DRUG THERAPY IN DRUG THERAPY IN ANESTHESIOLOGY AND ANESTHESIOLOGY AND

RESUSITATIONRESUSITATION

General anesthesiaGeneral anesthesia is the induction of a state of unconsciousness with the absence of pain sensation over the entire body, through the administration of anesthetic drugs.

It is used during certain medical and surgical procedures.

General anesthesia has many purposes including:• pain relief (analgesia)• blocking memory of the procedure (amnesia)• producing unconsciousness• inhibiting normal body reflexes to make surgery safeand easier to perform• relaxing the muscles of the body

General Anesthesia (cont’d)Anesthesia performed with general anestheticsoccurs in four stages which may or may not be observablebecause they can occur very rapidly:

• Stage One: Analgesia. The patient experiences analgesia

or a loss of pain sensation but remains consciousand can carry on a conversation.• Stage Two: Excitement. The patient may experiencedelirium or become violent. Blood pressure rises andbecomes irregular, and breathing rate increases. Thisstage is typically bypassed by administering a barbiturate,such as sodium pentothal, before the anesthesia.

General Anesthesia (cont’d)• Stage Three: Surgical Anesthesia. During this stage, theskeletal muscles relax, and the patient’s breathingbecomes regular. Eye movements slow, then stop, andsurgery can begin.• Stage Four: Medullary Paralysis. This stage occurs ifthe respiratory centers in the medulla oblongata of thebrain that control breathing and other vital functionscease to function. Death can result if the patient cannotbe revived quickly. This stage should never be reached.Careful control of the amounts of anesthetics administeredprevent this occurrence.

GENERAL ANESTHESIAAgents used for general anesthesia may be either

gases or volatile liquids that are vaporized and inhaledwith oxygen, or drugs delivered intravenously. A combinationof inhaled anesthetic gases and intravenous drugsare usually delivered during general anesthesia; thispractice is called balanced anesthesia and is used becauseit takes advantage of the beneficial effects of each anestheticagent to reach surgical anesthesia. If necessary, theextent of the anesthesia produced by inhaling a generalanesthetic can be rapidly modified by adjusting the

concentrationof the anesthetic in the oxygen that is breathedby the patient. The degree of anesthesia produced by anintravenously injected anesthesic is fixed and cannot bechanged as rapidly. Most commonly, intravenous anestheticagents are used for induction of anesthesia andthen followed by inhaled anesthetic agents.

General anesthesiaWhen general anesthesia was first introduced inmedical practice, ether and chloroform were inhaled withthe physician manually covering the patient’s mouth.Since then, general anesthesia has become much moresophisticated. During most surgical procedures, anestheticagents are now delivered and controlled by computerizedequipment that includes anesthetic gas monitoringas well as patient monitoring equipment. Anesthesiologistsare the physicians that specialize in the delivery ofanesthetic agents. Currently used inhaled general anesthetics

include halothane, enflurane, isoflurane, desfluorane, sevofluorane, and nitrous oxide.

General anesthesiaCommonly administered intravenous anesthetic agents

include ketamine, thiopental, opioids, and propofol.Ketamine (Ketalar) affects the senses, and produces adissociative anesthesia (catatonia, amnesia, analgesia)in which the patient may appear awake and reactive, butcannot respond to sensory stimuli. These propertiesmake it especially useful for use in developing countriesand during warfare medical treatment. Ketamine isfrequently used in pediatric patients because anesthesiaand analgesia can be achieved with an intramuscularinjection. It is also used in high-risk geriatric patientsand in shock cases, because it also provides cardiacstimulation.

General anesthesiaThiopental (Pentothal) is a barbiturate that induces a rapid hypnotic state of short duration. Because thiopental is slowly metabolized by the liver, toxic accumulation can occur; therefore, it should not be continuously infused. Side effects include nausea and vomiting upon awakening.

General anesthesia (cont’d)Opioids include fentanyl, sufentanil, and alfentanil, and

are frequently used prior to anesthesia and surgery as a

sedative and analgesic, as well as a continuous infusion

for primary anesthesia. Because opioids rarely affectthe cardiovascular system, they are particularly usefulfor cardiac surgery and other high-risk cases. Opioidsact directly on spinal cord receptors, and are freqentlyused in epidurals for spinal anesthesia. Side effects

mayinclude nausea and vomiting, itching, and respiratorydepression.

General anesthesia (cont’d)• Propofol (Diprivan) is a nonbarbiturate hypnotic agentand the most recently developed intravenous

anesthetic.Its rapid induction and short duration of action are

identicalto thiopental, but recovery occurs more quicklyand with much less nausea and vomiting. Also, propofolis rapidly metabolized in the liver and excreted inthe urine, so it can be used for long durations ofanesthesia, unlike thiopental. Hence, propofol is rapidlyreplacing thiopental as an intravenous induction agent.It is used for general surgery, cardiac surgery,

neurosurgery, and pediatric surgery.

General anesthesia (cont’d)General anesthetics are given only by anesthesiologists,the medical professionals trained to use them. Thesespecialists consider many factors, including a patient’sage, weight, medication allergies, medical history, and

general health, when deciding which anesthetic or combination of anesthetics to use. General anesthetics are usually inhaled through a mask or a breathing tube or injected into a vein, but are also sometimes given rectally.

General anesthesia is much safer today than it was inthe past. This progress is due to faster-acting anesthetics,improved safety standards in the equipment used todeliver the drugs, and better devices to monitor

breathing,heart rate, blood pressure, and brain activity duringsurgery. Unpleasant side effects are also less common.

General anesthesia Precautions

Patients who have had general anesthesia should not drink alcoholic beverages or take medication that slow down the central nervous system (such as antihistamines, sedatives, tranquilizers, sleep aids, certain painrelievers, muscle relaxants, and anti-seizure medication) for at least 24 hours, except under a doctor’s care.

LOCAL ANESTHESIALocal or regional anesthesia involves the injection or application of an anesthetic drug to a specific area of the body, as opposed to the entire body and brain as occurs during general anesthesia.

Local anesthetics are used to prevent patients fromfeeling pain during medical, surgical, or dental procedures.Over-the-counter local anesthetics are also availableto provide temporary relief from pain, irritation, anditching caused by various conditions, such as cold sores,canker sores, sore throats, sunburn, insect bites, poisonivy, and minor cuts and scratches.

LOCAL ANESTHESIATypes of surgery or medical procedures that regularlymake use of local or regional anesthesia include thefollowing:• biopsies in which skin or tissue samples are taken fordiagnostic procedures• childbirth• surgeries on the arms, hands, legs, or feet• eye surgery• surgeries involving the urinary tract or sexual organsSurgeries involving the chest and abdomen are usuallyperformed under general anesthesia.Local and regional anesthesia have advantages overgeneral anesthesia in that patients can avoid someunpleasant side effects, can receive longer lasting painrelief, have reduced blood loss, and maintain a sense ofpsychological comfort by not losing consciousness.

Regional anesthesiaRegional anesthesia typically affects a larger area thanlocal anesthesia, for example, everything below the waist.As a result, regional anesthesia may be used for moreinvolved or complicated surgical or medical procedures.Regional anesthetics are injected. Local anesthesia involvesthe injection into the skin or muscle or application to theskin of an anesthetic directly where pain will occur. Localanesthesia can be divided into four groups: injectable,

topical, dental (non-injectable), and ophthalmic.

Types of regional anesthesia include:

• Spinal anesthesia. Spinal anesthesia involves the injection of a small amount of local anesthetic directly into the cerebrospinal fluid surrounding the spinal cord (the subarachnoid space). Blood pressure drops are com mon but are easily treated.

• Epidural anesthesia. Epidural anesthesia involves theinjection of a large volume of local anesthetic directlyinto the space surrounding the spinal fluid sac (theepidural space), not into the spinal fluid. Pain reliefoccurs more slowly but is less likely to produce bloodpressure drops. Also, the block can be maintained forlong periods, even days.

Types of regional anesthesia include (cont’d):

• Nerve blocks. Nerve blocks involve the injection of ananesthetic into the area around a nerve that supplies aparticular region of the body, preventing the nerve fromcarrying nerve impulses to the brain.

Anesthetics may be administered with another drug,such as epinephrine (adrenaline), which decreases

bleeding, and sodium bicarbonate to decrease the acidity of a drug so that it will work faster. In addition, drugs may be administered to help a patient remain calm and more comfortable or to make them sleepy.

INJECTABLE LOCAL ANESTHETICS. These medicinesare given by injection to numb and provide pain relief tosome part of the body during surgery, dental procedures,or other medical procedures. They are given only by atrained health care professional and only in a doctor’soffice or a hospital. Some commonly used injectablelocal anesthetics are procaine (Novocain), lidocaine(Dalcaine, Dilocaine, L-Caine, Nervocaine, Xylocaine,and other brands), and tetracaine (Pontocaine).TOPICAL ANESTHETICS. Topical anesthetics, such asbenzocaine, lidocaine, dibucaine, pramoxine, butamben,and tetracaine, relieve pain and itching by deadening thenerve endings in the skin. They are ingredients in a varietyof nonprescription products that are applied to theskin to relieve the discomfort of sunburn, insect bites orstings, poison ivy, and minor cuts, scratches, and burns.These products are sold as creams, ointments, sprays,lotions, and gels.

DENTAL ANESTHETICS (NON-INJECTABLE). Somelocal anesthetics are intended for pain relief in the mouthor throat. They may be used to relieve throat pain,teething pain, painful canker sores, toothaches, or discomfortfrom dentures, braces, or bridgework. Somedental anesthetics are available only with a doctor’s prescription.Others may be purchased without a prescription,including products such as Num-Zit, Orajel, Chlorasepticlozenges, and Xylocaine.

OPHTHALMIC ANESTHETICS. Other local anestheticsare designed for use in the eye. The ophthalmic anestheticsproparacaine and tetracaine are used to numb the eyebefore certain eye examinations. Eye doctors may also usethese medicines before measuring eye pressure or removingstitches or foreign objects from the eye. These drugsare to be given only by a trained health care professional.

Precautions

People who strongly feel that they cannot psychologicallycope with being awake and alert during certainprocedures may not be good candidates for local orregional anesthesia. Other medications may be given inconjunction with the anesthetic, however, to relieve anxietyand help the patient relax.Local anesthetics should be used only for the conditionsfor which they are intended. For example, a topicalanesthetic meant to relieve sunburn pain should not beused on cold sores. Anyone who has had an unusual reactionto any local anesthetic in the past should check witha doctor before using any type of local anesthetic again.The doctor should also be told about any allergies tofoods, dyes, preservatives, or other substances.

Side effects of regional or local anestheticsA physician should be notified immediately if any ofthese symptoms occur:

• large swellings that look like hives on the skin, in themouth, or in the throat• severe headache• blurred or double vision• dizziness or lightheadedness• drowsiness• confusion• anxiety, excitement, nervousness, or restlessness• convulsions (seizures)• feeling hot, cold, or numb• ringing or buzzing in the ears• shivering or trembling• sweating• pale skin• slow or irregular heartbeat• breathing problems• unusual weakness or tiredness

CARDIOPULMONARY CARDIOPULMONARY RESUSCITATIONRESUSCITATION

Cardiopulmonary resuscitation, commonly Cardiopulmonary resuscitation, commonly called CPR, combines rescue breathing (one person called CPR, combines rescue breathing (one person breathing into another person) and chest breathing into another person) and chest compression in a lifesaving procedure performed compression in a lifesaving procedure performed when a person has stopped breathing or a person's when a person has stopped breathing or a person's heart has stopped beating. heart has stopped beating.

When performed quickly enough, CPR can When performed quickly enough, CPR can save lives in such emergencies as loss of save lives in such emergencies as loss of consciousness, heart attacks or heart "arrests," consciousness, heart attacks or heart "arrests," electric shock, drowning, excessive bleeding, drug electric shock, drowning, excessive bleeding, drug overdose, and other conditions in which there is no overdose, and other conditions in which there is no breathing or no pulse. The purpose of CPR is to breathing or no pulse. The purpose of CPR is to bring oxygen to the victim's lungs and to keep blood bring oxygen to the victim's lungs and to keep blood circulating so oxygen gets to every part of the body. circulating so oxygen gets to every part of the body. When a person is deprived of oxygen, permanent When a person is deprived of oxygen, permanent brain damage can begin in as little as four minutes brain damage can begin in as little as four minutes and death can follow only minutes later.and death can follow only minutes later.

CARDIOPULMONARY RESUSCITATIONCARDIOPULMONARY RESUSCITATION

There are three physical There are three physical symptoms that indicate a need for symptoms that indicate a need for CPR to be performed immediately CPR to be performed immediately and for emergency medical support and for emergency medical support to be called: to be called:

• unconsciousness unconsciousness • not breathing not breathing • no pulse detectedno pulse detected

CPR in basic life supportCPR in basic life support Figure A: The victim Figure A: The victim should be flat on his should be flat on his back and his mouth back and his mouth should be checked for should be checked for debris. Figure B: If the debris. Figure B: If the victim is unconscious, victim is unconscious, open airway, lift neck, open airway, lift neck, and tilt head back. and tilt head back. Figure C: If victim is Figure C: If victim is not breathing, begin not breathing, begin artificial breathing with artificial breathing with four quick full breaths. four quick full breaths. Figure D: Check for Figure D: Check for carotid pulse. Figure E: carotid pulse. Figure E: If pulse is absent, begin If pulse is absent, begin artificial circulation by artificial circulation by depressing sternum. depressing sternum. Figure F: Mouth-to-Figure F: Mouth-to-mouth resuscitation of mouth resuscitation of an infant.an infant.

CARDIOPULMONARY RESUSCITATIONCARDIOPULMONARY RESUSCITATIONThe steps usually followed in CPR are as follows: The steps usually followed in CPR are as follows:

• If the victim appears to be unconscious with either If the victim appears to be unconscious with either no breathing or no pulse, the person should be no breathing or no pulse, the person should be shaken or tapped gently to check for any movement. shaken or tapped gently to check for any movement. The victim is spoken to loudly, asking if he or she is The victim is spoken to loudly, asking if he or she is OK. If there is no response, emergency help must be OK. If there is no response, emergency help must be called and CPR begun immediately. called and CPR begun immediately.

• The victim is placed on his or her back on a level The victim is placed on his or her back on a level surface such as the ground or the floor. The victim's surface such as the ground or the floor. The victim's back should be in a straight line with the head and back should be in a straight line with the head and neck supported slightly by a rolled up cloth, small neck supported slightly by a rolled up cloth, small towel, or piece of clothing under the neck. A pillow towel, or piece of clothing under the neck. A pillow should not be used to support the head. The victim's should not be used to support the head. The victim's clothing should be loosened to expose the chest. clothing should be loosened to expose the chest.

• The rescuer kneels next to the victim, tilts the The rescuer kneels next to the victim, tilts the victim's head back, lifts the jaw forward, and moves victim's head back, lifts the jaw forward, and moves the tongue forward or to the side, making sure it the tongue forward or to the side, making sure it does not block the opening to the windpipe. The does not block the opening to the windpipe. The victim's mouth must be kept open at all times, victim's mouth must be kept open at all times, reopening as necessary. reopening as necessary.

CARDIOPULMONARY CARDIOPULMONARY RESUSCITATIONRESUSCITATION• The rescuer listens close to the victim's mouth for any The rescuer listens close to the victim's mouth for any

sign of breathing, and watches the chest for movement. sign of breathing, and watches the chest for movement. If the victim is found to be breathing, and has perhaps If the victim is found to be breathing, and has perhaps fainted, he or she can be placed in the recovery position fainted, he or she can be placed in the recovery position until medical assistance arrives. This is done by until medical assistance arrives. This is done by straightening the victim's legs and pulling the closest straightening the victim's legs and pulling the closest arm out away from the body with the elbow at a right arm out away from the body with the elbow at a right angle or 3 o'clock position, and the other arm across the angle or 3 o'clock position, and the other arm across the chest. The far leg should be pulled up over the victim's chest. The far leg should be pulled up over the victim's body with the hip and knee bent. This allows the victim's body with the hip and knee bent. This allows the victim's body to be rolled onto its side. The head should be tilted body to be rolled onto its side. The head should be tilted back slightly to keep the windpipe open. The head back slightly to keep the windpipe open. The head should not be propped up. should not be propped up.

• If the victim is not breathing, rescue breathing begins, If the victim is not breathing, rescue breathing begins, closing the victim's nostrils between a thumb and index closing the victim's nostrils between a thumb and index finger, and covering the victim's mouth with the finger, and covering the victim's mouth with the rescuer's mouth. Two slow breaths, about two seconds rescuer's mouth. Two slow breaths, about two seconds each, are breathed into the victim's mouth with a pause each, are breathed into the victim's mouth with a pause in between. This is repeated until the chest begins to in between. This is repeated until the chest begins to rise. The victim's head should be repositioned as often rise. The victim's head should be repositioned as often as necessary during the procedure. The mouth must as necessary during the procedure. The mouth must remain open and the tongue kept away from the remain open and the tongue kept away from the windpipe. windpipe.

CARDIOPULMONARY CARDIOPULMONARY RESUSCITATIONRESUSCITATION• When the chest begins to rise, or the victim begins to When the chest begins to rise, or the victim begins to

breathe on his or her own, the rescuer looks for signs breathe on his or her own, the rescuer looks for signs of circulation, such as coughing or movement. If a of circulation, such as coughing or movement. If a healthcare professional has arrived by this time, the healthcare professional has arrived by this time, the pulse will be checked before resuming resuscitation. pulse will be checked before resuming resuscitation.

• If chest compressions are needed to restart If chest compressions are needed to restart breathing, the rescuer will place the heel of a hand breathing, the rescuer will place the heel of a hand above the lowest part of the victim's ribcage where it above the lowest part of the victim's ribcage where it meets the middle-abdomen. The other hand will be meets the middle-abdomen. The other hand will be placed over the heel of the first hand, with fingers placed over the heel of the first hand, with fingers interlocked. Keeping the elbows straight, the rescuer interlocked. Keeping the elbows straight, the rescuer will lean his or her shoulders over the hands and will lean his or her shoulders over the hands and press down firmly about 15 times. It is best to press down firmly about 15 times. It is best to develop an up-and-down rhythm, keeping the hands develop an up-and-down rhythm, keeping the hands firmly on the victim's chest. firmly on the victim's chest.

• After the compressions, the rescuer will give the After the compressions, the rescuer will give the victim two long breaths. The sequence of 15 victim two long breaths. The sequence of 15 compressions and two breaths will be repeated until compressions and two breaths will be repeated until there are signs of spontaneous breathing and there are signs of spontaneous breathing and circulation or until professional medical help arrives. circulation or until professional medical help arrives.

There are certain importantThere are certain important precautions for precautions for rescuers to remember in order to protect the rescuers to remember in order to protect the

victim and get the best result from CPRvictim and get the best result from CPR • Do not leave the victim alone. Do not leave the victim alone. • Do not give chest compressions if the victim has a Do not give chest compressions if the victim has a

pulse. Chest compression when there is normal pulse. Chest compression when there is normal circulation could cause the heart to stop beating. circulation could cause the heart to stop beating.

• Do not give the victim anything to eat or drink. Do not give the victim anything to eat or drink. • Avoid moving the victim's head or neck if spinal Avoid moving the victim's head or neck if spinal

injury is a possibility. The person should be left as injury is a possibility. The person should be left as found if breathing freely. To check for breathing found if breathing freely. To check for breathing when spinal injury is suspected, the rescuer should when spinal injury is suspected, the rescuer should only listen for breath by the victim's mouth and only listen for breath by the victim's mouth and watch the chest for movement. watch the chest for movement.

• Do not slap the victim's face, or throw water on the Do not slap the victim's face, or throw water on the face, to try and revive the person. face, to try and revive the person.

• Do not place a pillow under the victim's head. Do not place a pillow under the victim's head.

Clinical death occurs when a patient's heartbeat and breathing Clinical death occurs when a patient's heartbeat and breathing have stopped. Since breathing rarely continues when the heart is have stopped. Since breathing rarely continues when the heart is stopped, clinical death is synonymous with cardiac arrest or stopped, clinical death is synonymous with cardiac arrest or cardiac death. The reversal of clinical death is sometimes cardiac death. The reversal of clinical death is sometimes possible through cpr, defibrillation, epinephrine injection, and possible through cpr, defibrillation, epinephrine injection, and other treatments. Resuscitation after more than 4 to 6 minutes other treatments. Resuscitation after more than 4 to 6 minutes of clinical death at normal body temperature is difficult, and can of clinical death at normal body temperature is difficult, and can

result in brain damage.result in brain damage.

Brain deathBrain deathBrain death (irreversible cessation of Brain death (irreversible cessation of all function of the brain) means death all function of the brain) means death of both the upper brain and brain of both the upper brain and brain stem. A person who is brain dead has stem. A person who is brain dead has lost both the capacity to think and lost both the capacity to think and perceive, as well as the control of perceive, as well as the control of basic body functions. basic body functions.