Pathophysiology (Nursing)

00:01 Hi, my name is Jill Beavers-Kirby, and today we're going to talk about pathophysiology. So what is pathophysiology? Well, it's broken down in Greek words, one meaning pathos which means disease, and physiology which means the study of all structural and functional changes in cells, tissues and organs. Anytime you see -ology on the end of a word, you want to know that that's the study of something. So pathophysiology are cellular and structural changes within the body and the effects that these changes cause on somebody. So then what is disease? Disease is a pathological disorder. It is not caused from trauma or injury. It can affect all the structures in all parts of an organism. It is, once again, not a result of a physical injury. So the features of disease include etiology, the pathogenesis, the morphological changes, and the clinical signs and symptoms.

01:13 So etiology. Once again we have the -ology ending on the end, so etiology is the study of why things are. So etiology can be biologic such as bacteria or viruses, they can be physical such as from trauma or burns, they can be chemical from alcohol or poisons, it can be inherited such as some types of heart disease can be inherited from family members, or they can be congenital which simply means that they've been there since birth. So what is pathogenesis? Many diseases are thought to be of a genetic predisposition or from an environmental cause. So from an environmental exposure, or it's just something in your genes or your DNA. So pathogenesis and etiology, even though they mean two different things, you might hear these two words used interchangeably.

02:12 Just remember that etiology is the study of the cause of the disease whereas the pathogenesis is what is causing the disease. You don't really need to get too hung up if they are used interchangeably. So morphology. Remember, we have that ending on the end, that means study of. This is the study of the function of cells or tissues. Morphologic changes, when you hear this, is referring to the changes in the cells or the tissues. Histology is the study of the actual individual cells.

02:46 So sometimes when describing a disease, you might hear that there are histological changes. This simply means that the changes are at a very cellular level. Sometimes histological changes are used to determine the cause of diseases.

03:00 Other manifestations of diseases are symptoms. Symptoms can be hard on patients and on caregivers, because symptoms are whatever the patient tells you.

03:13 Things like pain, dizziness, we can't see these. We just have to go by whatever the patients tell us. Whereas signs are things that we can actually see and measure, such as somebody's temperature or swelling or redness, also known as erythema. But remember, symptoms you can't see, it's just strictly based on what the patient tells you.

03:35 Signs, if you think of like a stop sign or a yield sign on the road, these are things that we can see and measure. So we often hear about the signs and symptoms the patient presented with were -- Syndromes, and you'll hear this term also, is the collection of the signs and symptoms. So an example of a syndrome is Down syndrome or irritable bowel syndrome.

03:59 Those are just a couple of examples. You can also have complications which are unfavorable developments of a disease. So a person with chronic obstructive pulmonary disease, a complication of that might be shortness of breath and wheezing, whereas sequelae are the natural progression of the disease. So as you have end-stage renal disease, meaning end-stage, you don't make any urine any more, you can end up on dialysis. That's a sequela of that disease.

04:36 So diagnostic tests. These will also help us with the pathophysiology. So diagnosis is the process of listening to the patient talk about their signs and symptoms, gathering a full history and physical, and utilizing the testing that we have available to us.

04:54 Diagnosis as I stated, requires a thorough history and physical exam.

05:00 I can't stress this enough. You really have to listen to the patient, listen to what they are saying. It is also important to listen to what they are not saying. You know, are they not complaining of abdominal pain even though they are complaining of nausea. So developing a diagnosis requires using all of your senses, looking at the patient, listening to the patient, utilizing tests that you have available, and weighing all this evidence. You want to make a diagnosis, a healthcare diagnosis, based on what is most easiest.

05:33 So if somebody comes in, sniffles, sneezes, runny nose, low grade fever, they probably have a cold, correct? They probably don't have lung cancer. So you always kind of want to think of the most simplest reason to explain all of the information that you've gathered from the patient. Age, gender, race and lifestyle can also aid you in your diagnosis. So for example, a man comes in with a large belly, saying he's having belly pain and cramping, I'm not going to to think he's pregnant because he's a man, this is impossible. So there are age-related diagnoses, gender-related diagnoses. So there's not one diagnosis that fits everybody. So when you use a diagnostic test, you have to take in to the quality of the test. So there are certain terms that we use to describe how good a test it is. One of these terms is validity. Simply wrote down, how valid is this test? Is it measuring what it says it's measuring? So is a milliliter measuring a milliliter? Another term we use to describe tests is reliability. How reliable is it? So this is how reliable are these results? If I repeat the results and you repeat the test, are we getting the same result? There are two other terms that we use to describe the quality of diagnostic tests. One is specificity.

07:06 So this is simply how specific is this test? So if a test is highly specific and it comes up with a positive result, the chances are that the test is positive.

07:19 For example, if you do a blood pregnancy test on a patient where you're looking for the beta hCG protein in the blood, that is highly, highly specific. So if that comes up positive, the chances are that you're pregnant. Not 100%, but very highly likely that you're pregnant. The sensitivity is how sensitive the test is. So for example, a highly sensitive test would be good in ruling out a disease. So once again, talking about the serum pregnancy test or serum blood test, if your beta hCG is negative, chances are you're not pregnant. So what is evolution of a disease? You're going to hear these terms used a lot. So acute means the acute phase of the disease. It doesn't mean that the disease is a cute little disease, it means the disease is new and it's been newly diagnosed, and it's in the beginning phase. You may or may not hear of a subacute phase. A subacute phase is the phase between the acute and the chronic.

08:31 So the disease is leaning towards the chronic phase of disease but it's not quite there yet. So if you think about somebody who has got kidney disease and is going into kidney failure, the initial insult when their creatinine was elevated would be considered the acute phase. Then as their kidney function leans more towards end-stage dialysis , that would be the subacute phase. The chronic phase is the continuing, long lasting phase of the disease. So once again, the end-stage renal disease, where a patient may or may not be receiving dialysis three times a week. You can also have flare ups which are called acute on chronic. You will hear this a lot used with somebody who has COPD. So they've been managing their breathing issues fine, fine, fine, and then all of the sudden spring time comes, things pollinate, they get acutely short of breath or they get upper respiratory infection. This causes an acute exacerbation of their chronic symptoms. And finally, the natural history of the disease.

09:39 This is simply talking about the natural prognosis, how it developed, how it's going to flow through someone's life, and more likely than not how the disease will end. Prognosis defines the probability of the outcomes of the disease.

09:56 Thank you. This has been Jill Beavers-Kirby discussing pathophysiology.