Inhalation Maneuver Research Articles

Sympathomimetics in acute severe asthma: inhaled or parenteral, nebulizer or spacer?

It is accepted today that all patients with acute asthma should be treated with a sympathomimetic, irrespective of previous therapy. This short review addresses the question of the optimal mode of administration of these drugs in acute severe asthma. Inhaled sympathomimetics are as effective as subcutaneous adrenaline, or intravenous salbutamol or terbutaline, and, as they produce fewer side-effects, are recommended as the best mode of administration. However, self-medication with a ready to use subcutaneous preparation may be indicated in those patients prone to very abrupt attacks. The conventional mode of inhalation therapy in acute asthma is nebulization, but equally effective bronchodilatation may be obtained with metered-dose inhalers combined with valved spacers. Tachypnoeic patients unable to perform a conventional inhalation manoeuvre can use one-way valve inhalation devices with repeated tidal breaths. Finally, sequential or even continuous inhalation techniques have recently been advocated, particularly in patients with impending respiratory failure.

Nebulization and selective deposition of LTD4 in human lungs.

The process of nebulization and deposition of LTD4 was studied in detail. The concentration of LTD4 in a saline solution decreased by approximately 90% after 2 min of nebulization in a DeVilbiss 35B ultrasonic nebulizer. This decrease was prevented by diluting LTD4 in a phosphate buffer, pH 7.4. Nebulization of tritiated LTD4 in this phosphate buffer did not cause any appreciable deterioration of the leukotriene, as demonstrated by an unchanged ratio between radioactivity and LTD4 concentration in the test solution before and after nebulization as well as in the condensed aerosol. The aerosol generated by the DeVilbiss 35B ultrasonic nebulizer was shown to generate particles with a mass median diameter of 1.3 microns (dry particle size). Interposition of a settling bag reduced the amount of large particles, reducing the mass median diameter to 0.84 microns (dry particle size). Nine healthy volunteers were challenged on separate days with 40 nmol LTD4 or 100 mumol histamine, and the changes in FEV1 and partial flow volume curves initiated at 50% of vital capacity (Vmax30) were measured. A relative diffuse deposition pattern was ensured by inhalation via a settling bag. These results were compared to challenges with a relatively central deposition pattern as ensured by inhalation directly from the nebulizer with brisk inhalation maneuvers. The diffuse deposition pattern caused minimal changes in FEV1 but pronounced effect in Vmax30. The effects of LTD4 and histamine on FEV1 and Vmax30 changed in parallel when the deposition of the mediators was changed to a more central pattern. This indicates that the two mediators do not differ with respect to any selective effects on different parts of the airways.

Auxiliary MDI Aerosol Delivery Systems

Aerosol delivered through metered-dose inhalers (MDI) offers a potentially convenient way to deliver bronchodilator agents and corticosteroids to the lungs of patients with asthma and COPD. Unfortunately, most patients are unable to coordinate satisfactorily their actuation with inhalation, a problem overcome by using auxiliary MDI aerosol delivery systems. Left to their own judgment, patients often inhale the aerosol with a high inspiratory flow rather than slowly to produce optimal aerosol deposition within the airways. This problem has been corrected by one of the auxiliary MDI aerosol delivery systems (InspirEase) through auditory, visual, and tactile feedback mechanisms. MDI devices release aerosol at a high jet velocity in large particle sizes, depositing most of the aerosol in the oropharynx which can lead to potential systemic absorption of adrenergic agonists with CNS and cardiovascular side effects, oral thrush, and suppression of adrenocortical activity. All the auxiliary MDI aerosol systems promote delivery of small aerosol particles and markedly diminish oropharyngeal impaction. Of all the systems, only InspirEase provides volume and flow feedback controls to ensure an optimal inhalation maneuver. Auxiliary MDI aerosol systems should always be used for aerosolized corticosteroid administration because they minimize oropharyngeal deposition and improve aerosol delivery efficiency.

Recent advances in the management of obstructive airways disease. Auxiliary MDI aerosol delivery systems.

Aerosol delivered through metered-dose inhalers (MDI) offers a potentially convenient way to deliver bronchodilator agents and corticosteroids to the lungs of patients with asthma and COPD. Unfortunately, most patients are unable to coordinate satisfactorily their actuation with inhalation, a problem overcome by using auxiliary MDI aerosol delivery systems. Left to their own judgment, patients often inhale the aerosol with a high inspiratory flow rather than slowly to produce optimal aerosol deposition within the airways. This problem has been corrected by one of the auxiliary MDI aerosol delivery systems (InspirEase) through auditory, visual, and tactile feedback mechanisms. MDI devices release aerosol at a high jet velocity in large particle sizes, depositing most of the aerosol in the oropharynx which can lead to potential systemic absorption of adrenergic agonists with CNS and cardiovascular side effects, oral thrush, and suppression of adrenocortical activity. All the auxiliary MDI aerosol systems promote delivery of small aerosol particles and markedly diminish oropharyngeal impaction. Of all the systems, only InspirEase provides volume and flow feedback controls to ensure an optimal inhalation maneuver. Auxiliary MDI aerosol systems should always be used for aerosolized corticosteroid administration because they minimize oropharyngeal deposition and improve aerosol delivery efficiency.

Physician Knowledge in the Use of Canister Nebulizers

The knowledge and skills of physicians were evaluated regarding some practical details of the usage of bronchodilators administered by canister nebulizers to determine the need for specific physician instruction in the correct usage. Fifty-five house officers and nonpulmonary attending staff from the Department of Medicine were interviewed individually. Each physician was handed a placebo canister and asked a series of standard questions regarding the recognition, assembly, and correct inhalation technique of the device. Correct assembly of the device was performed by 68 percent and 36 percent of house officers and attending staff, respectively. Only 40 percent of the participants correctly performed more than four of the seven steps felt to constitute a correct inhalation maneuver. The results reveal inadequacies in physicians' knowledge of the correct technical usage of canister nebulizers and suggest that greater attention be paid to instructing physicians in the correct inhalation technique if their role in patient education is to be effectively realized.

Improper Inhalation Technique-A Barrier to Good Asthma Control

Bronchial Asthma (BA) is a chronic airway disorder with significant morbidity and mortality but due to recent advances in the field of medicine most patients with BA can have complete symptom control and live a normal life. There are various routs of drug delivery for asthma control but among them aerosol inhalation is considered the optimal route. A number of pressured Metered Dose Inhalers (MDI) & Dry Powder Inhalers (DPI) are available for this purpose. However inhalation of therapeutic aerosols is not without difficulty, it requires precise instructions on the inhaler maneuvers, which is different from spontaneous normal breathing. Also, the characteristics of the inhaler device have to be suitable for the user. Available data indicate that, lack of knowledge demonstrated by health professionals & patients on the inhalation maneuvers & handling of inhalers resulting in a reduction of therapeutic benefit. The paper reviews the literature concerning the fundamental aspects of inhaler devices, inhalation maneuvers & device selection, in an attempt to increase the knowledge of and to optimize the clinical use of therapeutic inhalers. As a result of which Asthmatics can be kept under good control. Key words: Bronchial Asthma; MDI; DPI; Inhalation technique; Rotahaler; Cozyhaler. DOI: http://dx.doi.org/10.3329/fmcj.v6i2.9212 FMCJ 2011; 6(2): 104-106