PROGRESSIVE RESISTIVE LOADING ON ACCESSORY EXPIRATORY MUSCLES IN TETRAPLEGIA * P Gounden SUMMARY To investigate the effects of progressive resistive loading on accessory expiratory muscles in tetraplegia, 40 such patients undergoing standard pulmonary rehabilitation were randomly assigned to control (n = 20) and experimental (n = 20) groups. In total there were 8 women and 32 men with an average age of 31 years. Their lesions were between the fifth and eighth cervical segments. The majority of the patients sustained their injury during motor vehicle accidents. Prior to training, measurements of maximum expiratory mouth pressure and vital capacity were obtained from each group. The experimental group underwent eight weeks of training. The training involved the use of the PFLEX muscle trainer which allowed the patient to expire against a predetermined resistance. The initial resistive load was set at a level equivalent to 60 percent of the patient’s maximum expiratory mouth pressure. Each sub­ ject was required to train for half an hour each day for six days a week. The resistive load was increased at two weekly intervals to ensure optimal loading throughout the training period. The control group was excluded from any form of strenuous training, but continued with the standard pulmonary care which involved conventional breathing exercises and assistance in coughing. The eight week long course of progressive resistive loading on accessory expiratory muscle showed a significant improvement in mean vital capacity from 1.48 L to 1.98 L (p = 0.0001) and a dramatic improvement in mean expiratory muscle strength from 43.76 cmH20 to 68 cmH2o) (p = 0.0001). Comparison of the values in the control group which were obtained eight weeks apart, showed no significant changes. The present finding that expiratory muscle strength in tetraple- gics can be improved with specific training has important thera­ peutic implications. The increased PEmax should enable these subjects to generate higher intrathoracic pressure swings during coughing. Long term controlled studies should now be performed to deter­ mine the effects of this procedure on the clearance of bronchial secretions in such subjects. INTRODUCTION T he growing incidence o f spinal cord injuries in South Africa is directly related to physical injuries occurring as a result o f m otor vehicle accidents, interpersonal violence and sporting activities. T he m ost com mon location o f these injuries is the cervical spine. T he figures relating to the incidence o f cervical cord dam age in S outh Africa are com parable to those available for oth er W estern nations. In 1987 th e Conradie Hospital in th e Cape Province (one o f th e leading spinal care centres in S outh Africa) estim ated th at fifty p ercent o f all spinal injuries for th a t year involved the cervical spine. Pulm onary complications present a m ajor th reat to th e life­ span o f th e patient suffering from a com plete lesion a t any level o f Poobalam Gounden PhD Physiotherapy University of Durban-Westville, King Edward VIII Hospital, Natal University - Faculty of Medicine OPSOMMING In ’n studie om die effekte van progressiewe weestandslading op die aksesoriese spiere in kwadrupleS te bepaal, is 40 pasiente wat gestandariseerde pulmondre rehabilitasie on- dergaan, gebruik. Hulle is blindelings verdeel in 'n kontrole (n = 20) en ’n eksperimentele (n = 20) groep. Daar was 8 vroulike and 32 manlike pasiente met ’n gemiddelde ouder- dom van 31 jaar. Hul letsels wastussen C5 en C8. Die meeste pasiente het hul beserings tydens ’n motorongeluk opge- doen. Voor oefening is die maksimum ekspiratoriese monddruk en vitale kapasiteit gemeet in beide groepe. Die eksperimentele groep het 8 weke lank 'n oefeningprogram ondergaan. Die oefening het die gebruik van die PFLEX spierbouer ingesluit waardeur die pasienttoegelaat is om teen 'n voorafbepaalde weerstand uit te asem. Die aanvangsweerstandslading is gestel on 'n vlak gelyk aan 60 persent van die pasifint se maksimum ekspiratoriese monddruk. Elke pasifint moes vir ’n halfuur elke dag, ses dae per week, oefen. Die weerstand- slading is twee weekliks verhoog om optimale lading tydens die oefenperiode te behou. Die kontrole groep is weggehou van enige vorm van swaar oefening, maar het wel voortgegaan met die normale pul- monfire versorging, nl. konvensionele asemhalingsoefen- inge en hulp met hoes. Die 8 week lange kursus van progressiewe weerstandslading op die aksesoriese ekspiratoriese spiere het 'n betekenisvolle verbetering in die algemene vitale kapasiteit, van 1.48 L tot 1.98 L (p = 0.0001) meegebring. 'n Vergelyking in die waar- des in die kontrole groep voor en na 8 weke het geen merkwaardige veranderinge getoon nie. Die huidige bevinding dat ekspiratoriese spiersterkte in kwa- druplee verbeter kan word met spesifieke oefening, bring mee belangrike implikasies. Die stygende PEmax behoort pasiente intra-torakale drukveranderinge tydens hoes te gee. Lang termyn beheerde studies behoort nou gedoen te word om die effekte te bepaal wat hierdie prosedure op die mobi- lisering en verwydering van sekresies op sulke pasiente het. th e cervical cord (tetraplegia). T h e respiratory insufficiency in te tra ­ plegia is secondary to paralysis o f th e intercostal and abdom inal muscles U W A 7 ’8 T he expiratory muscle force is reduced to less than 40 percent o f it norm al values causing a serious im pairm ent on th e patient’s ability to cough 9'10'11'12. In addition to this, vital capacity has been shown to drop to levels less than 50 percent o f its norm al values 3,13,14,15,9 T hese factors a re closely association with th e incidence o f hypostatic pneum onia which has been shown to be o n e o f th e leading causes o f d eath in te trap le g ia16'17'18,19’20’21,22. In addition to this com prom ised pulm onary defence system the tetraplegic also develops ventilatory muscle w eakness caused by structural changes in the muscles th a t have been spared by th e lesion. CAPE TOWN: Full-time Physiotherapist needed for private practice in Blaaubergrand. No hospital work. Contact: P Vorster-Tel: (021) 557-4515 (w); (021) 52-5585 (h) Bladsy 4 Fisioterapie, November 1990, deel 46 no 4 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) A patient with a low lesion may have partial o r total innervation to the diaphragm, sternocleido-mastoid, scalene and trapezius muscles, which serve a vital role in maintaining adequate ventilatory function. The importance o f preventative respiratory therapy was re­ cently highlighted by Carter3, an internationally respected spinal care specialist. In a recent publication he expressed the following concern: “Certainly there are few, if any, areas elsewhere in the field o f medicine that require treatm ent prior to the onset o f pathology as does the respiratory muscle weakness in spinal cord injury.” H e considers the conditioning o f ventilatory muscle to be an important part o f the total pulmonary rehabilitation program m e3. This could be accomplished with the aid o f a specific training program m e which involves progressive loading o f the accessory muscles o f ventilation. Ventilatory muscle training in clinical practice is still in the experimental stage and the scientific basis for training has as yet not been firmly established4,24’25'248,27. Leith and Bradley, after a six week training program m e using isocapnic hyperpnoea achieved marked improvement in ventilatory muscle strength and endurance among a group o f normal subjects27. In 1980, Gross and co-workers tested the effect o f resistive inspiratory muscle training on a small group o f tetraplegics and found favourable results both in ventilatory muscle strength and e n d u r­ ance28. This study was designed to test the effect o f progressive resis­ tive loading on accessory expiratory muscles in tetraplegics with low cervical cord lesions. T he rationale for training was based on evi­ dence that tetraplegics retrain the use o f the clavicular part o f the pectoralis major and latissimus dorsi muscles during active expira­ tion16. This is a poorly researched area despite the fact that the tetraplegic suffers a far greater impairment in expiratory function than in inspiratory function16. METHOD Forty sedentary tetraplegics were studied. T here were eight females and thirty two males. Thirty three patients were registered in-patients at hospitals, while six w ere in institutions for the disabled. T he remaining patient was a successful businessman who lived on his own. Their dem ographic d ata are detailed in Tables 1 and 2. Approximately 40 percent o f them spent most o f their time in bed. They were p u t in supported sitting positions for only short periods. T he other 60 percent spent p art o f the day in wheelchairs and the rest o f th e day in bed. M ost were receiving some form o f rehabilitative procedure, TABLE 2: CLINICAL DETAILS OF THE PATIENTS IN THE EXPERIMENTAL GROUP CASE AGE SEX LEVEL OF NATURE OF POST-INJURY* NO SPINAL LESION INJURY PERIOD-MONTHS 1 25 M C5/6 STAB WOUND 12 2 30 M C6/7 MVA 31 3 27 M C5/6 FALL 8 4 33 M C7 MVA 12 5 30 M C6 DIVING INJURY 36 6 17 M C5/6 FALL - MOUNTAIN 5 7 16 M C6 RUGBY INJURY 5 8 35 M C7 MVA 4 9 22 M C6 MVA 7 10 20 M C6/7 MVA 7 11 24 M C6 MVA 48 12 24 F C6 MVA 60 13 45 F C5/6 MVA 4 14 ' 31 M C5/6 MVA 9 15 34 M C5 MVA 5 16 39 M C7 STAB WOUND 159 17 23 M C7 DM N G INJUJRY 31 18 30 M C6 MVA 46 19 24 M C7 FALL 38 20 27 F C6 MVA 21 * Indicates the post-injury stage at which the study was done either at the Occupational o r Physiotherapy D epartm ents. Their program m es w ere a t a low intensity level with either twice o r thrice a week attendances. N one o f these patients was involved in any form o f strenuous upper body training prior to o r during the study period. They w ere all in a clinically stable state and did not have any respir­ atory symptoms apart from the restrictive respiratory com prom ise secondary to ventilatory muscle paralysis. Subjects w ere randomly assigned to two groups, an experimental group and a control group. T here w ere twenty patients in each group. EVALUATION OF LUNG FUNCTION AND VENTILATORY MUSCLE STRENGTH PRIOR TO TRAINING B efore m easurem ents were taken, each patient was famil­ iarized with the experimental techniques so that learning would not produce spurious results. Vital capacity and maximum static respir­ atory pressures w ere m easured in all patients in two study positions (su p p o rted sitting and supine position). T h e vital capacity was m easured on a V italograph Spirom eter (from Medical Insturm en- tation). R ep eated determ inations were m ade until two technically satisfactory m easurem ents w ere obtained. T h e highest value o b ­ tained was recorded. T h e o rd er o f th e positions in which the spirome- tric m easurem ents w ere m ade was varied in random sequence. MEASUREMENTS OF VENTILATORY MUSCLE STRENGTH T he PEm ax ad the PImax were m easured on the Inspira­ tory/Expiratory Force M eter (Figure 1). T he PEm ax was m easured a t total lung capacity. A fter a maximum inspiratory effort the m outh piece was placed well into th e m outh and th e patient was asked to expire as forcefu lly and quickly as possible. T h e m ean o f th ree trials was recorded. This was followed by a short rest which lasted for approximately five m inutes after which th e PImax was m easured as follows: A fter a maximum expiratory effort the subject was asked to inspire with maximum force. T he m ethod o f docum entation was the sam e as that for the PEm ax values. T he ord er o f position in which the pressures w ere m easured was varied in random sequence. T he experimental group underw ent specific training for 8 weeks while the control group continued to receive conventional therapy. T he con­ ventional therapy did not include any form o f vigorous activity or resisted breathing manoeuvres. TABLE 1: CLINICAL DETAILS OF THE PATIENTS IN THE CONTROL GROUP CASE AGE SEX LEVEL OF NATURE OF POST-INJURY* NO SPINAL LESION INJURY PERIOD-MONTHS 1 25 M C6 MVA 4 2 28 M C7 MVA 4 3 24 F C7 MVA 4 4 27 F C5/6 MVA 25 5 34 M C6 DIVING INJURY 108 6 37 M C5/6 MVA 17 7 30 M C5/6 MVA 132 8 28 M C6 MVA 14 9 21 M C6 MVA 14 10 39 M C5/6 MVA 192 11 24 M C5 STAB WOUND 33 12 39 M C6 MVA 35 13 26 M C7 MVA 27 14 25 M C5/6 MVA 4 15 39 F C7 MVA 36 16 40 M C7 MVA 84 17 64 M C6 FALL 4 18 40 F C6/7 FALL 4 19 30 F C5 FALL 4 20 55 M C5/6 FALL 6 * Indicates the post-injury stage at which the study was done Physiotherapy, November 1990, vol 46 no 4 Page 5 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) VALUE FOR MONEY ULTRASONIC THERAPY Therasonlc Six The Therasonic Six is the latest application by EMS o f new technology to produce a single output, single frequency ultrasonic therapy unit. The Six incorporates many o f the features o f the more sophisticated 1032 unit - the same case, the same design o f treatment head, the same superb-quality push button type o f control panel; also the same waterproof carrying case fas an optional extraj. It is available in tw o versions - a 1 MHz model and a 3 MHz model. Both models are identical in everything except the operating frequency. The Therasonic Six weighs only 4.2 kg (9 lb). Facilities include: 1. 7 output levels -0 .1 , 0.2, 0.5, 0.75, 1.0, 1.5, 2.5 w /c m . 2. Pulsed and continuous modes. 3. Digital treatment timer. 4. Fully-immersible 5 sq cm treatment head (protected by automatic cut-out when not in patient contact). 5. Socket fitted to unit to allow for combination therapy (i.e. ultrasound w ith interferential, diadynamic, faradic). Brief Technical Specification Therasonic Six - 1 MHz Model and 3 MHz Model 100.120, 220, 240 V ~ 50/60 Hz 45 W 320 x 302 x 110 mm 4.2 kg Class 1: Type BF (IEC 601-1: 1977) I.1 MHz + / - 5% (3 MHz Model - 3.4 MHz + / - 5 : 60 -i> 50 - 40 - 30 • 2 0 - P R E -T R A IN IN G P O S T -T R A IN IN G The selection o f an appropriate training posture was based on the w ork undertaken in a preliminary study. This was necessary to standardise the exercise position in each patient. T he patients were therefore instructed to train in a particular position from which the pre- and post-training m easurem ents were also recorded. T he main­ tenance o f a single starting position was im portant to prevent adaptive changes in the muscle fibres caused by changes in posture as dem on­ strated by D anon, M ortola and Miller41,42,43. T herefore, the improve­ m ents in exspiratory muscle strength as shown in this study cannot be attrib u ted to adaptive changes in length tension ratio in the muscle fibres, which can sometim es be caused by postural changes44,43. In ord er to achieve optimal training effects the breathing strate­ gy was carefully controlled. Electromyographic examination o f the accessory expiratory muscles u n d ertak en in an o th er preliminary C ontinued on P age 15 Bladsy 10 Fisioterapie, November 1990, dee/ 46 no 4 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) C ontinued from Page 10 study showed maximum m otor unit activity during the forced resisted breathing following a deep inspiratory phase. During this forced phase the expiratory muscles were working concentrically against a predetermined resistance. It has previously been suggested that a strengthening program m e should devote 75 percent o f the training to concentric muscle work45. The deep inspiratory phase lengthened the inspiratory fibres and force expiratory phase cause concentric muscle work. This type o f training caused interm ittent loading on these muscles. The improvements in PEmax m easurem ents only became evi­ d ent after the fourth week o f training. These m easurem ents showed negligible changes in the early stages o f training. This m eant that the increased in expiratory muscle potential could not be attributed to non-specific learning effect. The are in fact a reflection o f the impact o f a specifically designed training program m e on ventilatory muscles. T he level o f the lesions in the experimental group ranged from the fifth to the eighth cervical segment. T herefore, all the subjects in this group had at least a partial innervation o f the clavicular part o f the pectoralis major and latissimus dorsi muscles. T he significant improvement in accessory expiratory muscle strength as represented by the increase in maximum expiratory m outh pressures could be attributed to several factors: • An improvement which could be due to muscle fibre hyper­ trophy44. • The threshold o f training stimulus might have initiated the recruitm ent o f a larger portion o f the partially innervated muscles. • Beside the known accessory expiratory muscles, the serratus anterior muscle as well as oth er u p p er thoracic muscles (spared by the lesion) may also have a role in the mechanism o f active expiration in tetraplegia. T he training stimulus might have recruited active contraction in these muscles. T here was a 16 percent improvement in the mean PImax signifying that inadvertent concentric conditioning o f the inspiratory muscles in the experimental group resulted in minor changes in muscle strength. Therapeutic intervention in the form o f specific training was administered at various stages in the post-injury period. Some p a ­ tients w ere studied four months after their injury while others were studied many years after the onset o f their injury (Table 2). Positive training effects were achieved in all patients. This implied that te tra­ plegics, at various stages in their post-injury period, may benefit from this form o f training. T he object o f the study was to determ ine the effect o f training on accessory expiratory muscles in tetraplegics. T he patients in the experimental group would not have been suitable to a scientifically viable study involving the quantification and shift o f secretions. A study o f this nature should be conducted only on patients with evidence o f increased sputum yield. T he subjects in the experimental group were free o f any respir­ atory infections at the time o f the study. T he selection criteria ex­ cluded patients with respiratory infections. Respiratory infection in any o f the subjects in the experimental group would have had an adverse effect on their exercise tolerance. This would have produced misleading results. A few patients form the experimental group, however, showed subjective evidence o f improvement in the ability to cough. This ability to effect a productive cough might have been due to an improvement in expiratory muscle strength. F urtherm ore, it was not possible to report on the length o f tim e for which the training effects would last since the m easurem ents w ere not monitored longitudinally after the allotted period o f eight weeks. CONCLUSIONS AND RECOMMENDATIONS T he conclusions drawn from this study indicate that specific training involving progressive resistive loading on the accessory expir­ atory muscles significantly improves muscle strength. T he study also showed that effective strength training should involve the use o f near maximal resistances throughout the allotted training period. Clinical evidence showed enhancem ent in the patient’s ability to cough. F u rth e r carefully controlled long-term studies are recom ­ m ended to investigate the effect o f accessory expiratory muscle train­ ing on morbidity and morality in patients with com plete lesions o f the cervical cord. These would need to monitor, inter alia: • T he duration for which the beneficial effects are maintained after a single training period • and consequently the frequency o f such a training program m e during rehabilitation • the volume o f sputum expectoration • the incidence o f infective complications. T he outcom e o f such studies will determ ine the long-term clinical value o f ventilatory muscle training in tetraplegia. REFERENCES 1. McCagg C. Post-operative management and acute rehabilitation of p a­ tients with spinal cord injuries. Orthop Clin North A m 1986; 17(1):171- 182. 2. Massery M. An innovative approach to assistive cough techniques. Top Acute Care Trauma Rehabil 1987; l(3):73-85. 3. Carter R E. Respiratory aspects of spinal cord injury management. Para­ plegia 1987; 25:262-266. 4. Clough P, Londenauer D, Hayes M, Zekany B. Guidelines for routine respiratory care of patients with spinal injuries. Phys Ther 1986; 66:1395- 1402. 5. Alvarez S E, Peterson M, Lonsford B R. Respiratory treatment of adult patients with spinal cord injury. Phys Ther 1981;61:1737-1745. 6. Axen K, Pineda H Schunfenthal H, Haas F. Diaphragmatic function following cervical cord injury./lrc/i Phys M ed Rehabil 1985;66:219-222. 7. McMichan J C, Michel L, Westbrook P R. Pulmonary dysfunction following traumatic quadriplegia: recognition, prevention and treatment. JAMA 1980;243:528-531. 8. Lerman R M, Weiss M S. Progressive resistive exercise in weaning high quadriplegics from the ventilator. Paraplegia 1987;25:130-135. 9. Robin M J. Respiratory monitoring in the intensive care unit. A m Rev Respir Dis 1988;138:1625-1642. 10. Fugl-Meyer A R. Effects of respiratory muscle paralysis in tetraplegic and paraplegic patients. ScandJRehab M ed 1971;3"141-150. 11. Leith D E. Cough. Phys Ther 1968;48:439-447. 12. Haas F, Axen K, Pineda H, Gandino D, Haas A. Temporal pulmonary function changes in cervical cord injury. A rch Phys M ed Rehabil 1985;66:139-144. 13. Guttman L, Silver J. Electromyographic studies on reflex activity of the intercostals and abdominal muscles in cervical cord lesion. Paraplegia 1865;3:1. 14. Tobin M J. Respiratory muscles in disease. Clinics in Chest Medicine 1988;9(2):264-286. 15. Estenne M, D e Troyer A. Relationship between respiratory muscle electromyogram and rib cage motion in tetraplegia. A m Rev Respir Dis 1985;132:53-59. 16. De Troyer A, Estenne M, Heilpom A. Mechanism of active expiration in tetraplegic subjects. N Engl J M ed 1986;314(12):740-744. 17. Cheshire D J E. Respiratory management in acute tetraplegia. Paraplegia 1964;1:252-261. 18. McMichan J C, Michel L, Westbrook P R. Pulmonary dysfunction follow­ ing traumatic quadriplegia : recognition, prevention and treatment. JAMA 1980;243:528-531. 19. Fugl-Meyer A R, Grimsby G. Ventilatory function in tetraplegic patients. ScandJ Rehabil M ed M D 1971;3:151-160. 20. Fom er J V. Lung volumes and mechanics of breathing in tetraplegia. Paraplegia 1980;18:258-266. 21. Ledsome J R, Sharp J M. Pulmonary function in acute cervical cord injury. A m Rev Respir Dis 1981;124:41-44. 22. Bergofsky E H . Mechanism for respiratory insufficiency aftercervical cord injury. A nn Intern Med 1964;61:435-447. 23. Engel W K. The essentiality o f histo- and cyto-chemical studies of skeletal muscles in the investigation of neurom uscular disease. Neurology 1972;12:778-794. 24 Axel R, Fugl-Meyer A R, Grimsby G. Respiration in tetraplegia and hemiplegia: a review. Int Rehab M ed 1984;6:186-190. 25. Gounden P. Ventilatory muscle training. Proceedings of Congress of S A Society of Physiotherapy, Johannesburg 1985. Physiotherapy, November 1990, vol 46 no 4 Page 1S R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )