Inhalation therapy in mechanical ventilation

Abstract

Patients with obstructive lung disease often require ventilatory support via invasive or noninvasive mechanical ventilation, depending on the severity of the exacerbation. The use of inhaled bronchodilators can significantly reduce airway resistance, contributing to the improvement of respiratory mechanics and patient-ventilator synchrony. Although various studies have been published on this topic, little is known about the effectiveness of the bronchodilators routinely prescribed for patients on mechanical ventilation or about the deposition of those drugs throughout the lungs. The inhaled bronchodilators most commonly used in ICUs are beta adrenergic agonists and anticholinergics. Various factors might influence the effect of bronchodilators, including ventilation mode, position of the spacer in the circuit, tube size, formulation, drug dose, severity of the disease, and patient-ventilator synchrony. Knowledge of the pharmacological properties of bronchodilators and the appropriate techniques for their administration is fundamental to optimizing the treatment of these patients.

In Vitro Evaluation of Aerosol Performance and Delivery Efficiency During Mechanical Ventilation Between Soft Mist Inhaler and Pressurized Metered-Dose Inhaler

“…Aerosol delivery efficiency during mechanical ventilation depends on several variables, such as humidity, aerosol generators, device position in the circuit, and ventilator parameters. [26][27][28] Jet nebulizers, vibrating mesh nebulizers, and pMDIs have been widely studied for use in mechanical ventilation. Delivery methods for the usage of SMIs in an intubated patient model have been found in only a few studies because delivering an effective performance of SMIs during mechanical ventilation provides a challenging scenario.…”

Evaluation of inhaled salbutamol effectiveness under supportive use of electrical impedance tomography in ventilated ICU patients: study protocol for a randomised controlled clinical trial

“…In this regard, a previous study could demonstrate that only 2.9% of the administered drug dose reached the distal airway in ventilated patients, compared with 11.9% in patients without artificial airway 16. A recently published review on inhalative drug therapy in mechanical ventilation stated that ventilator settings play a crucial role in inhaled drug delivery 14. A tidal volume of at least 500 mL, increased inspiratory time and a low inspiratory flow are general recommendations in order to optimise drug distribution in the lungs 14 20 21.…”

“…Nevertheless, attention should be paid to serious adverse effects of high (>500 mL) tidal volumes, especially in patients with acute or chronic airway obstructions. In these patients high tidal volumes can lead to dynamic hyperinflation or can cause a severe barotrauma 14. Furthermore, no clinical studies exist showing the beneficial effects of any particular ventilation mode on inhaled drug delivery 20 21.…”

“…The inhalative administration of drugs is an established, non-invasive and painless application form which is used in the treatment of obstructive airways diseases. An important advantage is that significantly higher local concentrations of the drug at the site of action are achieved without significant systemic exposure 13 14. Several studies could not show a benefit of inhaled medication 15–17.…”

“…Unfortunately, these studies could not address the crucial issue whether the medication was distributed effectively in critically ill and ventilated patients. To the present day, there is no established non-invasive real-time monitoring to measure or visualise the effectiveness or distribution of nebulised drugs in ventilated patients at bedside 14…”