Anesthesia- santosh dhungana
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Transcript of Anesthesia- santosh dhungana
anesthesiologist shall be responsible for
determining the medical status of the patient
developing a plan of anesthesia care
acquainting the patient with the proposed plan
ASA
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study evaluating methods of reducing preoperative anxiety thorough preoperative evaluation can be as effective as
an anxiolytic premedication
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Review available medical records
Interview and perform focused examination of the patient Discuss medical hx, including previous anesthetic experiences and
medical therapy
Assess those aspects of the patient’s physical condition that might affect decisions regarding perioperative risk and management.
Order/ review pertinent available tests and consultations as necessary for the delivery of anesthesia care
Order appropriate preoperative medications
Ensure that consent has been obtained for the anesthesia care- BRAN (benefit, risks, alternatives, if Not done then..)
Document in the chart that the above has been performed
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Current Problem- History of present illness
The proposed surgery – affects type of anaesthesia/ position
Other known problems- Any comorbidities (DM, HTN, psychiatric illness)
Drug history- Present therapy (prescription/ over-the-counter), alcohol, tobacco
Allergy history- drugs, food, latex, etc.
Anesthetic history- Previous anesthetics, operations, complications, h/o malignant hyperthermia (“allergy to anesthesia”)
System review- Screening of any undiagnosed systemic illnesses
Miscellaneous- Last oral intake (ER) 7/15/2014 7
General appearance- Comfortable, in distress, sick looking, physique, wt, ht, BMI
Vital signs- Temp, pulse, BP, RR
Head to toe examination- Pallor, icterus, clubbing, cyanosis, edema, dehydration, peripheral veins,
pre-existing iv cannulae
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dentition- loose or chipped teeth, caps, bridges, or dentures poor anesthesia mask fit expected in edentulous patients and
significant facial abnormalities
prominent upper incisors, large tongue, short neck suggest difficulty may be encountered during tracheal intubation
nostrils
thyromental distance: 5cms
Sternomental distance: 12.5 cms
mandibular protrusion test
flexon and Extension of the neck
Cervical spine- Important in trauma, RA, cervical spondylosis
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A screening evaluation regarding history of tobacco use, shortness of breath, cough, wheezing, stridor, snoring or sleep apnea
recent history of an upper respiratory tract infection
Patient's ability to carry on a conversation or to walk without dyspnea
Physical exam- assess the respiratory rate as well as the chest excursion, use of accessory muscles
Auscultation to detect decreased breath sounds, wheezing, stridor
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Site of surgery thoracic, aortic or upper abdominal surgery has highest risk
Type of surgery abdominal aortic aneurysm repair, thoracic, upper abdominal have
highest risks followed by neck, peripheral vascular, and neurosurgery
Neurosurgery and neck surgery associated with perioperative aspiration pneumonia
Laparoscopic surgery have lesser risk than open surgery
Duration of surgery longer the duration, longer the time exposure to anesthesia
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tobacco/ smoking increase carboxy-hemoglobin
decrease ciliary function
increase sputum production
stimulates cardiovascular system secondary to nicotine
asthma/COPD increased airway responsiveness
drugs may have adverse reactions with anesthetics
chronic CO2 retention in COPD
obstructive sleep apnea susceptible to the respiratory depressant and airway effects of
sedatives, narcotics, and inhaled anesthetics
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General appearance including weight, BMI
Vital signs Pulse and its characteristics( rate, rhythm, character, volume, delay,
all peripheral pulses)
BP (if needed in both arms)
Temperature, RR
Head to toe examination JVP, anemia, cyanosis, clubbing, edema
Precordial examination Inspection/Palpation- apical impulse, heave, thrills
Auscultation- heart sounds, murmurs
Auscultation of basal lung fields
Assessment of liver size and position
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Age associated with multisystem disease,
Previous MI 5-8% risk of periop reinfarction Mortality rate of reinfarction 36-70% Risk of reinfarction decreases with time
30% <3 mnths 6% >6mnths
CHF symptomatic CHF- predictor of perioperative pulmonary
edema
Hypertension Leading cause of concern Not a significant risk factor alone (esp. if <180/110), but due
its end-organ damage like LVF, renal failure and stroke 7/15/2014 15
DM risk of CAD, silent MI, renal insufficiency
Equal risk as nondiabetics with previous MI
VHD AS- 14 fold greater risk as compared with those without AS
risk of IE
Arrhythmias Frequent PVCs and nonsinus rhythms
CHB, LBBB, 2 heart block (Mobitz type II)
Others Smoking, hyperlipidemia, renal failure, anemia, depression,
hypoalbuminemia
Inflammatory markers: CRP, b-type natriuretic peptide7/15/2014 16
Renal disease- important implications for fluid management and metabolism of drugs.
Liver disease -associated with altered protein binding, volume of distribution of drugs, coagulation abnormalities
Musculoskeletal System- anatomy evaluated for procedures such as a nerve block, regional anesthesia, invasive monitoring
Neurological- history of prior stroke -increased risk for a perioperative stroke
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MET, metabolic equivalent of the task. 1 MET = consumption of 3.5 mL O2/min/kg of body weight.
Patients with MET less than 4 or 5 have higher risk of perioperative cardiac morbidity
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administration of drugs prior to anesthesia to allay apprehension
produce sedation
facilitate the administration of anesthesia to the patient
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Devoid of any side effects
Minimal depression of respiration andcardiovascular function.
Simple and pleasant to take.
Should act over reasonable period of time.
Should be effective in all patients.
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Relief of anxiety
Sedation
Amnesia
Analgesia
Drying of airway secretions
Prevention of autonomic
reflex responses
Reduction of gastric fluid volume and increased pH
Antiemetic effects
Reduction of anesthetic requirements
Facilitation of smooth induction of anesthesia
Prophylaxis against allergic reactions
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anxiolytics Children- syr promethazine (6.25 mg/ml)
5- 10 ml hs/ cm
Young adults- diazepam 5-10 mg hs/ cm
Elderly –lorazepam 1- 2mg hs/ cm
Antiemetics
Antacids/ ppi
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Hypertension Antihypertensive drugs to be continued except Losartan &
Diuretics
• RHD• Prophylactic antibiotics should be considered
• Patients on anticoagulant therapy- warfarin should be substituted by heparin 3-5 days prior to surgery
• IHD-• Anticholinergic mainly atropine to be avoided.
• Aspirin to be discontinued 7 days before surgery
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• Bronchodilators, steroids should be continued
• Prophylactic antibiotics in COPD patients
• Inhaled β2-agonists, cromolyn, or steroids should be continued up to the time of surgery
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Objectives
• avoid hypoglycemia, excessive hyperglycemia, ketoacidosis
• metformin should be held if there is decreased renal function- risk for the fear of Lactic acidosis.
• glimepiride (Sulfonylureas) should be held while the pt. is NPO
• Thiazolidinedione can be continued as they do not predispose to hypoglycemia
• α-glucosidase inhibitor should be held
• Premedication to avoid aspiration, N/V
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Well-controlled type 2 diabetics do not require insulin for minor surgery.
Poorly controlled type 2 diabetics and all type 1 diabetics having minor surgery and all diabetics having major surgery need insulin.
For major surgery, serum glucose > 270 mg/dL, the surgery should be delayed while rapid control is achieved with intravenous insulin.
If the serum glucose >400 mg/dL, surgery should be postponed and the metabolic state restabilized.
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Administer 1/2 to 2/3rd of the patient's usual intermediate-acting insulin subcutaneously on the morning of surgery
In addition to this basal insulin, a regular insulin sliding scale (RISS) can be added and titrated to blood glucose measurement.
Alternatively, an insulin infusion of 1 to 2 U/hr (100 U regular insulin in 100 mL normal saline at 1 to 2 mL/hr) can meet basal metabolic needs and be adjusted to maintain blood glucose at the desired level.
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With either method, a slow glucose infusion (dextrose 5% in water at 75 to 100 mL/hr) will prevent hypoglycemia while the patient is fasting.
Some authorities recommend a combination glucose-insulin or glucose-insulin-potassium infusions (GIK)
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Management of Diabetes Mellitus in Surgical Patientshttp://spectrum.diabetesjournals.org/content/15/1/44.full
Intraoperative GIK solution given to diabetic patients with CABG operation provides more stable CI, shorter time of MV, more stable values of potassium which provides normal rhythm and less AF onset, less insulin to maintain target glycemia. All the above mentioned provides more stable intraoperative hemodynamic and better recovery of diabetic
Glucose-Insulin-Potassium (GIK) solution used with diabetic patients provides better recovery after coronary bypass operations.
Straus S, Gerc V, Kacila M, Faruk C.
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“Sliding scale insulin” is not recommended for the management of hyperglycemia.
“set and forget”
Basal + pre-meal better
https://www.diabetessociety.com.au/documents/PerioperativeDiabetesManagementGuidelinesFINALCleanJuly2012.pdf
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Type II patients taking oral agents alone, RISS can be added to control blood glucose levels.
Patients receiving chronic insulin can be treated similarly to the type I patient by giving 1/2 the usual NPH insulin dose the morning of surgery, supplemented by a RISS, or an insulin infusion titrated to blood glucose.
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state of drug induced reversible unconsciousness and loss of protective reflexes
consist of hypnosis, amnesia, analgesia, relaxation of skeletal muscles, and loss of autonomic reflexes
Balanced anesthesia=
hypnotic+ amnesic + analgesics + muscle relaxant
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Components of GA Pre-anesthetic check up (PAC)
Premedication
Induction
Maintenance
Recovery
Postoperative Care
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Advantages fast onset of anesthesia than inhalation, (10-20 seconds)
induce total unconsciousness
avoidance of the excitatory phase of anesthesia (Stage II)
complications related to induction of anesthesia.
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Propofol (10 mg/ml)-
<55 yr – 2- 2.5mg/ kg slow iv
>55 yr- 1-1.5 mg/kg slow iv
Onset 30- 45 s
Duration- 20-75 min
Metabolism- hepatic conjugation
Excretion- urine
s/e- injection site burning, hypotension, apnea, rash pruritus, cardiac s/e
Most commonly used
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Ketamine (10mg/ml) 1-4.5 mg/kg slow iv once
1-2 mg/ kg infusion @ 0.5mg/kg/min
Produces dissociative anesthesia
Blocks NMDA receptors
Onset- 30 s
Duration- 5 -10 mins
Metabolised by liver
Excreted in urine
s/e- emergence reaction, htn, raised ICP, tachycardia, hallucinations
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Sodium thiopental ultra-short-acting barbiturate 4–6 mg/kg Largely replaced by propofol mainly metabolized to pentobarbital s/e- hypotension, apnea and airway obstruction caution with liver disease, severe heart disease,
severe hypotension, a severe breathing disorder, or a family history of porphyria
Etomidate (2mg/ml) 0.3-.6 mg/ kg iv over a minute Onset 60s; duration- 3-5 mins Hepatic metabolism, excreted in urine s/e- adrenal suppression, pain, apnea, arrythmias Less often used
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Advantages: Excellent analgesia
Minimal hemodynamic depression
Good suppression of endotracheal tube response
Problems: Respiratory depression
Incomplete suppression of intraoperative awareness
Used mainly for cardiac anesthesia and also in smaller doses as a part of balanced anesthesia for non-cardiac cases
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Fentanyl More lipid soluble than morphine
Rapid onset (60 sec)
Elimination half time (200 min) is longer than the duration of clinical effect
Very highly bound to lung as a function of time. So half-life of effect depends upon duration of administration because of an increase in storage.
Available as IV, transdermal patch & lollipop
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Isoflurane 1- 3% Rapid onset, short acting MAC 1.3% s/e N/V, hypotension, arrythmias
Sevoflurane 1.4- 2.6% Onset 2-3 min expensive s/e hypotension, respiratory irritation, seizures
Halothane potent anesthetic MAC 0.74 20% metabolized in liver s/e- liver injury 1in 10,000 Less preferred
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used for facilitate intubation of the trachea facilitate mechanical ventilation optimize surgical working conditions
Depolarizing muscle relaxant
Succinylcholine Nondepolarizing muscle relaxants
Short acting Intermediate acting Long acting
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Succinylcholine Most often used to facilitate intubation
dose- 1-1.5 mg/kg
Onset 30-60 seconds
duration 5-10 minutes
s/e- Cardiovascular, Fasciculation Muscle pain,
Increase IOP, Increase ICP, intragastricpressure
Malignant hyperthermia
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Nondepolarizing Muscle Relaxants Do not depolarized the motor endplate
Act as competitive antagonist Excessive concentration causing channel blockade
Act at presynaptic sites, prevent movement of Ach to release sites
Long acting Pancuronium
Intermediate acting Atracurium, Vecuronium, Rocuronium, Cisatracurium
Short acting Mivacurium
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Vecuronium Analogue of pancuronium
much less vagolytic effect and shorter duration than pancuronium
Onset 3-5 minutes
duration 20-35 minutes
Intubating dose 0.08-0.12 mg/kg
Elimination 40% by kidney, 60% by liver
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Neostigmine 0.03-0.07 mg/kg iv
Max dose 5mg
10-20 mins
Competitive inhibitor of choliesterase
Reverses action of muscle relaxants
Administered with anticholinergics
Atropine (
Glycopyrrolate (0.2 mg per 1 mg of neostigmine)
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Miller’s Anaesthesia- 7th Edition
Clinical Anaesthesia – Paul G. Barash, 6th Edition
ACC/AHA guidelines on perioperative cardiovascular assessment
Uptodate 21.2
Medscape
www.asahq.org
http://spectrum.diabetesjournals.org/content/15/1/44.full
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