Preoprative evaluation

Preoprative evaluationDept of anesthesia and critical care ,UBPreoprative evaluation is defined as a process of clinical assessment that precedes the delivery of anesthesia care for surgery and for non surgical procedures.Goals of preoperative assessmentAssessment of the patients overall health status.Uncovering of hidden conditions that could cause problems both during and after surgery.Perioperative risk determination.Optimization of the patients medical condition in order to reduce the patients surgical and anesthetic perioperative morbidity or mortality.Development of an appropriate perioperative care plan.Education of the patient about surgery, anesthesia, intraoperative care and postoperative pain treatments in the hope of reducing anxiety and facilitating recovery.Reduction of costs, shortening of hospital stay, reduction of cancellations and increase of patient satisfaction.8. Informed consent

Goals of the preoperative

evaluation is to ensure that the patient is in the best (or optimal)

condition.Information sources:-preoperative evaluation consists of consideration of informations from multiple sources that may include:Patient medical recordsInterviewPhysical examinationInvestigations

Steps of the preoperative evaluation :Problem Identification

Risk Assessment

Preoperative Preparation

Plan of Anesthetic Technique

I. Problem Identificationthrough :-

History (including a review of the patient's chart)

Physical examination

investigation

HistoryThe history is the most important component of the preoperative evaluation. The history should include :a past and current medical history a surgical history: significant blood loss a family history: adverse reactions associated with anesthesia should also be obtaineda social history :use of tobacco, alcohol and illegal drugs, a history of allergies, current and recent drug therapy, unusual reactions or responses to drugs any problems or complications associated with previous anesthetics

Previous anaestheticsPONVallergymalignant hyperpyrexiadifficult airwaydifficult IV accessThe history should include a complete review of systems to look for undiagnosed disease or inadequately controlled chronic disease. Diseases of the cardiovascular and respiratory systems are the most relevant in respect of fitness for anesthesia and surgery:-

Cardiovascular : hypertension ; ischemic , valvular or congenital heart disease; CHF or cardiomyopathy, , arrhythmias

Respiratory : COPD; restrictive lung disease; altered control of breathing (obstructive sleep apnea, CNS disorders, etc.)

Neuromuscular : CVA's; seizures; spinal cord Injury; disorders of NM junction e.g myasthenia gravis, MH

Endocrlne : DM; thyroid disease; pheochromocytoma; steroid therapy

GI - Hepatic : hepatic disease; gastresophageal reflux

Renal : renal failure

Hematologic : anemias; coagulopathiesPhysical Examination:-Should focus on evaluation of :

Upper airway

Respiratory system

Cardiovascular system

other systems problems identified from the history

airway evaluation should include:-Head and neck examination -Face -Oral cavity : mouth opening mandibular space tongue teeth Mallampati classificationAbnormal - Small or recessed chin: micrognatia, macroglossia - Buck, protruded, & loose teethInability to open mouth normally High arched palate Tonsillar hypertrophy Neck has limited range of motion Low set ears Significant obesity of the face/neck -swellings around the head and neck

Mallampati test:-Pridctive test for difficult laryngoscopy-used alone it correctly predicts about 50% of difficult laryngoscopies and has a false positive rate of up to 90%.-Examine the patients oropharynx from opposite the patients face while the patient opens their mouth maximally and protrudes their tongue without phonating. Check for visibility of or pharyngeal structures : Class I :Faucial pillars, soft palate ,and uvula visibleClass II:Faucial pillars , and soft palate visible uvula tip masked by the base of the tongue.Class III:Soft palate is visibleClass IV:Soft palate is not visibleclass III & IV are associated with an increased risk of difficult laryngoscopy.

Mallampati scoring system

Other pridictive tests:-Thyromental distance (Patil test ):distance from the tip of thyroid cartillage to the tip of mandible, neck fully extended.Normal >7cm. < 6 cm predicts approx. 75% difficult laryngoscopiesSternomental distance(Savva test):The distance from the upper boarder of manubrium to the tip of the mandible ,neck fully extended and mouth closed.< 12.5 cm associated with difficulty ( positive pridictive value 82 %)Mandibular protrusion: inability to protrude lower incisors beyond the upper incisors associated with increased risk of difficult laryngoscopies.

INVESTIGATION

INVESTIGATIONLab tests : should be ordered based on information obtained from the history and physical exam, the age of the patient and the complexity of the surgical procedure. Routine laboratory tests in patients who are apparently healthy on clinical examination and history are not beneficial or cost effective.only if indicated from the preoperative history and physical examination."Routine or standing" pre operative tests should be discouraged

-FBC : anticipated significant blood loss, suspected hematological disorder (eg.anemia,) or recent chemotherapy.

-Electrolytes : diuretics, chemotherapy, renal or adrenal disorders

-ECG : age >50 yrs. ,history of cardiac disease, hypertension, peripheral vascular disease, DM, renal, thyroid or metabolic disease.

-Chest X-rays: prior cardiothoracic procedures ,COPD, asthma, a change in respiratory symptoms in the past six months.

-Urine analysis : DM, renal disease or recent UTI.

tests for different systems according to history and examination

Risk Assessment-Perioperative risk is a function of :-the preoperative medical condition of the patient, the invasiveness of the surgical procedure and the type of anesthetic administered.

-Most of the work, however, addresses the operative risk according to the patient's

preoperative medical status.

American Society of Anesthesiologists Classification of Physical Status(The ASA grading system):- -simple description of the physical state of a patient (Table 2). - one of the few prospective descriptions of the patient general health which correlates with the risk of anesthesia and surgery1516. It is extremely useful and should applied to all patients who present for surgery. -Increasing physical status is associated with increasing mortality. -Emergency surgery increases risk dramatically, especially in patients in ASA class 4 and 5.

ASA Physical Status Classification System

medical statusmortalityASA Inormal healthy patient without organic, biochemical, or psychiatric disease0.06-0.08%ASA IImild systemic disease with no significant impact on daily activity e.g. mild diabetes, controlled hypertension, obesity .Unlikely to have an impact0.27-0.4%ASA IIIsevere systemic disease that limits activity e.g. angina, COPD, prior myocardial infarctionProbable impact 1.8-4.3% ASA IVan incapacitating disease that is a constant threat to life e.g. CHF, unstable angina, renal failure ,acute MI, respiratory failure requiring mechanical ventilationMajor impact 7.8-23%ASA Vmoribund patient not expected to survive 24 hours e.g. ruptured aneurysm9.4-51% ASA VIbrain-dead patient whose organs are being harvestedFor emergent operations, you have to add the letter E after the classification.

ASA IASA IIASA IIIASA IVASA VASA VIIII. Preoperative Preparation1.Anesthetic indications: Preanesthetic medication: is the use of drugs prior to anesthesia to make it more safe and pleasant. -To relieve anxiety benzodiazepines. -To prevent nausea and vomiting antiemetic. -To provide analgesia opioids. -To prevent bradycardia and secretion atropine. -Prophylaxis for pulmonary aspiration -H2-Antagonist , Non-particulate antacids2.Surgical indications: -Antibiotic prophylaxis for infective endocarditis. -Prophylaxis against DVT for high risk patients : low-dose heparin or aspirin intermittent calf compression, or warfarin. 3.Co-existing Disease indications: -Some medications should be continued on the day of surgery e,g B blockers, thyroxine. Others are stopped e.g oral hypoglycemics - Steroids within the last six months may require supplemental steroids

Common Preoperative Medications, Doses, and Administration Routes (adult)MEDICATIONADMINISTRATION ROUTEDOSE (mg)LorazepamOral, IV0.54MidazolamIVTitration of 1.02.5-mg dosesFentanylIVTitration of 25100g dosesMorphineIVTitration of 1.02.5-mg dosesMeperidineIVTitration of 1025-mg dosesCimetidineOral, IV150300RanitidineOral50200MetoclopramideIV510AtropineIV0.30.4GlycopyrrolateIV0.10.2ScopolamineIV0.10.421Summary of Fasting Recommendations to Reduce the Risk of Pulmonary Aspiration Ingested Material Minimum Fasting Period (Hours)Clear liquids 2 Breast milk 4Infant formula 6Non-human milk 6Light meal 6IV. Plan of Anesthetic TechniqueIs the patient's condition optimal?2.Are there any problems which require consultation or special tests? 3.Is there an alternative procedure which may be more appropriate? 4. What are the plans for postoperative management of the patient? 5. What premedication if any is appropriate?

23Finally, we plan our anesthetic technique :

Local or Regional anesthesia with 'standby monitoring with or without sedation.General anesthesia; with or without intubation. Spontaneous or controlled ventilation is used.3. Combined regional with general anesthesia.