Breathing pattern flow rate

MDI delivery efficiency depends on the patient s inspiratory flow rate, breathing pattern and hand-mouth coordination. Increases in tidal volume and decreases in respiratory frequency enhance the peripheral deposition in the lung. Most patients need to be trained to use the MDI correctly, as up to 70% of patients fail to do so [26, 30]. 

Finlay, W. H., and Gehmlich, M. G. (2000), Inertial sizing of aerosol inhaled from two dry powder inhalers with realistic breath patterns versus constant flow rates, Int. J. Pharm., 210, 83-95. 

A 34-year-old man developed palpitation, shortness of breath, and chest pain. He had smoked a quarter to a half an ounce of marijuana per week and had taken it 3 hours before the incident. He had ventricular tachycardia at a rate of 200/minute with a right bundle branch block pattern. Electrical cardioversion restored sinus rhythm. Angiography showed a significant reduction in left anterior descending coronary artery flow rate, which was normalized by intra-arterial verapamil 200 micrograms. 

Another factor which modifies the spreading rate of the primary film is the presence of microscratches or other microroughness on mechanically polished surfaces. These scratches are often 1000 A. or less wide and have width-depth ratios of no more than 10 [14]. The radius of curvature of such a trough may be as small as 1 x 10" cm. The pressure difference across a concave squalane surface wetting such a scratch will be of the order of kilograms per square centimeter. It is sufficient to induce rapid flow of oil along the bottom of the scratch until the radius of the oil surface in the scratch approaches infinity. Such open capillaries fill well ahead of the true diffusional advance of the primary film. Liquid spreads laterally from them by surface diffusion, so that a breath pattern reveals a network of squalane-wetted strips ahead of the slow moving film boundary. 

To demonstrate the dependence of regional deposition on particle dynamics monodisperse radiolabeled spherical particles of 3.2 g cm density and diameters between 0.3 and 10 pm were orally inspired with the tidal air from functional residual capacity by three subjects at the slow and fast patterns illustrated in Fig. 5 (1). Slow breathing is characterized by a breathing cycle period of 8 s and flow rate of 250 cm s fast breathing by a 4-s cycle period and flow rate of 750 cm s. Total and regional depositions are presented in Fig. 11 as functions... 

Figure 12 Total deposition and deposition in extrathoracic, upper and lower bronchial, and alveolar regions estimated with the ICRP semiempirical deposition model (3) for oral breathing of unit-density spheres at the reference resting pattern for an adult Caucasian male sitting awake (9) 15-s breathing-cycle period and flow rate of 300 cm s . ...

Particle Deposition Related to Breathing Patterns. An increase in tidal volume, while keeping the flow rate constant, will transport particles by convection deeper into the lung and increase their mean residence time in the lung. 

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