-pressure flow (IVPF) curves before and after abdominal strapping in eight C5-8 tetraplegic subjects. Strapping produced small and inconsistent changes in maximal Vexp and Pes and resulted in the development of small flow plateaus in only four patients. In tetraplegic subjects, abdominal strapping thus has small effects on forced expiration and is unlikely, therefore, to improve the efficiency of cough.

Abdominal Muscles↗
PubMed1998

Negative pressure ventilation versus conventional mechanical ventilation in the treatment of acute respiratory failure in COPD patients.

This case-control study was aimed to evaluate the effectiveness of negative pressure ventilation (NPV) versus conventional mechanical ventilation (CMV) for the treatment of acute respiratory failure (ARF) in patients with chronic obstructive pulmonary disease (COPD) admitted to a respiratory intermediate intensive care unit (RIICU) and four general intensive care units (ICU). Twenty-six COPD patients in ARF admitted in 1994-95 to RIICU and treated with NPV (cases) were matched according to age (+/-5 yrs), sex, causes triggering ARF, Acute Physiology and Chronic Health Evaluation (APACHE) II score (+/- 5 points), pH (+/-0.05) and arterial carbon dioxide tension (Pa,CO2) on admission with 26 patients admitted to ICU and treated with CMV (controls). The primary end points of the study were inhospital death for both groups and the need for endotracheal intubation for cases. The secondary endpoints were length and complications of mechanical ventilation and length of hospital stay. The effectiveness of matching was 91%. Mortality rate was 23% for cases and 27% for controls (NS), five cases needed endotracheal intubation, four of whom subsequently died. The duration of ventilation in survivors was significantly lower in cases than in controls, with a median of 16 h (range 2-111) versus 96 h (range 12-336) (P<0.02), whereas the length of hospital stay was similar in the two groups, with a median of 12 days (range 2-47) for cases vs 12 days (range 3-43) (NS) for controls. No complications were observed in cases, whereas three controls developed infective complications. These results suggest that negative pressure ventilation is as efficacious as conventional mechanical ventilation for the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease and that it is associated with a shorter duration of ventilation and a similar length of hospital stay compared with conventional mechanical ventilation.

Acute Disease↗
PubMed1997

Abdominal muscle recruitment and PEEPi during bronchoconstriction in chronic obstructive pulmonary disease.

BACKGROUND: It has been recently shown that, when breathing at rest, many patients with severe chronic obstructive pulmonary disease (COPD) contract abdominal muscles during expiration, and that this contraction is an important determinant of positive end expiratory alveolar pressure (PEEPi). In this study the effects of acute bronchoconstriction on abdominal muscle recruitment in patients with severe COPD were studied, together with the consequence of abdominal muscle action on chest wall mechanics. METHODS: Breathing pattern, pleural (PPL) and gastric (PGA) pressures, and changes in abdomen anteroposterior (AP) diameter were studied in 14 patients with COPD (mean forced expiratory volume in one second (FEV1) 1.06 (0.08) 1) under control conditions and during histamine-induced bronchoconstriction. RESULTS: The analysis of plots of PGA versus the AP diameter of the abdomen revealed that during maximal broncho-constriction (decrease in FEV1 of 34.8% (95% confidence intervals (CI) 29.9 to 39.7)) the expiratory rise in PGA increased significantly whereas end expiratory abdomen AP diameter decreased, indicating marked abdominal muscle recruitment. As a consequence, the rib cage compartment accounted for all of the volume of hyperinflation during bronchoconstriction (mean value 0.66 I, 95% CI 0.49 to 0.83). Positive end expiratory alveolar pressure during progressive bronchoconstriction was related directly to the expiratory rise in PGA and inversely to the expiratory time. CONCLUSIONS: The results indicate that, in patients with severe COPD, the abdominal muscles are recruited during acute bronchoconstriction. This recruitment probably preserves diaphragm length at the beginning of inspiratory muscle contraction despite the hyperinflation, and contributes significantly to positive end expiratory alveolar pressure. The degree of dynamic pulmonary hyperinflation during bronchoconstriction can be overestimated if abdominal muscle contraction is not assessed.

Abdominal Muscles↗
PubMed1997

Respiratory muscle function and control of breathing in patients with acromegaly.

Increase in lung size has been described in acromegalic patients, but data on respiratory muscle function and control of breathing are relatively scarce. Lung volumes, arterial blood gas tensions, and respiratory muscle strength and activation during chemical stimulation were investigated in a group of 10 patients with acromegaly, and compared with age- and sex-matched normal controls. Inspiratory muscle force was evaluated by measuring pleural (Ppl,sn) and transdiaphragmatic (Pdi,sn) pressures during maximal sniffs. Dynamic pleural pressure swing (Ppl,sw) was expressed both as absolute value and as percentage of Ppl,sn. Expiratory muscle force was assessed in terms of maximal expiratory pressure (MEP). In 8 of the 10 patients, ventilatory and respiratory muscle responses to hyperoxic progressive hypercapnia and to isocapnic progressive hypoxia were also evaluated. Large lungs, defined as total lung capacity (TLC) greater than predicted (above 95% confidence limits), were found in five patients. Inspiratory or expiratory muscle force was below normal limits in all but three patients. During unstimulated tidal breathing, respiratory frequency (fR) and mean inspiratory flow (tidal volume/inspiratory time (VT/tI)) were greater, while inspiratory time (tI) was shorter than in controls. Minute ventilation (V'E) and mean inspiratory flow response slopes to hypercapnia were normal In contrast, four patients had reduced delta(VT/tI)/arterial oxygen saturation (Sa,O2) and three had reduced deltaV'E/Sa,O2. Ppl,sw(%Ppl,sn) response slopes to increasing end-tidal carbon dioxide tension (PET,CO2) and decreasing Sa,O2 did not differ from the responses of the normal subjects, suggesting normal central chemoresponsiveness. At a PET,CO2 of 8 kPa or an Sa,O2 of 80%, patients had greater fR and lower tI compared with controls. Pdi,sn and Ppl,sn related both to deltaV'E/deltaSa,O2 (r=0.729 and r=0.776, respectively) and delta(VT/tI)/deltaSa,O2 (r=0.860 and r=0.90, respectively). Pdi,sn also related both to deltaV'E/deltaPET,CO2 (r=0.8) and delta(VT/tI)/deltaPET,CO2 (r=0.76). In conclusion, the data suggest the relative independence of pneumomegaly and respiratory muscle strength. Peripheral (muscular) factors appear to modulate a normal central motor output to give a more rapid pattern of breathing.

Acromegaly↗
PubMed1997

Respiratory mechanics in patients with tense cirrhotic ascites.

Lung volumes are decreased by tense ascites and increase after large volume paracentesis (LVP). The overall effect of ascites and LVP on the respiratory function is poorly understood. We studied eight cirrhotic patients with tense ascites before and after LVP. Inspiratory muscle force (maximal transdiaphragmatic pressure (Pdi,max), and the lowest pleural pressure (Pp1,min)) was assessed while the patients were seated. Rib cage and abdominal volume displacements, as well as pleural and gastric pressures were measured during quiet breathing while the patients were supine. Pdi,max and Ppl,min were normal and did not change after LVP (from 84.2+/-19.7 to 85.2+/-17.0 cmH2O and from 68.3+/-19.7 to 74+/-15.9 cmH2O, respectively). The abdominal contribution to the generation of tidal volume was greater than that of the rib cage (79 vs 21%), a pattern which did not change after LVP (73 and 27%). Before LVP, tidal swings both of pleural pressure (Ppl,sw) and transdiaphragmatic pressure (Pdi,sw) were large (15.3+/-4.3 and 18.5+/-3.9 cmH2O, respectively) and the load on inspiratory muscles was increased as a consequence of elevated dynamic elastance of the lung (El,dyn) (11.4+/-2.6 cmH2O x L(-1)) and ("intrinsic") positive end-expiratory pressure (PEEPi) (4.3+/-3.5 cmH2O). LVP reduced the load on the inspiratory muscles, as shown by the significant decrease in Ppl,sw (10.6+/-2.0 cmH2O), Pdi,sw (12.8+/-3.0 cmH2O), El,dyn (10.0+/-2.0 cmH2O x L(-1)) and PEEPi (1.1+/-1.3 cmH2O). The amount of fluid removed was closely related to changes in Ppl,sw and PEEPi. We conclude that the strength of the inspiratory muscles is normal or reduced in seated cirrhotic patients. In the supine position, tense ascites results in an increase in lung elastic load and development of positive end-expiratory pressure, with a consequent overload and increased activation of inspiratory muscles. Large volume paracentesis decreases overloading and activation, but does not change the strength of the inspiratory muscles.

Ascites↗
PubMed1997

In vivo ultrasound assessment of respiratory function of abdominal muscles in normal subjects.

Ultrasonography has recently been proposed for assessing changes in thickness and motion of the diaphragm during contraction in humans. Data on ultrasound assessment of abdominal muscles in humans are scarce. We therefore investigated the changes in thickness and the relevant mechanical effects of abdominal muscles using this technique during respiratory manoeuvres in normal subjects. We evaluated the thickness of the abdominal muscle layers in six normal male subjects (aged 26-36 yrs) using a 7.5 MHz B-mode ultrasound transducer. Gastric (Pg) and mouth pressures, muscle thickness of external oblique (EO), internal oblique (IO), transversus abdominis (TA) and rectus abdominis (RA) were assessed at functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), during progressive (PEEs) and maximal expiratory efforts (MEEs) against a closed airway and during homolateral (HTR) and contralateral (CTR) trunk rotation. Abdominal muscle thickness was found to be reproducible (coefficient of variation and two-way analysis of variance). Compared to FRC, the thickness of IO, TA and RA significantly increased at RV and during MEEs, whereas EO remained unchanged; at TLC, the thickness of IO and TA significantly decreased. During PEEs, a significant relationship between increase in Pg and TA thickness was observed in all subjects, the thickness of the other abdominal muscles being inconsistently related to Pg. Finally, a significant increase in the thickness of IO and EO was found during HTR and CTR, respectively. We conclude that during maximal expiratory manoeuvres, transversus abdominis, internal oblique and rectus abdominis thickened similarly. Transversus abdominis seems to be the major contributor in generating abdominal expiratory pressure during progressive expiratory efforts. External oblique seems to be preferentially involved during trunk rotation. These results suggest the possible value of studying the abdominal muscles by ultrasonography in various respiratory disorders.

Abdominal Muscles↗
PubMed1997

Negative pressure ventilation in COPD patients with acute on chronic respiratory failure.

Negative pressure ventilators act by exposing the surface of the chest wall to subatmospheric pressure during inspiration. During negative pressure ventilation (NPV), tidal volume is related to the peak of the inspiratory negative pressure and the pressure waveform generated by the ventilator pump; for the same peak of negative pressure a square wave produces a greater tidal volume than a half sine wave. Several uncontrolled studies suggest that NPV may have a potential therapeutic role in the treatment of acute on chronic respiratory failure in patients with chronic obstructive pulmonary disease (COPD), reducing the need for endotracheal intubation. Recently, NPV has been used with a good outcome as a first-line treatment in COPD patients with severe acute respiratory failure and hypoxic hypercapnic coma. The positive results of these reports need to be confirmed by further controlled studies before recommending the generalized use of NPV in COPD patients with acute respiratory failure as standard care.

Acute Disease↗
PubMed1996

Intermittent negative pressure ventilation in the treatment of hypoxic hypercapnic coma in chronic respiratory insufficiency.

BACKGROUND: In recent years non-invasive ventilatory techniques have been used successfully in the treatment of acute on chronic respiratory failure (ACRF), but careful selection of patients is essential and a comatose state may represent an exclusion criterion. The aim of this retrospective and uncontrolled study was to evaluate whether a non-invasive ventilatory technique such as the iron lung could also be used successfully in patients with hypoxic hypercapnic coma, thus widening the range for application of non-invasive ventilatory techniques. METHODS: A series of 150 consecutive patients with ACRF and hypoxic hypercapnic coma admitted to our respiratory intensive care unit were evaluated retrospectively. The most common underlying condition was chronic obstructive pulmonary disease (79%). On admission a severe hypoxaemia (Pao2 5.81 (3.01) kPa) and hypercapnia (Paco2 14.88 (2.78) kPa) associated with a decompensated acidosis (pH 7.13 (0.13)) were present, the Glasgow coma score ranged from 3 to 8, and the mean APACHE II score was 31.6 (5.3). All patients underwent intermittent negative pressure ventilation with the iron lung. The study end point was based on a dichotomous classification of treatment failure (defined as death or need for endotracheal intubation) versus therapeutic success. RESULTS: There were 45 treatment failures (30%) and 36 deaths (24%). Nine patients (6%) required intubation because of lack of airway control. The median total duration of ventilation was 27 hours per patient (range 2-274). The 105 successfully treated cases recovered consciousness after a median of four hours (range 1-90) of continuous ventilatory treatment and were discharged after 12.1 (9.0) days. CONCLUSIONS: These results show that, in patients with acute on chronic respiratory failure and hypoxic hypercapnic coma, the iron lung resulted in a high rate of success. As this study has the typical limitations of all retrospective and uncontrolled studies, the results need to be formally confirmed by controlled prospective studies. Confirmation of these results could widen the range of application of non-invasive ventilatory techniques.

Aged↗
PubMed1996

Breathing pattern and carbon dioxide retention in severe chronic obstructive pulmonary disease.

BACKGROUND: The factors leading to chronic hypercapnia and rapid shallow breathing in patients with severe chronic obstructive pulmonary disease (COPD) are not completely understood. In this study the interrelations between chronic carbon dioxide retention, breathing pattern, dyspnoea, and the pressure required for breathing relative to inspiratory muscle strength in stable COPD patients with severe airflow obstruction were studied. METHODS: Thirty patients with COPD in a clinically stable condition with forced expiratory volume in one second (FEV1) of < 1 litre were studied. In each patient the following parameters were assessed: (1) dyspnoea scale rating, (2) inspiratory muscle strength by measuring minimal pleural pressure (PPLmin), and (3) tidal volume (VT), flow, pleural pressure swing (PPLsw), total lung resistance (RL), dynamic lung elastance (ELdyn), and positive end expiratory alveolar pressure (PEEPi) during resting breathing. RESULTS: Arterial carbon dioxide tension (PaCO2) related directly to RL/PPLmin, and ELdyn/PPLmin, and inversely to VT and PPLmin. There was no relationship between PaCO2 and functional residual capacity (FRC), total lung capacity (TLC), or minute ventilation. PEEPi was similar in eucapnic and hypercapnic patients. Expressing PaCO2 as a combined function of VT and PPLmin (stepwise multiple regression analysis) explained 71% of the variance in PaCO2. Tidal volume was directly related to inspiratory time (TI), and TI was inversely related to the pressure required for breathing relative to inspiratory muscle strength (PPLsw, %PPLmin). There was an association between the severity of dyspnoea and both the increase in PPLsw (%PPLmin) and the shortening in TI. CONCLUSIONS: The results indicate that, in stable patients with COPD with severe airflow obstruction, hypercapnia is associated with shallow breathing and inspiratory muscle weakness, and rapid and shallow breathing appears to be linked to both a marked increase in the pressure required for breathing relative to inspiratory muscle strength and to the severity of the breathlessness.

Aged↗
PubMed1996

Negative pressure ventilation in the treatment of acute respiratory failure: an old noninvasive technique reconsidered.

Noninvasive mechanical ventilatory techniques include the use of negative and positive pressure ventilators. Negative pressure ventilators, such as the "iron lung", support ventilation by exposing the surface of the chest wall to subatmospheric pressure during inspiration; whereas, expiration occurs when the pressure around the chest wall increases and becomes atmospheric or greater than atmospheric. In this review, after a description of the more advanced models of tank ventilators and the physiological effects of negative pressure ventilation (NPV), we summarize the recent application of this old technique in the treatment of acute respiratory failure (ARF). Several uncontrolled studies suggest that NPV may have a potential therapeutic role in the treatment of acute on chronic respiratory failure in patients with chronic obstructive pulmonary disease and restrictive thoracic disorders, reducing the need for endotracheal intubation. In the paediatric field, after substantial technical improvement, NPV has been successfully reintroduced for the treatment of ARF due to neonatal distress syndrome and bronchopulmonary dysplasia, and for the weaning from positive pressure ventilation in intubated patients. The positive results of these reports need to be formally confirmed by further prospective and controlled studies before recommending the generalized use of negative pressure ventilation in acute respiratory failure as a standard of care.

Contraindications↗
PubMed1995

Mechanical loading and control of breathing in patients with severe chronic obstructive pulmonary disease.

BACKGROUND: High neural drive to the respiratory muscles and rapid and shallow breathing are frequently observed in patients with chronic obstructive pulmonary disease (COPD), and both mechanical and chemical factors are thought to play a part. However, the interrelation between these factors and the modifications in the control of breathing are not clearly defined. The effects of an acute decrease in mechanical load by the administration of a high dose of a beta 2 agonist were studied. METHODS: Nine spontaneously breathing patients with severe COPD took part in the study. Criteria for entry were FEV1 of < 40% of predicted and an improvement in FEV1 of < 200 ml after inhalation of 400 micrograms fenoterol. The following parameters were measured: lung volumes, tidal volume (VT), respiratory frequency (Rf), maximal pleural pressure during a sniff manoeuvre (PPLmax), pleural pressure swings (PPLsw), lung resistance (RL), RL/PPLmax ratio, and surface electromyographic activity (EMG) of diaphragm (EDI) and parasternal (EPS) muscles. Arterial oxygen saturation (SaO2), end tidal carbon dioxide pressure (PETCO2), and the electrocardiogram were also monitored. Each variable was measured under control conditions and 20 and 40 minutes after the inhalation of 800 micrograms fenoterol. In five patients the effects of placebo were also studied. RESULTS: Fenoterol resulted in an increase in FEV1 and decrease in FRC. SaO2 did not change, while PETCO2 fell and heart rate increased. The VT increased, and Rf decreased, PPLsw fell and PPLmax increased, thus the PPLsw/PPLmax ratio fell. Both RL and RL/PPLmax also fell, and a substantial decrease in EDI and EPS was observed. Changes in PPLsw were related to changes in FEV1 and RL. Changes in VT and Rf, and EDI/TI and EPS/TI were also related to changes in PPLsw and RL/PPLmax ratio, but not to changes in FEV1. No variation was observed with placebo. CONCLUSIONS: In patients with severe COPD a decrease in inspiratory muscle loading relative to the maximal available strength, as expressed by the RL/PPLmax and PPLsw/PPLmax ratios, appears to be the major determinant of changes in breathing pattern and inspiratory muscle activity (decrease in EMG).

Aged↗