20110213

PREOPERATIVE PREPARATION

Mangari

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Preoperative preparation
•Preoperative visit
•Assess the risk of anesthesia and surgery
•Informed consent
•Fasting
•Premedication
 

Preoperative visit
Inadequate pre op.preparation may be a major contributory factor to the perioperative morbidity & mortality. It is essensial that anesthetist visits every patient before surgery.


The purpose of it :
•Establish rapport with the patient
–Meet the doctor with the patient
–Discuss possible causes of anxiety regarding anesthetic and surgical manner
–Explain how the patient will be cared for during and after anesthesia and about pain relief
–Establish a doctor-patient relationship that reduces patient anxiety by building trust & respect
•Assessment of physical status
Order special investigations

Fears related to anesthesia (Sheffer)
•He may tell secrets
•The operation will start too soon
•He may wake up during surgery
•He may not wake up after surgery
•Fears of mutilation, vomitting & cancer


Incidence of anxiety
•Type of surgery :
–GUT 80%
–Possible cancer, disabling 85%
•Sex : women higher than men
•Type of body build :
Asthenic > normal or over weight (pyknic)


Successful approach (Buskirk)
•Treat all patients as human being
•Be friendly, explain your visit & your plan
•Be patient & sympathetic
•Listen to his concern, answer all questions in understanding and warm manner
•Allay patient’s fears


History and physical examination
Personal and family history
Hereditary conditions associated with anesthesia : porphyria, malignant hyperthermia, haemophilia
Previous operations & anesthetics
Allergies
Medications ; drug interaction
Habits : alcohol and smoking
Diseases of CVS and respiratory systems

Alcoholism
•Impairment of liver function
•Heart ; cardiac arrhythmia
–Cardiac contractility decrease
–Cardiomyopathy
•Kidney ; diuretic effect by inhibiting ADH
•Plasma catecholamine increase
•Metabolic & respiratory acidosis from alcohol intoxication
•Increases the anesthetic requirement


Smoking
Ciliary function reduce, disturbing tracheobronchial clearance
Increase production and thicken of sputum
Strong risk factor for coronary heart disease and occlusive peripheral arterial disease
Systolic hypertension is potentiated
Decrease cerebral blood flow and increase risk of stroke
Increase gastric volume & acidity
Increase COHb level, decrease blood O2 content & O2 delivery to tissue
Increase catecholamine : CVS responses & O2 requirement increase
Respiratory complication increase 5-7 times

Recomendations


COHb fall to normal level ; stop smoking 48 hours preoperatively
Reduction of sputum volume & post op complications ; stop smoking 4 weeks pre operatively
 

Physical examination
General condition : name, age, weight.
B.P. pulse rate & temperature.
Cardiopulmonary examination including
-Cyanosis in finger tips
-V. jugularis engorgement

Obesity

Airway problems
Mechanical ventilation is impaired ; tendency to hypoventilation e.c. fix thorax & elevated diaphragm
Easily developed hypoxia e.c.
- FRC is reduced
- V/Q ratios are low
•Difficult estimate circulatory volume by V.J. pressure and difficulty in venipuncture
•CVS disorders :
–Hypertension 3X more
–Ischemic H.D 2X more
–CVD/CVA 3X more
•DM 3-4 X more
•Increase gastic volume, acidity & pressure
Airway :
-Neck : short, distance from mentum to hyoid ( -> 5 cm)
-Mouth : mouth opening, loose or damage teeth, protruding upper incissors
Vertebral column : anatomical deformities may render some blocks in practical

Simple Bedside cardiopulmonary function


Sebarase’s test : 2-3 deep breaths – hold as long as possible
Time : +- 40 seconds ; normal
30-40 seconds ; diminished reserve
< 20 seconds ; severely compromised
 
Match test : The ability to blow out a standard match held 6 inches from the open mouth ;negative ; max breathing cap low  
Tilt test 

Laboratory testing 
Routine lab.test in pts who are apparently healthy (history & clinical exam) are invariably of little use and wasting. 
Blood : 
Hb, leuco ; all female, male > 50, major surgery, clinically indicated
Ureum, creatinine ; pt > 50, renal & hepatic diseases, diabetes, abnormal nutritional state
Blood sugar ; DM, vascular disease, corticosteroid drugs
Urinalysis ; every pt, very inexpensive and may occasionally reveal an undiagnosed diabetic or UTI
Chest X Rays :
- History of pulmonary and cardiac disease
- Tbc endemis
- Smoking
ECG ; pt > 40, hypertension, history of cardiac disease

Assess the risk of anesthesia and surgery

ASA (American Society of Anesthesiologist) grading system
Class I : A normally healthy individual, the pathology which surgery is needed only localized
Class II : A patient with mild or moderate systemic disease
Class III : A patient with severe systemic disease that is not incapacitating (limits the pt activity)
Class IV : A patient with incapacitating systemic disease that is a constant threat to life
Class V : A moribund patient who is not expected to survive 24 hour with or without operation
Class E : Added as a support for emergency operation. All pts induced in ASA I-V that need emergency operation get a higher ASA grade

CARDIAC RISK

CRITERIA & POINTS
Hystory
-Age > 70 years ................................poin 5
-MI in previous 6 mo...........................poin 10
 

Physical examination
-S3 gallop or jugular vein distension......poin 11
-Important VAS...................................poin 3

Electrocardiogram
-Rhythm other than sinus or
premature atrial contraction on
last preoperative ECG...........................poin 7
-> 5 premature ventricular
contractions/m in documented at
anytime before operation.......................poin 7

General status : PO2 < 60 or PCO2 > 50 mmHg, K < 3.0 or HCO3 < 20 Meq/l, BUN > 50 or
Cr > 3.0 mg/dl, abnormal SGOT, signs of
chronic liver disease or patient bed ridden
from non cardiac causes..........................poin 3
Operation
-Intraperitoneal, intrathoracic, or aortic
operation...............................................poin 3
-Emergency operation..............................poin 4
TOTAL POSSIBLE POINTS 53


Informed consent

A patient active knowledgeable authorization to allow a specific procedure to be provided by an anesthesiologist.
Consent must be informed to ensure that the patient has sufficient information about the procedures, their risks, and benefits.
Obtaining informed consent honors a patient’s right to self determination whether GA, regional anesthesia, or i.v sedation.
Without the patient’s consent, the physicion may liable for assault and battery. When the patient is a minor or otherwise not competent to consent (mentally disturbed or drugs), the consent must be obtained from someone legally authorized to give it, such as parent, guardian, or close relative.
Written documentation of the informed consent is included in the patient chart and is signed by the patient or their representative.
 

Fasting
To prevent aspiration of gastric content
NPO after midnight has been questioned nowadays.
Hazard fasting ³ 12 hours :
- Hydration is compromised
- Fasting for 1 day may deplete liver glycogen &
  greater risk for hepatic toxicity
Fasting for ³ 1 day increases FFA ; à lower the threshold  to epinephrine induced arrhythmia.
Recommendation : NPO 4 hours
Gastric emptying is delayed by : anxiety, pain, trauma, and pregnancy.
 

A study to unpremedicated patients
oral intake 150 ml water 2-3 hours pre operatively ; R.G.V low, pH more alkaline (72%)





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150 ml water + ranitidine 150 mg  only 2% had RGV > 25 ml pH < 2,5 To avoid hypoglycemia and thirsty and in order pediatric pts calm & cooperative : - Milk 10 ml/kg 4 hours before surgery - Dextrose 5% 10 ml/kg 2 hours before surgery Premedication Objectives are : •Allay anxiety & fear •Reduce secretions •Analgesia •Enhance the hypnotic effect of G.A. agent •Reduces post op nausea and vomitting •Produce amnesia •Reduction in vagal reflex •Limit sympathoadrenal responses Drugs for premedication Sedativa, tranquilizer Narcotics-analgetics Alkaloid belladona as antisecretion and reduce vagal reflex to the heart from : –drugs –impuls afferent abdomen, thorax, and eyes Antiemetic Sedative Sedative in appropiate dose can reduce anxiety and stress, in higher dose become hypnotic. Barbiturate : •Ultra short acting –Thiopentone / penthotal –Methohexitone, hexobarbitone –Especially detoxification in liver •Medium acting : –Pentobarbitone –Quinalbarbitone –Butobarbitone –A part of them are detoxificated in liver, small part are excreted by kidney •Long acting : –Phenobarbitone (Luminal) –All of them are excreted by kidney Barbiturate  cerebral protection Because : cerebral metabolism , cerebral oxigen consumption , C.B.F. , & I.C.P.  Medium Acting Medium acting that most suitable for premedication •depress CNS, start from cortex, RAS, medulla spinalis, use for anti convulsant •depress myocard  bradycardi, cardiac output   hypotension •BMR  •depress liver and kidney function •crossing placental barrier •Interfere other drugs link and metabolism (enzyme induction) •No analgetic effect Premedication  Sedativa Pentobarbitone sodium / nembutal and quinal barbitone sodium / seconal  less depress respiration and circulation, non teratogenic, and because it is detoxificated in liver, suite for kidney function disturbance. –Inject 60 mg/cc, i.m, 2 hour pre op. –Capsule 50 and 100 mg –Adults dose 1,5-2 mg/kg BW oral, rectal –Children 3-4 mg/kg BW oral, rectal –Duration of action : 3-4 hours Phenobarbitone / luminal –Because the excretion through kidney, barbiturate suite for liver function disturbance –Sedative dose 30 – 50 mg –Hypnotic dose 100 mg for adult, 3-5 mg/kg BW for children Tranquilizer : Benzodiazepines Benzodiazepines : anxiolysis – sedation – amnesia Preferable to the barbiturate -Produce amnesia -Greater therapeutic index -Less cardiovascular and respiratory deppression -Longer duration of action Tranquilizer : Phenothiazine Phenothiazine : sedative-antiemetic, antihistamine (Phenergan), antipiretic (central vasodilatation), central sympatic depression, and minimize the effect of adrenalin in perifer => less tension (Largactil), dose : 25-50 mg oral/i.m

Diazepam
- Lorazepam
- Midazolam

Diazepam : insoluble in water but lipid soluble  - Injection painful (venous irritation)

- Absorption from i.m unreliable but rapidly
absorbed from GI tract
Metabolism principally in the liver produces active metabolites : methyl diazepam, oxazepam, 3-hydroxy diazepam  prolonged CNS depression
•Minimal cardiovasculer effect
•Ventilatory response to CO2 depressed increase PaCO2 especially in association with other respiratory depressant
•Anticonvulsant in tetanus and epilepsy
•Mild muscle relaxant property at spinal cord level and potentiate non depolarizing muscle relaxant
•Retrogade amnesia especially when combine with meperidine or hyoscine
•Rapidly passes the placental barrier
Doses
oral : 0,2 – 0,5 mg/kg
i.v : 0,1 – 0,2 mg/kg
induction : 0,3 – 0,5 mg/kg
MIDAZOLAM
The efect are faster and shorter, duration approximately 60 minutes
Anterograde amnesia, has no anticonvulsant effect
Dose : 0,15–0,1 mg/kg BW, i.m/i.v  adult
 0,5 mg/kg BW, oral  children
No pain when injected  because of water soluble
Possibility become phlebitis is small
CBF is decrease  ICP decrease  cerebral protection
Relaxation effect
Not interfere coronary circulation  safe for ischemic heart disease, in other way diazepam interfere CVR  unsafe
DROPERIDOL/ INAPSINE
Tranquilizer butyrophenone, phenothiazine like effect
Forced antiemetic, ICP can be decrease because of mild cerebral vasoconstriction
Alpha adenergic receptor blockade  hypotensi, it can prevent catecholamine induced arrhythmia
Apathis
Dose : 2,5-5 mg; duration 6-8 hours
Side effect : dyskinetic involuntary movement (extrapyramidal disturbance)
Occasionally dysphoric reaction

Morphine

Narcotic-analgetic standard for strong pain, euphoria
Sedativa-postural hypotension  because of vasodilatation and myocard depression (depression of vasomotor center)
Constrict the sphincter of gut, peristaltic   constipation
BMR , addiction-hystamine release positif
Depression of cough reflex post op  secret accumulation  atelectasis
ICP rise in intracranial injury
Respiratory center depression  CO2 ¬ CBF ¬
Parasympatic tone:
- Bronchus  bronchoconstriction
- Eyes  myosis
Through placental blood barrier
Dose : 10-15 mg i.m/s.c, duration until 6 hours
Children : 0,1 mg/kg bodyweight
Disadvantages:
•Nausea and vomittus  not be used in intraocular operation
•COPD or asthma  worsening

PETHIDINE/ MEPERIDINE

•Depression of RC, emetic effect, euphoria and dizziness are less than morphine
•Less histamine release  fine for asthma
•Through placental blood barrier  not be given before umbilical cord is cut
•Atropine like effect : saliva  dry mouth
eyes  mydriasis
•Dose : 50-100 mg
Child : 0,5-1 mg/kg BW; duration 2-4 hours
•Stronged analgetic, 100 x morphine
•CVS effect are minimal so the histamine release
•Duration : 45’-60’
•Dose : 0,05-0,1 g I.m, 1 hour pre.op.
•Disadvantages:
-Respiratory depression
-Bradycardi, miosis
-Bronchoconstriction
-somatic muscle spasm
ANTAGONIST OF NARCOTIC
If RC depression, antagonist of narcotic can be given:
•Nallorphine 5mg iv  Lorvan 1 mg iv
•Naloxone/ narcane is better for respiratory depression
•Dose: 0,2-0,4 mg iv

Anticholinergic drugs

Perthidin & Phenergan have anticholinergic effect
•Sulfas atropin / alkaloid belladona
•anti secretion of salivatory, respiratory tract and sweat glands  be aware of patient with fever
•Glycopyrolat is an antisecretion 2x and more longer than SA , no central effect
•vagal block, needs a high dose until 1 - 2 mg
•CNS : Tendency to stimulate CNS, hyoscine sedation
•Light bronchodilator
•CVS : tachycardi  be aware to thyrotoxicosis and ischemic HD, cardiomyopathy
•GI : intestine and urinary tracts peristaltic   constipation and urine retension
•BMR ¬  be aware to thyrotoxicosis
•dose : 0,005 - 0,01 mg/kgWB
•duration of action : im until 90’ ; iv 30’-45’
•Combination of those drugs  patient comes to the operation room still aware but sleepy, calm, cooperative, there are no complications during and after the operation
•Doses and drugs combination are decided by patient condition and anesthetis experience and skills

OPERATION CANCELLED

•Anemia: Hb < 10gr% In Research Hb < 10gr%  it’s not increase morbiditas/ mortalitas. If circulating volume is enough, Hb 8 gr%  it’s not necessary to get tranfusion •Syok: Anesthesia  depression of vital organs  syok is worsening. Volume replacement  until blood pressure > 80mmHg, good peripheral condition, diuresis is enough
•Temperatur: 380C  antipyretica, find focal infection
especially respiratory tract
Respiratory Infection
•Influenza, pharyngitis, bronchitis  elective operation is delayed
•Airways instrument :
- trauma of infection mucosa  resp. obstruction, spasm, hypersecretion  Post operative respiratory complication.
- infection spread
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