RISK FOR UNSTABLE BLOOD GLUCOSE LEVEL (CARE PLAN GUIDE)

This is my first post regarding Care Plans in English. All  information in this blog about care plans is just a guide as they need to be individualized and rationales (which I omitted) should be included, each diagnosis developed is based on NANDA International label.

RISK FOR UNSTABLE BLOOD GLUCOSE LEVEL (NANDA -1 diagnosis)

Definition: risk for variation of blood glucose/sugar levels from the normal range.

Common Risk Factors

-Insulin deficiency or insulin excess.

-Excessive glucose intake in relation to metabolic needs.

-Medication side effects.

-Imbalance of activity and food intake.

Common Expected Outcome

-Patient maintains blood glucose levels within defined target ranges.

Source: Nursing Care Plans Diagnoses, Interventions and Outcomes. Meg Gulanick, 8th Edition.

EMERGENCY TREATMENT FOR DIABETES

If not treated quickly enough, fluctuations in blood glucose levels can lead to a person with diabetes becoming unwell and losing consciousness. The two conditions associated with diabetes are:

• hyperglycaemia - high blood glucose
• hypoglycaemia - low blood glucose.

The more common emergency is hypoglycaemia which affects brain function and can lead to unconsciousness if untreated.

Diabetic ketoacidosis (DKA) is a life threatening complication in patients with untreated diabetes or improperly managed diabetes. It is most common among type 1, but it can also occur in type 2 if the body becomes physiologically stressed, for example during an infection.  

Signs and symptoms of hypoglycaemia and hyperglycaemia in type 1 diabetes

• Hypoglycaemia (low blood sugar)

Hypoglycaemia occurs when any insulin in the body has moved too much glucose out of the bloodstream and blood glucose levels have become very low. This is usually because the patient has taken too much insulin, exercised too vigorously or consumed alcohol on an empty stomach. This is commonly called a 'hypo'. Usually hypoglycaemia can be corrected simply by eating or drinking something with a high glucose content. If hypoglycaemia is not corrected, it can progress to more advanced symptoms such as slurred speech, confusion and ultimately unconsciousness. If a person loses consciousness they will need to have an emergency injection of a hormone called glucagon to raise the level of glucose in their blood.

Some people with diabetes are at particular risk of hypoglycaemia:

-those who frequently experience hypoglycaemia, even if they are able to treat themselves

-people who have poor awareness of hypoglycaemia symptoms

-people who fast (e.g. during Ramadan)

-those who vary their eating or exercise patterns

-older people, particularly those in the early stages of dementia

-people with poor mental health

-people with a learning disability

-people with alcohol-related health problems

-people with poor injection technique

-people not using glucose lowering therapies correctly (e.g. dose or timing)

-women who are pregnant or breastfeeding.

Hypoglycaemia has potentially severe consequences for some groups of people e.g. those who drive, work at heights, or live alone.

• Hyperglycaemia (high blood glucose)

Hyperglycaemia occurs when the body cannot produce any, or enough, insulin to regulate blood glucose. Consequently blood glucose levels become too high. This happens when there is no insulin to move glucose out of the bloodstream and into the cells to produce energy. The symptoms of hyperglycaemia are similar to the main symptoms of diabetes but they can come on suddenly and severely. If left untreated, hyperglycaemia can lead to diabetic ketoacidosis (DKA), which can eventually cause unconsciousness and even death. Hyperglycaemia can occur for several reasons including:

-eating too much

-being unwell

-steroid use e.g prednisolone.

Signs and symptoms of hypoglycaemia and hyperglycaemia in type 2 diabetes

• Hypoglycaemia (low blood glucose)

People with type 2 diabetes who manage the condition with a combination of healthy eating and physical activity are not usually at risk of hypoglycaemia. If people are not taking any medications to lower their blood glucose levels, they don't tend to drop too low to cause a 'hypo' episode. Severe hypoglycemia is also very rare among people with type 2 diabetes who are taking blood glucose lowering medications such as metformin (Glucophage).

However people with type 2 diabetes who take medications that increase the amount of insulin released from the pancreas can be at risk of low blood glucose levels. These medications include Gliclazide, Glipizide and Glimpiride. Hypoglycemia also can happen in people with type 2 diabetes who use insulin.

• Hyperglycaemia (high blood glucose)

Type 2 diabetes develops because the body either can not produce enough insulin or because the cells in the body do not respond properly to insulin. Consequently, blood glucose levels become too high. This happens when there is no insulin available to move glucose out of the bloodstream and into the cells to produce energy. As with type 1 diabetes, the symptoms of hyperglycaemia are similar to the main symptoms of diabetes but can come on suddenly and severely and for the same reasons as stated with type 1 diabetes.

If left untreated, hyperglycaemia untreated can lead to a hyperosmolar, hyperglyceamic state. People with type 2 diabetes are extremely unlikely to develop diabetic ketoacidosis (DKA) and are more likely to develop Hyperosmolar Hyperglycaemic State or HHS. Like DKA, this condition is also life threatening with a high mortality rate.

The initial treatment will depend on the person's level of conciousness and their ability to self treat. 

Diabetic ketoacidosis (DKA)

DKA is a life threatening complication in people with untreated diabetes or improperly/difficult to managed diabetes. It is most common in type 1 diabetes but it can also occur in type 2. The difference between hyperglycaemia and DKA relates to the level of ketones and dehydration.

Frequently people with undiagnosed type 1 diabetes present to hospitals with DKA. DKA can also occur in people with diabetes who have an overwhelming infection or in people who have misadministered their insulin doses. Before insulin injections became available, DKA was a major cause of death in patients with type 1 diabetes. DKA mimics the signs and symptoms of newly diagnosed type 1 diabetes and if not corrected, DKA progresses to more advanced symptoms of laboured breathing (Kussmaul respiration), coma and eventually, death.

The signs and symptoms of DKA include:

• feeling sluggish progressing to extreme tiredness
• fruity smell to breath (similar to the smell of nail polish remover)
• extreme thirst, despite large fluid intake
• constant urination (may include bedwetting)
• extreme weight loss
• oral thrush or yeast infections that won't resolve
• muscle wasting
• vomiting - this is a late sign and at this point, 

DKA is life threatening and medical attention should be sought immediately, particularly if they are unable to keep fluids down. DKA in pregnancy and children can be lethal so requires an emergency hospital admission.

Source: RCN

DIABETES

Diabetes is a common condition affecting all aspects of an individual’s life. Associated complications can be costly and have a significant affect on the person's quality of life. With the help and support of nursing staff the condition can be managed. Self-management skills are an essential part of diabetes care for every patient.

Diabetes is a common long-term health condition caused by too much glucose, a type of sugar, in the blood. It is also known as diabetes mellitus. 

Diabetes is a condition where the amount of glucose in a person’s blood is too high because their body is unable to process the glucose properly. This could be for two reasons:

• the pancreas doesn’t produce any insulin, or not enough, to help glucose enter the cells of the body
• the insulin that is produced does not work properly – this is known as insulin resistance.

Insulin is the hormone produced by the pancreas that allows glucose to enter the body’s cells. Here the glucose is used as fuel, providing the body with energy for body function, movement and everyday living. Insulin is vital for life.

If a person has diabetes, their body cannot make proper use of glucose. The glucose builds up in their blood and they are unable to produce the energy needed for everyday life.

Types of diabetes

Type 1 diabetes

Type 1 diabetes develops when the insulin-producing cells in the body have been destroyed and the body is unable to produce insulin. No one knows why this happens but the most likely reason is that the body has an abnormal reaction to the cells. This could be triggered by an infection or virus but again this is not known for sure. Type 1 diabetes is often referred to as insulin-dependent diabetes. It can develop at any age but usually appears before the age of 40, and especially in childhood. A person with type 1 diabetes will need to take insulin injections for life. They will also need to ensure that their blood glucose level stays balanced by eating a healthy diet and carrying out regular blood tests. People with type 1 diabetes make up only 10% of all people with diabetes. 

Type 2 diabetes

Type 2 diabetes develops when the body can still produce some insulin but not enough for it to function properly, or when the cells in the body do not react properly to insulin. This is called insulin resistance. The treatment of type 2 diabetes centres on lifestyle management including a healthy diet, regular exercise and the person monitoring their blood glucose level. As the condition progesses over time oral glucose therapies are also used, with or without additional insulin injections. There are several oral therapies for diabetes. Some help the body to use insulin more effectively whilst others increase the amount of insulin that the body produces.

Type 2 diabetes is often associated with obesity. Obesity-related diabetes is sometimes referred to as maturity-onset diabetes because it is more common in older people. However, it is also increasingly becoming more common in children, adolescents and young people of all ethnicities. 

Diagnosis of diabetes

Type 1 diabetes symptoms normally develop very rapidly, sometimes over a couple of weeks. They tend to be more severe. Type 2 diabetes symptoms are normally milder and develop slower. These symptoms are caused by the effect of diabetes on the body.

If the level of glucose in the blood becomes too high, excess glucose is removed from the blood by the kidneys and excreted via the urine (glycosuria). This results in greater urine production and causes the patient to urinate frequently. Water held in the cells is required to replace lost blood volume, and thus causes dehydration and thirst.

What are the main symptoms for type 1 diabetes?

There are the major indicators of diabetes:

• polyuria - the need to urinate frequently
• polydipsia - increased thirst & fluid intake
• polyphagia - increased appetite
• weight loss
• tiredness.

Symptoms of type 1 diabetes can develop quickly, over weeks or even days.

What are the other major signs of diabetes?

• Blurred vision - A change in glucose absorption can bring about a change in the shape of the lens in the eye, leading to an altered vision quality. This can cause blurred vision, a common complaint that can indicate type 1 or type 2 diabetes.

• Diabetic ketoacidosis - Diabetic ketoacidosis occurs when the body begins to break down stores of fat as an alternative source of energy, leading to a build-up of acids in the blood known as ketones. This can result in weight loss and muscle wasting. Diabetic ketoacidosis is a very rare complication of diabetes. Ketoacidosis can result in coma and possibly death if left untreated.

Other symptoms are:

• itchiness around the vagina or penis or getting thrush regularly
• cramps
• constipation
• skin infections

What are the main symptoms for type 2 diabetes?

In type 2 diabetes the signs and symptoms are not always obvious as the condition develops slowly over a period of years. It may only be picked up in a routine medical check up. The common symptoms are:

• tiredness
• poor healing process
• malaise
• sometimes weight gain.

Thirst and polyuria will develop as hyperglycaemia progresses, particularly in the elderly. It is important to be vigilant for the signs and symptoms of diabetes as early diagnosis and treatment can reduce the risk of developing complications later. Many people have type 2 diabetes for years without knowing it because early symptoms can be general.

Tests to diagnose diabetes and pre-diabetes.

HbA1c Blood test.

HbA1c will become the most common method of diagnosing diabetes, as recommended by WHO. This test measures recent average blood glucose level. The test measures a part of the red blood cells. Glucose in the blood attaches to part of the red blood cells. This part can be measured and gives a good indication of an average blood glucose over the previous 2-3 months. A blood sample is required. An HbA1c of 48mmol/l (6.5%) or more is a diagnostic of diabetes in most situations. HbA1c is also used to monitor diabetes in a patient and will normally be done every 2-6 months. Patients with diabetes aim to lower the HbA1c level to below a target level normally around 6.5% - 7.5%. However, the target level is set by the diabetes team, as the levels may vary for each patient.

When it cannot be used:

• children and young people
• if patient is suspected of having type 1 diabetes
• patients has symptoms of diabetes for less than two months
• patients who are acutely ill
• if patient is taking medication that may cause rapid glucose rise, for example steroids
• patient has acute pancreatic damage, including pancreatic surgery.
• pregnancy
• patients with abnormal red blood cells such as Thalissaemia.

Random blood glucose test

In a medical emergency, when a patient (most often a child) has such high glucose levels that they are drifting in and out of a coma, a blood glucose reading can be taken by taking a blood sample to measure the glucose with no consideration to when the last meal was eaten. A level of 11.1 mmol/L or more in the blood sample indicates diabetes. A further blood glucose test will need to be done to confirm the diagnosis.

Fasting blood glucose test (FBG)

The FBG test is taken using a blood sample obtained following a period of fasting (so no food or drink, except water) of at least eight hours. The fast normally starts from midnight. A sample of blood is taken early the next day, before food or drink. A level of 7.0 mmol/L or more after an overnight fast indicates diabetes. To confirm the diagnosis, it is usually necessary to repeat the test a second time on a different day.

Oral glucose tolerance test (OGTT)

For this test the patient fasts from midnight and then a baseline fasting blood glucose test is taken. The patient then consumes a drink which contains 75g of glucose (lucozade is normally used) and then they wait for 2 hours before their blood glucose is measured again. This test is different from the others as the patient drinks a sugary drink as a way of measuring how the pancreas manages the glucose. In a person without diabetes glucose levels rise and fall quickly, as the body naturally produces insulin to lower the blood glucose. A person with diabetes will see a sharp rise and a sustained high level of glucose. This is because the pancreas is unable to deliver the needed insulin to lower the glucose in the blood. A blood glucose level of 11.1 mmol/L or more in the blood sample taken after two hours indicates diabetes.

Urine test for glucose

A simple dipstick test can detect glucose in a sample of urine. In a dipstick test a doctor or nurse uses a special chemical strip which is dipped into a sample of the patient's urine. Colour changes on the strip show whether there is glucose in the urine sample. Some people have kidneys that are more 'leaky', and glucose may leak into urine with a normal blood level. If a patient's urine contains any glucose a blood test should be carried out to measure the blood level of glucose to confirm, or rule out, diabetes.

Whether a fasting glucose, random glucose or HbA1c is used to test for diabetes it will generally need repeating as there should be evidence of 2 results using the same testing method to confirm diagnosis test.

Treatment of diabetes

Diabetes cannot be cured, but it can be managed. Treatment aims to:

• keep blood glucose levels as near normal as possible
• reduce any other risk factors that may present and increase the risk of the patient developing complications - particularly to keep blood lipids (cholesterol) low and to lower blood pressure if it is high
• detect any complications as early as possible. Early diagnosis and treatment can prevent or delay some complications from getting worse.

The type of treatment that a patient will require will also depend on the type of diabetes that they have. Treatment falls in to the two broad categories of lifestyle and medication.

Lifestyle

A patient diagnosed with diabetes will need to take additional care of their health. They will need on-going advice and support about maintaining a healthy diet, keeping active and monitoring their health. Diabetes does not have to be a burden, people can live normal active and healthy lives and very small adjustments to their lifestyle can make signifcant improvements. Most diabetes management relies on a person 'self managing' the condition so their motivation is a major key to effective treatment.

People diagnosed with pre-diabetes can slow down or prevent the condition from developing into type 2 diabetes by making lifestyle changes as well. The following are significant factors in the management of diabetes and should be discussed with each person:

• healthy eating
• keeping active
• weight management
• smoking cessation and alcohol consumption
• emotional wellbeing.

Medication

Treatment for diabetes aims to help people with the condition to control their blood glucose levels and minimise the risk of developing complications over time.

Treatment for type 1 diabetes

Lack of insulin production by the pancreas makes type 1 diabetes particularly difficult to control. A management plan defined by the diabetes team that centres around the needs and goals of a person typically includes dietary advice and maintaining a constant health weight, home blood glucose monitoring and exercising regularly. Unfortunately, the treatment cannot eliminate the need for insulin or reverse the disease.

There is also a sub-type of type 1 diabetes known as 'brittle diabetes' (or 'labile diabetes'). This type of diabetes is particularly hard to control. People who have brittle diabetes will experience frequent, extreme swings in blood glucose levels, causing episodes of hyperglycaemia or hypoglycaemia. These fluctuations are more serious and tend to result in frequent hospital visits, interruption to employment and can often contribute to psychological issues such as stress.

Insulin

All patients with type 1 diabetes will need to have daily insulin injections as their body is unable to produce any insulin. The injections come in the form of a syringe, insulin pen or insulin pump. The reason that insulin is injected is because if it were taken as a tablet, it would be broken down in the stomach and would not enter the blood stream. When a person is first diagnosed, the diabetes team will teach them the correct procedure for their injections. This involves showing them when, where and how to inject themselves and how to adjust insulin doses. They will explain how to store the insulin and safely dispose of the needles.

Each person who is taking insulin has to carry an 'Insulin Passport' or 'Insulin Safety Card'.

Treatment for type 2 diabetes

It is possible for a person to initially control the symptoms of type 2 diabetes by following a healthy diet, taking regular exercise and keeping their blood glucose levels within an agreed target range. Type 2 diabetes is a progressive condition so they may eventually need to take diabetes medication which will usually be in tablet form. A treatment programme will be tailored to suit the person's needs by the diabetes team and will typically include one or a combination of the following:

• changing to a healthier diet
• medication such as Metformin
• insulin therapies.

Keeping blood glucose levels under control is vital in reducing the risk of diabetes complications. If a person is overweight, weight loss can often help to reduce the extent of diabetes symptoms. Type 2 diabetes is effectively controlled when a person is involved in the management of their own programme of treatment. Effective 'self management' is essential to successfully achieving their healthy targets for HbA1c, blood pressure and cholesterol levels. A person with type 2 diabetes may need (or eventually need) medicatiion that reduces high levels of blood glucose. In the first instance this will usually be glucose-lowering tablets (sometimes a combination of more than one type of tablet) and it may also include injectable insulin. Some oral medications for lowering blood glucose levels can cause hypoglycaemia for example, Gliclazide, Glipizide and Glimpiride.

Source: RCN 

THE PREVENTION AND TREATMENT OF PRESSURE ULCERS

Source: NICE 2005, RCN

PRESSURE ULCERS (IMPAIRED SKIN INTEGRITY) 

CARE PLAN

The National Pressure Ulcer Advisory Panel defines pressure ulcer as "a localized injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure in combination with shear and/or friction".

Common related factors:
-Extremes of age.
-Inmobility.
-Imbalanced nutritional state.
-Mechanical factors (friction, shear and pressure)
-Pronounced bony prominences.
-Impaired circulation.
-Impaired sensation.
-Incontinence.
-Moisture.
-Radiation.
-Chronic disease state.
-Inmunological deficit.
-Impaired cognition.

Defining characteristics:
-Destruction of skin layers.
-Disruption of skin surfaces.
-Invasion of body structures.
-Pressure ulcer stages:

• Deep tissue injury (new stage): purple or maroon localized area of intact skin or blood-filled blister resulting from pressure damage or underlying soft tissue.
• Stage I

• Stage II

• Stage III

• Stage IV

• Unstageable: Full thickness tissue loss in which actual depth of ulcer is completely obstructed by slough or eschar in the wound bed.

Common expected outcomes:
-Patient receives stage-appropiate wound care, experiences pressure reduction and has controlled risk factors for prevention of additional ulcers.
-Patient experiences healing of pressure ulcers.

Source: Nursing Care Plans Diagnoses, Interventions and Outcomes. Meg Gulanick, 8th Edition.

FACTORES PSICOSOCIALES QUE MODULAN LA RESPUESTA DE ESTRÉS

Hoy sabemos que la respuesta de estrés puede ser modulada por diferentes factores, los principales factores psicosociales son:

1. Control: la exposición a un agente estresante que no es controlable genera respuestas de estrés más pronunciadas, la percepción de control que se tenga a pesar de que se carezca del mismo es muy importante para determinar la respuesta de estrés.

En el ámbito de la psicología se habla del locus de control, un locus de control interno se refiere a un rasgo caracterizado por la percepción de la persona de que los sucesos tienen lugar principalmente como resultado de sus propias acciones. Lo contrario sería el locus de control externo, que se caracteriza por la percepción de que los sucesos tienen lugar principalmente como resultado de las decisiones de otros, del destino, del azar.

Delante de una situación incontrolable, las personas con tendencia al locus de control interno presentan unas respuestas de estrés más elevadas que las personas con tendencia al locus de control externo.

Atribuir la falta de control a causas internas generará una disminución de la autoestima y aumentará la respuesta de estrés.

2. Capacidad de predecir: tener que mantener una respuesta de afrontamiento en una situación en la que se carece de información predictiva podría ser más estresante, asimismo, dificulta la recuperación de la respuesta de estrés si los estímulos estresantes son impredecibles. Un mismo agente estresante produce diferentes efectos dependiendo de si el sujeto tiene o no la capacidad de predecir su ocurrencia. Según la hipótesis de Seligman, lo más importante para reducir el estrés sería la seguridad que proporciona la capacidad de predicción.

3. Recursos y escapes de la frustración: los seres humanos buscamos continuamente escapes y salidas a la frustración

4. Apoyo social: el soporte social puede minimizar la reactividad cardiovascular ante un agente estresante agudo. El aislamiento social parece estar relacionado con los niveles de noradrenalina intratumorales en el carcinoma ovárico. La noradrenalina se ha relacionado con el crecimiento y la progresión del cáncer de ovario.

El apoyo social no sólo modula la respuesta de estrés, también presenta amplios beneficios sobre la salud y el bienestar a lo largo de la vida de una persona.

5. Percepción del curso de la situación: el tener una percepción de que la situación empeora puede constituirse como un factor psicológico que modula nuestro bienestar y nuestra satisfacción personal con la situación que nos toca vivir. Asimismo, también puede modular la actividad del eje HPA.

6. Novedad: la novedad puede constituirse como un agente estresante, la respuesta del eje HPA también es sensible a la novedad de la situación.

Las primeras exposiciones a situaciones nuevas y emocionalmente cambiantes provocan aumentos del cortisol en sangre.

7. Voluntad o determinación de hacer algo: el ejercicio no solamente es ventajoso para fomentar el nacimiento de nuevas neuronas sino que también ayuda a mantener un equilibrio y un entorno óptimo en nuestro cerebro.

El ejercicio parece ser muy beneficioso para nuestra salud y un factor importante para reducir el estrés. Si dejamos a un animal hacer ejercicio de forma voluntaria aumenta su tasa de generación de nuevas neuronas en la formación hipocampal y los niveles de estrés se reducen, no obstante, si obligamos a la rata a realizar la misma cantidad de ejercicio, se produce una intensiva respuesta de estrés.

Por tanto, un factor que también puede modular la respuesta de estrés es el tener la voluntad o la determinación de hacer algo.

Estilos de conducta y de temperamento

Diferentes estudios etológicos han mostrado la existencia de dos estilos principales de afrontamiento: un estilo reactivo y un estilo proactivo caracterizados por la presencia de diferentes rasgos conductuales y neuroendocrinos.

Los animales proactivos presentan una tendencia a llevar a cabo una conducta cuando se presenta el agente estresante para intentar reducir su impacto. Los animales reactivos se limitan a evitarlo.

Los sujetos con estilo proactivo de afrontamiento muestran en respuesta a la estimulación estresante una reactividad más baja del eje HPA (bajos niveles de glucocorticoides) con una alta reactividad simpática (altos niveles de catecolaminas). Los animales con estilo reactivo presentan una mayor actividad tanto del eje HPA como de la rama simpática del sistema nervioso autónomo. Estos estilos de afrontamiento podrían explicar la vulnerabilidad diferencial al estrés que media la aparición de enfermedad, en tanto que se caracterizan por presentar un valor adaptativo diferente y un patrón neuroendocrino distinto.

Fuente: Estrés y cerebro, Diego Redolar Ripoll, UOC.

ESTRÉS Y SUEÑO

El porqué dormimos es una cuestión que hoy en día no está resuelta, existen diferentes hipótesis que intentan dar una respuesta a la misma, inicialmente se plantearon tres grupos de teorías:

1. Teorías circadianas: entienden el sueño como en mecanismo para mantener al animal en un estado de inactividad cuando no es adaptativo llevar a cabo algún tipo de conducta o interacción con el medio que promueva su supervivencia. El dormir permitiría conservar los recursos energéticos y disminuír la susceptibilidad a sufrir algún tipo de daño.
2. Teorías de la recuperación: se centran en que la vigilia produce una serie de modificaciones en la homeostasis corporal que se han de corregir de alguna forma para restaurar el cuerpo y volver a los niveles basales, dormir permitiría recuperar el equilibrio interno.
3. Teorías energéticas: se basan en la conservación energética.

Lo que tiene que quedar claro es que el dormir se encuentra conservado evolutivamente en animales que van desde la mosca de la fruta hasta el propio ser humano. Además, dormir es necesario para la supervivencia. La privación del sueño en mamíferos produce pérdida de peso, fallos en la regulación de la temperatura, alteraciones de la respuesta inmunitaria, reducción de las capacidades cognitivas, alteración del estado de ánimo, alucinaciones e incluso la muerte.

El sueño de los mamíferos y de las aves puede dividirse en:

-sueño REM (Rapid Eye Movement, movimientos oculares rápidos) también llamado sueño paradójico ya que muchas de las características que lo definen se parecen más al estado de vigilia que al de sueño. El registro de actividad eléctrica del cerebro muestra un patrón de actividad rápido y desincronizado. Presencia de movimientos oculares rápidos en buena parte del estadio y parálisis temporal de la musculatura estriada de todo el cuerpo (mecanismo que protege al organismo de posibles lesiones).

-sueño NREM (sin movimientos oculares rápidos) se subdivide en cuatro estadios, a lo largo de los cuales el sueño se muestra progresivamente más profundo. El sueño del estadio 1 es ligero y frecuentemente no se tiene sensación aún de estar durmiendo, abundan los movimientos corporales y es frecuente encontrar alucinaciones hipnagógicas como la sensación de "caer al vacío".

El sueño del estadio 2 es más profundo y el umbral para despertar es más alto, los movimientos oculares lentos característicos del primer estadio desaparecen y el tono muscular se reduce aún más.

El estadio 3 y 4 se denominan sueños de ondas lentas (SOL) por la abundancia de un patrón de actividad cerebral denominado ritmo delta.

Sueño y memoria

El aprendizaje y la memoria son mecanismos que suponen un gran gasto energético para la persona.

Las funciones principales del sueño podría ser reducir a un nivel estructural la conectividad en el cerebro, el sueño podría desempeñar un papel importante en la normalización de los cambios sinápticos causados por el aprendizaje acaecido en la vigilia, el proceso de consolidación de la memoria depende del fortalecimiento de las sinapsis.

Después del aprrendizaje aumenta la necesidad de sueño, tareas de aprendizaje que implican regiones cerebrales específicas inducen cambios locales en la intensidad del sueño. La actividad neural durante el sueño puede reactivar circuitos neurales implicados en el aprendizaje.

La privación de sueño puede considerarse como un agente estresante. Agente estresantes, sobre todo de tipo psicológico y social, pueden deteriorar la cantidad y la calidad de nuestro sueño.

Este efecto parece depender de la CRH, la administración cerebral de esta hormona suprime el sueño.

La falta de sueño induce un aumento de los niveles tanto de glucocorticoides como de actividad simpática. Niveles altos de glucocorticoides generados por la privación de sueño debilitan algunas formas de energía almacenadas en el cerebro, podría explicar por qué la memoria se ve tan mermada cuando estamos faltos de sueño.

Fuente: Estrés y cerebro, Diego Redolar Ripoll, UOC.

ESTRÉS Y MEMORIA

Desde los primeros teóricos del estudio de la emoción, se ha sabido que las situaciones con mucha carga emocional se recuerdan mejor que las situaciones neutras. Autores como Larry Cahill y James L.McGaugh sugieren que los acontecimientos emocionalmente activadores y estresantes aumentan la memoria al poner en marcha sistemas que regulan el almacenamiento de la información que se está adquiriendo, esta hipótesis se conoce como hipótesis de la modulación emocional de la memoria, que enfatiza el papel de la amígdala en la facilitación del proceso de consolidación de la memoria en otras regiones del cerebro después de que la situación emocional haya tenido lugar. La influencia de tres sustancias (adrenalina, noradrenalina y glucocorticoides) sobre la amígdala parece resultar primordial para la modulación del almacenamiento de la memoria en la corteza, afectando a los procesos de consolidación de la memoria en curso.

Los efectos del estrés sobre la memoria dependen de su magnitud y duración. Ciertos niveles de estrés en momentos puntuales pueden facilitar los procesos mentales de aprendizaje y memoria. No obstante, si aumentamos la duración y magnitud del estrés, éste puede ocasionar modificaciones en los mecanismos de plasticidad sináptica, cambios morfológicos en el cerebro e incluso la muerte celular y la supresión del nacimiento de nuevas neuronas.

Para adaptarnos a nuestro entorno hemos de ser enormemente flexibles y capaces de modificar nuestras pautas en función de lo que nos vayamos encontrando. Los circuitos cerebrales pueden verse modificados como resultado de la experiencia. Esta capacidad de cambiar el cerebro es más notable e importante durante unas ventanas temporales denominadas períodos críticos y se denomina neuroplasticidad.

Durante los estadios iniciales del desarrollo resulta muy maleable y susceptible a la reorganización estructural y funcional, pero a medida que avanzamos en su desarrollo nos cuesta más modificarlo. No obstante, un cerebro adulto es capaz de aprender cosas nuevas todos los días. Asimismo, cuando experimenta una lesión, también puede reorganizarse para minimizar los efectos de ésta.

El entorno modifica nuestro comportamiento, puesto que cambia nuestro sistema nervioso. Los mecanismos por los que las experiencias cambian nuestra conducta se encuentran íntimamente relacionados con el aprendizaje, proceso por el cual adquirimos nueva información o conocimiento. La memoria constituye el proceso por el que este conocimiento es codificado, almacenado y, más tarde, recuperado.

En la formación de la memoria podemos distinguir tres estadios:

1. La adquisición de información por medio de los sentidos.
2. Proceso de consolidación: se produce la actividad neural necesaria para fijar las asociaciones establecidas durante el aprendizaje. Hasta que esas asociaciones no son fijadas, la memoria es susceptible de disrupción.
3. Recuperación: reactiva las memorias almacenadas para que puedan ser usadas como guía de la propia conducta.

A medida que envejecemos, el hipocampo experimenta una degeneración importante. La pérdida de memoria asociada al envejecimiento se debe a la pérdida de neuronas en dicha estructura. Por este motivo, se va perdiendo la capacidad de consolidar y almacenar las nuevas memorias, manteniendo la capacidad de acceder a los recuerdos que tenemos afianzados desde hace tiempo en nuestro almacén, la corteza.

El hipocampo es muy sensible a las hormonas del estrés, su sobreexposición a estas hormonas presenta un claro efecto tóxico, todos los episodios estresantes  que han tenido lugar a lo largo de nuestras vidas pueden haber aumentado la probabilidad de que suframos problemas de memoria durante el envejecimiento.

Estudios de neuroimagen han mostrado la presencia de atrofia hipocampal en asociación con el estrés y con las alteraciones cognitivas y psiquiátricas relacionadas con los glucocorticoides.

La adquisición y la consolidación de memorias con un alto contenido emocional o de situaciones estresantes para la persona están moduladas por los glucocorticoides, estas hormonas regulan la funcionalidad del glutamato en los procesos plásticos de consolidación de la memoria.

Los glucocorticoides no solo afectan al aprendizaje y a la consolidación de la memoria sino también a los procesos de recuerdo y recuperación de la información.

Fuente: Estrés y cerebro, Diego Redolar Ripoll, Universitat Oberta de Catalunya.