ANAESTHETIC IMPLICATIONS IN CONCURRENT DISEASES

ANAESTHETIC IMPLICATIONS IN CONCURRENT DISEASES Presenter: Dr. Pavani .M. S Moderator: Dr. Deepak. B.S Classification Diseases involving endocrine systemDisorders of nutritionDiseases involving the cardiovascular systemDiseases of central nervous system, neuromuscular diseases , mental disordersDiseases involving kidneys, disorders of electrolytesDiseases involving GI tract and liverDiseases involving haematopoiesis and various forms of cancerGeriatric diseases Haematological disordersDiseases related to erythrocytes:- Anaemia PolycythemiaAnaemia:- clinically reduced no of circulating RBCs Defined as Hb < 11.5g/dl /hct< 36%(women) , Hb1% every 24hrs acute blood loss or intravascular haemolysisAdverse effect of anaemia is impaired tissue oxygen delivery due to reduced CaO2Compensatory mechanismsRight ward shift of oxyhaemoglobin dissociation curve release of oxygen from Hb to tissuesTissue redistribution of blood to myocardium, brain, muscles from skin and kidneysIncreased cardiac output as an indicator of decreased blood viscosity.Management of anaesthesia.Avoid iatrogenic hyperventilationAvoid hypothermiaMaintaining normovolemic hemodilution and blood salvage in case of surgical blood lossVolatile anesthetics less soluable due to decrease in concentration of lipid rich RBCs uptake increased. But no clinical differences in rate of induction due to increased cardiac outputTransfusion trigger:- 10/30 rule.. But Hb < 6g/dl is definitive indication.In MI patients Hb > 7g/dl should be maintainedIf expected bld loss < 15% no transfusion requiredIf 15-30% replace with crystalloidsIf >40% require blood transfusionIn massive transfusion PRBC: FFP: Platelet to be transfused in ratio of 1:1:1 Hemolytic anaemiasCan be due to:Extravascular haemolysis or Intravascular haemolysisCharacterized by reticulocytosis, increased MCV, unconjugated bilirubinemia, increased LDH levels, decreased serum haptoglobinHereditary spherocytosisAD disease with defect in ankyrin and spectrinAbnormal osmotic fragility and shortened half lifeHaemolytic crisis often precipitated by viral or bacterial infectionPigmented gall stones, splenomegalyAnaesthetic risk depends on severity of anaemia and whether haemolysis is stableEpisodic anaemia triggered by infection and cholelithiasis to be asked in preop evaluationUse of long term CPB excessive haemolysis

Hereditary elliptocytosisAD disorder due to abnormality in spectrin or glycophorinPrevalent in malaria endemic areasMost patients are heterozygous and rarely have hemolysisAcanthocytosisSeen with abetalipoproteinemia, cirrhosis and pancreatitisCholesterol or sphingomyelin accumulation on outer membrane of erythrocyte speculated appearance signals splenic macrophages hemolysis

Paroxysmal nocturnal hemoglobinuria Result in complement mediated RBC hemolysisDue to reduction in glycosophosphatidyl glycanAre also at risk for venous thrombosis due to compliment activationIn absence of protectin dysplastic or aplastic anemiaNocturnal hemolysis is due to CO2 retention and subsequent acidosisManagement:- Avoid predisposing factors like hypoxemia, hypoperfusion, hypercarbiaInhalational agents and propofol are more advantageous than thiopentalMaintain adequate hydrationDisorders of red cell metabolismEmbden-meyerhoff pathway:- Defects are associated with red cell rigidity and reduced life span hemolysisPhosphogluconate pathway:- lack of glucose -6- phosphate dehydrogenase or glutathione reductase presence of denatured Hb precipitates on inner surface hemolysisMethamoglobin reductase deficiency:- Inability to counteract oxidation of Hb to methemoglobin, thus Hb is in ferric form that will not transport oxygen. Type 1 NAD-diaphorase deficiency have small amounts of methamoglobin accumulation in the cells Type II disease have severe cyanosis and Mental retardationGlucose-6-phosphate deficiency:- X linked disorder. Half life is 60daysClassification :- Class1( 55% preoperative exchange transfusion and preventing hemo concentration during surgeryReduced oxygen affinity:- shifts ODC to right. Eg: methamoglobinemiaHere ferric state of iron moiety is maintained thus reducing oxygen transport tissue hypoxiaMay exhibit slate grey pseudo cyanosis despite normal PaO2

Management :- invasive arterial monitoring to measure BP, check saturation, methemoglobin levels by serial ABG analysisAcidosis to be correctedECG should be closely monitored for signs of ischemiaAvoid local anaesthetics, nitrates and N2OTreatment:- 1-2mg/kg of 1% methylene blue in saline over 3-5min. To repeated after 30min.In patients with G6PD deficiency exchange transfusion is preferredAnaemia due to drug and radiation associated marrow damageChemotherapy and many drugs cause pancytopeniaHigh energy radiation produces anaemia resulting from marrow damage . Depending upon intensity of radiation aplastic anaemia may result

Anaemia due to infection associated marrow damageDue to direct invasion of marrow by infectious agent as in military TBDue to immunosuppression of stem cell growth resulting in aplastic anaemia as in viral hepatitis, EBV infection, HIV infection, rubellaParvo virus B19 causes acute reversible pure red cell aplasia in patients with congenital haemolytic anemiaTissue oxygen delivery and haematocrit

Polycythemia Can be relative polycythemia or primary polycythemia( polycythemia vera)Hct > 55-60% exponential increase in blood viscocity reduction in blood flowMore prone for thrombotic eventsPolycythemia vera due to mutation in JAK-2 gene.Diagnosis:-elevated Hb level (>18.5 g/dL in men and >16.5 g/dL in women) and either the presence of the JAK2 mutation or two of the following: hypercellularity of the bone marrow, a subnormal serum erythropoietin level, and endogenous erythroid colony formation.Look for budd chairi syndrome, generalised pruiritis, coronary or cerebral thrombosis, pulmonary HTN.H/o previous phlebotomies, thrombotic complications, myelofibrosisPerioperatively prone for thrombosis and haemorrhageHemorrhage due to acquired VWF disease due to low ultralarge VWF required for platelet adhesionPhlebotomy and avoiding dehydration reduce risk of thrombosis and haemorrhage perioperativelyMaintaining Hct 55% to prevent perioperative complications. PorphyriasInherited or acquired group of enzymatic defects involved in haeme biosynthesisRate limiting step ALA synthase enzyme. Heme exhibits negative feedback on ALA synthase.Thus decrease in heameincrease in ALA synthase activityincreased porphyrin accumulaton in tissues.Acute porphyrias cause severe neuropathy neuronal damage and axonal degeneration due to direcet toxicity of ALA synthetase enzyme or reduced intraneuronal haeme level

Erythropoeitic porphyrias cause skin toxicity but lack neurotoxicity. PCT is the only hepatic porphyria without neurotoxicity and acute crisisMost frequently porphyria crisis is drug precipitated frequent drug being barbituratesFasting, dehydration, infection, psychological stress, excessive alcohol intake, drugs precipitating factors for acute porphyria crisis.Acute attacks occur in only 4 types of porphyrias AIP, HCP, VP, PLP

Signs and symptoms include:- severe abdominal pain, vomiting, anxiety, confusion, autonomic dysfunction manifested by hypertension, tachycardia, dehydration, electrolyte abnormalities like hyponatremia, hypokalemia, hypocalcemia.Tachycardia is indicator of disease state progressionEarly detection of high risk patients by cDNA sequencing is of great benefit.Preoperatively:- check for signs of acute porphyria crisisIf established porphyria look for precipitating factors and last attackNeurological evaluation focusing on mental condition, peripheral neuropathy. And in acute crisis consider cranial dysfunction and bulbar symptomatology may lead to respiratory falilurePremedications to reduce stress. Benzodiazepines are considered safe. Opioids are safe except for pentazocineIntraoperatively :- regional can be given if no neurological involvement notedWhile in crisis to be avoided as patients are uncooperative, labile hemodynamic stability and hypovolemia are more pronounced with sympathectomyDiazepam , midazolam can be safely given in crisis.Thiopentone, etomidate, ketamine at high concetrations cause crisis .Propofol can be used as inducing agentVolatile anaesthetics, vecuronium, succinylcholine,atracurium safe in porphyriaPancuronium is contraindicatedPropranololo given to treat tachycardia and hypertension in crisis.Alpha methyl dopa and hydral;azine contraindicatedAnticonvulsant prophylaxisMonitoring for crisis to be continued postop for 5days.Thank u