Aims Carotid–femoral pulse wave velocity (PWV), a direct measure of aortic stiffness, has become increasingly important for total cardiovascular (CV) risk estimation. Its application as a routine tool for clinical patient evaluation has been hampered by the absence of reference values. The aim of the present study is to establish reference and normal values for PWV based on a large European population. Methods and results We gathered data from 16 867 subjects and patients from 13 different centres across eight European countries, in which PWV and basic clinical parameters were measured. Of these, 11 092 individuals were free from overt CV disease, non-diabetic and untreated by either anti-hypertensive or lipid-lowering drugs and constituted the reference value population, of which the subset with optimal/normal blood pressures (BPs) (n = 1455) is the normal value population. Prior to data pooling, PWV values were converted to a common standard using established conversion formulae. Subjects were categorized by age decade and further subdivided according to BP categories. Pulse wave velocity increased with age and BP category; the increase with age being more pronounced for higher BP categories and the increase with BP being more important for older subjects. The distribution of PWV with age and BP category is described and reference values for PWV are established. Normal values are proposed based on the PWV values observed in the non-hypertensive subpopulation who had no additional CV risk factors. Conclusion The present study is the first to establish reference and normal values for PWV, combining a sizeable European population after standardizing results for different methods of PWV measurement.

Determinants of pulse wave velocity in healthy people and in the presence of cardiovascular risk factors

Objective
The incidence, pathophysiology, and consequences of patient-ventilator asynchrony are poorly known. We assessed the incidence of patient-ventilator asynchrony during assisted mechanical ventilation and we identified associated factors.

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Patient-ventilator asynchrony during assisted mechanical ventilation

ContextNoninvasive ventilation (NIV) has been associated with lower rates of
endotracheal intubation in populations of patients with acute respiratory
failure.ObjectiveTo compare NIV with standard treatment using supplemental oxygen administration
to avoid endotracheal intubation in recipients of solid organ transplantation
with acute hypoxemic respiratory failure.Design and SettingProspective randomized study conducted at a 14-bed, general intensive
care unit of a university hospital.PatientsOf 238 patients who underwent solid organ transplantation from December
1995 to October 1997, 51 were treated for acute respiratory failure. Of these,
40 were eligible and 20 were randomized to each group.InterventionNoninvasive ventilation vs standard treatment with supplemental oxygen
administration.Main Outcome MeasuresThe need for endotracheal intubation and mechanical ventilation at any
time during the study, complications not present on admission, duration of
ventilatory assistance, length of hospital stay, and intensive care unit mortality.ResultsThe 2 groups were similar at study entry. Within the first hour of treatment,
14 patients (70%) in the NIV group, and 5 patients (25%) in the standard treatment
group improved their ratio of the PaO2 to the fraction of inspired
oxygen (FIO2). Over time, a sustained improvement in PaO2 to FIO2 was noted in 12 patients (60%) in the NIV group,
and in 5 patients (25%) randomized to standard treatment (P = .03). The use of NIV was associated with a significant reduction
in the rate of endotracheal intubation (20% vs 70%; P
= .002), rate of fatal complications (20% vs 50%; P
= .05), length of stay in the intensive care unit by survivors (mean [SD]
days, 5.5 [3] vs 9 [4]; P = .03), and intensive care
unit mortality (20% vs 50%; P = .05). Hospital mortality
did not differ.ConclusionsThese results indicate that transplantation programs should consider
NIV in the treatment of selected recipients of transplantation with acute
respiratory failure.

https://jamanetwork.com/journals/jama/articlepdf/192270/jce90013.pdf

Noninvasive ventilation for treatment of acute respiratory failure in patients undergoing solid organ transplantation: a randomized trial.

Background In patients with acute exacerbations of chronic obstructive pulmonary disease, mechanical ventilation is often needed. The rate of weaning failure is high in these patients, and prolonged mechanical ventilation increases intubation-associated complications. Objective To determine whether noninvasive ventilation improves the outcome of weaning from invasive mechanical ventilation. Design Multicenter, randomized trial. Setting Three respiratory intensive care units. Patients Intubated patients with chronic obstructive pulmonary disease and acute hypercapnic respiratory failure. Intervention A T-piece weaning trial was attempted 48 hours after intubation. If this failed, two methods of weaning were compared: 1) extubation and application of noninvasive pressure support ventilation by face mask and 2) invasive pressure support ventilation by an endotracheal tube. Measurements Arterial blood gases, duration of mechanical ventilation, time in the intensive care unit, occurrence of nosocomial pneumonia, and survival at 60 days. Results At admission, all patients had severe hypercapnic respiratory failure (mean pH, 7.18+/-0.06; mean PaCO2, 94.2+/-24.2 mm Hg), sensory impairment, and similar clinical characteristics. At 60 days, 22 of 25 patients (88%) who were ventilated noninvasively were successfully weaned compared with 17 of 25 patients (68%) who were ventilated invasively. The mean duration of mechanical ventilation was 16.6+/-11.8 days for the invasive ventilation group and 10.2+/-6.8 days for the noninvasive ventilation group (P = 0.021). Among patients who received noninvasive ventilation, the probability of survival and weaning during ventilation was higher (P = 0.002) and time in the intensive care unit was shorter (15.1+/-5.4 days compared with 24.0+/-13.7 days for patients who received invasive ventilation; P = 0.005). Survival rates at 60 days differed (92% for patients who received noninvasive ventilation and 72% for patients who received invasive ventilation; P = 0.009). None of the patients weaned noninvasively developed nosocomial pneumonia, whereas 7 patients weaned invasively did. Conclusions Noninvasive pressure support ventilation during weaning reduces weaning time, shortens the time in the intensive care unit, decreases the incidence of nosocomial pneumonia, and improves 60-day survival rates.

Noninvasive Mechanical Ventilation in the Weaning of Patients with Respiratory Failure Due to Chronic Obstructive Pulmonary Disease: A Randomized, Controlled Trial

International Consensus Conferences in Intensive Care Medicine: noninvasive positive pressure ventilation in acute Respiratory failure.

Effect of Nasal Pressure Support Ventilation and External PEEP on Diaphragmatic Activity in Patients with Severe Stable COPD

The aim of this study was to evaluate whether pressure support ventilation (PSV) requires different diaphragmatic efforts and patient-ventilator matching, according to the underlying disease. Four groups of patients requiring PSV were studied: Group A, recovering from an episode of acute respiratory failure due to adult respiratory distress syndrome (ARDS); Group B, with postsurgical complications; and two subsets of chronic obstructive pulmonary disease (COPD) patients, with "normal" static compliance of the respiratory system (Cst,rs) (Group C) or elevated Cst,rs (Group D). Ventilatory pattern, transdiaphragmatic pressure (Pdi), the pressure-time product of the diaphragm (PTPdi), static (PEEPi,stat) and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn), Cst,rs and resistance of the total respiratory system (Rrs) were recorded. The matching between patient and ventilator was analysed, recording the number of "ineffective efforts" (inspiratory efforts not efficient enough to trigger a new ventilator cycle, despite a positive deflection in Pdi). A satisfactory blood gas equilibrium arterial oxygen saturation (Sa,O2 > 93%, with a pH > 7.32) was obtained in the various groups with different levels of PSV. Minute ventilation was found to be significantly higher in Groups A and B, due to the longer expiratory time (tE) in the COPD groups. Group A (2 out of 7), Group B (3 out of 7), Group C (3 out of 5) patients showed sporadic "ineffective efforts". All Group D patients manifested continuous mismatching with the ventilator, so that the pressure-time product of the diaphragm per minute (PTPdi/min), reflecting the metabolic work of the diaphragm, was not different in the four groups. Tidal volume and the spontaneous inspiratory efforts were similar in the four groups, but the number of breaths delivered by the ventilator was significantly higher in Groups A and B. The application of different levels of pressure support ventilation in patients with acute respiratory failure due to different pathologies, led them to breathe with comparable pressure time product of the diaphragm. The majority of the patients showed mismatching with the ventilator, although this effect was more pronounced in the groups with chronic obstructive pulmonary disease.

https://erj.ersjournals.com/content/erj/10/1/177.full.pdf

Patient-ventilator interaction and inspiratory effort during pressure support ventilation in patients with different pathologies.

We studied survival and failure or success of weaning from mechanical ventilation (MV) in 42 consecutive chronic obstructive pulmonary disease (COPD) patients requiring prolonged MV (more than 21 days) after an episode of acute respiratory failure requiring admission to our Intermediate Intensive Care Unit (IICU). Parameters including arterial blood gases, pulmonary function tests, respiratory muscle force, neuromuscular drive, and nutritional status were recorded during a phase of clinical stability, in order to identify the features related to survival and weaning. All the patients were submitted to a comprehensive rehabilitation programme. Successful weaning from MV was defined as complete respiratory autonomy for at least 48 h. Twenty three patients were successfully weaned from MV after an average period of 44 days (Group A), requiring no further MV during their stay in hospital, whilst the remaining 19 patients were not able to be disconnected from the ventilator (Group B). The discriminant analysis showed that weaning from MV was significantly associated with arterial carbon dioxide tension (PaCO2), neuromuscular drive (P0.1), maximal inspiratory pressure (MIP), arterial oxygen tension (PaO2), the ratio of respiratory frequency to tidal volume (f/VT) and the serum protein level. Other pulmonary function tests (forced expiratory volume in one second (FEV1), FEV1/forced vital capacity (FVC), anthropometric data, nutritional status, number of pulmonary exacerbations during MV and evidence of cor pulmonale, were similar in the two groups. The discriminant equation considering PaCO2 and MIP could separate the two groups with an accuracy of 84%. The overall survival at 2 yrs was 40%; in Group B it was significantly lower than in Group A (22 vs 68%). Most of the deaths occurred within the first 120 days after intubation.(ABSTRACT TRUNCATED AT 250 WORDS)

https://erj.ersjournals.com/content/erj/7/9/1645.full.pdf

Survival and prediction of successful ventilator weaning in COPD patients requiring mechanical ventilation for more than 21 days

Objective
To evaluate the short-and long-term prognosis of patients with chronic obstructive lung disease (COLD) who had noninvasive mechanical ventilation (NMV) for acute respiratory failure (ARF).

/pdf/non-invasive-mechanical-ventilation-in-severe-chronic-1ufo4t7w66.pdf

Non-invasive mechanical ventilation in severe chronic obstructive lung disease and acute respiratory failure: short- and long-term prognosis

BACKGROUND--Intermittent positive pressure ventilation applied through a nasal mask has been shown to be useful in the treatment of chronic respiratory insufficiency. Pressure support ventilation is an assisted mode of ventilation which is being increasingly used. Invasive ventilation with intermittent positive pressure, with or without positive end expiratory pressure (PEEP), has been found to affect venous return and cardiac output. This study evaluated the acute haemodynamic support ventilation by nasal mask, with and without the application of PEEP, in patients with severe stable chronic obstructive pulmonary disease and hypercapnia. METHODS--Nine patients with severe stable chronic obstructive pulmonary disease performed sessions lasting 10 minutes each of pressure support ventilation by nasal mask while undergoing right heart catheterisation for clinical evaluation. In random order, four sessions of nasal pressure support ventilation were applied consisting of: (1) peak inspiratory pressure (PIP) 10 cm H2O, PEEP 0 cm H2O; (2) PIP 10 cm H2O, PEEP 5 cm H2O; (3) PIP 20 cm H2O, PEEP 0 cm H2O; (4) PIP 20 cm H2O, PEEP 5 cm H2O. RESULTS--Significant increases in arterial oxygen tension (Pao2) and saturation (Sao2) and significant reductions in arterial carbon dioxide tension (PaCO2) and changes in pH were observed with a PIP of 20 cm H2O. Statistical analysis showed that the addition of 5 cm H2O PEEP did not further improve arterial blood gas tensions. Comparison of baseline values with measurements performed after 10 minutes of each session of ventilation showed that all modes of ventilation except PIP 10 cm H2O without PEEP induced a small but significant increase in pulmonary capillary wedge pressure. In comparison with baseline values, a significant decrease in cardiac output and oxygen delivery was induced only by the addition of PEEP to both levels of PIP. CONCLUSIONS--In patients with severe stable chronic obstructive pulmonary disease and hypercapnia, pressure support ventilation with the addition of PEEP delivered by nasal mask may have short term acute haemodynamic effects in reducing oxygen delivery in spite of adequate levels of SaO2.

https://thorax.bmj.com/content/thoraxjnl/48/5/523.full.pdf

Stefano Nava

Papers

Effect of Nasal Pressure Support Ventilation and External PEEP on Diaphragmatic Activity in Patients with Severe Stable COPD

Patient-ventilator interaction and inspiratory effort during pressure support ventilation in patients with different pathologies.

Survival and prediction of successful ventilator weaning in COPD patients requiring mechanical ventilation for more than 21 days

Non-invasive mechanical ventilation in severe chronic obstructive lung disease and acute respiratory failure: short- and long-term prognosis

Haemodynamic effects of pressure support and PEEP ventilation by nasal route in patients with stable chronic obstructive pulmonary disease.