Byline: Andrea Salzman, MS, PT
It may not be a question for the ages, but it is an important question to ask. Is aquatic exercise safe for my patient with COPD, CHF, MI or other cardiopulmonary disorders?
There are 5 prevalent myths that have edged into the collective medical psyche and which must be tackled in order to suss out the truth. In order to do so, it is important to first understand what happens when a person stands immersed in water, before placing a single limb in motion.
So, What Happens to the Heart & Lungs During Immersion?
During immersion, the water’s pressure pushes inwardly and — at any given depth -- equally on the body.
So if I stand at rest with my legs immersed in 3’ of water, both knees will experience an equal amount of circumferential pressure pushing into the joint. And while the pressure is equal at any given depth, it increases as the depth increases. This phenomenon helps explain why vertical immersion (standing upright) produces such a different hemodynamic response from horizontal immersion (floating or swimming). Let’s explore what happens, step by step, from the moment I step into the water.
First, I experience an external pressure from the water; this pressure is known as hydrostatic pressure. How strong is this pressure? Well, it depends on the depth. During immersion in 100 cm of water (about 3.3’ of water), the water exerts an external pressure of 76 mm of mercury. If I go deeper (say 5’), the pressure at my feet becomes even greater, reaching > 100 mm of mercury. Compare this with the much lower pressures (40-60 mm) I would experience during surface swimming 1,2
Second, this “hydrostatic pressure” compresses the venous and lymphatic vessels in my legs inward. End result? A large shift in blood and lymph from my legs to my abdomen and (if I am immersed deep enough) to my thorax. If I am immersed all the way to the neck, the increase in central volume is quite substantial (around 700 ml). Three cups may not sound like much, but it represents a 60% increase in central volume. In contrast, during swimming, there is no pressure differential, so blood is not “assisted” back up to my heart.1,2
Third, around 1/4 of this increased thoracic volume ends up in the chambers of my heart. My left ventricular preload increases by 40-70 ml, and — per Starling’s Law — this stretch of muscle fibers results in a more powerful contraction. My left ventricle ejects 35-45% greater stroke volume every time it pumps out blood, meaning that cardiac output increases by around 1500 ml/minute during clavicle level immersion. In fact, vertical immersion in water up to my neck produces a similar stroke volume to that of a deconditioned subject exercising to max capacity on land.1,2 This effect is age dependent — older patients show a smaller increase in volume, temperature dependent — the warmer the water, the greater the volume increase, and disease-specific —patients with severe CHF may not show this increase in stroke volume.1
Fourth, a portion of the displaced volume of blood ends up in the large vessels of my lungs.1,2 More on this later.
Fifth, my brain recognizes this large change in central volume and – via the sympathetic nervous system – decreases the vasoconstriction of my blood vessels. This reduces both peripheral vascular tone and systemic vascular resistance by 30% (at thermoneutral temperatures). According to Becker, this drop is long lasting – starting during the first hour of immersion and persevering for a period of hours thereafter. This vasodilation of the peripheral system decreases end-diastolic pressures in the heart.1
So, with this background information in mind, let’s examine the 5 myths that often prevent medical professionals from prescribing aquatic exercise.
Myth #1. Aquatic exercise has been shown to produce dangerous stressors on the cardiac system and should not be prescribed for the cardiac compromised client.
Several generations of cardiologists have made an understandable — yet consequential — error in prescribing pool exercise to their compromised patients. What is this profound error? They have treated swimming and vertical aquatic exercise as identical twins. Swimming and vertical water exercise are not created equal and should never be treated the same when prescribing exercise for the cardiopulmonary compromised client. So how did this misconception come to pass?
Chalk it up to the staying power of partial information. There was a handful of well-reported scientific studies done in the 1970s and 80s, all examining the safety of exercise for the cardiac patient.3-6 Ground-breaking stuff, really.
These papers, by and large, were trying to answer the question “Swimming: yes or no?” for the post-infarction patient with left ventricular dysfunction. Their collective findings showed that swimming — even swimming at a relatively glacial pace — resulted in an increase in cardiovascular and hormonal stress.2
Of special note was the fact that swimming could result in VO2 of 54-87% of max, even for qualified swimmers.2The weakish swimmer? Mama, call the EMT.
Those poor souls were hitting 90%+ of max VO2. Take home message: Swimming can be dangerous for the cardiac patient, especially the cardiac patient who looks more akin to Lucille Ball than Michael Phelps when taking the proverbial lap.
Because of these highly publicized studies, a generation of physicians made the swimming pool verboten for all cardiac patients. What they meant to do was spread the message that post-MI and CHF patient should stay away from swimming, a semi-valid conclusion. What they ended up doing is telling them is to stay away from the pool. Big diff.
So, what should we be telling our cardiac compromised patients about immersion? Here are the facts as we know them, based not on rumor or misinterpreted studies, but on the latest published evidence.
Swimming and vertical aquatic exercise produce completely different hemodynamic effects on the body. Patients with cardiac histories, especially those who are not strong swimmers, should not participate in swimming without clearance from their physician.2-6 In contrast, vertical exercise is safe for a large percentage of cardiac patients (for the exceptions, read on).
There is a big difference (hemodynamically speaking) between immersion to the chest and immersion to the neck. Immersion to the neck can produce abnormal hemodynamic responses temporarily in cardiac patients.2 Although present, these may not be of clinical significance.2
Decompensated heart failure is an absolute contraindication for water therapy. Patients with severe heart failure (NYHA IV) should not participate in immersion.2
Caution is “prudent” when working with individuals with severe valvular insufficiency, because cardiac enlargement may mechanically worsen this problem during full immersion.1
Subjective impressions are no guarantee that the left ventricle is tolerating the increased volume caused by immersion. Clinicians should not solely rely on the patient’s report that he is “feeling good” when assessing safety.2
Therapeutic water exercises in a pool can be allowed for patients with Q-wave myocardial infarctions older than 6 weeks, and/or mild and moderate CHF, provided that patients are in an upright position and immersed no deeper than the xiphoid process.2
Recent studies indicate that immersion may be a very useful tool in rehabilitation of the patient with mild to moderate CHF.1 For example, one study of patients with CHF examined the effects of immersion in warm water 1-2x/day, 5 days/week for a month. The end result was nearly astonishing. The patients showed an improvement in ejection fraction of nearly 30%, longer and better sleep cycles, and improved quality of life and well-being.7
Immersion in water temperatures ranging from 31-38° Celsius (87.8-100.4° Fahrenheit) are generally considered safe for both the normotensive and hypertensive patient.1
Now that we understand the effects of immersion and exercise on the cardiac patient, let’s turn our attention to the individual with pulmonary compromise.
Myth #2. Aquatic exercise has been shown to produce dangerous stressors on the pulmonary system and should not be prescribed for the respiratory compromised client.
It’s true, immersion in water does dramatically affect the diaphragm, rib cage and lungs. And while this can be a bad thing (making it difficult for the patient to draw a breath if the water is too deep), it can also be easily converted into a good thing (a progressive resistive exercise program for strengthening the muscles of respiration).
As already discussed, the hydrostatic pressure of the water creates a large cephalic shift in blood. This blood floods the large vessels of the lungs, making it more difficult to draw a breath. In addition, the diaphragm is displaced upwards (due to hydrostatic pressure pushing on the abdomen), and the rib cage is restricted from expansion (due to hydrostatic pressure pushing on the rib cage). These three forces combine to create a 60% increase in the work of breathing when the person is immersed in neck-deep water.1
Even in the healthy client, passive immersion results in a 10% decrease in vital capacity and a 46% decrease in residual volume.8 Because the lung volume decreases (in part because the rib cage shrinks), airway resistance explodes by 58%.9 In addition, the central vascular engorgement seen in the cardiac system (as described above) influences lung volumes by reducing lung compliance and promoting gas trapping in the lungs.8
In the COPD client, passive immersion has been shown to produce a similar predictable effect: a 12% decrease in vital capacity, a 14% decline in forced expiratory volume—1 second, and an 18% decline in peak expiratory flow.8 Despite this, no acute respiratory attacks or other adverse reactions were seen.
But what happens when COPD patients start to exercise? Surely exercise in water must be contraindicated? Actually, no. Let’s look at what recent studies have shown about the effect of immersion plus exercise on the respiratory client.
Despite the mildly negative effects of immersion on lung function, head-out water immersion appears to be safe and well tolerated in patients with COPD. The authors of a 2011 systematic review postulate that the effect of hydrostatic pressure on the diaphragm may actually give the COPD patient a mechanical advantage for breathing, similar to that sought by patients in the “lean forward” position. They suggest that pools with graduated depths are ideal, allowing the patient to find the perfect level of immersion.8
The effect of the ambient air and water temperature and humidity in the aquatic setting is unknown. In general, the better the ventilation, the better for everyone. 8
Medications such as rescue inhalers should be brought poolside. Oxygen delivery systems should be secured and pulse oximetry may be necessary to determine oxygen response to immersion and exercise. 8
There is a lack of conclusive evidence about whether water-based exercise is MORE effective than its land-based counterpart. Several studies show more improvement in peak and endurance walking capacity with water exercise. Some studies also show an improvement in quality of life, but these results were not unanimous. The jury remains out on whether water based exercise is more effective, but it appears to be as effective and, more importantly, feasible and safe. 8
Aquatic exercise may be a growing option for COPD patients who are unable to exercise on land due to comorbidities or other reasons. 8
In conclusion, vertical aquatic exercise is safe, feasible and potentially more effective for the patient with COPD than its land-based counterpart. But who says working with the cardiopulmonary population in water is even billable?
Myth #3. Cardiopulmonary training – performed in water – is not a skilled intervention and cannot be billed to insurance.
We all expect to get paid for what we do with our patients… and health insurance companies expect us to explain why. Because the CPT code for aquatic therapy (97113) brings in higher payments than its land-based counterparts (such as 97110), insurance companies are extra vigilant about medical necessity.9 Because of this, providers must take extra pains to justify the use of water, note objective deficits in ADLs, ROM, mobility, strength, balance, etc., use pain scales and report pain’s impact on function, and specify the how and whys of the exercises given.10
Several questions need to be considered when documenting necessity of aquatic therapy for your cardiopulmonary patient. In addition to whether or not the patient has functional impairments and deficits that require skilled therapy, you need to justify that water has a therapeutic effect not attainable by your patient on land; that the gains in the pool will translate into function on land; and that research supports the efficacy of aquatic intervention.10 Payers want to know fun facts such as whether the therapy truly required the skill of a therapist’s intervention, whether a group class would be sufficient, and when the patient will be progressing to land-based exercise.10
“Fortunately” for the cardiopulmonary-compromised patient, the requirement of skilled intervention with exercise can be a safety issue alone. Therapists should clearly document if the patient is at risk for any cardiac or pulmonary event - this alone may justify the skill of a therapist.
Myth #4. Facilities must invest in expensive aquatic equipment in order to provide a challenging respiratory environment.
The most precious resource you should invest as an aquatic therapist is your imagination. Upkeep of a pool has its expenses, sure, but there is no need to purchase expensive cardiovascular equipment (such as treadmills or water bikes) in order to create a cardiopulmonary challenge. As already noted, just the immersion of the body creates a training effect of the cardiac and pulmonary systems.1,2 In addition, the viscosity of the water already provides resistance to movement, creating an elevation in heart rate; to increase the work load, simply speed up the movements.1
Looking for equipment ideas? Some simple, low-budget items can make a big difference. Consider stocking up on 1” PVC pipe (to create a progressive resistive exercise program for the expiratory muscles) and a dozen or so ping pong balls or egg flips to blow across the water to challenge the expiratory pressure and effort exerted by the respiratory patients.
Make use of buoyant objects of varying dimensions (balls, foam dumbbells, kickboards) to push down into the pool water; the effort engages the core, provides a strong platform for the diaphragm to function… and provides upper body strengthening to boot.
Yoga positions such as the Warrior poses, tree, and balancing half-moon performed during immersion couple respiratory work with balance and strengthening challenges… and are free.11 For more ideas like this, see Salzman’s column in Advance for PTs “Aquatic Therapy for COPD Patients? Why clinicians should believe in the power of the pool”.12
The more creative you are, the less money you need to spend on specialized equipment. So, save your money on expensive underwater treadmills and head to the local Dollar Store to stock up on equipment!
Myth #5. If your patient does not have respiratory compromise, the air quality in the pool area is not a health concern.
As kids we were told “don’t swim for 30 minutes after eating” lest we get sick.
Now as therapists, we can eat and swim all we want, but it is the air in our pool facility that may make us sick. Poorly ventilated pools are not just hazardous to patients with respiratory compromise; they are potentially dangerous for us as well.
How does this happen? Combined chloramines (trichloramine) are the byproduct of chlorine once it mixes with other chemicals and sweat.13 Trichloramine creeps its way off the pool surface into the air and finds its way into the respiratory tracts of people in the pool and those sitting on the side of the pool.14 Kappel discusses how the disinfection byproducts, or DPIs, in the air of a natatorium that is not well ventilated should be of more concern than our previous focus of "recreational waterborne illnesses."13
Looking for further proof of the potential risks of poor ventilation in indoor pools? A 2004 study examined the effects that exercising in and around heavily chlorinated water; the study tested the subjects for exercise-induced bronchoconstriction.15 The research investigated what would happen to subjects exercising in the pool versus subjects running or cycling on the deck with pool chlorine concentrations being 0.0ppm, 0.5ppm, and 1.0ppm, respectively. The subjects’ forced expiratory volumes (FEV1) fell about 20% at 0.5ppm and 60% at 1.0ppm. You might think that makes sense for the person in the pool, but it was the same for the subjects on the deck, those who were not even touching the water!
In other words, the poorly ventilated pool can be quite hazardous to anyone's respiratory health, regardless of pathology. In our attempt to "go green" and make buildings more energy efficient for tax deductions, we have compromised the inflow of fresh air to our indoor pool environments…. and created a risk for respiratory toxicity.
Conclusion
Don’t let unfounded rumors stop you from choosing aquatic therapy for your patients with cardiac or pulmonary compromise. Instead, take a citation-supported walk through the literature to destroy the most pervasive myths about this topic. Then take a breath, let it out (through pursed lips, of course) and put on your suit. It’s time to get those cardiopulmonary compromised patients in the pool!
References
1. Becker, B. (2009). Aquatic therapy: Scientific foundations and clinical rehabilitation applications. PMR, 1(9), 859-863.
2. Meyer, K., & Leblanc, M.-C. (2008). Aquatic therapies in patients with compromised left ventricular function and heart failure. Clinical & Investigative Medicine. 31(2):E90-E97.
3. Magder, S., Linnarsson, D., and Gullstrand, L. (1981). The effect of swimming on patients with ischemic heart disease. Circulation, 63:979-986.
4. Heigenhauser, G. F., Boulet, D., Miller, B., & Faulkner, J. A. (1977). Cardiac outputs of post-myocardial infarction patients during swimming and cyclic. Medicine and Science in Sports, 9(3), 143–147.
5. McMurrary, R. G., Fieselman, C., Avery, K. E., & Sheps, D. S. (1988). Exercise hemodynamics in water and on land in patients with coronary artery disease. Journal of Cardiopulmonary Rehabilitation, 8(2), 69–75.
6. Lehmann, M., Sodar, H., Dürr, H., Samek, L., Gastmann, U., & Keul, J. (1988). [Behavior of heart rate, blood pressure, lactate, glucose, noradrenaline and adrenaline level in coronary heart disease patients in the course of light swimming stress]. Zeitschrift für Kardiologie, 77(8), 508–14.
7. Tei, C., Tanaka, N. (1996). Comprehensive therapy for congestive heart failure: A novel approach incorporating thermal vasodilation. Intern Med, 35, 67-69.
8. McNamara, R. J. (2009). Water-based exercise training for chronic obstructive pulmonary disease. (J. A. Alison, Ed.)Cochrane Database of Systematic Reviews, (2). Retrieved from http://search.ebscohost.com/login.aspx?direct=true&db=chh&AN=CD008290&site=ehost-live
9. Salzman, A. (2013, March 11). Why water? a decision matrix for aquatic therapy. Advance for Physical Therapy and Rehab Medicine, Retrieved from http://www.physical-therapy.advanceweb.com/Columns/Water-Wisdom/Why-Water-A-Decision-Matrix-for-Aquatic-Therapy.aspx
10. Salzman, A. (2013, August 03). Documentation of medical necessity for aquatic therapy: a greater hurdle than for therapeutic exercise. Retrieved from http://www.aquatictherapist.com/index/2012/08/documentation-of-medical-necessity-for-aquatic-therapy-a-greater-hurdle-than-for-therapeutic-exercis.html
11. Drake, M., and Brown, K. (n.d.).Yoga in the pool. Canadian Living, Retrieved from http://www.canadianliving.com/health/mind_and_spirit/yoga_in_the_pool.php
12. Salzman, A. (2013). Aquatic Therapy for COPD Patients? Why clinicians should believe in the power of the pool. Advance for Physical Therapy & Rehab Medicine, Retrieved from http://physical-therapy.advanceweb.com/Columns/Water-Wisdom/Aquatic-Therapy-for-COPD-Patients.aspx
13. Kappel, R. (2008, June). Watered down: One. Aquatics International, Retrieved from http://www.aquaticsintl.com/air-quality/watered-down-one.aspx
14. Smith, M. (2007, March 30). Swimming pool air may be hazardous. Retrieved from http://www.medpagetoday.com/Pulmonology/Asthma/5359
15. Mees, P. (2004). Breathing easier in the pool. Physician and Sportsmedicine, 32(7).
Great information to keep up!