Author Archives: Alila Medical Media

The Digestive System, with Animation.

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The digestive system is composed of 2 main components: the gastrointestinal tract, or GI tract, where digestion and absorption take place; and accessory organs which secrete various fluids/enzymes to help with digestion. The GI tract is a continuous chain of hollow organs where food enters at one end and waste gets out from the other. These organs are lined with layers of smooth muscles whose rhythmic contractions generate waves of movement along their walls, known as peristalsis. Peristalsis is the force that propels food down the tract.
Digestion is the process of breaking down food into smaller, simpler components, so they can be absorbed by the body. Basically, carbohydrates such as sugars and starch are broken down into glucose, proteins into amino acids, and fat molecules into fatty acids and glycerol.
Digestion starts in the oral cavity where the food is moistened with saliva and chewed, food bolus is formed to facilitate swallowing. Saliva is secreted by the salivary glands and contains the enzyme amylase, which breaks down starch into maltose and dextrin that can be further processed in the small intestine. Saliva also contains salivary lipase, which starts the process of fat digestion.
The food bolus is propelled down the esophagus by peristalsis into the stomach, the major organ of the GI tract. The stomach produces gastric juice containing pepsin- a protease, and hydrochloric acid which act to digest proteins. At the same time, mechanical churning is performed by muscular contraction of the stomach wall. The result is the formation of chyme – a semi-liquid mass of partially digested food. Chyme is stored in the stomach and is slowly released into the first part of the small intestine – the duodenum. The duodenum receives the following digestive enzymes from accessory organs:
– Bile, produced in the liver and stored in the gallbladder; bile emulsifies fats and makes it easier for lipase to break them down.
– Pancreatic juice from the pancreas. This mixture contains proteases, lipases and amylase and plays major role in digestion of proteins and fats.
The small intestine also produces its own enzymes: peptidases, sucrase, lactase, and maltase. Intestinal enzymes contribute mainly to the hydrolysis of polysaccharides.
The small intestine is where most of digestion and absorption take place. The walls of the small intestine absorb the digested nutrients into the bloodstream, which in turn delivers them to the rest of the body. In the small intestine, the chyme moves more slowly allowing time for thorough digestion and absorption. This is made possible by segmentation contractions of the circular muscles in the intestinal walls. Segmentation contractions move chyme in both directions. This allows a better mixing with digestive juices and a longer contact time with the intestinal walls.
The large intestine converts digested left-over into feces. It absorbs water and any remaining nutrients. The bacteria of the colon, known as gut flora, can break down substances in the chyme that are not digestible by the human digestive system. Bacterial fermentation produces various vitamins that are absorbed through the walls of the colon. The semi-solid fecal matter is then stored in the rectum until it can be pushed out from the body during a bowel movement.

ECG/EKG Reading Made Easy with Animation

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Lead 2 is most popular among the 12 leads. This is because the net movement of the heart’s impulses is toward lead II, making it the best general view. Unless otherwise specified, we will be looking at lead 2.

Our analysis will include the following: heart rate, heart rhythm, P wave, PR interval, QRS complex, ST segment.

For heart rate: Identify the QRS complex – usually the biggest on an ECG; count the number of small squares between two consecutive QRS complexes and calculate the heart rate with this formula. If this number is variable, count the number of QRS complexes on a 6 second strip and multiply by 10. A normal heart rate is between 60 and 100 beats per minute. A rate of less than 60 bpm is bradycardia; heart rate of more than 100 bpm is tachycardia.

For rhythm: measure the intervals between the R waves. If these intervals vary by less than 1.5 small squares, the rhythm is regular; if the variation is greater than 1.5 small squares, the rhythm is irregular.

P wave represents depolarization of the atria initiated by the SA node. Presence of a normal P wave therefore indicates sinus rhythm. P waves are most prominent in leads II, III, aVF and V1.

Absence of P waves indicates non-sinus rhythms. Absence of P waves and presence of irregular narrow QRS complexes are the hallmark of atrial fibrillation. The baseline may be undulating or totally flat.

A sawtooth pattern instead of regular P waves signifies atrial flutter. These are called flutter waves. The number of flutter waves preceding a QRS complex corresponds to number of atrial contractions to one ventricular contraction.

P wave is the summation of 2 smaller waves resulting from depolarization of the right atrium followed by that of the left atrium. Normal P waves are rounded, smooth and upright in most leads. In V1, P wave is biphasic, with an initial positive deflection corresponding to activation of the right atrium, and a subsequent negative deflection, resulting from activation of the left atrium.

Unusual morphology of P waves is indicative of atrial enlargement. In right atrial enlargement, depolarization of the right atrium lasts longer than normal and its waveform extends to the end of that of the left atrium. This results in a P wave that is taller than normal, more than 2.5 small squares. Its duration remains unchanged, less than 120ms. In V1, this is seen as a taller initial positive deflection of the P wave, more than 1.5 small squares. Right atrial enlargement is usually due to pulmonary hypertension.

In left atrial enlargement, depolarization of the left atrium lasts longer than normal. This results in a wider P wave, of more than 3 small squares. The waveform may also be notched. In V1 the negative portion of P wave is deeper and wider. Left atrial enlargement is commonly due to mitral stenosis.

P-wave inversion in the inferior leads indicates a non-sinus rhythm. When this happens measure the PR interval. If the PR interval is less than 3 small squares, the rhythm is started in the AV junction – AV nodal junctional rhythm. If the PR interval is more than 3 small squares, the origin of the rhythm is within the atria – ectopic atrial rhythm.

The PR interval is measured from the start of the P wave to the start of the QRS complex and reflects the conduction through the AV node.

A longer than normal PR interval signifies an abnormal delay in the AV node, or an AV block. A consistent long PR interval of more than 5 small squares constitutes first-degree heart block. It might be a sign of hyperkalemia or digoxin toxicity. A progressive prolongation of PR interval followed by a P wave WITHOUT a QRS complex is the hallmark of second-degree AV block type I.

A shorter than normal PR interval, of less than 3 small squares, signifies that the ventricles depolarize too early. There are 2 scenarios for this to happen:

Pre-excitation syndrome: presence of an accessory pathway bypassing the AV node.
AV nodal (junctional) rhythm: Non-sinus rhythm initiated from around the AV node area instead of the SA node. In this case, P waves are either absent or inverted in the inferior leads.

The QRS complex represents depolarization of the ventricles. A normal QRS complex is narrow, between 70 and 100 ms. A wider QRS complex, resulting from an abnormally slow ventricular depolarization, may be caused by:

– A ventricular rhythm: rhythms originated from ectopic sites in the ventricles. OR

– An impaired conduction within the ventricles in conditions such as bundle branch block, hyperkalemia or sodium-channel blockade.

A QRS complex wider than three small squares despite sinus rhythm is the hallmark of bundle branch block. When bundle branch block is suspected, check leads V1 and V6 for characteristic patterns of the QRS complex.
The ST segment extends from the end of the S wave to the start of the T wave. A normal ST segment is mostly flat and level with the baseline. Elevation of more than two small squares in the chest leads or one small square in the limb leads, indicates the possibility of myocardial infarction.

Pericarditis causes a characteristic “saddleback” ST segment elevation and PR segment depression in all leads except aVR and V1, where the reverse – ST depression and PR elevation – are seen.

Neumonía, con Animación

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La neumonía es una infección común de los pulmones que afecta en su mayoría a los sacos de aire microscópicos – los alvéolos. La función del sistema respiratorio es intercambiar oxígeno y dióxido de carbono entre el cuerpo y el medio ambiente. Este proceso ocurre en los alvéolos de los pulmones. El oxígeno inhalado pasa de los alveolos a la sangre de los capilares mientras el dióxido de carbono se traslada desde la sangre hasta los alvéolos para ser exhalado fuera del cuerpo. En las personas con neumonía, estos sacos de aire están llenos de líquido o pus, lo que dificulta el proceso de intercambio gaseoso, resultando en dificultad respiratoria y un reflejo de toser. Otros síntomas pueden incluir dolor de pecho, fiebre, escalofríos y confusión.

La neumonía no es una sola enfermedad. Un gran número de diversos organismos pueden causar neumonía. La neumonía bacteriana es la más común, siendo el Streptococcus pneumoniae el principal culpable. La neumonía viral es más común en los niños pequeños. Una variedad de virus están implicados, cada uno de ellos predominando en diferentes épocas del año.

La neumonía por lo general empieza como una infección del tracto respiratorio superior – un resfriado o gripe, que luego se disemina hacia los pulmones. Las vías más comunes de transmisión son a través de la inhalación de gotitas de aerosol contaminadas y por la aspiración de las bacterias orales hacia los pulmones.

El escenario en el cual se desarrolla la neumonía es una información importante en la medida en que ayuda a identificar la fuente del agente causante y por lo tanto el enfoque del tratamiento. Generalmente, la neumonía adquirida en la comunidad es menos peligrosa que la neumonía asociada al cuidado de la salud, nosocomial o asociada a ventilación mecánica. Esto es por qué una infección contraída por fuera de los centros de salud tiene menor probabilidad de involucrar bacterias multirresistentes. Los pacientes intrahospitalarios son también más propensos a tener otros problemas de salud y un sistema inmunológico debilitado y por lo tanto están en menor capacidad de combatir la enfermedad.

La neumonía se diagnostica a menudo sobre la base de exámenes físicos y una radiografía de tórax. La evaluación clínica para los niños se basa principalmente en una alta frecuencia respiratoria, tos, presencia de retracción de la pared torácica inferior, y el nivel de consciencia. Los adultos suelen ser examinados en busca de signos vitales y presencia de crepitaciones en el pecho – el sonido estrepitoso proveniente de un pulmón enfermo.

La neumonía bacteriana es tratada con antibióticos. La elección de los antibióticos depende de la edad, las condiciones de salud del paciente y de cómo fue adquirida la infección. La neumonía viral causada por virus de la gripe puede ser tratada con medicamentos antivirales. La hospitalización puede ser necesaria para los casos graves con dificultad respiratoria, especialmente en los niños pequeños, los ancianos, y aquellos con otros problemas de salud.

Chronic Obstructive Pulmonary Disease (COPD), with Animation

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Chronic obstructive pulmonary disease, or COPD, is a PROGRESSIVE inflammatory lung disease characterized by INCREASING breathing difficulty. Other symptoms include cough, most commonly with mucus, chest tightness and wheezing. COPD develops as a result of LONG-TERM exposure to irritants such as smoke, chemical fumes or dusts, and may go UNNOTICED for years. Most people show symptoms after the age of 40 when the disease is already in its advanced stage.
Pathology

The lungs consist of millions of air tubes or airways, called bronchi and bronchioles, which bring air in and out of the body. These airways end with tiny air sacs – the alveoli – where the gas exchange process takes place. REPEATED inhalation of irritants results in a CHRONIC inflammatory response which brings in a large amount of defensive cells along with inflammatory chemicals from the immune system. Inflammation of the airways causes them to thicken and produce mucus, NARROWING the air passage – this is known as CHRONIC BRONCHITIS. Inflammatory chemicals also dissolve alveolar walls, resulting in DESTRUCTION of the air sacs – this is EMPHYSEMA. COPD is, basically, a COMBINATION of these two conditions.
Causes

Tobacco smoking is accountable for about 90% of COPD cases. These include current, former smokers and people frequently exposed to second-hand smoke.
Extended contact with harmful chemicals such as fumes from burning fuel or dusts, at home or workplace, may also cause COPD.
Genetics has been implicated in a small number of cases. Notably, a condition known as alpha-1 antitrypsin deficiency, or AAT deficiency, has been shown to increase risks for COPD and other lung diseases. AAT protein protects the lungs from damaging effects of enzymes released during inflammation. Low levels of AAT make lung tissues more vulnerable to destruction when inflamed. While people with AAT deficiency may develop COPD even WITHOUT smoking or exposure to harmful irritants, AAT deficient smokers are at MUCH greater risks.

Diagnosis

COPD is diagnosed based on symptoms, history of exposure to irritants and lung function tests. The major test for COPD is SPIROMETRY, in which the patient is asked to blow into a tube connected to a machine – a spirometer. Spirometry evaluates pulmonary functions by measuring the volume and the speed of air flow during inhalation and exhalation.

Treatments

There is no cure for COPD but treatments can relieve symptoms, prevent complications and slow down progression of the disease. The first and most essential step to treatment is to stop smoking and/or improve air quality at home and workplace. These are also the most effective measures in preventing the disease.
Other treatments include:
-Medication: bronchodilators are used to widen the airways; steroids to relieve inflammation.
-Vaccination against flu and pneumococcal pneumonia: this is to prevent serious complications COPD patients may have with these respiratory infections.
-Supplemental oxygen: this can improve quality of life provided that the patient no longer smokes.
-Breathing exercises and other therapies as part of a pulmonary rehabilitation program.
-Finally, surgery may be performed for severe cases when other methods fail. Surgical procedures include bullectomy, lung volume reduction surgery, where damaged parts of the lung are removed; and lung transplant, where the entire diseased lung is replaced with a healthy lung from a deceased donor.

Infecção do Trato Urinário, com Animação.

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A infecção do trato urinário, ou ITU, é uma infecção em qualquer parte do sistema urinário – os rins, ureteres, bexiga e uretra.
Uma infecção da uretra, ou uretrite, pode causar sensação de queimação ao urinar e corrimento esbranquiçado. A infecção da bexiga, ou cistite, pode resultar em dor pélvica, aumento da frequência urinária, dor ao urinar e sangue na urina. Uma infecção renal, ou pielonefrite aguda, podem causar dor nas costas (possivelmente apenas em um lado), febre alta, calafrios e náuseas.
ITUs ocorrem tipicamente quando a bactéria entra no trato urinário através da uretra e multiplica-se na bexiga. Mais comumente, essas bactérias vêm a partir do trato digestivo, através das fezes. ITUs são mais comuns em mulheres devido à sua anatomia. Especificamente, a curta distância do ânus para a abertura da uretra e da bexiga, tornando mais fácil para as bactérias atingirem o sistema urinário a partir do trato digestivo. É por isso que a maioria das ITUs ocorrem, principalmente, em mulheres e afetam a bexiga e a uretra.
Outras bactérias podem ser trazidas com o contato sexual. As mulheres que usam certos tipos de controle de natalidade, como diafragmas ou agentes espermicidas, apresentam maior risco. A deficiência hormonal, durante a menopausa, também torna as mulheres mais vulneráveis à infecção.
Infecção apenas na bexiga pode ser facilmente tratada com antibióticos. No entanto, se não for tratada, uma infecção do trato urinário inferior podem espalhar-se para os rins, tornando-se mais perigosa. Uma infecção renal pode resultar em danos permanentes nos rins. Em casos raros, a infecção também pode se espalhar para a corrente sanguínea, podendo ser fatal.
Infecções do trato urinário podem ser evitadas seguindo os seguintes passos:
• Beber bastante líquidos – pois, aumentará a frequência urinária para expulsar as bactérias.
• Limpar da frente para trás depois de uma evacuação – isso ajuda a impedir que as bactérias nas fezes se espalhem para a uretra.
• Esvaziar a bexiga logo após a relação sexual para expulsar as bactérias.
• Evitar produtos femininos que podem irritar a uretra, como duchas e pós.
• Evitar diafragmas e espermicidas como métodos de controle de natalidade.

Eczema – Atopic Dermatitis, with Animation.

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Eczema, or dermatitis, is a group of conditions characterized by inflammation of the skin. Among the many types of dermatitis, the most common is atopic dermatitis, also known as atopic eczema. Very often, when not specified otherwise, the term “eczema” is used to describe the atopic type.
Symptoms of atopic dermatitis include rashes, redness, scaling, and occasionally small blisters. Depending on the patient’s age, these patches may appear on the face, scalp, neck, inside the elbows, behind the knees, on the buttocks, hands and feet. The condition evolves in the form of recurrent inflammatory flare-ups followed by periods of remission. Flare ups can be triggered upon contact with irritants such as soap, detergents, rough fabric or certain foods. A dry atmosphere, changes in temperature, dental eruptions and stress are also common triggers. Over time, the skin can become thickened, bumpy and constantly itch, even when the inflammation is not flaring up. Atopic eczema usually starts in early childhood and MAY last into adult life. Most children outgrow the disease with age but their skin may remain dry and easily irritable.
Atopic dermatitis is an allergic disease. The cause is unknown but it is likely to involve genetic and environmental factors. Atopic eczema often runs in families whose members also tend to develop hay fever, asthma and certain food allergies. Most notable is the gene that encodes for filaggrin, a protein involved in water retention and is responsible for the skin barrier function. Mutations in the filaggrin gene cause dry skin and, as a result, a strong susceptibility to the disease. Eczema is NOT contagious.
There is no cure for atopic dermatitis. Treatments aim to relieve symptoms, reduce frequency of flare ups and prevent skin infection. A treatment plan may include:
– Lifestyle changes: bathe at least once a day but avoid soaps; wear silk clothing and avoid wool; avoid allergy triggers.
– Skincare: use oil-based, fragrance-free moisturizers to keep the skin hydrated during remissions.
– Medications: anti-inflammatory drugs such as steroid creams can be used during flare-ups. Antibiotics may be required if skin infection occurs.

Epilepsy, Types of Seizures, with Animation.

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Epilepsy is a group of neurological diseases characterized by recurrent seizures. Seizures happen as a result of a sudden surge in the brain’s electrical activities. Depending on which part of the brain is affected, a seizure may manifest as loss of awareness, unusual behaviors or sensations, uncontrollable movements or loss of consciousness.

Mechanism

The brain is a complex network of billions of neurons. Neurons can be excitatory or inhibitory. Excitatory neurons stimulate others to fire action potentials and transmit electrical messages, while inhibitory neurons SUPPRESS this process, preventing EXCESSIVE firing. A balance between excitation and inhibition is essential for normal brain functions. In epilepsy, there is an UP-regulation of excitation and/or DOWN-regulation of inhibition, causing lots of neurons to fire SYNCHRONOUSLY at the same time.

Types of Seizures

If this abnormal electrical surge happens within a limited area of the brain, it causes PARTIAL or FOCAL seizures. If the entire brain is involved, GENERALIZED seizures will result. Partial seizures subdivide further to:

Simple partial: depending on the affected brain area, patients may have unusual feelings, strange sensations or uncontrollable jerky movements, but remain conscious and aware of the surroundings.
Complex partial seizure on the other hand involves a loss or changes in consciousness, awareness and responsiveness.

Generalized seizures subdivide further to:

Absence seizures: this type occurs most often in children and is characterized by a very brief loss of awareness, commonly manifested as a blank stare with or without subtle body movements such as eye blinking, lip smacking or chewing. People with absence seizures may not be aware that something is wrong for years. Kids who start having absence seizures in early years stand a good chance of outgrow them without treatment.
Tonic seizures are associated with stiffening of muscles and may cause the person to fall, often backwards.
Atonic seizures, also known as drop attacks, are characterized by a sudden loss of muscle tone, which may cause the person to collapse or drop down.
Clonic seizures are associated with rhythmic jerking muscle movements. Most commonly affected are the muscles of the neck, face, arms and legs. Clonic seizures are rare.
Myoclonic seizures are brief jerks or twitches of a muscle or a group of muscles. There can be one or many twitches occurring within a couple of seconds.
The most common and also most dramatic are tonic-clonic seizures, also known as convulsive seizures, which are combinations of muscle stiffening and jerking. This type is what most people relate to when they think of a seizure. It also involves sudden loss of consciousness and sometimes loss of bladder control. A tonic-clonic seizure that lasts longer than 5min requires immediate medical treatment.

Causes

Epilepsy may develop as a result of a brain injury, tumor, stroke, previous infection or a birth defect.

Generalized seizures that start in childhood are likely to involve genetic factors. Epilepsy due to a single gene mutation is rare. More often, an interaction of multiple genes and environmental factors is responsible. Hundreds genes have been implicated. Examples include genes encoding for GABA receptors – major components of the inhibitory circuit, and ion channels. Many genetic disorders that cause brain abnormalities or metabolic conditions have epilepsy as a primary symptom. The cause of epilepsy is unknown in about half of cases.

Diagnosis is based on observation of symptoms, medical history, and an electroencephalogram, or EEG, to look for abnormal brain waves. An EEG may also help in differentiating between partial and generalized seizures. Genetic testing maybe helpful when genetic factors are suspected.

Treatment

There is no cure for epilepsy but various treatments are available to control seizures.

Medication successfully controls seizures for about 70% of cases. Many anti-epileptic drugs are available which target sodium channels, GABA receptors, and other components involved in neuronal transmission. Different medicines help with different types of seizures. Patients may need to try several drugs to find the most suitable.
Dietary therapy: ketogenic diet has been shown to reduce or prevent seizures in many children whose seizures could not be controlled with medication. Ketogenic diet is a special high-fat, low-carbohydrate diet that must be prescribed and followed strictly. With this diet, the body uses fat as the major source of energy instead of carbohydrates. The reason why this helps control epilepsy is unclear.
Nerve stimulation therapies such as vagus nerve stimulation in which a device placed under the skin is programmed to stimulate the vagus nerve at a certain rate. The device acts as a pacemaker for the brain. The underlying mechanism is poorly understood but it has been shown to reduce seizures significantly.
Finally, a surgery may be performed to remove part of the brain that causes seizure. This is usually done when tests show that seizures are originated from a small area that does not have any vital function.

Cardiac Axis Explained, with Animation.

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Cardiac axis is the net direction of electrical activity during depolarization. In a healthy heart, the net movement is downward and slightly left. This axis is altered, or deviated, in certain conditions. For example, in left ventricular hypertrophy the axis is skewed further left; while right ventricular hypertrophy results in a deviation to the right.

Cardiac axis can be determined by examining the 6 limb leads, which look at the heart from different angles in a vertical plane. The QRS axis is the most important, and also the easiest to be determined, as it represents ventricular depolarization. The QRS axis is considered normal when it is between -30 and +90 degrees. Left axis deviation is between -30 and -90 degrees. Right axis deviation goes between +90 and +180 degrees. The rest is known as northwest axis or extreme axis deviation.

Remember that depolarization TOWARD a lead produces a POSITIVE deflection; depolarization AWAY from a lead gives a NEGATIVE deflection. Impulses moving at a 90 degree angle relative to a lead produce an isoelectric, or equiphasic result with positive and negative deflections of similar amplitude.

There are several methods to estimate the QRS axis; we here discuss 2 of them.

The quadrant method.

This method looks at the QRS complex in lead 1 and lead aVF. If the QRS complex is mostly positive in both leads, the axis is somewhere in between the 2 leads, which is in the normal range. If it’s negative in lead I and positive in aVF, the axis is running away from lead I but toward aVF and is thus in the lower right quadrant. The diagnosis is right axis deviation. A positive value in lead I and negative in lead aVF, place the axis in the upper left quadrant, which interprets as possible left axis deviation. A more accurate method will be needed to further determine if it is borderline normal or left deviation. Negative values of the QRS complex in both leads are indicative of extreme axis deviation.

The isoelectric lead method

This method consists of finding the isoelectric or equiphasic lead – the one with equal, or closest to equal, negative and positive deflections. In other words, the one with zero, or nearest to zero, net amplitude. The axis line is perpendicular to the direction of the isoelectric lead. Now, look at the lead that runs nearest to this line. If the QRS complex is positive in that lead, the axis points to roughly the same direction as the lead. If it is negative, the axis points to the opposite direction.

There is also a method for exact calculation of the heart axis but it is rarely used in clinical practice.

Pneumonia, with Animation.

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Pneumonia is a common infection of the lungs affecting mostly the microscopic air sacs – the alveoli. The function of the respiratory system is to exchange oxygen and carbon dioxide between the body and the environment. This process takes place in the alveoli of the lungs. Inhaled oxygen moves from the alveoli into the blood in the capillaries while carbon dioxide relocates from the blood to the alveoli to be exhaled out of the body. In people with pneumonia, these air sacs are filled with fluid or pus, hindering the gas exchange process, resulting in difficulty breathing and a cough reflex. Other symptoms may include chest pain, fever, chills and confusion.

Pneumonia is not a single disease. A large number of various organisms can cause pneumonia. Bacterial pneumonia is the most common, with Streptococcus pneumoniae being the main culprit. Viral pneumonia is more common in young children. A variety of viruses are implicated with each of them predominating in different times of the year.

Pneumonia commonly starts as an infection of the upper respiratory tract – a cold or flu, which then spreads to the lungs. The most common routes of transmission are through inhalation of contaminated aerosol droplets and aspiration of oral bacteria into the lungs.

The setting in which pneumonia develops is an important information as it helps to identify the source of the causative agent and hence the treatment approach. Generally, community-acquired pneumonia is less dangerous than health care-associated, hospital-acquired, or ventilator-associated pneumonia. This is because an infection contracted outside health care facilities is less likely to involve multidrug-resistant bacteria. Patients who are already in hospitals are also most likely to have other health problems and weakened immune system and are thus less able to fight the disease.

Pneumonia is often diagnosed based on physical exams and a chest X-ray. Clinical assessment for children is primarily based on a rapid respiratory rate, a cough, presence of lower chest wall indrawing, and the level of consciousness. Adults are usually checked for vital signs and presence of chest crackles – the rattling noise coming from a diseased lung.

Bacterial pneumonia is treated with antibiotics. The choice of antibiotics depends on the patient’s age, health conditions and how the infection was acquired. Viral pneumonia caused by influenza viruses may be treated with antiviral drugs. Hospitalization may be required for severe cases with breathing difficulty, especially for young children, the elderly, and those with other health problems.

ECG de 12 Derivaciones Explicado, con Animación.

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Las actividades eléctricas del corazón pueden ser recogidas en la piel por medio de electrodos. Un electrocardiógrafo registra estas actividades y las muestra gráficamente. Los gráficos muestran el potencial eléctrico, o voltaje, GLOBAL del corazón conforme cambia a través del tiempo durante un ciclo cardíaco.
Las 12 derivaciones del ECG representan 12 vistas eléctricas del corazón desde 12 ángulos diferentes. El procedimiento convencional de 12 derivaciones implica colocar 10 electrodos en el cuerpo: uno en cada miembro y seis en el tórax.
Hay 6 derivaciones de los miembros y 6 derivaciones precordiales.
Las 6 derivaciones de los miembros miran al corazón en un plano frontal y se obtienen a partir de 3 electrodos colocados en el brazo derecho, brazo izquierdo, y pierna izquierda. El electrodo de la pierna derecha es un electrodo a tierra.
La medida del voltaje requiere de 2 polos: negativo y positivo. El electrocardiógrafo usa el polo negativo como referencia cero. Por lo tanto, la posición del polo positivo es el “punto de vista”, y la línea que conecta los dos polos es la “línea de visión”.
Las derivaciones I, II, y III son BIpolares – miden el potencial eléctrico entre 2 de los 3 electrodos de los miembros: la derivación I representa el voltaje entre el brazo derecho – polo negativo – y el brazo izquierdo – polo positivo, y por lo tanto mira el corazón desde la izquierda. La derivación II detecta el voltaje entre el brazo derecho – negativo – y la pierna izquierda – positivo – formando la vista INFERIOR IZQUIERDA. De forma similar, la derivación III mide el potencial eléctrico entre el brazo izquierdo – negativo – y la pierna izquierda – positivo, observando el corazón desde un ángulo INFERIOR DERECHO.
Las derivaciones aVR, aVL, y aVF, o “derivaciones ampliadas de los miembros”, son UNIpolares. Estas utilizan UN electrodo de un miembro como el polo positivo, y toman el promedio de las aportaciones de los OTROS dos como la referencia cero. De esta forma, aVR mira el lado SUPERIOR DERECHO del corazón; aVL mira el lado SUPERIOR IZQUIERDO del corazón; y aVF mira a la pared INFERIOR del corazón.
Las derivaciones precordiales miran el corazón en un plano HORIZONTAL. Estas son derivaciones unipolares. Los electrodos torácicos correspondientes actúan como los polos positivos. La referencia de valor negativo es la misma para todas las derivaciones precordiales y se calcula como el promedio de las aportaciones de los tres electrodos de los miembros.
La DESpolarización EN DIRECCIÓN a la derivación produce una onda POSITIVA; la DESpolarización EN DIRECCIÓN CONTRARIA a la derivación da una onda NEGATIVA. Lo CONTRARIO es verdadero para la REpolarización. De esta forma, las derivaciones que miran al corazón desde diferentes ángulos pueden tener ondas apuntando en diferentes direcciones.

Medical Information Illustrated

Medical and health topics fully illustrated with pictures and videos for easy understanding.

Author Archives: Alila Medical Media

The Digestive System, with Animation.

ECG/EKG Reading Made Easy with Animation

Neumonía, con Animación

Chronic Obstructive Pulmonary Disease (COPD), with Animation

Infecção do Trato Urinário, com Animação.

Eczema – Atopic Dermatitis, with Animation.

Epilepsy, Types of Seizures, with Animation.

Cardiac Axis Explained, with Animation.

Pneumonia, with Animation.

ECG de 12 Derivaciones Explicado, con Animación.