Aquatic Physiotherapy Group
Aquatic Physiotherapy
Level 3 Course
Literature Review
The Effectiveness of Aquatic Physiotherapy in Patients with
Haemophilia: A Review of the Literature
Nicola Blum
Senior Physiotherapist
Victorian Paediatric Rehabilitation Service
Monash Children’s Hospital
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
The Effectiveness of Aquatic Physiotherapy in Patients with Haemophilia: A review of the
literature.
Nicola Blum
Senior Physiotherapist
Victorian Paediatric Rehabilitation Service
Monash Children’s Hospital
_____________________________________________________________________________________
1
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
Abstract
Haemophilia and its secondary complications can have a detrimental impact on the quality of life
of its sufferers. Aquatic based interventions are often recommended for these patients because of
the therapeutic benefits water based activities offer. Evidence suggests aquatic physiotherapy
could be beneficial and effective for haemophilia patients especially following bleeds. This
literature review investigates the evidence of aquatic exercise therapy in a haemophilia
population to 1) determine the role of this intervention and to 2) determine its effective dosage.
A literature review was undertaken using specific search terms and after an inclusion and
exclusion process, four articles fit the criteria. Within these studies, participants’ range of motion
(ROM), strength, pain and aerobic capacity was measured. It was noted in these studies, that
ROM, strength, pain and aerobic capacity all improved within an aquatic intervention. However
these results must be taken with caution, as the studies were of poor quality with poor
methodological rigour and potential bias. This review highlights there is a lack of supporting
evidence for aquatic physiotherapy in patients with haemophilia and further research into this
area is indicated especially to determine the best practice guidelines and an effective dosage of
such an intervention.
Keywords: haemophilia, aquatic physiotherapy, aquatic therapy, hydrotherapy, water therapy,
water exercise.
Introduction
Haemophilia, a congenital genetic disorder (Kargarfard, et al., 2013) is a result of an inherited
recessive trait in the X chromosome (Souza, et al., 2011). It occurs in sufferers as a result of a
deficiency in coagulation factor VIII (Haemophilia A), and IX (Haemophilia B) (CuestaBarriuso, et al., 2013; Souza, et al., 2011). Haemophilia A is the most common form of
Haemophilia with an estimated 90% percent of all cases (Souza, et al., 2011).
In Australia, Haemophilia is estimated to affect approximately 3000 people who are mostly
males (Haemophilia Foundation Australia, 2014). However, whilst very rare, females can also be
affected (Haemophilia Foundation Australia, 2014). A study by Kargarfard, et al (2013)
conducted in Iran reported as high as one in every 10 000 newborn has Haemophilia A.
_____________________________________________________________________________________
2
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
There are three types of Haemophilia depending on the percentage of the blood clotting factor
(Cuesta-Barriuso, et al., 2013). The smaller the percentage of blood clotting factor, the more
severe the form of haemophilia. The three types are seen below:
•
Mild Haemophilia (>5-40% FVIII/FIX) with bleeding during surgical procedures or from
severe injuries,
•
Moderate Haemophilia (1-5% FVIII/FIX) with bleeding from slight injuries,
•
Severe Haemophilia (<1% FVIII/FIX) characterised by spontaneous bleeding.
Joint bleeds, also known as a haemoarthrosis, is the most prevalent and degenerative
complication in patients with haemophilia. It is estimated that 80% of bleeds occur as a
haemoarthrosis (Rodrigues-Mechan, 1996). The symptoms of a haemoarthrosis include severe
pain, swelling and inflammation, increased skin temperature, reduced range of motion, muscle
atrophy as well as synovial involvement (Cuesta-Barriuso, et al., 2013; Kargarfard, et al., 2013).
Without the proper treatment, a haemoarthrosis can lead to capsular and tendon contractures of
the affected joints attributing to detrimental consequences of the musculoskeletal system and the
function of haemophilia patients (Cuesta-Barriuso, et al., 2013). Furthermore, in haemophilia
sufferers, chronic arthropathy is also a major cause of morbidity (Cuesta-Barriuso, et al., 2013).
The elbow, knee and ankle are the most common joints involved in a haemoarthrosis however
the hip and shoulder can also be affected, though infrequently (Rodrigues-Mechan, 1996).
Furthermore, a joint that is affected by several bleeds within 3-6 months is susceptible to further
articular degeneration (Jansen, et al., 2008) and may lead down a negative path to haemophilic
arthritis, with a similar presentation to that of rheumatoid arthritis (Mazloum, et al., 2014).
Presently, haemophilia sufferers are often treated with replacement therapy. However prior to the
availability of factor VIII and IX, treatment included bed rest, ice, splinting and/or braces and
patients who did not have replacement therapy may have had up to five damaged joints by the
age of 20 years (Heijnen, 2008). However with the current improvements in medical advances,
such as replacement therapy, bleeding is reduced and its secondary complications such as
haemoarthropathies can be prevented (Heijnen, 2008).
_____________________________________________________________________________________
3
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
Alongside replacement therapy, regular physical activity is important in patients with
haemophilia in preventing further damage and injury to their joints especially in patients who
have haemoarthroses (Heijnen, 2008). Souza, et al., (2011) state the importance of physical
activity for patients with haemophilia for the benefits of improving strength and skeletal muscle
cross- sectional area, flexibility, and decreased body fat.
However, in patients where exercising and walking on land may exacerbate pain, further limit
range of motion (ROM) and increase swelling or inflammation, exercise undertaken in water
provides an effective medium to exercising on land, thus providing more benefits over a land
based program. Mazloum, et al., (2014) report that the effect of buoyancy and unloading the
lower extremities, encourages patients to exercise more effectively, leading to improved
outcomes. Heijnen, (2008) supports the use of aquatic physiotherapy for haemophilia patients
who have painful or stiff joints especially in the early stages of rehabilitation following a
haemoarthrosis, muscle bleed or chronic arthropathy. Furthermore, Heijnen, (2008) reports
aquatic physiotherapy can help patients who have chronic synovitis, bridging the gap of land
based mobilisation and following long periods of bed rest or weaning from a splint.
This review investigates the current evidence of water based therapy programs in patients with
haemophilia and to determine what improvements can be achieved with this intervention.
Methods
To obtain the articles, five databases were systemically searched (PubMed, Medline, CINAHL,
PEDro and Cochrane). The keywords as can be seen in Table 1 were haemophilia and aquatic
physiotherapy or aquatic therapy or hydrotherapy or water therapy or water exercise. Articles
were included if in the abstract they were pertaining to aquatic physiotherapy or word derivative
equivalent alone (aquatic physiotherapy, aquatic therapy, hydrotherapy, water therapy, water
exercise) and with land based physiotherapy in a haemophilia population. They were excluded if
they were not in English. The process can be seen in figure 1. There were no date limits placed
on the databases. Each article was critically appraised using the PEDro scale as can be seen in
table 2.
_____________________________________________________________________________________
4
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
Table 1. Keywords used in search strategy
Population
Haemophilia (AND)
Intervention
aquatic physiotherapy (OR)
aquatic therapy (OR)
hydrotherapy (OR)
water therapy (OR)
water exercise
Articles retrieved n= 68
PubMed- 54
Pedro 1
Cochrane 5
Medline- 4
CINAHL- 4
Review of title and abstract
• Removal of duplicates and systematic
reviews
Included if:
• Published in English
• Study in a Haemophilia population
• Involved in aquatic physiotherapy
or equivalent intervention
Eligible n= 4
Figure 1. The process of searching for articles.
_____________________________________________________________________________________
5
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
Table 2. Break down of the four studies into their methodological parts.
Study design
Garcia,
et al.,
(2009)
Pre-test
posttest
Mazloum, et al.,
(2014)
Kargarfard, et al.,
(2013)
Vallejo, et al.,
(2010)
Semi
experimental pretest post-test
Pre-test post-test
4
4
Level of evidence
4
Supervised quasiexperimental and
perspective with
non- randomised
pre-test- post-test
control group
4
Eligibility criteria were
specified
Subjects were randomly
allocated to groups (in a
crossover study, subjects
were randomly allocated an
order in which treatments
were received)
Allocation was concealed
No
Yes
No
Yes
No
No
Yes
No
No
No
No
No
Groups were similar at
baseline regarding the most
important prognostic
indicators
There was blinding of all
subjects
There was blinding of all
therapists who administered
the therapy
There was blinding of all
assessors who measured at
least one key outcome
Measures of at least one key
outcome were obtained from
more than 85%
of the subjects initially
allocated to groups
All subjects for whom
outcome measures were
available received the
treatment or control
condition as allocated or,
where this was not the case,
data for at least one key
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
_____________________________________________________________________________________
6
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
outcome was analysed by
“intention to treat”
The results of betweenYes
group statistical
comparisons are reported for
at least one
key outcome
The study provides both
No
point measures and
measures of variability for
at
least one key outcome
Total of Yes
3
Yes
Yes
Yes
Yes
Yes
Yes
6
5
5
Results
As can be seen in table 3 and table 4 below, the search yielded four studies for review. Of these,
three studies investigated the effect on warm water exercise on joint ROM (Table 3). These
studies were by Garcia, et al., (2009), Kargarfard, et al., (2013), and Mazloum, et al., (2014).
Furthermore Mazloum, et al., (2014) investigated pain and Kargarfard, et al., (2013) looked at
knee flexion and extension strength in their studies. In addition a study by Vallejo, et al., (2010)
investigated the effects of training in motor performance in patients with haemophilia (Table 4).
Table 3. Review of articles investigating focusing on ROM.
ROM
Article
Participants
Program
intervention
Garcia, et al., (2009)
9 children with
haemophilia and
arthropathies between 5
and 13 years of age.
9 children with no
pathology.
30 minute program
consisting of:
1. Vertical cycling
in suspension at
2.10m depth with
a floatation
device under the
Mazloum, et al.,
(2014)
40 patients
Therapeutic exercise13
Hydrotherapy- 14
Control- 13
Not specified.
Kargarfard, et al.,
(2013)
20 males with
moderate
haemophilia- 10 in
experimental group
and 10 in control
group
40-60 minutes of
water exercise therapy
consisting of:
• Warm upProgressive
aerobic
_____________________________________________________________________________________
7
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
armpits for 10
minutes.
2. Controlled
breathing for 3
minutes.
3. Transverse,
sagittal and
longitudinal
rotation control
through games for
10 minutes.
4. Activities for
buoyancy,
balance and
immobility
control for 7
minutes.
Program frequency
Program duration
Program provided
by
Is there a control
group?
Comparison to
land intervention
Could program be
replicated?
Outcome measures
2 times per week
Not specified.
Not specified
Not specified
4 weeks
Not specified
activity 5074% of
maximal heart
rate. Activity
not specified.
• Main plan- 10
simple
movements in
the water – 5
for the upper
limb and 5 for
the lower
limb. For a
duration of 1
minute each of
maximal
power or for
patients who
were
experiencing
pain for as far
as tolerable.
• Cool down- 5
minutes.
Flexibility
movement
however not
specified.
Exercises were
progressed by
increasing time and
quality of the
exercise.
3 times per week
8 weeks
Not specified
No.
Yes
Yes
No.
Yes
No
No.
No.
No.
Elbow, knee and ankle
ROM- measuring the
arch of active articular
Pain- VAS.
Knee Flexion and
extension ROM.
Elbow flexion and
extension ROM.
Ankle dorsiflexion
_____________________________________________________________________________________
8
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
movement at each joint.
Adherence
Long term follow
up
Not specified.
No.
Not specified.
No.
and plantarflexion
ROM. Knee extension
and flexion ROM
strength.
Not specified.
No.
Table 4. Research into the effect of aquatic training on motor performance by Vallejo, et al.,
(2010).
Motor performance
Article
Vallejo, et al., (2010)
Participants
13 patients.
Program
1 hour Aquatic trainingintervention
• Warm up- 50m crawl or back stroke, running on the spot in the shallow
end of the pool and circles forward and backward of the hip and shoulder
at shoulder depth.
• Main section- 2 blocks:
o 1. muscular endurance and muscle strengthening Muscular endurance- 2 sets of 20 repetitions per exercise
with active 30sec pauses (slow running on spot)• Flexion- extension of shoulder
• Abduction- adduction of shoulder
• 45° Abduction- adduction of shoulder in frontal
plane
• Flexion- extension of elbow.
 Muscle strengthening- 2 30 second sessions per exercise
with a relaxation time 2 minutes where balance exercises
were performed.
• Horizontal and vertical traction movements at the
participants’ maximal performance speed.
o 2. Aerobic capacity which was extensive and continuous and was
made up of 3 phases with 2 levels within each phase which was
progressed by an increase in each participant’s maximal heart
rate.
 Exercises were performed for a length of 50m and
repeated 4 times for a duration of 20 minutes.
• Backstroke of legs and arms.
• Front crawl with arm movements.
• Full arm movements in either backstroke or front
crawl as selected by the participants.
• Swimming backwards
• Relaxation- Stretching exercises of the upper and lower limbs- 2 sets of 8
_____________________________________________________________________________________
9
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
Program
frequency
Program
duration
Program
provided by
Program
design
Is there a
control
group?
Comparison
to land
intervention
Could
program be
replicated?
Outcome
measures
Adherence
Long term
follow up
exercises lasting 30 seconds each.
3 times per week.
9 weeks
Not specified
Pre-test post-test
No.
No.
Yes.
Oxygen uptake, relative oxygen uptake, Carbon dioxide, respiratory quotient,
heart rate and the distance ran in the Cooper test.
4 abandoned study.
No.
These studies above do support an aquatic therapy intervention for improvements in ROM and
strength of affected joints, improving motor performance and reducing pain.
The evidence reveals that ROM does improve with aquatic therapy intervention. Garcia, et al.,
(2009) noted that in the group of patients with haemophilia, there was an improvement in the
ankle and knee ROM, however no change in the elbow ROM (N.B. statistical significance was
not reported). They suggest that these improvements may be due to the properties of the water
including buoyancy, hydrostatic pressure as well as the thermodynamics of the heated water
(Garcia, et al., 2009). In contrast, Kargarfard, et al., (2013) reported on a significant
improvement in the ROM of all joints investigated on: left and right knees, ankles and elbow
joints. Interestingly, their control group revealed that with a lack of intervention, the affected
joints of patients with haemophilia will worsen highlighting the vital need for intervention in this
population. Mazloum, et al., (2014) noted a significant improvement in knee flexion and
extension ROM in both the land and aquatic exercise groups following intervention but no
difference between them.
_____________________________________________________________________________________
10
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
Kargarfard, et al., (2013) as previously outlined above also investigated knee flexion and
extension strength prior to and following a water based program. They reported an improvement
in the power in knee extension and knee flexion of both knee joints following the intervention. In
this literature review, this was the only study to investigate strength of any joint. To date no other
studies have investigated strength with an aquatic intervention in haemophilia patients.
Mazloum, et al., (2014) as outlined previously also looked at pain intensity when comparing a 4
week land based exercise intervention group with aquatic exercise intervention group compared
to a control group. They reported there was an improvement in both the land and aquatic exercise
groups when compared to the control, with a bigger improvement in the aquatic exercise therapy
compared to the land exercise group (N.B. statistical significance was not reported).
Vallejo, et al., (2010) reported that there is an improvement after an aquatic training intervention
on patients who had haemophilic arthropathies. Vallejo, et al., (2010) measured the distance
covered in the Cooper test, the relative oxygen uptake, carbon dioxide, respiratory quotient and
heart rate. The Cooper test, a 12 minute test where the participants runs as far as able, is highly
correlated with the VO2Max (Quinn, 2014). Compared to the results before the intervention,
there was a significant difference in VO2 and relative VO2, CO2, respiratory quotient and the
distance covered in the Cooper test. However there was no difference noted in the heart rate
before and after the training.
Discussion
Of the four articles yielded, improvements post aquatic based intervention were seen in ROM in
the elbow, ankle and knee, in knee extension and flexion strength, in motor performance and
with a reduction in pain. This is of important clinical significance as patients undertaking aquatic
physiotherapy programs may have improvements in their ROM and strength of their affected
joints, improvements in their aerobic capacity as well as a reduction in their pain levels and
larger improvements in pain over patients undergoing land based interventions. These
improvements could ultimately improve their physical activity and participation leading to
improvements in the quality of life, however further research is required to support this. As all of
the studies were of poor (level 4) quality of evidence on the PEDro scale with small group sizes,
_____________________________________________________________________________________
11
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
had poor methodological rigour as well as potential bias, caution needs to be taken when
examining the results.
There were several pitfalls in the methodology of these studies. Among these were a lack of
randomisation in patient groups, lack of comparison to a control or land based programs, poor
comparisons to normal populations and a lack of long term follow up.
The studies by Garcia, et al., (2009) and Vallejo, et al., (2010) had no control groups nor was
there a land based group comparison for these studies and the study by Kargarfard, et al., (2013).
In contrast, the study by Mazloum, et al., (2014) did have a control group and did compare to a
land based intervention. Furthermore the study by Garcia, et al., (2009) unjustly compared
haemophilia patients to a group of patients with no pathology or arthropathy.
Of the four studies reviewed, only one study which was undertaken by Kargarfard, et al., (2013),
randomly allocated the subjects. This lack of randomisation in the studies could have potentially
led to bias in the results.
In all of the four studies reviewed, the provider of the program was not identified. This may have
led to further biased results as the tester may have been the program provider and may not have
been blinded for the study. It could be suggested that the lack of any specialist training for
performing these treatments by the program provider, which may be required for this population,
could ultimately have a negative effect on the intervention’s outcomes and ultimately on future
patient’s outcomes. In addition, these studies did not report on having a blind assessor.
Of the four studies reviewed, none looked at a long term follow up of their intervention on this
patient group. Long term follow up studies are required to support the effectiveness of these
programs and determine the optimal length of treatment for maintaining improvements.
The study by Garcia, et al., (2009), had a control group but the group’s participants did not have
haemophilia nor did they have any articular anomalies. A comparison of an intervention group
of haemophilia patients to a group of non-haemophilia participants in an aquatic environment
does not truly reflect a typical comparison between a control and experimental group in a
population undergoing treatments.
_____________________________________________________________________________________
12
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
To date, Mazloum, et al., (2014) is the only article that has measured pain in patients with
haemophilia. Research confirms that pain has a detrimental impact on patients with haemophilia
and would be an important outcome of an intervention. Mazloum, et al., (2014) found that
aquatic based programs lead to bigger improvements in pain reduction. This finding is of
important clinical significance, especially for patients with haemophilia who are experiencing
high pain levels, where the pool may be a more suitable environment over land. As a result, both
clinical and future research should include pain in its outcomes to determine the improvements
of aquatic based programs on pain in patients with haemophilia.
The American College Sports Medicine guidelines for improvements in strength in the normal
population state that training should include 1-3 sets of 8-12 repetitions at a minimum of 2 nonconsecutive days per week (American College of Sports Medicine, 2013). The study by
Kargarfard, et al., (2013) which investigated knee flexion and extension strength did not specify
its length of program, frequency nor details of program intervention. Despite their result with an
increase in knee flexion and extension strength, this program is not reproducible due to a lack of
a specified dosage.
Lastly, the second aim of this literature review was to determine the dosage of an aquatic
physiotherapy intervention for patients with haemophilia. However, due to the lack of specificity
and poor quality of evidence this was not achieved. Within the four studies, the program varied
between 30 and 60 minutes of intervention, between 2 and 3 times per week and lasting over a
range of 4-9 weeks. As can be seen, due to the lack of specificity of the programs’ parameters, a
dosage for an aquatic physiotherapy intervention was not determined. These studies did not
reveal an optimal duration of a treatment session and overall program length, nor did it state the
frequency of treatment and length of session with sessions varying between 30 and 60 minutes of
therapy. For example, the study by Garcia did not state how long their intervention was for.
Whereas there was conflicting durations for Mazloum, et al., (2014) and Kargarfard, et al.,
(2013) with 4 weeks and 8 weeks respectively for improvements in ROM. Future research needs
to be undertaken to determine if there is an effectiveness of aquatic physiotherapy treatment of 4
weeks compared 8 weeks of intervention. Furthermore, to improve motor performance, 9 weeks
has been supported by Vallejo, et al., (2010). However, could these improvements be seen in
_____________________________________________________________________________________
13
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
shorter durations? As previously stated, further research is required to determine the optimal
dosage of intervention for patients with haemophilia.
Conclusion
A review of the literature of aquatic intervention in the haemophilia population reveals that
improvements in ROM and strength of affected joints can occur, with improvements in pain as
well as improvements with aerobic capacity. However caution should be taken when interpreting
these results as the research was conducted in poorly designed studies with small sample sizes
with potential bias. Despite these encouraging results, an effective dosage of an aquatic
physiotherapy intervention, was not achieved due to the conflicting and minimal evidence
supported in the literature. Higher quality studies with larger sample sizes and better
methodological rigour whilst limiting bias, need to be undertaken to provide the evidence in
determining best practice of aquatic physiotherapy in patients with haemophilia as well as
determining the optimal dosage when providing this intervention.
_____________________________________________________________________________________
14
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
References
American College of Sports Medicine, 2013. Resistance Training for Health and Fitness.
[Online]
Available at: https://www.acsm.org/docs/brochures/resistance-training.pdf
[Accessed 26th October 2014].
Cuesta-Barriuso, R., Gomez-Conesa, A. & Lopez-Pina, J., 2013. Physiotherapy Treatment in
Patients with Haemophilia and Chronic Ankle Arthropathy: A Systematic Review.
Rehabilitation Research and Practice, Volume 2013, pp. 1-10.
Garcia, M. et al., 2009. Variations of the Articular Mobility of Elbows, Knees and Ankles in
Patients with Severe Haemophilia Submitted to Free Active Movimentation in a Pool with Warm
Water. Haemophilia, Volume 15, pp. 386- 389.
Haemophilia Foundation Australia, 2014. Haemophilia. [Online]
Available at: https://www.haemophilia.org.au/bleedingdisorders/haemophilia
[Accessed 26th October 2014].
Heijnen, L., 2008. The Role of Rehabilitation and Sports in Haemophilia Patients with Inhibitors.
Haemophilia, Volume 14, pp. 45-51.
Jansen, N., Roosendaal, G. & Lafeber, F., 2008. Understanding haemophilic arthropathy: an
exploration of current open issues. British Journal of Haemotology, Volume 143, pp. 632-640.
Kargarfard, M., Dehghadani, M. & Ghias, R., 2013. The Effect of Aquatic Exercise Therapy on
Muscle Strength and Joint's Range of Motion in Hemophilic Patients. International Journal of
Preventative Medicine, Volume 4, pp. 50-56.
Mazloum, V., Rahmana, N. & Khayambashi, M., 2014. Effects of Therapeutic Exercise and
Hydrotherapy on Pain Severity and Knee Range of Motion in Patients with Hemophilia: A
Randomized Controlled Trial. International Journal of Preventative Medicine, Volume 5, pp.
83-88.
Quinn, E., 2014. Fitness Test- 12 Minute Run Fitness Test for Endurance. [Online]
Available at: http://sportsmedicine.about.com/od/fitnessevalandassessment/a/12MinRun.htm
[Accessed 29th October 2014].
Rodrigues-Mechan, E., 1996. Effects of Haemophilia on Articulations of Children and Adults.
Clinical Orthopaedics and Related Research, Volume 328, pp. 7-13.
Souza, J. et al., 2011. Haemophilia and Exercise. International Journal of Sports Medicine,
Volume 33, pp. 83-88.
_____________________________________________________________________________________
15
Aquatic Physiotherapy and Haemophilia
______________________________________________________________________________
Vallejo, L. et al., 2010. Influence of Aquatic Training on the Motor Performance of Patients with
Haemophilic Arthropathy. Haemophilia, Volume 16, pp. 155-161.
_____________________________________________________________________________________
16