Giuseppe Liistro

Pharyngeal shape and dimensions in healthy subjects, snorers, and patients with obstructive sleep apnoea.

To characterise the relation between pharyngeal anatomy and sleep related disordered breathing, 17 men with complaints of snoring were studied by all night polysomnography. Ten of them had obstructive sleep apnoea (mean (SD) apnoea-hypopnoea index 56.3 (41.7), age 52 (10) years, body mass index 31.4 (5.3) kg/m2); whereas seven were simple snorers (apnoea-hypopnoea index 6.7 (4.6), age 40 (17) years, body mass index 25.9 (4.3) kg/m2). The pharynx was studied by magnetic resonance imaging in all patients and in a group of eight healthy subjects (age 27 (6) years, body mass index 21.8 (2.2) kg/m2, both significantly lower than in the patients; p less than 0.05). On the midsagittal section and six transverse sections equally spaced between the nasopharynx and the hypopharynx several anatomical measurements were performed. Results showed that there was no difference between groups in most magnetic resonance imaging measurements, but that on transverse sections the pharyngeal cross section had an elliptic shape with the long axis oriented in the coronal plane in normal subjects, whereas in apnoeic and snoring patients the pharynx was circular or had an elliptic shape but with the long axis oriented in the sagittal plane. It is suggested that the change in pharyngeal cross sectional shape, secondary to a reduction in pharyngeal transverse diameter, may be related to the risk of developing sleep related disordered breathing.

Primary care spirometry

Primary care spirometry is a uniquely valuable tool in the evaluation of patients with respiratory symptoms, allowing the general practitioner to diagnose or exclude chronic obstructive pulmonary disease (COPD), sometimes to confirm asthma, to determine the efficacy of asthma treatment and to correctly stage patients with COPD. The use of spirometry for case finding in asymptomatic COPD patients might become an option, once early intervention studies have shown it to be beneficial in these patients. The diagnosis of airway obstruction requires accurate and reproducible spirometric measurements, which should comply with the American Thoracic Society (ATS)/European Respiratory Society (ERS) guidelines. Low acceptability of spirometric manoeuvres has been reported in primary care practices. This may hamper the validity of the results and affect clinical decision making. Training and refresher courses may produce and maintain good-quality testing, promote the use of spirometric results in clinical practice and enhance the quality of interpretation. Softening the stringent ATS/ERS criteria could enhance the acceptability rates of spirometry when used in a general practice. However, the implications of potential simplifications on the quality of the data and clinical decision making remain to be investigated. Hand-held office spirometers have been developed in recent years, with a global quality and user-friendliness that makes them acceptable for use in general practices. The precision of the forced vital capacity measurements could be improved in some of the available models.

Noninvasive ventilation for acute respiratory failure: a prospective randomised placebo-controlled trial

The aim of the present study was to clarify whether the known effects of noninvasive positive-pressure ventilation (NPPV) in patients with respiratory failure are real or due to placebo effects and whether early application of NPPV in the emergency department leads to rapid improvement of the patients condition and outcome. A prospective randomised placebo-controlled study was conducted in 20 patients with severe acute respiratory failure (ARF) secondary to an acute exacerbation of chronic obstructive pulmonary disease (COPD) or acute pulmonary oedema, not improving under conventional medical therapy and on the edge of intubation. Patients received either conventional medical therapy plus two-level NPPV (bi-level NPPV) or conventional medical therapy plus “placebo” NPPV. The main outcome measures involved the need for endotracheal intubation in the bi-level NPPV arm and in the placebo arm after crossing over to active NPPV. Morbidity, length of stay, mortality and the effect of the ventilatory mode on clinical, arterial-blood gas parameters, and the sternocleidomastoid muscles electromyogram (EMG) activity were also measured. The 10 patients in the active NPPV group rapidly improved and none needed intubation. Placebo NPPV resulted in no change in the clinical condition of patients that continued to worsen and the 10 patients were crossed over to active NPPV. Three patients were intubated. No differences in terms of morbidity, length of stay or mortality between the two groups were observed. Active NPPV (but not placebo NPPV) led to a rapid and significant improvement in the clinical parameters, pH and the carbon dioxide tension in arterial blood and to a decrease in respiratory frequency and sternocleidomastoid EMG activity. Early application of bi-level noninvasive positive-pressure ventilation in patients with severe acute respiratory failure, due to chronic obstructive pulmonary disease and acute pulmonary oedema, leads to a rapid improvement in clinical status and blood gases. Noninvasive positive-pressure ventilation had no placebo effect.

Postoperative pain and side effects after uvulopalatopharyngoplasty, laser-assisted uvulopalatoplasty, and radiofrequency tissue volume reduction in primary snoring.

Objectives We compared, in a prospective study, the side effects and the postoperative complications of three procedures commonly used for the treatment of primary snoring.

Residual effect of nCPAP applied for part of the night in patients with obstructive sleep apnoea

The aim of the present study was to assess whether nasal continuous positive airway pressure (nCPAP) treatment, applied for only a few hours at the beginning of the night, has any residual effect on sleep and breathing during the ensuing hours of unassisted sleep in patients with obstructive sleep apnoea syndrome (OSAS). In 27 patients with newly-diagnosed OSAS, effective nCPAP was applied during the first part of the night and then withdrawn. Polysomnographic parameters after nCPAP withdrawal were compared with those of the corresponding part of the diagnostic polysomnography performed a few days or weeks before and with those of the first part of night on nCPAP. After 255+/-63 (mean+/-SD) min of sleep with normalization of sleep and breathing parameters under nCPAP, there was partial improvement of OSAS severity during the remaining 124+/-56 min of nocturnal sleep without treatment; mean oxygen saturation, desaturation index (equivalent to the apnoea/hypopnoea index) and movement arousal index all improved significantly with respect to the diagnostic night (p=0.001). This improvement was not accounted for by a change in sleep architecture. We conclude that there is an improvement in severity of obstructive sleep apnoea syndrome after only 4 h of nasal continuous positive airway pressure. This carryover effect could explain why a number of patients with obstructive sleep apnoea syndrome apply nasal continuous positive airway pressure for only part of the night or not every night.

Determinants of Fi,O2 with oxygen supplementation during noninvasive two-level positive pressure ventilation.

To maintain arterial oxygen saturation (Sa,O2) above 90% in patients with acute respiratory failure, oxygen (O2) is often added to the circuit of two-level noninvasive positive pressure ventilation (NPPV). However, the final inspiratory oxygen fraction (Fi,O2) is not known. To clarify this issue, the effect of different inspiratory positive airway pressures (IPAP) of the oxygen tubing connection site and the flow rate of O2, on Fi,O2 was assessed. The effects of the tidal volume (VT) and the respiratory rate on the Fi,O2 were then clarified in a model study. The Fi,O2 varied depending on the point where O2 was added to the circuit. When all other variables were constant, the connection closest to the exhaust port (ventilator side) gave the highest Fi,O2. Increases in IPAP led to decreases in Fi,O2. Finally, Fi,O2 increased with O2 flow, although it was difficult to obtain an Fi,O2 >0.30 unless very high O2 flows were used. Paradoxically, NPPV with low IPAP values and without O2 supplementation led to a Fi,O2 <0.21 at the circuit-patient interface. VT and respiratory rate did not appear to influence Fi,O2. To conclude, when using noninvasive positive pressure ventilation with two-level respirators, oxygen should be added close to the exhaust port (ventilator side) of the circuit. If inspiratory airway pressure levels are >12 cmH2O, oxygen flows should be at least 4 L·min−1.

Continuous positive airway pressure treatment for sleep apnoea: compliance increases with time in continuing users

Continuous positive airway pressure (CPAP) remains the best treatment for sleep apnoea syndrome (SAS). In the 1990s, many authors reported on daily compliance, but all of the studies utilised relatively short periods of follow-up that did not exceed a few years. The mean annual rate of CPAP use in patients with SAS was prospectively recorded. In the current study, the results are presented along with compliance data from patients who started CPAP between 1991 and 1998 and were still using it by the end of 2003. The cohort was chosen in order to obtain ≥5 yrs of follow-up for each patient. In total, there were 204 patients. For the whole group, mean±sd compliance reached 321±90 and 393±84 min after 1 and 10 yrs, respectively. There was no significant change in the first 2 yrs, with a significant increase from the third year onwards. Compliance, or its evolution over time, was not correlated either to the baseline polysomnographical data (except slightly for the CPAP pressure), to the difference of these data before and under CPAP therapy, to the age of retirement or to changes in the marital status. In conclusion, very long-term compliance with continuous positive airway pressure increases by a mean of 8 min·day−1 per year of follow-up in patients with sleep apnoea syndrome.

Diagnostic certainty, co-morbidity and medication in a primary care population with presumed airway obstruction : the DIDASCO2 study.

STUDY OBJECTIVES To document the rate of diagnostic certainty, co-morbidity and use of medication in patients with presumed obstructive airway disease (OAD) in a primary care setting. METHODS Twenty-six general practitioners (GPs) were asked to select the last 50 contacts with patients older than 40 years of age who were taking bronchodilators and/or inhaled corticosteroids or who had known OAD. After reviewing their medical data on file, the GPs gave their diagnostic opinion and rated their certainty about the diagnosis using a Likert-type scale. RESULTS Analysis of 1126 files revealed that in at least 523 patients (46.4%), a diagnostic work-up was judged necessary. The GPs judged that 6% of the patients had no OAD. Less than 33% of the study population underwent spirometry during the two years preceding the survey. The number of co-morbid conditions was on average 2.2 for patients with asthma and 3.2 for patients with COPD. Patients with presumed COPD took significantly more drugs (mean, 5.1; 95% CI, 4.8-5.3) than did patients with other diagnostic labels (mean, 4.6 95%; CI, 4.4-4.8). CONCLUSIONS We confirmed the underuse of spirometry as a diagnostic tool in presumed airway obstruction in primary care. Nearly half of the patients older than 40 years who were taking bronchodilators and/or inhaled corticosteroids needed a diagnostic work-up. This population had a high prevalence of co-morbidity and polypharmacy.

Volumetric capnography as a bedside monitoring of thrombolysis in major pulmonary embolism

ObjectiveTo describe the use of volumetric capnography, a plot of expired CO2 concentration against expired volume, in monitoring fibrinolytic treatment of major pulmonary embolism.Design and settingTwo case reports in the emergency department of a teaching hospital.PatientsTwo conscious and spontaneously breathing patients (69- and 31-year-old women) with major pulmonary embolism requiring thrombolysis. Decision for thrombolysis was based on the association of right ventricular afterload on echocardiography, with respiratory failure and hypotension in the first patient, and dyspnea and hemodynamically stable parameters in the second one.InterventionsSuccessive capnographic measurements were performed before, during, and after thrombolysis. Curves of volumetric capnography were obtained from a sidestream gas monitor with flow sensor and an arterial blood gas analysis for CO2 partial pressure.Measurements and resultsWe calculated late deadspace fraction, previously suggested as the most effective capnographic parameter in the diagnosis of pulmonary embolism. Late deadspace fraction decreased in the two patients, respectively, from 64.4% to 1.1% and from 25.6% to 5.7% after thrombolysis, with a concomitant disappearance of right heart dysfunction signs on echocardiography.ConclusionsVolumetric capnography can monitor thrombolysis in major pulmonary embolism. Differences between volumetric capnography technology and the more traditional arterial to end-tidal CO2 gradient are important to take into account for clinical application.

Respiratory muscle workload in intubated, spontaneously breathing patients without COPD: pressure support vs proportional assist ventilation

ObjectiveTo compare the respiratory muscle workload associated with pressure support ventilation (PSV) and proportional assist ventilation (PAV) in intubated and spontaneously breathing patients without COPD.Design and settingProspective study, intensive care unit university hospital.InterventionsTwenty intubated patients, during early weaning, PSV settings made by clinician in charge of the patient, and two levels of PAV, set to counterbalance 80% (PAV 80) and 50% (PAV 50) of both elastic and resistive loads, respectively. The patients were ventilated in the following order: 1) PSV; 2) PAV 50 or PAV 80; 3) PSV; 4) PAV 80 or PAV 50; 5) PSV. PSV settings were kept constant.MeasurementsArterial blood gases, breathing pattern and respiratory effort parameters at the end of each of the five steps.Main resultsPSV and PAV 80 had the same effects on work of breathing (WOB). The pressure-time product (PTP) was significantly higher during PAV 80 than during PSV (90±76 and 61±56 cmH2O·s·min-1, respectively, P <0.05). Tidal volume was comparable, albeit more variable with PAV 80 than with PSV (variation coefficient, 43% vs 25%, respectively, P <0.05). PAV 50 entailed a higher respiratory rate, lower tidal volume, and higher WOB and PTP than PSV and PAV 80. PaO2/FiO2 and SaO2 were lower with PAV 50 than with PSV and PAV 80.ConclusionIn a group of intubated spontaneously breathing non-COPD patients, PAV 80 and PSV were associated with comparable levels WOB, whereas PTP was higher during PAV 80. PAV 50 provided insufficient respiratory assistance.