External High Frequency Oscillation in Normal Subjects and in Mechanically Ventilated Patients

A Oscilação Oral de Alta Freqüência (OOAF), ou Oral High Frequency Oscillation (OHFO), vem sendo estudada como um novo recurso fisioterapêutico, desde a década de 80, como sendo uma técnica de desobstrução brônquica. Para GAVA e ORTENZI (1998), a OOAF pode ser utilizada como coadjuvante à fisioterapia respiratória no tratamento de doenças pulmonares que se caracterizam pelo aumento de secreção brônquica. É atribuído a OOAF o descolamento da secreção brônquica, o aumento da função pulmonar e a melhora da oxigenação. Diversos autores descrevem sobre os aparelhos que estão disponíveis no mercado. Contudo, apresentam uma forma básica que lembra um pequeno cachimbo, em que, no seu interio,r existe um canal, onde está acentuada uma pequena esfera de aço. Na realidade, é um fiel resistor de limiar pressórico gravitacional, o qual permite a frenagem do fluxo expiratório, por produzir curtas e sucessivas interrupções à passagem do fluxo, que permitem uma repercussão oscilatória produzida por resistor do aparelho, que é transmitida à árvore brônquica. Atualmente, existem três modelos distintos no mercado: Flutter, Shaker e Acapella. (VOLSKO et al 2003). CARVALHO (2001) ressalta que a pressão positiva oscilatória,atua promovendo a dilatação dos brônquios até as estruturas periféricas, facilitando deslocamento do muco e inibindo o colapso precoce brônquico, tendo como conseqüência, uma diminuição da resistência respiratória e o aumento do volume de reserva expiratória. Estudamos prospectivamente, 14 pacientes, de ambos os sexos, com idade variando de 22 a 71 anos, portadores de vários tipos de doenças, tendo em comum o aumento da secreção brônquica. O presente estudo foi realizado na Unidade de Terapia Intensiva do Hospital VITA Volta Redonda.

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Aerosol deposition in the human lung: Effect of high-frequency oscillation on the deposition characteristics of an inhaled nebulized aerosol

Clinical Science ◽

10.1042/cs0750535 ◽

1988 ◽

Vol 75 (5) ◽

pp. 535-542 ◽

Cited By ~ 6

Author(s):

Simon H. L. Thomas ◽

Jackie A. Langford ◽

Robert J. D. George ◽

Duncan M. Geddes

Keyword(s):

Deposition Rate ◽

High Frequency ◽

Regional Distribution ◽

Normal Subjects ◽

Aerosol Deposition ◽

High Frequency Oscillation ◽

Particle Sizes ◽

Frequency Oscillation ◽

Regional Deposition ◽

Peripheral Lung

1. Oral high-frequency oscillation (OHFO) may have important effects on aerosol deposition in the lungs. In order to investigate these, a technique was devised to measure regional deposition rates of a nebulized radio-labelled aerosol in the lungs during normal tidal breathing. 2. The effect of three frequencies of OHFO on pulmonary aerosol deposition rate (PADR) in four normal subjects and five patients with chronic airways obstruction (CAO) were assessed using the technique. 3. In separate experiments employing three normal subjects, the effect of OHFO was studied on the deposition rate of aerosol on the oropharynx and delivery apparatus, and on the amount and characteristics of aerosol inhaled by the subjects. 4. Total PADR was significantly reduced by OHFO at 8 Hz and 16 Hz in the normal subjects, and by all three frequencies of OHFO in the CAO patients. In the normal subjects, the regional distribution of aerosol deposition was unchanged, but in the CAO patients a larger proportion of total aerosol deposition occurred in peripheral lung. 5. OHFO reduced the oropharyngeal aerosol deposition rate, increased the loss of aerosol to the atmosphere before inhalation, and increased the deposition of aerosol on the delivery apparatus. The end result was a reduction in the amount of aerosol inhaled, and in the particle sizes measured at the mouthpiece. 6. We conclude that OHFO reduces the amount of aerosol inhaled, but may improve peripheral deposition of inhaled aerosol in patients with CAO. This effect may be of value in the clinical administration of nebulized drugs.

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Ventilatory saving by external chest wall compression or oral high-frequency oscillation in normal subjects and those with chronic airflow obstruction

Clinical Science ◽

10.1042/cs0690349 ◽

1985 ◽

Vol 69 (3) ◽

pp. 349-359 ◽

Cited By ~ 13

Author(s):

R. J. D. George ◽

R. J. D. Winter ◽

S. J. Flockton ◽

D. M. Geddes

Keyword(s):

Chest Wall ◽

High Frequency ◽

Minute Ventilation ◽

Airflow Obstruction ◽

Normal Subjects ◽

High Frequency Oscillation ◽

Tidal Breathing ◽

Frequency Oscillation ◽

Resonant Frequencies ◽

High Frequency Oscillations

1. Oscillation of the air within the lungs at high frequency is associated with an increased clearance of CO2. Because of the high frequency and low volume of these oscillations, spontaneous breathing is unhindered and the technique has potential value as a supplement to ventilation. 2. High-frequency oscillations were superimposed upon tidal breathing by using a loudspeaker attached to a mouthpiece (oral high-frequency oscillation, OHFO) or by external chest wall compression (ECWC). We set out (a) to compare the changes in ventilation and breathlessness by using OHFO and ECWC in normal subjects with those in patients with chronic airflow obstruction (CAO), and (b) to relate the pattern of saving to the resonant frequencies of the respiratory system as a whole (fOT, 5–10 Hz in normal subjects, 16–26 Hz in CAO) and those of the ribcage(foc,70 Hz). 3. OHFO reduced minute ventilation (VE) by up to 46% in normal subjects (P < 0.01) and 29% in CAO (P < 0.01) without any rise in CO2. ECWC reduced VE by 27% in normal subjects (P < 0.01) and 16% in CAO (P < 0.01) without a rise in CO2. 4. High-frequency oscillation by either method relieved breathlessness in those with CAO and was comfortable and well tolerated. 5. In normal subjects for was discrete and varied little with respiration. Maximum savings occurred around for (5–10 Hz). 6. In CAO, there was no obvious single resonant frequency and flow and pressure signals were intermittently in phase over a band of about 10 Hz. Thus the reductions in minute ventilation were only loosely related to for (13–26 Hz). Neither group reduced VE at foc (65–75 Hz). 7. OHFO has considerable potential in the management of patients with CAO, where it may be of value as an assistance to breathing and in the relief of breathlessness. ECWC, although effective in principle, is impractical by our methods and awaits the development of an acceptable delivery system.

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