Deane Hillsman, M.D.
University of California at Davis, USA

Dynamic Hyperinflation (DH) has been recognized for many years, but has been a relatively neglected entity in pulmonary rehabilitation. Only recently there has been better understanding of the importance of this problem in COP D and Asthma, and a resurgence of interest. There is now strong evidence that the ventilatory response to DH by traditional mechanisms of chemical and mechanical feedback control are not adequate. Therefore, there is a need for cognitive breathing control, so-called "Breathing Exercises" or "Breathing Pattern" training to correct this lesion.

This presentation will discuss the physiology of DH, why cognitive breathing control is needed, and breathing strategies to prevent and correct DH. Controversi es in breathing strategies will be raised.

Chest Physiotherapy generally involves two distinct, but overlapping modalities. The first is classic physiotherapy involving chest wall mobilization, re-direction of pathologic movement to so-called "diaphragmatic breathing," respiratory coordination, and chest wall strengthening. The second is Breathing Pattern (BP) training. As generally practiced in COPD this is a slower respiratory rate, with a more prolonged expiratory phase and a larger Tidal Volume. S pecific breathing strategies to prevent and/or correct the DH lesion will be discussed.

The problem of expiratory Dynamic Bronchial Compression (DBC) and strategies to minimize this lesion by controlled lung volumes and passive expiration will be discussed. The necessity for active expiration under certain circumstances, and therefore exacerbation of DBC, will be discussed.

Conclusion: Every corrective breathing training strategy component has some undesirable consequences. The optimal chest wal l movement and BP strategy therefore is the best compromise among several conflicting requirements. Advocacy for a particular method must be cautious, and take this reality into account. Proper strategy must result in adequate Alveolar Ventilation, minimal Work of Breathing, optimal dyspnea control, and adequate respiratory muscle rest.

Dyspnea relief by chest physiotherapy techniques are substantially related to Dynamic Hyperinflation (DH) and the prevention and/or correction of this physiologic lesion. This presentation will describe Chest Physiotherapy techniques to correct this problem.

Hyperinflation was first described by Dixon and Brodie in 1903 (Dixon WE, Brodie TG. Contributions to the physiology of the lungs. Part 1. The bronchial muscles, their innervation, and the action of drugs upon them. J. Physiol (Lond) 1903; 29: 97-173).

This diagram from the 1955 edition of The Lung, by Julius Comroe et al shows the basic concept of progressive Air Trapping and an increase in the Residual Volume and Functional Resi dual Capacity (FRC) with increasing airway obstruction. Note the parallel decrease in the Inspiratory Capacity (IC), a common method to evaluate Dynamic Hyperinflation.

This diagram is from a 1958 paper by William Miller (Am. J. Medicine; Vol.24, January/June, p.929, 1958), showing 1200cc of Air Trapping after only se ven hyperventilation breaths following a spirogram. Clearly, by the 1950's the process of Dynamic Hyperinflation was well known, and Dr. Miller had demonstrated it could be a very dynamic process. Of interest, the first six references in Dr. Miller's paper referred to United Kingdom chest physiotherapy publications from the 1930's.

Remarkably, chest physiotherapy techniques failed to take root in the United States, despite the enthusiasm of som e advocates. And likewise the statement in Dr. Comroe's authoritative and popular 1955 text The Lung, "If patients with air trapping are taught to breathe out slowly, they can often breathe out more completely. This is one of the rational objectives of breathing exercises."

Most probably the demise of early chest physiotherapy attempts in the United States can be traced to an American Thoracic Society consensus conference, the so-called "Sugarloaf Conference" (Conference on the Scientific Basis of Respiratory Therapy; Am. Review of Respiratory Disease, Vol. 110, No.6, December 1974). Despite the introductory chapter "Physical Therapy" by Dr. Thomas Petty (pp. 129-131) pointing out the positive results and enthusiasm of some reputable pumonologists in this emerging field, the Sugarloaf Conference proceeded to essentially ignore chest physical therapy, and by non-recommendation doomed this specialty to oblivion in the United States. The tragic results of this misguided non-recommendation are now slowly emerging.

However, it is realistic to acknowledge the subject of "Breathing Exercises" has been a controversial one, as articulated by the 1992 statement from the European Respiratory Society:
"...until more definitive evidence is available, breathing training cannot be recommended in COPD..." (Pulmonary Rehabilitation in Chronic Obstructive Pulmonary Disease (COPD) with Recommendations for its use - Donner, CF, Howard, P; Europe an Respiratory Journal, 5, 266-275, 1992)
It seems clear the advocates of chest physiotherapy for COPD have a burden to demonstrate the need for their services to the pulmonary community, and a responsibility to demonstrate the scientific validity of their techniques.

There are many types of so-called "Breathing Exercises," as seen for example with:

• Chest mobilization techniques (several varieties).
• Respiratory muscle strengthening exercises A.) Strength training B.) Enduranc e training (several varieties of each).
• Diaphragm awareness and use (several varieties).
• Thoracic - Diaphragm coordination (several varieties).
• Hyperventilation Syndrome (several varieties).
• Cervical fracture - chest paralysis (several varieties).
• Yoga / Meditation / numerous non-medical techniques.

It seems clear that the term "Breathing Exercises" means many things to many people, and as generally used is literally a "Tower of Babel" resulting in an almost meaningl ess term. As such it is not surprising there is controversy surrounding this subject. Any rational discussion of Breathing Exercises requires a precise definition of what one means by Breathing Exercises, and precisely what one is doing therapeutically in that domain of interest.

The authors definition of "Breathing Exercises" relates to the therapeutic Breathing Pattern associated with COPD / Emphysema / severe Asthma which is, breathing pattern training (in conjunction with chest physi cal therapy techniques) that promotes the minimal necessary level of Alveolar Ventilation in conjunction with minimal Work of Breathing.

While empirical knowledge strongly suggests this pattern is one of a slower respiratory Rate, a larger Tidal Volume, a prolonged expiratory phase, and non-forced respiratory effort, the precise definition of the optimal Breathing Pattern / Breathing Exercise has yet to be defined by advanced pulmonary mechanics studies. Indeed, the precise ventilatory pattern wi ll probably be found to be somewhat variable between different patients.

Undisputed is the need to prevent and/or correct Air Trapping and Dynamic Hyperinflation. This re-awakening of interest in DH has progressively emerged over approximately the past decade, as witnessed by multiple quality papers from the pulmonary community from many sources throughout the world.

Particularly interesting is a paper by Canadian researcher Dr. Denis O'Donnell and colleagues, who have been studying DH i n COPD and Asthma for about the last decade. This paper is "Dynamic Hyperinflation and Exercise Intolerance in Chronic Obstructive Pulmonary Disease" (Am J Respir Crit Care Med Vol 164. pp 770-777, 2001). Twenty five age matched normals were compared to 105 COPD patients (average age 64; average FEV1 0.94 L/S) while exercising doing cycle ergometry. A remarkably revealing Figure 3 from that paper is listed below.

Note the Tidal Volumes are plotted in black within the Total Lung Capacity range, revealing the increased Functional Residual Capacity (i.e. the EELV or End Expiratory Lung Volume) in the COPD patients. With exercise the Tidal Volumes progressively increase, and at peak exercise the Respiratory Rate was 30.7 and 30.3 for the normals and patients respectively. Note particularly the end-expiration level. The FRC remains essential ly stable in the normal subjects, but rises progressively in the COPD patients, indicating progressive Air Trapping and Dynamic Hyperinflation.

Though the Respiratory Rates are not plotted, the apparent immediate increase in FRC in the COPD patients would indicate these patients were in a state of DH at rest, or just bordering on DH. Therefore, these patients (average FEV1 0.94) were intolerant to even a slight increase in their Respiratory Rate. Clearly, even a slight increase in respiratory frequency is precipitating Dynamic Hyperinflation, this because of a typical vicious cycle phenomenon, with progressively increasing hyperventilation making the DH lesion progressively worse. This is pathologic "Relative Hyperventilation" i.e. relative to the diseased lung's inability to tolerate this "normal" increased ventilatory rate with exercise.

The same Dynamic Hyperinflation lesion is also present in Asthma. The reader is encouraged to read the paper by O'Donnell and colleagues "Breathlessness during Acute Bronchoconstriction in Asthma: Pathophysiologic Mechanisms (Am. Rev. Resp. Dis.; Vol 148, pp 1452-1459, 1993). And likewise their paper on bronchodilator influence in Dynamic Hyperinflation "Response of Lung Volumes to Inhaled Salbutamol in a Large Population of Patients With Severe Hyperinflation" (CHEST; Vol 121: 1042-1050, 2002).

What this study clearly reveals is a failure of the multiple traditional breathing regulatory feedback control mechanisms. The implications are profound, and go far beyond any partial relief that might be given by traditional bronchodilator therapy.

In order to efficiently correct the Dynamic Hyperinflation lesion it is clear that mandatory cognitive breathing control techniques must be employed to efficiently correct Dynamic Hyperinflation.

The scientific justification for physical therapy breathing control techniques is now clear. Breathing training in significant COPD and Asthma is no longer an optional and controversial component of therapy. Breathing training must now be considered a critically important and mandatory requirement in COPD and Asthma.

Chest Physiotherapy in COPD / Emphysema has two major components:
      1.) Traditional physiotherapy techniques (chest joint and muscle mobilization; muscula r stretching, strengthening, movement and coordination.
      2.) Breathing Pattern training.

Consider the classic Emphysema "Barrel Chest" deformity from Dr. Netter noted below.

Note the general overinflation, including the upper chest. The upper chest now moves in the so-called "pump handle" up and down movement, due to actio n of the accessory "strap" muscles of respiration. This is a "trick movement" rescue attempt to increase ventilation. The lower chest is overinflated and less mobile as to the normal so-called "bucket handle" lateral and upward motion of the rib cage. This region of the chest normally is the major area of rib movement to assists breathing, and is the stabilizing region of diaphragm attachment necessary for that muscle to work properly. The diaphragm is the dominant chest wall organ of respir ation.

The entire rib cage movement is relatively "frozen" and immobile. This is due to chronic overinflation, both anatomic overinflation related to alveolar destruction as well as Dynamic Hyperinflation. In this process of overdistention the respiratory excursions move into a stretched position of inefficient functionality, and rib movements are lessened. Essentially the ribs become (relatively) immobilized. The rib joints respond in a typical manner (e.g. as do the joints of an arm or leg placed in a cast, the surrounding joints are relatively immobile following cast removal) by pericapsular fibrosis and even greater loss of mobility.

The initial therapy problem is therefore one of mobilizing the chest wall structures and then re-directing proper muscular action to optimize ventilatory capacity. This requires an understanding of chest wall anatomy ( from Grant, An Atlas of Anatomy, 3rd Edition, 1951) and correct mechanics.

Note the upper ribs are relatively straight, and generally pointed downward, i.e. the posterior joints connecting to the spine are higher than the anterior costo-chondral joints. The inspiratory Internal Intercostal muscles are attached from the upper rib in an anterior slanting manner down to the next lower rib. Therefore, when these inspiratory muscles contract these ribs move in an upward manner, i.e. the "pump handle" movement. This movement is assiste d by the accessory neck "strap" muscles attaching to the upper ribs.This "pump handle" movement involves mainly the upper four ribs, and lifts the chest upward and outward.

Note the lower ribs are much more curved, and again the posterior joint is higher. The Internal Intercostal muscles are attached in a similar anterior slanting manner. However, when these muscles contract, because of the curved rib shape, these ribs move mainly in a lateral and outward manner, i.e. the "bucket han dle" movement. This involves mainly the four lowest ribs. Note, with each rib pulling on the rib below there is a multiplier expansion effect, which produces this dominant rib motion of breathing.

This diagram is from the text "Respiration in Health and Disease," by Reuben and Louis Cherniack, 1961. The Pump Handle and Bucket Handle movements and related rib joint motions are well displayed.

This diagram is also from Cherniack and Cherniack.

It shows the diaphragm attachment to the lower ribs. Because of the upward curved nature of the diaphragm attaching to the curved lower ribs, when the diaphragm, (the major organ of chest wall movement promoting i nspiration) contracts, the transverse lower chest movement is enhanced, i.e. the Bucket Handle movement. However, if the chest is overinflated, and the diaphragm relatively flattened, diaphragm contraction promoting inspiration is therefore impaired, because the ribs are now pulled relatively inward on inspiration.

Restoring the diaphragm position to a better curved anatomic level of functionality is imperative.

The "frozen" chest must first be mobilized, in order for proper muscular activity to take place. Mobilization should concentrate on lower-lateral chest movement and expansion. The objective is to obtain more allowable thoracic "breathing room," as without an increased chest wall movement capacity any effort to improve breathing patterns will be limited.

The following three pictures are from the Brompton Hospital manual of "Physiotherapy for Medical a nd Surgical Thoracic Conditions," 1967.

Unilateral Chest Expansion may be done by the patient or assisted by a physiotherapist. The hand is placed on the lower rib margin in the mid to anterior axillary line. Deep exhalation is encouraged, while gently but firmly compressing the chest wall. The spine should be held straight during manipulation. On inspi ration the pressure is promptly removed, allowing for a natural elastic chest recoil. This results in a minimal effort, facilitated flow of air which the patient usually appreciates. Progressively greater excursions are attempted as the chest wall is felt to loosen.Note the emphasis on expiration, which will correct Dynamic Hyperinflation. Joint mobilization may be facilitated, particularly those articulating with the spine, by gentle deep massage and local heat or diathermy.

Every patient should have their own Breathing Belt for self help Belt Exercises.

A Breathing Belt may be constructed from an old sheet. The length is approximately floor to shoulder height. To construct a belt, begin with a width of about 14 to 16 inches. Fold the sheet lengthwise and sew the edge. Then again fold the sheet lengthwise and sew around all edges, and cross-stich to maintain the shape. The final width will be about 3 to 4 inches.

Unilateral Belt Exercises for the left chest is done by fixing the Breathing Belt under the outside

of the left leg, then bringing the belt under the right arm and then placing it around the left lower rib margin. The belt is then grasped with the right hand over the center of the chest. Then, during deep exhalation the right hand pulls on the belt to compress the left lower chest. At the beginning of inspiration the pressure is promptly released to permit chest recoil and a sudden inflow of air. Generally posture should be held erect. However, during exhalation the patient my achieve greater chest compression by leaning to the left, while pulling the belt to the right. While this may be useful as an advanced mobilization trick, routine use of this technique should not be encouraged, as it may promote undesirable "trick movements."

The patient should try to develop a breathing rhythm, and progressively deepen both inspiration and expiration, while applying progressively firmer expiration tension to the belt. Again, the emphasis is on expiration.

Bilateral Chest Expansion may be done by the patient, or with therapist assistance. The technique is best done semi-reclining upright in a comfortable chair. Note the hand placement at the lower rib margins in the mid to anterior axillary lines. Patient's beginning a rehabilitation program can usually be easily taught on their first office visit to place their hands in this position and to "Concentrate on breathing OUT, and when you breathe in, put the air where your hands are." This notion seems foreign to most patients, and they should be reassured that "You can't take in a breath of fresh air until you first get rid of the last breath of stale air." Patients are usually gratified to note some immediate improvement to their dyspnea distress, despite the simplicity of these instructions. This is mainly due to reduction of Dynamic Hyperinflation.

Later, as the patient progress, they may be taught to apply external rib pressure for chest mobilization, and still later the specifics of strengthening and coordinated diaphragm breathing.

In a month or so, when the chest is moving better, there is usually a need for inspiratory muscle strengthening as these muscles are often weakened by being relatively encased within the rigid thorax. On occasion one may even observe intercostal indrawing with inspiration as the mobilization process advances. This indrawing corrects as the intercostal muscles strengthen. For the first three or four months the breathing training as described provides sufficient muscular stress for proper rehabilitation. Thereaft er there is a place for an additional inspiratory work load, which may be provided by a number of commercially available devices. Whatever device is used, the inspiratory work load should be sufficient for muscle training stress, approximately 30-40 cm H2O pressure.

A more advanced Belt Exercise technique can also provide inspiratory muscular exercise. Instead of abruptly discontinuing external compression at the beginning of inspiration, the compressing pressure is gradually relaxed, in a manner that always applies a slight degree of resistance to expansion, and therefore encourages active but gentle inspiratory muscle effort. Then, as strength improves, the relaxing inspiratory force applied can be made more resistive, to encourage greater muscular training effort to enhance the strengthening objective.

For the patient with extremely atrophied inspiratory muscles with very low resistive pressure requirements, physiotherapists will recognize this is in fact a form of the PNF (Proprioceptive Neuro muscular Facilitation) technique.

Bilateral Breathing Belt Exercises should be a part of the daily routine of all patients in the first months of rehabilitation training, and practiced periodically thereafter to maintain these skills. During active rehabilitation training the Belt Exercise should be done only twice daily, for only five minutes, and come at the end of a five minute Breathing Training session which will be described later.

The technique is performed by placing the B reathing Belt around the back, and then each end positioned over the lower rib margins. The right hand grasps the left end in the left anterior axillary line, and likewise the left hand grasps the right end in the right anterior axillary line, with the hands and arms crossing each other in front of the chest. The belt should be snuggly fitting, so the patient can easily feel the chest moving with quiet respiration. It is usually best to be comfortably seated, though the technique may be done l ying supine.

After a larger than usual inspiration breath, slowly perform a long and exaggerated exhalation, using slight muscular effort to exhale. Then, about half way through expiration apply a firm and progressive pressure to the lower chest regions by pulling on both ends of the belt equally. The manner of chest compression requires careful instruction. If too abrupt and forced it can be damaging. Patients usually relate well to the analogy of wringing out a wet towel, with the inst ruction "If you try to suddenly wring out a wet towel you will get some water. But if you gradually but firmly wring the towel out you will get more water with less effort."

Then, after a long exhalation, abruptly remove the belt pressure and simultaneously breathe in gently. The patient should try to feel a satisfying rush of air going into the lower-lateral chest regions. Again, the emphasis is on expiration, to mobilize the chest and reduce Dynamic Hyperinflation (and coinciden tally aid in peripheral secretion removal). Inspiration should be focused on the lower-lateral chest, gentle, and smoothly coordinated with any inspiration effort. Forced or gasping inspiration is an abnormal trick movement and must be eliminated. Note carefully that any voluntary expiration effort should be minimal, to minimize Dynamic Bronchial Compression and therefore minimize premature peripheral airway closure. This carefully targeted rise in intra-abdominal pressure will promote the upward dis placement of the diaphragm to a more normal curved position, which in turn will improve diaphragm functionality.

As a subset of this exercise patients should be taught the Inspiration Limitation technique. There is a natural tendency for the dyspneic patient to want to take in a full breath of air. This only perpetuates the Dynamic Hyperinflation lesion. They should be taught to limit their inspiratory effort to only 75-80% of their desired normal breath volume. This is an excellent trick for u rgent Dynamic Hyperinflation correction if done over several breaths. Patients who understand this trick seem to instinctively select an appropriate inspiration volume and therefore prevent Dynamic Hyperinflation.

Repeat this slow breathing cycle only about five times at the beginning, to prevent fatigue. Later when the patient is better mobilized and stronger the cycles of exercise may last a minute or two. The entire exercise should not exceed five minutes, and be done only twice daily after the five minute period of breathing pattern training as described later. This limited exercise time appears to be quite adequate, and prevents undue fatigue and boredom. Therapy and exercise routines that intrudes excessively on the patient's life style is an invitation to non-compliance.

Patients usually find the crossed motion of the hands and pulling on expiration to be quite confusing. It is very helpful for the physiotherapist to teach the method by holding the patient's hands and then pulling on same to give the patient an understanding of the rhythm of the exercise and the proper pressure to apply, and when to release that pressure.

Patients may tend to rock forward during exhalation and straighten up during inspiration. If not too exaggerated and done in a coordinated manner this is helpful, as this will give greater chest compression and overinflation reduction.

A very long expiration with exaggerated forward bending, to the point where the hands are now on the patient's legs and p ressing firmly into the upper abdomen to force further lung emptying is known as the "Respiratory Squeeze." This is a good technique (though it is fatiguing) for emergency lung deflation in cases of acute Dynamic Hyperinflation. This is also an excellent technique for mobilizing peripheral retained mucus (to be followed be the so-called "Huff Cough" technique for final secretion expectoration).

NOTE: Patients usually complain of diffuse aching chest wall pain for about six weeks a fter chest mobilization. This is normal, and reflects the usual complaints of stiff joints and muscles now being re-activated.

BELLY PUFFING. In a wide spectrum of neurologic and muscular diseases, patients develop so-called "Trick Movements" in an attempt to compensate for lost functionality. There are good Trick Movements which aid functionality, and bad Trick Movements which interfere with functionality. The physiotherapist must learn to recognize undesirable Trick Movements and eliminate th em, while enhancing productive compensatory movements. Belly Puffing is a bad Trick Movement.

Belly Puffing is easy to perform, and therapists should learn the technique to gain insight as to how readily this can be done. Lying supine (in order to eliminate an artifact of abdominal content movement), practice puffing the abdomen in and out. Then, puff the abdomen out while exhaling, and pull the belly in while inhaling. Normally of course the abdomen expands due to decent of the diaphrag m on inspiration, and conversely contracts as the diaphragm rises on expiration. The Belly Puffing trick movement is therefore an abnormal artifact, which is exactly opposite of normal abdominal breathing movements. It must be carefully watched for, and eliminated.

A traditional technique to teach "Diaphragm (or Abdominal) Breathing" is to have the patient place one hand on the anterior upper chest and the other just below the xiphoid. The patient is then instructed to not move the upper hand while br eathing in, and simultaneously make the lower hand move outwards with inspiration. This traditional technique should be abandoned, as it encourages the abnormal Trick Movement of Belly Puffing.

The abnormal "pump handle" upper chest movement will go away naturally if the patient is consistently coached to perform Diaphragm Breathing by concentrating on the "bucket handle" movement on the lower-lateral rib margin at the mid to anterior axillary line position. The abdominal movement that develops subsequently will then more accurately reflect true diaphragm excursions.

Along with breathing physiotherapy it is important to begin general measures directed at peripheral muscle reconditioning. Typically patients with exertional dyspnea limitation become sedentary and deconditioned. The deconditioned muscle metabolizes inefficiently, requiring more oxygen and giving off more CO2 and acid metabolites for a given work load than well conditioned muscles. The deconditioned patient therefore must pro vide more ventilation than normally required, adding an additional ventilatory burden. Typically this leads to a vicious circle of less activity and further deconditioning. Improving peripheral muscle conditioning is therefore very important in overall pulmonary rehabilitation, in order the patient may be more mobile with relatively less ventilatory needs.

It is beyond the scope of this presentation to discuss peripheral exercise programs. Generally this author recommends endurance oriented training f or the legs (to enhance walking mobility) and to some degree strength oriented training for the arms (to enhance activities of daily living such as getting out of a chair).

When the chest wall has been restored to better functionality, it is now necessary to instruct the breathing apparatus as to what to do. This is the domain of Breathing Pattern Training.

Dating to at least the 1930's, largely em piric chest physiotherapy techniques evolved for treating COPD and Asthma, mainly in the United Kingdom. The breathing pattern component generally called for a slowing of the respiratory Rate, an increase in the Tidal Volume, and a prolongation of the Expiratory Time phase.

Specifics of the various respiratory parameters were not defined. At the 1995 ISARP conference this author presented a visual biofeedback technique to permit precise definition of the inspiration and expiration parameters (See: "A visual biofeedback method to define and teach breathing patterns" and "Clinical experience with a visual biofeedback method in COPD rehabilitation" Biological Psychology; Vol. 43 No. 3, pages 261 and 243-244, June 1996).

Briefly, an inspiration / expiration mechanical "Breathing Prescription" is designed by menu selection as a volume versus time analog display. A cursor blinks along this analog to prompt the patient where to be breathing. The patient's real time breathing signal is displayed. In the example shown the inspiratory effort is below the programmed line, therefore instructing the patient to inspire faster. The objective is to have the patient make a perfect match on the Breathing Prescription line.

Here is an example of a patient Air Trapping with Dynamic Hyperinflation. In the upper screen the patient's display is routinely blanked out, in order to obtain a standardized picture (Tidal Volume 1000cc, Respiratory Rate 10 bpm) of the patient's native breathing pattern. Note on expiration the patient's Resting Expiratory Level (REL) does not return to baseline, i.e. the Functional Residual Capacity (FRC) is increasing due to Dynamic Hyperinflation. The lower screen is with the patient following the Breathing Prescription. Note she is doing very well, with the REL now returning to the baseline FRC, thus resolving any Dynamic Hyperinflation. When you can see the patient breathe it provides much insight, and when the patient can see what they need to do they can easily relate to complex instructions.

A copy of this training record is routinely given to the patient. Note the hand written no tations of good performance, and performance that needs correcting. Note also the training instructions to practice their breathing training only twice a day, and for only five minutes.

Patients are instructed to recline in a comfortable chair, to relax, and to concentrate and to "Put this breathing picture in your mind." This five minutes of breathing pattern practice was then followed by five minutes of Belt Exercise. The brief periods of training done only twice daily avoid und ue fatigue, and boredom, and are only minimally intrusive on the patient's life style. Generally within two to three months most patients exhibit substantial breathing skills on follow-up review. Note carefully this breathing prescription is one that will prevent Dynamic Hyperinflation.

While the time of development of breathing skills is perhaps slower than in some programs, the fact that the vast majority of the training is shifted to the patient (generally only 2 to 4 physician / therapist v isits are needed in the first three months of rehabilitation), it is clear this is a very cost effective breathing re-training method.

Using this same patient example, strategies of Dynamic Hyperinflation correction have been drawn.

The commonest and usually best deflation strategy is a non-forced, or minimally forced, prolongation of the expiratory time by a pproximately 25%. This will minimize the problem of Dynamic Bronchial Compression (DBC) as discussed below. Repeated over several breaths all Dynamic Hyperinflation should be corrected, and the patient comfortable within 10 or so breaths. If this does not correct or substantially reduce the acute dyspnea level, probably the patient is making the mistake of fully inspiring and therefore re-establishing the overinflation lesion. In this case the Inspiration Limitation technique will resolve the problem. The second basic strategy is a forced expiration technique, without expiration prolongation. The technique is fatiguing, and to be used only as a rescue technique for severe overinflation. Properly done it should promptly resolve the Dynamic Hyperinflation lesion.

Patients should be thoroughly instructed in recognizing and avoiding the Rescue Breathing Pattern which is a common psychological based reason for acute dyspnea attacks. Anxi ety is a common trigger for hyperventilation, and anxiety based on the dyspnea sensation is a particularly powerful emotional stimulus to induce hyperventilation. In the COPD patient this can trigger Dynamic Hyperinflation.

Typically a COPD patient will experience mild exertion dyspnea, become anxious, hyperventilate, and promptly convert a mild dyspnea situation into a severe dyspnea attack. For details see the authors ISARP 2000 presentations "The Rescue Breathing Pattern: Physiologic and Psycholog ic Consequences in COPD" and "A Breathing Pattern Training and Portable Activation System: Use in the Rescue Breathing Pattern in COPD" (Biological Psychology; Proceedings of the 7th Annual Meeting of ISARP, Vol. 56 No. 1, pp 63-81, March 2001).

This simple cartoon illustrates Dynamic Bronchial Compression by reducing the lung to one alveolus and one peripheral airway within the chest. As the chest wall moves inward on expiration, pressure is generated on the alveolus to produce exhalation. At the same time this necessary driving pressure is also being applied to the peripheral airways. If the peripheral airways are deficient in elastic support, to maintain the airway in an open position, a Critical Closing Pressure is exceeded and the airway collapses, with a resul ting increased airway obstruction and air flow limitation.

This more complete DBC illustration is also taken from Comroe's text. It is clear from these diagrams that it is necessary to generate a positive driving force within the chest to achieve expiration. However, if the driving exhalation force is excessive, there will be premature peripheral airway collapse and expiration will be impaired. This is a particularly severe problem in Emphysema, where the airways are distorted and deficient in elastic support to help maintain an open state.

This leads to a fundamental chest physiotherapy problem and conflict. Dynamic Hyperinflation correction requires a decrease in the overinflated FRC. However, the Dynamic Bronchial Compression lesion will be helped by an increased FR C, which will relatively expand the lung and therefore enhance the elastic support of the airways. Both therapy concepts and concerns are valid. The problem then becomes one of which pathophysiological lesion is dominant, and how far can one apply a competing therapy modality before imposing an added functional burden.

Proponents favoring an increased working lung volume include chest physiotherapy pioneers Diana Innocenti and Dr. Claude Lum ("Breathing Exercises in the Treatment of Em physema" Physiotherapy; pp. 437-441, December, 1966). Their concerns are valid, and must be addressed within the problem of the Dynamic Hyperinflation lesion.

While it is desirable to maintain a totally passive exhalation by using only the elastic recoil of the chest wall to provide the driving pressure (to minimize DBC), at times this is not possible. Some added expiratory force may be required if the patient cannot return to their FRC baseline, or, if the expiratory time becomes so pro longed that the overall respiratory Rate is excessively slowed. If needed, the expiratory force should be applied as late as possible during exhalation, and only the minimum force necessary should be applied. Indeed, this is a challenging task that touches more on the art of chest physiotherapy.

NOTE: For patients with a flattened diaphragm secondary to severe overinflation, a moderate degree of upper abdominal compression at the end of expiration may aid in forcing the diaphragm into a better working position.

Occasionally forced expiration can be a useful technique for emergency decompression of severe hyperinflation. However, this is a "brute force" technique and very exhausting, and should only be used in a limited manner, and with discretion.

The physiologic conflict may be put in perspective by this modified diagram from O"Donnell and colleagues.

Line "A" is a theoretical maximal correction of Dynamic Hyperinflation. Line "C" is a theoretical level of Dynamic Hyperinflation correction where Dynamic Bronchial Compression first begins. Line "B" is a theoretical level where Dynamic Hyperinflation correction results in a dominant Dynamic Bronchial Compression lesion. QUESTION: Where would the reader place Line B ?

The answer to this question would clarify important practical chest phys iotherapy technique questions and controversy. It awaits study by advanced pulmonary mechanics research. Perhaps the promising Expiratory Flow Limitation (EFL) estimation method by Eltayara, Becklake, and Volta et al (Relationship between chronic dyspnea and expiratory flow limitation in COPD patients. Am J Respir Crit Care Med 1996; 154: 1726-1734) might be used to advantage here.

Many of the chest physiotherapy techniques and breathing pattern manipulations have both benefici al as well as adverse consequences on other parts of overall physiologic needs. With this in mind, one should be cautious about strong advocacy for one or another particular technique. The focus should be on the dominant physiologic problems, and resolving these problems with the best possible compromise strategies, while keeping in mind potential adverse consequences of the therapy program.

Regardless of any therapy controversies, chest physiotherapy in COPD and Asthma resides on a firm scientific fo undation, and long standing empiric experience of beneficial results in dyspnea relief. The time for re-introduction into the United States seems long overdue.