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Complication during anesthesia

Bradycardia Tachycardia Atrial arrhythmia Ventricular arrhythmia Heart block Hypotension Hypertension Myocardial ischemia Cardiac arrest Embolism Hypoxemia Hypercapnia Hypocapnia Respiratory obstruction Intubation problems Aspiration of gastric content Adverse drug effects Malignant hyperthermia Porpheria Hypothermia Hyperthermia injury

Delayed recovery
The duration of impaired consciousness depend on :1 the drug used Volatile with high blood/ gas solubility coefficientBarbiturates : large dosesBenzodiazepinesopioid with long duration2 The timing of drug use : if given toward the end of the procedur3 Pain : long duration drugIf not :Hypoglycemia (diabetic patient)HyperglycemiaCerebral pathologyHypoxemia HypercapniaHypotensionHypothermiaHypo – osmolar or TURP syndromHypothyrodismHepatic & renal failure

Cyanosis
Postoperative hypoxemia is common & may be caused by many factors Detected using a pulse oximeter Causes of postoperative hypoxemia Atelectasis Diffusion hypoxia Hypoventilation Bronchospasim Aspiration Pnumothorax Pulmonary embolism Pulmonary oedema Hypoxemia may be corrected by oxygen or increase concentration of oxygen Oxygen therapy device Nasal cannula :2 L /min =28%, simple ,easy to use & well tolerated. May dry nasal membrane. Simple facemask : 35-50%, simple and easy to use. If flow < 5L/min accumulate CO2 Venturi mask : 24, 28, 31, & 60%. Simple, reliable, effective. Non- rebreathing mask : 60-90%, tight fitting & flow rate should adjusted to prevent collapse of reservior bag during inspiration.

Fluid Management

All patient except those undergoing the most minor surgical procedures require venous access & IV fluid therapy.Some require transfusion of blood or blood component.Maintenance of a normal intravascular volume is highly desirable in the perioperative period.The anesthesiologist should be able to assess intravascular volume accurately & replace any fluid or deficits & ongoing losses. Errors in fluid replacement or transfusion may result considerable morbidity or even death.physiology Body water content varies with age & sex as percentage of body weight TBW ICF(%) ECF(%)Neonate 75 40 35Infant 70 40 30Adult male 60 40 20Adult female 55 35 20Elderly 45 30 15 Approximately two – third of total body (TBW) is intracellular (ICF) & one third is extracellular fluid (ECF).The ECF is further subdivided into interstial fluid & plasma .

The fate of intravenous fluid

The redistribution of infused fluid within the body will depend on its composition relative to that of each compartment . Salt solutions are excluded from ICF by the cell membrane Na+/ K+ pump . Dextrose (5%) behaves like water & is distributed throughout the TBW . ECF ICF ISF plasma Saline (0.9 %) 0 4/5 1/5 Dextrse ( 5%) 2/3 1/4 1/12 These figure demonstrate why large volume of crystaloids are required to expand plasma volume . To replace a given blood loss requires 3 times the volume as saline (0.9%) or 9 times the volume as dextrose (5%) .

Intravenous fluids

Intravenous fluid therapy may consist of infusion crystalloid, colloid or accombination of both.Crystalloid solutions are aqueous solutions of low- molecular weight ions (salts) with or without glucose .Colloid solutions also contain high – molecular weigh substances such as proteins or large glucose polymers .Colliod solutions maintain plasma colliod oncotic pressure & for the most part remain intravascular .Crystaloid solutions rapidly equilibrate with & distributed throughout the entire ESF Crystaliod solutionsA wide variety of solutions are avialable .Solutions are chosen according to the type of fluid loss being replaced .Losses primarily due to water loss are replaced with hypotonic solutions .Losses that involve both water & electrolyte deficits are replaced with isotonic electrolyte solutionsGlucose is provided in some solutions to maintain tonicity or to prevent ketosis & hypoglycemia.


Commonly used crystalloid solutions
Sodium chloride 0.9%Glucose 5%Glucose 4% + saline 0.18%Glucose 5% + saline 0.45%Lactate ringers (Hartmann solution)Sodium bicarbonate 8.4%Colloid solutions The osmotic activity of the high molecular weight substances in colloids tends to maintain these solutions intravascularly.While the intravascular half – life of a crystalloid solution is 20 – 30 minutes, most colliod solutions have intravasclar half – lives between 3 – 6 hours .The substantial cost & occasional complications associated with colliods tends to limit their use .Generally accepted indication for colloids include :Fluid resuscitation in patient with severe intravascular fluid deficit (eg. Hemorrhagic shock) prior to the arrival of blood for transfusion .Fluid resuscitation in the presence of severe hypoalbominemia or conditions associated with large protein losses such as burn .

Several colloids solutions are generally available :

Blood derived colloid include :Albumin 5%Plasma protein fraction 5%Synthetic colloids include Detrose starchesGelatins Hetastarch ( Hydroxyethyl starch)Normal requirment :WaterA normothermic 70 – kg man with normal metabolic rate loses approximately 2500 ml of water / day : - urin 1500 ml - faeces 100 ml - sweat 500 ml - lung 400 mlWater is gained from : - ingested fluid 1500 ml - food 800 ml - metabolism 400 mlMaintenance requirement are therefore approximately 1.5 ml / kg /hr

Sodium ( Na+)

Loss in faeces & sweat is about 10 mmol / day . Renal excretion being mainly dependent on dietray intake Average requirements are 1 mmol / kg. This could be provided by : - 2500 ml of 4% dextrose with 0.18 saline over 24 hours . - 2000 ml of 5% dextrose & 500 ml of 0.9% saline over 24 h Potassium (K+) loss is via the same routes as sodium , but renal retension is less efficient . The average requirement is 1 mmol / kg . This should be added to the infusion regime .

Abnormal losses

These are common in surgical patientThey may be sensible or insensible & either overt or covertLosses from the gut are common eg. Nasogastric suction, diarrhea, vomiting, or sequestration of fluid within the gut lumen (eg. Intestinal obstruction) .Replacement with saline 0.9% with 13 – 20 mmol/L of K+ as KCL .Increased insensible losses from the skin & lungs occur in presence of fever & hyperventilationThe usual insensible losses from skin & lung increase by 12% for each 1 C rise in body temperature.Sequestration of fluid at the site of operative trauma is a form of fluid loss which is common in surgical patient .This fluid is frequently referred to as (third space) loss .Third space losses are not measured easily .Sequestrated fluid is reabsorbed after 48 – 72 h .

Existing deficits

These occur preoperatively & arise primarily from the gut . Dehydration with accompanying salt loss is a common disorder in the acute surgical patient . Assessment of dehydration This is a clinical assessment based upon the following : History : How long has the patient had abnormal loss of fluid ? How much has occurred eg. Frequency of of vomiting ? Examination Specific features are : Thirst Dryness of mucous membrane Loss of skin turgor Orthostatic hypotension Tachycardia Reduced jugular venous pulse Decreased urin out put

The severity of dehydration may be described clinically as :

Mild dehydrationloss of 4% of body weight (approximately 3 L in 70 kg patient) Reduced skin turgorSunken eyeDry mucous membraneModerate dehydration Loss of 5 – 8% body weight (approximately4 – 6 L in 70 kg patient)OliguriaOrthostatic hypotensionTachycardiaAddition to the aboveSever dehydrationLoss of 8 – 10 % body weight (7 L in 70 kg patient)Profound oliguriaCompromised cardiovascular function

Laboratory assessment

The degree of haemoconcentration & increase in albumin concentration may be helpful in the absence of anemia & hypoproteinaemia Increased blood urea concentration & urin osmolality (>650 mosmo/kg) confirm the clinical diagnosis Perioperative fluid requirements : Fluid therapy can be divided into : Maintenance Deficit Replacement requirment : which is further subdivided into : - Blood loss - Third space loss


Maintenance fluid requirements
In adult & pediatric patients can be determined by the following formula :(4 : 2 : 1) Weight Rate For the first 10 kg 4 ml /kg /hFor the next 10- 20 kg add 2 ml /kg /hFor each kg above 20 kg add 1 ml/ kg /hEx. What are maintenance fluid requirement for a 25 – kg child ?Answer : 40 + 20 + 5 = 65 ml / hUsually replaced by D5 Ѕ NS with 20 meq /L KCLDeficit In addition to a maintenance infusion , any preoperative fluid deficits must be replacedEx. If 5- kg infant has not received oral or intravenous fluid for 4 hours prior to surgery?A deficit of 80 ml has occurred (5kg x 4ml/kg /h x 4 h)Deficit = maintenance x hours of fasting

requirement in aliquots of :

- 50 % in the first hour - 25 % in the 2 nd hour - 25 % in the 3 rd hour In the example above, a total of 60 ml would be given in the first hour (80/2 + 20 ) 40 ml would be given in the 2 nd & 3 rd hour (80/4 + 20 ) Preoperative fluid deficit are usually replaced with a balanced salt solution eg. Lactate ringer injection . Replacement requirements : are subdivided into : - Blood loss - Third space loss
preoperative fluid deficit are typically administered with hourly maintenance

Blood loss

The blood volume of : - Premature 100 ml /kg - Full term neonate 85-90 ml /kg - Infant 80 ml /kg - Adult 65- 70 ml/kg Blood loss is typically replaced with non – glucose containing crystalloid eg. 3 ml of lactated ringer injection for each ml of blood loss Or colloid solutions eg. 1 ml of 5% albumin per ml of blood lost .Blood loss in excess of 15% of blood volume in adult are usually replaced by infusion of stored blood Third space loss Is impossible to measure & must be estimated by the extent of surgical procedure .One popular guideline is : - 2 ml/kg/ h for relatively a traumatic surgery eg. Strabismus correction - 6-10 ml/kg/h for traumatic procedure eg. Abdominal abscess Third space loss is usually replaced with lactate ringer injection

Postoperative requirements

In the postoperative period, normal maintenance fluid should be given(= 1.5 ml/kg/h) as 4% dextrose with 0.18 salineAdditional fluid may be required in the following circumstances :If blood or serum is lost freom drains If GIT losses continue ex. From NG tube or fistulaAfter major surgery eg. Total gastrectomy, when additional water & electrolytes may be required for 24 – 48 h to replace continuing third space lossesDuring rewarming if the patient has became hypothermic during surgery Normally K+ is not administered in the first 24 – 48 h after surgery as endogenous release of K+ from tissue trauma & catabolism warrants restriction




رفعت المحاضرة من قبل: Mostafa Altae
المشاهدات: لقد قام 16 عضواً و 171 زائراً بقراءة هذه المحاضرة








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