Pascal Matte

Exercise capacity in patients supported with rotary blood pumps is improved by a spontaneous increase of pump flow at constant pump speed and by a rise in native cardiac output.

Exercise capacity is improved in patients supported with continuous flow rotary blood pumps (RP). The aim of this study was to investigate the mechanisms underlying this improvement. Ten patients implanted with a RP underwent cardiopulmonary exercise testing (CPET) at 6 months after surgery with hemodynamic and metabolic measurements (RP group). A group of 10 matched heart failure patients were extracted from our heart transplant database, and the results of their last CPET before transplantation were used for comparison (heart failure [HF] group). Peak VO(2) was significantly higher in RP than in HF patients (15.8 ± 6.2 vs. 10.9 ± 3 mL O(2)/kg.min) reaching 52 ± 16% of their predicted peak VO(2). The total output measured by a Swan-Ganz catheter increased from 5.6 ± 1.6 to 9.2 ± 1.8 L/min in the RP group and was significantly higher at rest and at peak exercise than in the HF group, whose output increased from 3.5 ± 0.4 to 5.6 ± 1.6 L/min. In the RP group, the estimated pump flow increased from 5.3 ± 0.4 to 6.2 ± 0.8, whereas the native cardiac output increased from 0.0 ± 0.5 to 3 ± 1.7 L/min. Cardiac output at peak exercise was inversely correlated with age (r = -0.86, P = 0.001) and mean pulmonary artery pressure (r = -0.75, P = 0.012). Maximal exercise capacity is improved in patients supported by RP as compared to matched HF patients and reaches about 50% of the expected values. Both a spontaneous increase of pump flow at constant pump speed and an increase of the native cardiac output contribute to total flow elevation. These findings may suggest that an automatic pump speed adaptation during exercise would further improve the exercise capacity. This hypothesis should be examined.

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.

Effect of continuous positive airway pressure administration during lung stereotactic ablative radiotherapy: a comparative planning study

PurposeBy increasing lung volume and decreasing respiration-induced tumour motion amplitude, administration of continuous positive airway pressure (CPAP) during stereotactic ablative radiotherapy (SABR) could allow for better sparing of the lungs and heart. In this study, we evaluated the effect of CPAP on lung volume, tumour motion amplitude and baseline shift, as well as the dosimetric impact of the strategy.MethodsTwenty patients with lung tumours referred for SABR underwent 4D-computed tomography (CT) scans with and without CPAP (CPAP/noCPAP) at two timepoints (T0/T1). First, CPAP and noCPAP scans were compared for lung volume, tumour motion amplitude, and baseline shift. Next, CPAP and noCPAP treatment plans were computed and compared for lung dose parameters (mean lung dose (MLD), lung volume receiving 20 Gy (V20Gy), 13 Gy (V13Gy), and 5 Gy (V5Gy)) and mean heart dose (MHD).ResultsOn average, CPAP increased lung volume by 8.0% (pu202f<u20090.001) and 6.3% (pu202f<u20090.001) at T0 and T1, respectively, but did not change tumour motion amplitude or baseline shift. As a result, CPAP administration led to an absolute decrease in MLD, lung V20Gy, V13Gy and V5Gy of 0.1u202fGy (pu202f=u20090.1), 0.4% (pu202f=u20090.03), 0.5% (pu202f=u20090.04) and 0.5% (pu202f=u20090.2), respectively, while having no significant influence on MHD.ConclusionsIn patients referred for SABR for lung tumours, CPAP increased lung volume without modifying tumour motion or baseline shift. As axa0result, CPAP allowed for axa0slight decrease in radiation dose to the lungs, which is unlikely to be clinically significant.ZusammenfassungZielsetzungAus der Erhöhung des Lungenvolumens und der Verringerung der atembedingten Tumorbewegungsamplitude beim Einsatz des kontinuierlichen positiven Atemwegsdrucks (CPAP „continuous positive airway pressure“) während der stereotaktischen ablativen Strahlentherapie (SABR „stereotactic ablative radiotherapy“) könnte ein erhöhter Schutz von Lunge und Herz resultieren. Diese Studie untersucht die Auswirkung der CPAP auf Lungenvolumen, Tumorbewegungsamplitude und „baseline shift“ sowie deren Einfluss auf die Dosisverteilung.MethodenVon 20xa0Patienten mit Lungentumoren, für die eine SABR indiziert ist, wurden zu zwei verschiedenen Zeitpunkten (T0/T1) 4‑D-Computertomographie-(CT-)Aufnahmen mit und ohne CPAP (CPAP/noCPAP) angefertigt. Zuerst wurden die CPAP- und noCPAP-Aufnahmen hinsichtlich Lungenvolumen, Tumorbewegungsamplitude und „baseline shift“ verglichen. Anschließend wurden CPAP- und noCPAP-Bestrahlungspläne erstellt und bezüglich der Dosisverteilung auf Herz und Lunge gegenübergestellt.ErgebnisseIm Durchschnitt vergrößerte CPAP das Lungenvolumen zu T0 und T1 um 8% (pu202f<u20090,001) bzw. 6,3% (pu202f<u20090,001), ohne Tumorbewegungsamplitude und „baseline shift“ zu verändern. Im Ergebnis verringerte die CPAP die mittlere Strahlendosis auf die Lunge um 0,1u202fGy (pu202f=u20090,1) und die Volumenparameter V20Gy, V13Gy und V5Gy jeweils um 0,4% (pu202f=u20090,03), 0,5% (pu202f=u20090,04) und 0,5% (pu202f=u20090,2), ohne die Strahlendosis auf das Herz zu beeinflussen.SchlussfolgerungBei Patienten, deren Lungentumor einer SABR unterzogen wurde, vergrößerte die CPAP das Lungenvolumen, ohne die Tumorbewegungsamplitude oder den „baseline shift“ zu beeinflussen. Infolgedessen wurde die Strahlendosis auf die Lunge leicht verringert, deren klinische Relevanz ist jedoch unwahrscheinlich.

Dyspnée laryngée après extubation: efficacité de la ventilation non invasive à deux niveaux de pression

Abstract Endotracheal reintubation for post-extubation acute respiratory distress is sometimes difficult due to the presence of laryngeal edema. In the present study, a report was made on two patients with post-extubation acute respiratory distress syndrome, whose clinical condition deteriorated even with optimal medical treatment. The onset of acute respiratory acidosis and the progressive loss of consciousness could have justified intubation and the use of mechanical ventilation. However, noninvasive bilevel nasal positive pressure ventilation was introduced, thereby avoiding a more aggressive therapeutic option: a rapid positive response was obtained in both cases.