Jonathan Dugernier

Influence of inspiratory flow pattern and nebulizer position on aerosol delivery with a vibrating-mesh nebulizer during invasive mechanical ventilation: an in vitro analysis.

BACKGROUND Aerosol delivery during invasive mechanical ventilation (IMV) depends on nebulizer type, placement of the nebulizer and ventilator settings. The purpose of this study was to determine the influence of two inspiratory flow patterns on amikacin delivery with a vibrating-mesh nebulizer placed at different positions on an adult lung model of IMV equipped with a proximal flow sensor (PFS). METHODS IMV was simulated using a ventilator connected to a lung model through an 8-mm inner-diameter endotracheal tube. The impact of a decelerating and a constant flow pattern on aerosol delivery was evaluated in volume-controlled mode (tidal volume 500 mL, 20 breaths/min, inspiratory time of 1 sec, bias flow of 10 L/min). An amikacin solution (250 mg/3 mL) was nebulized with Aeroneb Solo(®) placed at five positions on the ventilator circuit equipped with a PFS: connected to the endotracheal tube (A), to the Y-piece (B), placed at 15 cm (C) and 45 cm upstream of the Y-piece (D), and placed at 15 cm of the inspiratory outlet of the ventilator (E). The four last positions were also tested without PFS. Deposited doses of amikacin were measured using the gravimetric residual method. RESULTS Amikacin delivery was significantly reduced with a decelerating inspiratory flow pattern compared to a constant flow (p<0.05). With a constant inspiratory flow pattern, connecting the nebulizer to the endotracheal tube enabled similar deposited doses than these obtained when connecting the nebulizer close to the ventilator. The PFS reduced deposited doses only when the nebulizer was connected to the Y-piece with both flow patterns or placed at 15 cm of the Y-piece with a constant inspiratory flow (p<0.01). CONCLUSIONS Using similar tidal volume and inspiratory time, a constant flow pattern (30 L/min) delivers a higher amount of amikacin through an endotracheal tube compared to a decelerating inspiratory flow pattern (peak inspiratory flow around 60 L/min). The optimal nebulizer position depends on the inspiratory flow pattern and the presence of a PFS.

Neurally Adjusted Ventilatory Assist During Weaning From Respiratory Support in a Case of Guillain-Barre Syndrome

We report a case of Guillain-Barré syndrome complicated by respiratory failure requiring mechanical ventilation. Neurally adjusted ventilatory assist (NAVA) allowed proper patient-ventilator synchronization by pressure support proportional to the electrical activity of the diaphragm (Edi). Prolonged ventilation with NAVA seems feasible in patients with neuromuscular impairment, but the weaning process conducted by a continuous monitoring of Edi for pressure support titration needed to be assessed in a Guillain-Barré syndrome patient. Beginning on day 12 after hospital admission, the patient was ventilated with NAVA for 8 d. The NAVA level (pressure support per unit of Edi) was decreased from 1.2 cm H2O/μV to zero over the 8-d period. A simultaneous decrease in the tidal volume/Edi ratio was interpreted as a sign of recovery. A spontaneous breathing trial was successfully performed on day 20, followed by decannulation 4 d later. In conclusion, NAVA should be further investigated in patients with Guillain-Barré syndrome, particularly during the weaning period.

Pulmonary Drug Delivery Following Continuous Vibrating Mesh Nebulization and Inspiratory Synchronized Vibrating Mesh Nebulization During Noninvasive Ventilation in Healthy Volunteers

BACKGROUND A breath-synchronized nebulization option that could potentially improve drug delivery during noninvasive positive pressure ventilation (NIPPV) is currently not available on single-limb circuit bilevel ventilators. The aim of this study was to compare urinary excretion of amikacin following aerosol delivery with a vibrating mesh nebulizer coupled to a single-limb circuit bilevel ventilator, using conventional continuous (Conti-Neb) and experimental inspiratory synchronized (Inspi-Neb) nebulization modes. MATERIALS AND METHODS A crossover clinical trial involving 6 noninvasive ventilated healthy volunteers (mean age of 32.3 ± 9.5 y) randomly assigned to both vibrating mesh nebulization modes was conducted: Inspi-Neb delivered aerosol during only the whole inspiratory phase, whereas Conti-Neb delivered aerosol continuously. All subjects inhaled amikacin solution (500 mg/4 mL) during NIPPV using a single-limb bilevel ventilator (inspiratory positive airway pressure: 12 cm H2O, and expiratory positive airway pressure: 5 cm H2O). Pulmonary drug delivery of amikacin following both nebulization modes was compared by urinary excretion of drug for 24 hours post-inhalation. RESULTS The total daily amount of amikacin excreted in the urine was significantly higher with Inspi-Neb (median: 44.72 mg; interquartile range [IQR]: 40.50-65.13) than with Conti-Neb (median: 40.07 mg; IQR: 31.00-43.73), (p = 0.02). The elimination rate constant of amikacin (indirect measure of the depth of drug penetration into the lungs) was significantly higher with Inspi-Neb (median: 0.137; IQR: 0.113-0.146) than with Conti-Neb (median: 0.116; IQR: 0.105-0.130), (p = 0.02). However, the mean pulmonary drug delivery rate, expressed as the ratio between total daily urinary amount of amikacin and nebulization time, was significantly higher with Conti-Neb (2.03 mg/min) than with Inspi-Neb (1.09 mg/min) (p < 0.01). CONCLUSIONS During NIPPV with a single-limb circuit bilevel ventilator, the use of inspiratory synchronized vibrating mesh nebulization may improve pulmonary drug delivery compared with conventional continuous vibrating mesh nebulization.

Kinesiterapia in rianimazione

In collaborazione con l’intera equipe del servizio di rianimazione, il kinesiterapista partecipa alla valutazione clinica per assicurare la gestione respiratoria e la mobilizzazione precoce del paziente. Il kinesiterapista inizia con la valutazione dei segni di distress respiratorio per identificare la causa di quest’ultimo e orientare il trattamento. Egli tratta l’ingombro bronchiale del paziente utilizzando tecniche di disingombro manuali (modulazione del flusso espiratorio, rieducazione alla tosse) e strumentali (ventilazione con percussioni intrapolmonari, insufflazione/exsufflazione meccanica, aspirazione endotracheale). Inoltre, partecipa alla gestione del paziente ipossiemico e/o ipercapnico attraverso l’introduzione dell’ossigenoterapia e la regolazione appropriata dei parametri ventilatori in ventilazione meccanica tanto invasiva quanto non invasiva. Il comfort respiratorio del paziente e lo svezzamento dalla ventilazione meccanica e dall’ossigeno sono due obiettivi chiave della kinesiterapia respiratoria in rianimazione. Il kinesiterapista inizia precocemente la mobilizzazione del paziente. Egli mira al rinforzo muscolare globale e analitico (per esempio, i muscoli respiratori) per promuovere l’autonomia funzionale e l’autonomia respiratoria del paziente. Per fare cio, sono indispensabili un approccio multidisciplinare, una limitazione della sedazione e una nutrizione ottimale. I benefici muscoloscheletrici, respiratori e psicologici della mobilizzazione precoce del paziente di rianimazione sono noti. Praticate nella maggior parte dei pazienti in respirazione spontanea o intubati e ventilati, le tecniche di mobilizzazione vanno dalla mobilizzazione passiva al letto alla deambulazione del paziente fuori dalla sua stanza.

Kinesiterapia en reanimación

En colaboracion con el conjunto del equipo del servicio de reanimacion, el kinesiterapeuta participa en la evaluacion clinica para garantizar el tratamiento respiratorio y la movilizacion precoz del paciente. La kinesiterapia se inicia con la evaluacion de los signos de dificultad respiratoria para descubrir su causa y orientar el tratamiento. Trata la congestion bronquial del paciente mediante el uso de tecnicas de descongestion manual (modulacion del flujo espiratorio, rehabilitacion con la tos) e instrumentales (ventilacion con percusiones intrapulmonares, insuflacion/exuflacion mecanica, aspiracion endotraqueal). Ademas, participa en el tratamiento del paciente hipoxemico y/o hipercapnico mediante la instauracion de la oxigenoterapia y el reglaje adecuado de los parametros ventilatorios tanto en ventilacion mecanica invasiva como en la no invasiva. El confort respiratorio del paciente y la retirada de la ventilacion mecanica y de la oxigenoterapia son dos objetivos clave de la kinesiterapia respiratoria en reanimacion. El kinesiterapeuta inicia precozmente la movilizacion del paciente. Se dirige al refuerzo muscular global y analitico (por ejemplo, los musculos respiratorios) para promover la autonomia funcional y la autonomia respiratoria del paciente. Para ello son indispensables un tratamiento multidisciplinario, una limitacion de la sedacion y una nutricion optima. Son conocidos los beneficios musculoesqueleticos, respiratorios y psicologicos de la movilizacion precoz del paciente en reanimacion. Realizada en la mayoria de los pacientes en respiracion espontanea o intubados y ventilados, las tecnicas de movilizacion van desde la movilizacion pasiva en la cama a la deambulacion del paciente fuera de su habitacion.

Lung Deposition of a Radiolabeled Aerosol With Two Ventilation Modalities During Invasive Mechanical Ventilation: A Randomized Comparative Study

Volume-controlled ventilation has been suggested during nebulization to optimize lung deposition although promoting spontaneous ventilation is targeted for ventilated patient management. Comparing topographic lung aerosol deposition during volume-controlled and spontaneous ventilation in pressure support has never been performed.