General Surgery Sheet #2 By Wafa'a Iseid

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General Surgery Sheet #2 By Wafa'a Iseid

Post by Sura on 16/2/2012, 10:03 pm

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Sura

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تاريخ التسجيل : 2010-09-29

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Re: General Surgery Sheet #2 By Wafa'a Iseid

Post by Shadi Jarrar on 30/3/2012, 4:24 pm

Preoperative evaluation & preparation for anesthesia & surgery

-As you know any patient undergoes surgery he will take anesthetic type either local or general anesthesia but we are going to focus on patients undergoing surgery under general anesthesia. General anesthesia itself is stressful for the patient.
- Surgical procedures and administration of anesthesia are associated with a complex stress response that’s proportional to the following:
• The magnitude of injury (the surgery itself).
• Total operating time
• Amount of intraoperative blood loss
• Degree of postoperative pain

>>so for these factors, any surgery has a stress and we have to prepare our patients for these stresses and measure the risk for the patient also we have to know before surgery what we are going to do for him and the surgery itself.
-The adverse metabolic and hemodynamic effects of this stress response can present many problems in the perioperative period.
-Decreasing the stress response to surgery and trauma is the key factor in improving outcome and lowering the length of hospital stay as well as the total costs of patients care.
It is well recognized that safe and efficient surgical and anesthesia practice requires an optimized patient. Preoperative preparation of the patient may be a major contributory factor to the primary causes of perioperative mortality
Goals for preoperative evaluation:

1. Documentation of the conditions for which surgery is needed.
2. Assessment of the patient’s overall health status.
3. Uncovering of hidden conditions that could cause problems both during and after surgery.
4. Perioperative risk determination.
5. Optimization of the patient’s medical condition in order to reduce the patient’s surgical and anesthetic perioperative morbidity or mortality.
6. Development of an appropriate perioperative care plan.
7. Education of the patient about surgery, anesthesia, intraoperative care and postoperative pain treatments in the hope of reducing anxiety and facilitating recovery.
8. Reduction of costs, shortening of hospital stay, reduction of cancellations and increase of patient satisfaction.

>>so we have very important goals to measure and to do before surgery. Not any patient we want to do surgery for him we’ll use general anesthesia and without knowing these things otherwise we’ll get a lot of problems. Sometimes we have emergency...emergency is another factor but we are talking about elective surgery, evaluation for a patient undergoing an elective surgery; general assessment>> the first thing in general assessment is the history.
 General Health Assessment:

History: ,most important component of the general assessment; this includes:
• Past and current medical history (we have to ask the patient about previous and current medical illnesses).
• Surgical history (previous operations).
• Family history of the patient.
• Social history (use of tobacco, alcohol and illegal drugs) >> because these drugs will affect the medications and the anesthesia that you are going to give him.
• History of allergies.
• Current and recent drug therapy; because there’re a lot of medications that interact with anesthesia and the patient’s health during surgery.
• Unusual reactions or responses to drugs.
• Problems or complications associated with previous anesthetic agents. For example if the patient underwent an operation previously and faced problems...we have to ask him about the problems that he faced.
• Family history of adverse reactions associated with anesthesia.
• In children, the history should also include birth history, focusing on risk factors such as prematurity at birth, perinatal complications and congenital chromosomal or anatomic malformations
• History of recent infections, particularly upper and lower respiratory tract infections.
• The 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. In adults, the most important thing in medical history is the cardiovascular history and the respiratory history.

Physical examination: we should do physical examination for surgery.

• The physical examination should be built on the information gathered during the history.
• focused pre-anesthesia physical examination which includes:
• Assessment of the airway.
• Examination of the lungs.
• Examination of the heart.
• Documentation of Vital signs.
• Unexpected abnormal findings on the physical examination should be investigated before elective surgery.

>>so the most important thing in preoperative assessment is the history and physical examination. As we said earlier, in any patient undergoing surgery, we have to focus on cardiovascular and respiratory examination, if we found any abnormal finding, we have to do further investigations.
-In history and physical examination, if the patient is in a good general condition; he doesn’t have previous or current medical illnesses, there’s no need for any laboratory test to be done before the surgery…BUT why?? It’s found that in general population, with good general condition, only 5 % of patients may have abnormal laboratory findings in spite of having good general condition. So it’s not cost-effective to do laboratory investigations before surgery to any patient not indicated by general examination or history taking.
Laboratory work up
Routine laboratory tests in patients who are apparently healthy on clinical examination and history are not beneficial or cost effective
Lab tests should be ordered based on information obtained from:
1. The history and physical exam.
2. The age of the patient
3. The complexity of the surgical procedure (ex. blood loss, prolonged procedure).

 Indications for specific preoperative tests:


 Drug history:

• A history of medication use should be obtained in all patients. Especially the geriatric population consumes more systemic medications (more than one drug). Numerous drug interactions and complications arise in this population and special attention should be paid to them
• Administration of most drugs should be continued up to and including the morning of operation. although some adjustment in dosage may be required (eg. antihypertensive medication, insulin, he should continue taking anti hypertensive medication up to and including the morning of operation).
• Some adjustments in dosage may be required (e.g. antihypertensives, insulin). (If a patient takes antihypertensive medication, after admission to the hospital, we have to measure the blood pressure and sometimes we have to adjust the dose to get the blood pressure controlled. Ex. If the patient is taking insulin for diabetes, we have to adjust the insulin dose).
• Some drugs should be discontinued preoperatively. For example, monoamine oxidase (MAO)inhibitors should be withdrawn 2-3 weeks before surgery because of the risk of interactions with drugs used during anesthesia.
• Oral concontraceptive pills also should be discontinued at least 6 weeks before elective surgery because of the increased risk of venous thrombosis.


Recently, the American Society of Anesthesiologists (ASA) examined the use of herbal supplements and the potentially harmful drug interactions that may occur with continued use of these products preoperatively11–13. All patients are requested to discontinue their herbal supplements at least 2 weeks prior to surgery
**The use of medications that potentiate bleeding needs to be evaluated closely with a risk-benefit analysis for each drug and with a recommended time frame for discontinuation based on drug clearance and half-life characteristics. For example, a patient undergoing anticoagulation therapy; increasing the bleeding time so we can’t go for surgery if the INR value is more than 1.5 because of the risk of bleeding so we have to stop the anticoagulation therapy before surgery. Stoppage of the anticoagulation therapy depends on the half life of the drug. If the patient is taking Warfarin, stop it 4-5 days before the surgery to normalize the INR. Aspirin should be discontinued 7-10 days before surgery to avoid excessive bleeding and thienopyridines (such as clopidogrel) for 2 weeks before surgery. Selective cyclooxygenase-2 (COX-2) inhibitors do not potentiate bleeding and may be continued until surgery. Oral anticoagulants should be stopped 4-5 days prior to invasive procedures, allowing INR to reach a level of 1.5 prior to surgery We have to measure the risk for Warfarin stoppage and the benefit of surgery. We have to ask why he’s taking Warfarin. If he’s taking Warfarin because he has undergone valve surgery or because of deep venous thrombosis...So there’s a risk for Warfarin stoppage. Warfarin should be discontinued during surgery; 24 hours before surgery and 24 hours after surgery...so there’s 48 hours in which the patient is not under anticoagulation therapy. We’ve to measure the risk, we’ve to ask the patient, ask his treating physician and measure the benefit of surgery. For example, if the patient has to undergo an elective surgery (such as what’s done for malignancy); we have to stop Warfarin and we have to be aware of the risk of thrombosis or coagulation. If the elective surgery was plastic or esthetic surgery; its benefit is not that important so here the risk of Warfarin stoppage is high.
-Aspirin should be discontinued 7-10 days before surgery to avoid excessive bleeding (the half life of Aspirin is 7-10 days).
 Perioperative risk assessment:

1. The preoperative medical condition of the patient
2. The invasiveness of the surgical procedure; there’re major surgical procedures and minor surgical procedures. If a normal patient needs to do a major surgical procedure and another patient has medical conditions and needs to do a minor surgical procedure, the risk would be nearly equal for both patients>> so there’re more than one factor to determine the risk of surgical procedures; the patient himself, the surgical procedures and the type of anesthesia administered.
3. The type of anesthetic administered.


The ASA grading system was introduced originally as a simple description of the physical state of a patient It is extremely useful and should applied to all patients who present for surgery. Increasing physical status is associated with increasing mortality.

Class 5  (The chance of death from anesthesia is more than 60-70%).
E: we add “E” for emergency surgery. The risk of Class 1E is more than Class 1 alone. And in general, the risk of emergency surgery is more than that of elective surgery.

 Surgery-related complications:
Surgery-related morbidity and mortality generally fall into one of three categories: cardiac, respiratory and infectious complications The overall risk for surgery-related complications depends on individual factors and the type of surgical procedure:

1. Individual factors (surgical risk factors related to type of patients):
• Advanced age  increased likelihood of underlying diseases.
• Respiratory and cardiac disease
• Malnutrition
• Diabetes mellitus

2. Type of surgical procedures ( surgical factors related to surgical procedures):
• Major vascular
• Intraabdominal
• Intrathroracic
• Intracranial
• Urgent and emergency surgery.
>>All of these are major surgeries in which they put the patient in a high risk for anesthesia or complications.
3. Anesthetic problems ( surgery related risk factors):
• Airway problems
• Failure to provide adequate ventilation leading to hypoxia
• Fortunately, the number of critical incidents involving anesthetics alone appear to be decreasing in recent years (in the past anesthesia was a major risk factor; and some patients died because of anesthesia and they suffered from airway problems and hypoxia and there was a morbidity and mortality of hypoxia but now this shouldn’t occur with normal patients if we made a proper assessment that we talked about in this lecture. The risk of death is very little because of fabrication of new medications.

 Assessing cardiovascular risk: one of the most important risk factors that we should be aware of because most of patients that we deal with have problems related to their heart.
-regarding the cardiovascular risk, it can be determined by:
• Patient-Related Predictors/patients’ cardiovascular risk.
• Functional Capacity of the patient.
• Surgery-Related Predictors

**first we look to the patient who has heart condition and we look for things that may increase the risk of surgery related to his condition, functional activity for the patient and what the surgery we are going to do…all of these determine the risk that the patient may encounter during surgery.

 Patient-Related Predictors:
A 6-week period is necessary for the myocardium to heal after an infarction and for the thrombosis to resolve. Patients with coronary revascularization done within the preceding 40 days should also be classified as high-risk patients. Because of sympathetic stimulation and hypercoagulability during and after surgery, patients with major predictors have a five times greater perioperative risk. Only vital or emergency surgical procedures should therefore be considered for these patients. All elective operations should be postponed and the patients properly investigated and treated.

; because he may suffer from myocardial infarction during the surgery and consequently he may die.
Intermediate-risk factors are proof of well established but controlled coronary artery disease. Diabetes mellitus is included in this category because it is frequently associated with silent ischemia and represents an independent risk factor for perioperative mortality.
Minor risk factors are markers of an increased probability of coronary artery disease, but not of an increased perioperative risk
 Functional capacity: we ask about the patient himself... how his activity at home is...About his cardiac condition.

-Metabolic Equivalent of Oxygen Consumption (MET): a chart that’s filled with scores for 10 or more.

≥ 10 MET: -athletic patient who practices swimming, tennis, and bicycle.
-heavy professional work.
>>this patient has good conditions; as his heart withstands all these efforts. So the risk of general anesthesia is low.
>>so we ask the patient about the cardiovascular risk, the patient’s related factors, previous diseases and his functional capacity.

Surgery-Related Predictors (there’re major surgery and minor surgery):

 Perioperative cardiac complications:

• Myocardial infarction during surgery or immediately after surgery
• Pulmonary edema
• Ventricular fibrillation
• Primary cardiac arrest
• Complete heart block
>>all these complications can lead to death.
Q: What’s the difference between cardiac arrest and complete heart block?
A: Cardiac arrest means there’s no perfusion to tissues. The complete heart block is a type of cardiac arrest; cardiac arrest could be caused by arrhythmia, or maybe caused because the heart is working without pumping blood. In this case it’s a type of cardiac arrest but not complete heart block???!!
That what’s answered by the doctor and here’s what wiki says: Cardiac arrest: the cessation of normal circulation of the blood due to failure of the heart to contract effectively. Heart block: disease in the electrical system of the heart that can cause lightheadedness, syncope (fainting), and palpitations.

 Management recommendations (for cardiovascular risk):

1. Acute surgical emergency: even if the patient has cardiac problem, major problem, his functional capacity is very low, we have to do the surgery but before the surgery we have to do the following:

• Simple and critical tests
• Rapid assessment of cardiovascular vital signs
• CBC
• Kidney function
• Volume status
• Hematocrit
• Electrolytes
• Renal function
• Urine analysis
• ECG

>> These tests have to be done even for emergency surgery as they don’t take much time to be done (nearly one hour). Only the most essential tests and interventions are appropriate until the acute surgical emergency is resolved. A more thorough evaluation can be conducted after surgery

2. Elective surgery for patient with cardiovascular problem:

• The decision to proceed with elective surgery begins with an assessment of risk. Assess the patient’s preoperative risk factors and the risks associated with the planned surgery (patient related and surgery related risk factors).
• The decision to undergo further testing depends upon the interaction of the patient’s risk factors, surgery- specific risk and functional capacity. (This means if we are going to do a major surgery for a patient with intermediate risk we have to do some investigations before doing the surgery.
If a major risk predictor is present, nonemergency surgery should be delayed for medical management, risk factor modification and possible coronary angiography. For patients at intermediate clinical risk, both the exercise tolerance and the extent of the surgery are taken into account with regard to the need for further testing.
3. preoperative noninvasive cardiac testing: testing is indicated if any two of the following factors are present:

• Intermediate clinical predictor
• Poor functional capacity (less than 4 metabolic equivalents)
• Procedure with high surgical risk

>>if the patient has two of these factors>> we’ve to do other cardiac testing such as treadmill test* and taking a consultation from his cardiologist.





Importantly, no preoperative cardiovascular testing should be performed if the results will not change perioperative management. The results of noninvasive testing can then be used to determine further perioperative management. Such management may include intensified medical therapy or cardiac catheterization, which may lead to coronary revascularization or potentially to cancellation or delay of the elective noncardiac operation.
Assessing pulmonary risk
careful history taking and physical examination are the most important parts of preoperative pulmonary risk assessment.

Postoperative pulmonary complications (PPCs)

• Pneumonia
• Atelectasis*
• Bronchitis
• Bronchospasm
• Hypoxia
• Respiratory failure with prolonged mechanical ventilation
• Exacerbation of underlying chronic lung disease

*Atelectasis: collapse or closure of alveoli resulting in reduced or absent gas exchange.
 Risk factors for postoperative pulmonary complications:

• Procedure-related risk factors: primarily based on how close the surgery is to the diaphragm (when do we expect that pulmonary complications may occur after surgery? When the surgery is closer to the diaphragm or upper abdominal and thoracic surgery...these are the highest risk procedures for any patient having previous pulmonary condition).
• Length of surgery (more than 3 hours)
• General anesthesia.
• Emergency surgery.
• Underlying chronic pulmonary disease
• Symptoms of respiratory infection.
• Smoking.
• Age >60 years
• Obesity
• Presence of obstructive sleep apnea
• Poor exercise tolerance
• Poor general health status.

 Preoperative pulmonary risk-reduction strategies:

• Encourage smoking cessation for at least 8 weeks preoperatively
• Treat airflow obstruction in patients with chronic obstructive pulmonary disease or asthma
• Give antibiotics and delay surgery if pulmonary infection is present; any patient suffering from upper respiratory tract infection if he exposed to general anesthesia when undergoing elective surgery, he will be at high risk for pneumonia. So he must be treated first and then he can undergo elective surgery. But in emergency cases, we can go for general anesthesia despite the presence of upper respiratory tract infection.
• Begin patient education regarding lung-expansion maneuvers. The education begin before surgery so the patient be able to do it by himself after surgery (In any surgery that’s done under general anesthesia, after the operation the patient can’t catch his breath, exhausted and in pain, so we give him incentive spirometry to help the him in breathing. We educate the patient how to use it before the operation).
 Diabetes mellitus:

• Perioperative morbidity and mortality are greater in diabetic than in non-diabetic patients.
• The diabetic patient who needs elective surgery should be carefully assessed preoperatively for symptoms and signs of peripheral vascular, cerebrovascular and coronary disease.
• Diabetics have a higher incidence of death after MI than non-diabetics
• 8- 31% of type II diabetic patients are reported to have asymptomatic coronary artery disease on stress testing. Diabetic patients also may have cardiac problems.
• Adequate control of blood glucose ( should be less than 180 mg/dL)
• Oral hypoglycemic agents are withheld (stopped) the day of surgery for an agent with a short half-life and up to 48 h preoperatively for a long acting agent. Because during surgery, the patient is fasting and consequently he may suffer from hypoglycaemia.

 Complications of perioperative hyperglycemia:

• Dehydration
• Impaired wound healing
• Inhibition of white blood cell chemotaxis and function associated with an increased risk of infection
• Worsened CNS and spinal cord injury under ischemic or hypoxic conditions
• Hyperosmolarity leading to hyperviscosity and thrombogenesis>> so diabetic patients are at increased risk for deep vein thrombosis (DVT) postoperatively.
 Hypoglycemia occurs if:

• Glucose < 50 mg/dL
• Long acting oral hypoglycemic agents (he’s fasting during the day of surgery)
• Insulin preparations given preoperatively
• perioperative fasting

 Symptoms:

• Brain anoxia
• Hypoxia
• Confusion
• Irritability
• Fatigue
• Headache
• Somnolence: decrease level of consciousness.
• Seizures
• Focal neurologic deficits
• Coma
• Death

 Perioperative management of anticoagulation surgery in the anticoagulated patient:

- If a patient taking Warfarin needs to get his tooth extracted, what should you do??
-For skin incision or any operation to be done, the INR should be less than 1.5…first we stop Warfarin by bridging therapy…give heparin infusion because the half life of heparin is 4 hours while the half life of Warfarin is 4-5 days …so first we stop the Warfarin 4 days before the operation and admit the patient to the hospital and give him heparin infusion…then stop the heparin infusion 6 hours before the operation…by doing this, the patient is having a normalized INR during the surgery…the day after the surgery we start giving heparin with Warfarin…the Warfarin needs 3 days to reach the INR…so in this 24 hours the INR is normal and this period (the 24 hours) carries the risk of coagulation. For example, if the patient takes Warfarin because of valve disease, he may have thrombosis in his valves or if he’s taking Warfarin because of venous thrombosis, he may have deep venous thrombosis.
- For patients who don’t take anticoagulants and undergo a lengthy operation without moving their lower extremities; the anesthesia itself may cause deep venous thrombosis. So before the operation while making the assessment for patients we should be aware of patients who are at high risk for deep venous thrombosis and give them prophylactic heparin Sub Q (subcutaneous) or low molecular weight heparin sub Q. So you have to know the risk factors for DVT.
 Risk factors for deep venous thrombosis (DVT):

• Age >40 years
• Obesity
• Varicose veins
• High estrogen pill (oral contraceptive pills containing estrogen).
• Previous DVT or pulmonary embolism
• Previous malignancy
• Infection
• Heart failure or recent infarction
• Polycythemia or thrombophilia
• Immobility ( bed rest over 4 days)
• Major trauma
• Duration of surgery.
>> All of these are risk factors for DVT, if one or two of them is present, anticoagulation prophylaxis prior to surgery must be given.

General Surgery lec. #2
Date of the lec.: 14.12.2012
Dr.Rami Addasi
Done by: Wafa’a Iseid
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Shadi Jarrar
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عدد المساهمات : 997
النشاط : 12
تاريخ التسجيل : 2009-08-28
العمر : 26
الموقع : Amman-Jordan

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