Somnolence : a very sleepy state.

Anesthesia

Anesthesia is a procedure that is administered to control pain, heart rate, blood pressure and other vital parameters during a surgical procedure. It is temporary state which allows the patient to recover and gain control of his coordination a few hours after a surgical procedure.

Anesthesia is an exact procedure which requires theoretical and practical expertise. Any kind of dosage variation can be fatal to the patient. During general anesthesia, patients are advised to abstain from eating and drinking 12 hours before the procedure as it may lead to aspiration associated complications during the procedure. Thorough examination of the patient history is done to evaluate for drug sensitivity and allergic patterns with respect to the type of anesthesia administered. Anesthetics such as inhalants or IV forms are given depending upon the type of surgical procedure.

General anesthesia

General anesthesia is administered during complicated procedures such as cardio thoracic surgery, oncogenic or organ specific surgery. In this procedure, the patient goes into a stage of total unconsciousness with administration of anesthetic gases and intravenous anesthetics such as halothane, Sevoflurane, Enflurane, Desflurane, Isoflurane, Propofol, etomidate and thiopental. Some anesthetics such as Propofol are hypnotic in nature. It has been widely used because of its nature to bring back the patient to conscious state a few hours after the surgical procedure. In addition to the inhalant and intravenous forms of anesthesia which are administered, neuromuscular blockage is also required as it helps in respiratory ventilation along with intubation. Most of these neuromuscular blockade agents are derived from curare compounds which is a skeletal muscle relaxant.

Local anesthesia

Local anesthetics are either administered as a combination with general anesthetics are as a post-operative anesthetic agent. Most of the local anesthetics are amides and esters. Some of the local anesthetic amides include lidocaine, prilocaine, ropivacaine and etidocaine. The ester forms of these anesthetics include tetracaine, procaine, cocaine and benzocaine. Local anesthetic drugs are given directly in the region where the surgical procedure has to take place. Most dental procedures involve the administration of local anesthetics. The patient is conscious and experiences numbness only in the region where the procedure is being done.

Regional anesthesia

This form of anesthesia is given to block pain in a larger area of the body where the procedure is done. Patient is sedated in most cases. Regional anesthetic drugs usually work on the principle of nerve block caused in the peripheral region. This includes a procedure called spinal anesthesia where the drug is administered in a specific area of the spine to numb the corresponding region of the body. Regional anesthesia is administered at a specific location to numb the region for surgical intervention. Local anesthetics are administered either in the topical or injectable form to desensitize the area of surgical intervention.

Risk factors of anesthesia

Malignant hyperthermia is one of the rare yet life threatening complications of anesthesia. This adverse reaction is caused when succinyl choline (muscle relaxant) is administered. In this reaction, the muscle fibers of the body tend to dissociate from each other. Spinal and epidural anesthetic procedures have headaches as side effects due to the leakage of cerebrospinal fluid from region of injection. Nausea, vomiting and nerve damages are some of the predominant side effects of anesthetic procedures. These are controlled by administration of IV medications. In some patients, the insertion of endotracheal tube during procedures such as bronchoscopy may lead to sore throat for a few days. Apart from all the presumptive risk factors and side effects of anesthetic drugs, some have toxic effects on liver and kidneys. In such conditions, patients are examined for tolerance and toxicity before administering anesthetic gases such as halothane.

Hypoxia

The body needs a specific amount of Oxygen to function normally and when this amount is lowered the body experiences hypoxia. Hypoxia literally means lack of oxygen for effective ventilation.

Hypoxemia refers to a state of abnormally low level of Oxygen in the blood.
Anoxia refers to the condition of absence of Oxygen supply to an organ or tissue
Anoxemia refers to the condition where the blood stream contains below normal amount of Oxygen.

Hypoxia is primarily classified into:

Generalized hypoxia: affects the entire body, may occur in normal healthy people when they scale high altitudes.
Local hypoxia: affects one particular region of the body.

When the level of oxygen in the blood reduces, it leads to the condition. People suffering from conditions like ischemia or blockage/constriction of blood vessels may suffer from hypoxia. In general when people travel from low to high altitudes, they may face this problem as the oxygen level depletes with altitude.

Hypoxia causes

Any condition wherein the body is deprived of oxygen can lead to hypoxia. Major causes that lead to the condition include:

• Severe head trauma
  
• Ischemia
  
• Asthma Severe Asthma can result in hypoxia and in Hypercarbia or Hypercapnia (elevated levels of Carbon dioxide CO₂ in blood)
  
• Pulmonary embolism
  
• Carbon monoxide poisoning
  
• Chronic alveolar hypo ventilation
  
• Shock can result in cellular hypoxia in the extremities
  
• Suffocation
  
• Choking
  
• High altitude climbing
  
• Inadequate ventilation

Types of hypoxia

Hypemic hypoxia: Obstruction in the ability of the blood to deliver oxygen, caused by carbon monoxide poisoning.

Anemic Anoxia: Occurs due to a decrease in the hemoglobin or RBC making it too little for the blood to carry oxygen. Anemia may be the result of iron deficiency, hemorrhage or shortened life span of RBC owing to an autoimmune disease.

Histotoxic: When the required amount of oxygen reaches the body part, however it does not utilize it because of its reduced ability, it is called as histotoxic hypoxia. Cyanide poisoning, for example, incapacitates a cellular enzyme essential for oxygen utilization. Other causes include: Alcohol, narcotics, acetone, formaldehyde and some anesthetic agents.

Hypoxic: Also called as Hypoxemic Anoxia: When the body does not receive the required amount of oxygen it leads to low partial pressure of oxygen in the blood thus leading to hypoxic hypoxia. The oxygen pressure of the blood which gets supplied to other body tissues is too low to push and flood the hemoglobin with oxygen. High altitude has lower density of air and lower pressure of oxygen than at sea level. Altitude Sickness occurs because the partial pressure of oxygen decreases with altitude. Hypoxemia is the direct result of lower oxygen in the high altitude which translates to lower level oxygen in the blood.

Stagnant: Obstruction of blood that carries oxygen. It can be due to exposure to cold, diseases which stifle blood circulation to the extremities or ergot poisoning.

Pulse Oximetry, a non invasive test is useful to diagnose Hypoxia. A blood test like serum lactate test can show elevated levels of lactic acid - the result of starvation of oxygen in tissues. The normal level of lactic acid is less than 2 mmol/L. However an increase in lactic acid alone does not indicate hypoxia and some form of Anoxia does not increase the lactic acid concentration. Symptoms may be dangerous on the onset and may include the following:

Generalized hypoxia

• Tachypnea or rapid breathing
  
• Severe headache
  
• Dizziness
  
• Nausea
  
• Tingling sensation
  
• Visual impairment
  
• Shortness of breath
  
• Bluish tint on the lips or on finger tips
  
• Coma
  
• Seizures
  
• Euphoria
  
• Mental fatigue
  
• Muscle fatigue

• Hot and cold flashes
  
• Discoloration of skin
  
• Pain in the area of hypoxia
  
• Severe hypoxia may cause gangrene

Hypoxia Treatment

Some types of Hypoxia cannot be prevented. Treatment depends on the severity of the condition and the appearance of the clinical symptoms. Treatment may include the following:

• Restoration of the tissue oxygen by supplementing the air supply with 100 % oxygen.
  
• Blood pressure and heart rate should be brought back to normal.
  
• In case of high altitudes, the person should be given sufficient rest and should not climb any further.
  
• Hypoxemic hypoxia patients can be put on blood transfusion.
  
• Proper medication and timely treatment can help save the life.

Memory Loss

Memories of persons vary depending on the individual's state of mind and the content of the information. There are 2 basic types of memory - Implicit which refers to the unconscious level occurring in basal ganglia and the Explicit that refers to the conscious level (occurring in medial temporal structures). Episodic memory refers to the record of events (episodes) and the relationship with the person. Short term memory is synonymous with working memory. This is a specialized term referring to information about the current task. Commonly also referred to as amnesia, memory loss can be described as a degree of forgetfulness or failure to recall past events which is above the normal level. At times, memory loss is limited to an inability to recall events that are recent, but sometimes it could also be for events from the past or both.

Types of memory loss

Depending upon its cause, memory loss could be sudden or gradual, and permanent or temporary. A transient global amnesia is rare and is a complete but temporary memory loss. In anterograde amnesia on the other hand, the individual cannot recall recent events occurring after a trauma but can recall events of distant past. Retrograde amnesia is when the individual cannot recollect events preceding or leading up to the trauma. But he/she can recall all subsequent events. A transient global amnesia is rare and is a complete but temporary memory loss.

Causes for short term memory loss

Short term memory loss is a symptom of many possible causes including disease, dyslexia, depression, injury or chronic drug and alcohol abuse. Other possible causes for amnesia can be Alzheimer's disease, brain tumor, Creutzfeldt-Jakob disease, meningitis, Parkinson's disease, Pick disease, epilepsy, stroke and West Nile virus. A stroke is construed as one of the most serious reasons for a short term memory loss.

Research findings have established that the structural differences in cortical neurons depend on gonadal hormones in laboratory animals. Other studies on women show that their cognitive tasks changed throughout the menstrual cycle based on the fluctuating estrogen levels.

A head trauma can sometimes result in short term memory loss and this can happen even when concussion is not sustained. Psychiatric disorders such as dissociative fugue, dissociative identity disorder and other types of amnesia can cause short term memory loss. Severe psychological stress can push a person beyond his/her coping abilities can cause memory loss among other mental disturbances. Research reveals that stress hormones kill or inhibit the growth of brain cells adversely affecting memory. The more prolonged the depression, the more extensive the damage. Hormonal imbalance can play havoc and lead to short term memory loss. During menopause, memory loss symptoms are often seen in women.

Treating memory issues

Mental exercises, herbal supplements, certain drugs as well as a healthier lifestyle can all help in treating short term memory loss. If the memory loss is chronic and it interferes with everyday life then it is essential to consult the doctor to identify the cause and eliminate the serious condition.