Warning Signs for Acute Congestive Heart Failure: Pleural Effusion

These notes are based on observations & research relevant to Coco's particular case, which involved pleural effusions. Her condition included mitral valve insufficiency. The guidelines given are intended only to help a pet owner without other resources decide whether a pet should be taken immediately to an emergency clinic, not as a conclusive diagnostic checklist. They are strictly the opinions of the author, and are not documented or substantiated by any authorities. If competent medical advice is available, it should be taken. In that case, the observable symptoms listed may be helpful to a veterinary professional in his advising the pet "owner". Some of the symptoms are subtle and subjective, and therefore might be missed by an untrained person. The assumption is, that if these symptoms are detectable past a certain stage by an untrained person, an emergency situation probably exists.

What causes congestion due to heart failure?
The heart functions in two ways. It pushes blood out through the arteries, and sucks it in from the veins. The greatest pressure is on the arterial side. Pressure is minimal on the venous side. The greater volume of blood builds up on the venous side, waiting to be pumped back through. (Normal state). When the heart is failing to function up to a certain level of efficiency, there is a buildup on the venous side in excess of what the heart can draw in. At some point, there is seepage from this buildup (in the form of plasma fluids, not necessarily whole blood) out of the vascular system into organs and body tissues. This is the congestion that is referred to in congestive heart failure. Location of the congestion varies, and can be an indication of where the defect of the heart lies. One form, which Coco had, results in clear fluid leaking into the pleural space, outside the lobes of the lung, but inside the pleura which contains the lung. The effect is to limit the expansion of the lungs, both by filling space, and by breaking the contact with the pleura which is part of the mechanism of lung expansion.

Postural Signs
Due to the fact that congestive fluids are often relatively "free" and unconfined, they are subject to shifting within the body. This makes some positions more comfortable than others for the pet. One sign of congestion is a reluctance to lie down on the side to sleep, or restlessness and frequent getting up when attempting to sleep in this position. Cats with congestion will often try to sleep sitting up, so that the fluids settle away from the heart and lungs. In extreme cases, cats are even described as trying to sleep standing up.

General Demeanor and Responsiveness
Nature of breathing

The most obvious effect of pleural effusion is increased effort of breathing. This may not be noticed until the congestion has progressed, for two reasons. One is that cats have a natural tendency to "mask" their symptoms, which is easily done by self-limiting their activity so that they never get out of breath. The other is that, like humans, cats have a certain reserve capacity to their lungs. Until the congestion limits lung expansion below this reserve, there would be no functional effect. (Unless strenuous activity which normally relied on reserve capacity was engaged in.)

Early signs of excessive congestion are a lessened activity level. (Which also could be due to any number of other medical reasons, or hot weather, or laziness.) Overall attitude may not change, the kitty may just choose to step up rather than jumping, walk rather than running. It is possible that nothing is noticed until relatively easy activity results in breathlessness. If the kitty seems to lie around a lot, and when returning from the cat box sits breathing quickly for a bit, and always prefers to lie in the "sphinx" position, never curled up, this bears a closer look.

At some point in time, the restriction will become observable as a "catch" in breathing. When Coco had a pleural effusion developing, but still not at emergency levels, her breathing would seem normal, but slightly quicker. Upon listening closely for a number of minutes, a pattern became apparent. Inhalation would start normally, but at about what would usually be the halfway point, would stop abruptly. Exhalation would also sound normal, but would be about equal in length to the inhalation (I believe that normal is about twice as long, rather than equal). This was noticeable, when we learned to look for it, when no other symptoms other than reduced activity and breathlessness after exertion were apparent.

As the congestion increased, activity became less. Coco remained stationary most of the time, with only trips to the litter box or food bowl when necessary (due to inactivity, of course, these were less frequent). After these excursions, she would be obviously out of breath, and would sit with forelegs extended, concentrating on her breathing for a few minutes before she could relax and lie down in the sphinx position.

Up to this point, there was no feeling of immediate threat to life. When she was at this stage, we felt safe, for instance, to wait until morning to see the vet. We brought her food and water to her, held them where she could eat and drink with minimal movement, and carried her to the litter box and back when appropriate. (We knew, because she would start to get up. In her condition, she would not do that for any other reason.) As long as she stayed at this stage, we were even confident in waiting a day to be able to take her to the senior partner of the hospital if he was not in that day. With breathing ability restricted, stress becomes a very real issue, and can have disastrous consequences.

In the next stage, breathing became the only activity. There was be no apparent pain, but Coco could not be distracted to eat or drink, and if taken to the litter box would lie in it. She had one overwhelming priority, that of pumping enough air to survive. As long as she was able to do this, the breathing was calm and steady, and there was no sense of immediate peril. If not able to get her to the vet's immediately, she could hold out for many hours or overnight, as long as she was not moved. (The leakage into congestion is slow, so changes in condition are gradual.)

I mention the various stages relative to (my) perception of immediate threat to life for one reason: stress. Obviously, once the condition is noticed, appropriate treatment should be initiated as soon as possible. However, since we had at great length finally found a vet in whom we felt we could confidently place Coco's life, we felt on two occasions that nursing Coco through the hours necessary to see him were justified versus the risk involved in subjecting her to the stress of another vet. Each incidence is definitely a judgement call, which should be made with a clear head if possible. My intention was to give some guidelines, from my experience only, by which some leeway might be expected to exist. What also must be factored in, of course, is that the further the problem progresses, the greater the actual risk that stress presents. Also the treatment necessary. If detected early enough, the vet may treat it with medicines, including a diuretic to help drain the existing fluid. If a large volume is present, as it was with Coco, it may need to be drained by thoracentesis, a very delicate procedure in which a large needle is placed very close to the lung. If the kitty cannot be anaesthetized, there can be a very real but unavoidable risk. This is one procedure where absolute confidence is placed in the hands of the person performing it.

Percussion and Auscultation.
Percussion and auscultation are diagnostic techniques that may be useful in detecting the presence of fluid in the body cavity. Auscultation is simply the medical term for listening, usually through a stethoscope. With practice, meaningful information can be obtained by listening with your ear held against your pet's side. The hardest part is often getting the purring to stop. Percussion is a technique in which you listen on one side, and tap on the other. The existence of fluid will effect the resonance of the sound as it passes through the body.

Unfortunately, my memory is not fresh enough to accurately describe the limited success I had with these techniques on Coco. Auscultation, especially, is a skill to be learned with practice, and is to a certain extent subjective with relationship to a healthy cat. I will try to give some general hints that I hope may be useful. I would strongly recommend the purchase of a stethoscope (less than $10 for a simple model, less than $25 for one with 3 heads to cover every anticipated use. Recommended is one with a standard (pediatric) head, and a bell head).

Percussion as described in the texts involves laying the fingers of the left hand on one side of the body, and striking the middle knuckle of the middle finger with the middle finger of the right hand, while listening on the other side (with or without a stethoscope). In practical terms, none of us have three hands. I found that I was able to pick up resonance by tapping/slapping with the flat of the first knuckle of the middle finger, using the other hand to hold the stethoscope on the other side.

Pleural effusion was most generally detectable back of the lungs, i.e. toward the tail. My memory tells me that the presence of fluid between the tapping point and the listening point was evidenced by hearing a bell-like note pass across. The logic being that fluid is a better conductor of sound than air. On looking it up in my old vet manual, the opposite is indicated - resonance indicates air, lack of resonance, fluid. Either my memory, or my interpretation, is incorrect. My recommendation is to be aware of the technique, try it on your cat at all positions until you become familiar with the way he/she sounds inside. Then you will be in a position to tell if a change has occurred, which if nothing else may be meaningful to your vet.

Auscultation with a stethoscope can tell a lot about the insides of a body. It takes a lot of practice, but there are detailed descriptions in the literature that should enable anybody to get some kind of a handle on it, at least for their own purposes. As regards pleural effusion, the main usefulness that I found was that I could hear a muffled heartbeat further back (behind the lungs) when fluid was present than when it was not. Becoming accustomed to the sound of your cat's heart is a good exercise.

THE PRIMARY USE OF THE STETHOSCOPE:
While you are practicing auscultation (love that word), you will find that most of the time, you are listening to your baby purr. It will lull you almost to sleep at first, until you remind yourself that you are trying to engage in serious business. You will probably not do what the book says, however, which is to shake the kitty or display a dog. What you will do is try to escape the purr by moving the stethoscope south, away from the source. What you will find there is a delightful and ever-changing assortment of musical gurgles, squirts, and other indescribable pleasures. Eventually, maybe kitty will get bored and stop purring. Maybe not.