santosh k dhunganaMD GP JR IIanesthesiapre-op/ pre-anespre-op assessmentpre-anesthetic prescribinginduction agentsmuscle relaxantsreversalwe will cover3/24/20142goals reduce patient riskreduce morbidity of surgery promote efficiency reduce costs
pre-op assessment3/24/20143 anesthesiologist shall be responsible for determining the medical status of the patient developing a plan of anesthesia care acquainting the patient with the proposed planASAbasic standards for pre-anesthetic care3/24/20144study evaluating methods of reducing preoperative anxiety thorough preoperative evaluation can be as effective as an anxiolytic premedication3/24/201455Review available medical recordsInterview and perform focused examination of the patientDiscuss medical hx, including previous anesthetic experiences and medical therapyAssess those aspects of the patients 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 careOrder appropriate preoperative medicationsEnsure 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 performedsteps of pre-op assessment- ASA3/24/20146Current Problem- History of present illnessThe proposed surgery affects type of anaesthesia/ positionOther known problems- Any comorbidities (DM, HTN, psychiatric illness)Drug history- Present therapy (prescription/ over-the-counter), alcohol, tobaccoAllergy 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 illnessesMiscellaneous- Last oral intake (ER)history3/24/20147General appearance- Comfortable, in distress, sick looking, physique, wt, ht, BMIVital signs- Temp, pulse, BP, RRHead to toe examination- Pallor, icterus, clubbing, cyanosis, edema, dehydration, peripheral veins, pre-existing iv cannulaegeneral examination3/24/20148dentition- 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 intubationnostrilsthyromental distance: 5cmsSternomental distance: 12.5 cmsmandibular protrusion testflexon and Extension of the neckCervical spine- Important in trauma, RA, cervical spondylosisairway3/24/20149
3/24/201410A screening evaluation regarding history of tobacco use, shortness of breath, cough, wheezing, stridor, snoring or sleep apnearecent history of an upper respiratory tract infectionPatient's ability to carry on a conversation or to walk without dyspneaPhysical exam- assess the respiratory rate as well as the chest excursion, use of accessory musclesAuscultation to detect decreased breath sounds, wheezing, stridor
respi3/24/201411Site of surgerythoracic, aortic or upper abdominal surgery has highest riskType of surgeryabdominal aortic aneurysm repair, thoracic, upper abdominal have highest risks followed by neck, peripheral vascular, and neurosurgeryNeurosurgery and neck surgery associated with perioperative aspiration pneumoniaLaparoscopic surgery have lesser risk than open surgeryDuration of surgerylonger the duration, longer the time exposure to anesthesiathe predictors of perioperative pulmonary risk- surgery related factors3/24/201412tobacco/ smokingincrease carboxy-hemoglobindecrease ciliary functionincrease sputum production stimulates cardiovascular system secondary to nicotineasthma/COPDincreased airway responsivenessdrugs may have adverse reactions with anestheticschronic CO2 retention in COPDobstructive sleep apneasusceptible to the respiratory depressant and airway effects of sedatives, narcotics, and inhaled anesthetics
the predictors of perioperative pulmonary risk- patient related factors3/24/201413General appearance including weight, BMIVital signsPulse and its characteristics( rate, rhythm, character, volume, delay, all peripheral pulses)BP (if needed in both arms)Temperature, RRHead to toe examinationJVP, anemia, cyanosis, clubbing, edemaPrecordial examinationInspection/Palpation- apical impulse, heave, thrillsAuscultation- heart sounds, murmursAuscultation of basal lung fieldsAssessment of liver size and positioncvs3/24/201414Ageassociated with multisystem disease,Previous MI5-8% risk of periop reinfarctionMortality rate of reinfarction 36-70%Risk of reinfarction decreases with time 30% 6mnthsCHFsymptomatic CHF- predictor of perioperative pulmonary edemaHypertensionLeading cause of concern Not a significant risk factor alone (esp. if 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.insulin therapy3/24/201430Administer 1/2 to 2/3rd of the patient's usual intermediate-acting insulin subcutaneously on the morning of surgeryIn 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.In type I Diabetics3/24/201431With 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)
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 diabeticGlucose-Insulin-Potassium (GIK) solution used with diabetic patients provides better recovery after coronary bypass operations.Straus S,Gerc V,Kacila M,Faruk C.
3/24/201435Sliding scale insulin is not recommended for the management of hyperglycemia.set and forgetBasal + pre-meal betterhttps://www.diabetessociety.com.au/documents/PerioperativeDiabetesManagementGuidelinesFINALCleanJuly2012.pdf3/24/201436Type 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. In Type II Diabetics3/24/20143737Clear liquids- 2hrBreast milk- 4 hrLight snacks/ cerelac - 6 hrFull meal- 8 hrNPO3/24/201438state of drug induced reversible unconsciousness and loss of protective reflexesconsist of hypnosis, amnesia, analgesia, relaxation of skeletal muscles, and loss of autonomic reflexesBalanced anesthesia=hypnotic+ amnesic + analgesics + muscle relaxant
General anesthesia3/24/201439Components of GAPre-anesthetic check up (PAC)PremedicationInductionMaintenanceRecovery Postoperative Care
3/24/201440Advantagesfast 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.
Inducing agents- iv3/24/201441Propofol (10 mg/ml)-55 yr- 1-1.5 mg/kg slow ivOnset 30- 45 sDuration- 20-75 minMetabolism- hepatic conjugationExcretion- urines/e- injection site burning, hypotension, apnea, rash pruritus, cardiac s/eMost commonly used
Inducing agents- iv3/24/201442Ketamine (10mg/ml)1-4.5 mg/kg slow iv once1-2 mg/ kg infusion @ 0.5mg/kg/minProduces dissociative anesthesiaBlocks NMDA receptorsOnset- 30 sDuration- 5 -10 minsMetabolised by liverExcreted in urines/e- emergence reaction, htn, raised ICP, tachycardia, hallucinations
3/24/201443Sodium thiopentalultra-short-acting barbiturate46mg/kgLargely replaced by propofolmainly metabolized topentobarbitals/e- hypotension,apneaandairwayobstructioncaution with liver disease, severeheart disease, severehypotension, a severebreathing disorder, or a family history of porphyriaEtomidate (2mg/ml)0.3-.6 mg/ kg iv over a minuteOnset 60s; duration- 3-5 minsHepatic metabolism, excreted in urines/e- adrenal suppression, pain, apnea, arrythmiasLess often used
3/24/201444Advantages:Excellent analgesiaMinimal hemodynamic depressionGood suppression of endotracheal tube responseProblems:Respiratory depressionIncomplete suppression of intraoperative awarenessUsed mainly for cardiac anesthesia and also in smaller doses as a part of balanced anesthesia for non-cardiac cases
Intravenous Anesthetics-opioids3/24/201445FentanylMore lipid soluble than morphineRapid onset (60 sec)Elimination half time (200 min) is longer than the duration of clinical effectVery 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
Intravenous Anesthetics3/24/201446Isoflurane1- 3%Rapid onset, short actingMAC 1.3%s/e N/V, hypotension, arrythmias
Sevoflurane1.4- 2.6%Onset 2-3 minexpensives/e hypotension, respiratory irritation, seizures
Halothanepotent anestheticMAC 0.7420% metabolized in livers/e- liver injury 1in 10,000Less preferredInducing agents-inhalational3/24/201447Difficult IV accessAnticipated difficult airwayChildren