DIFFERENTIAL DIAGNOSIS

Dr. ImranMANAGEMENT OF INTRAOPERATIVE BRONCHOSPASM

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Definition: constriction of smooth muscles of bronchi & bronchioles.BRONCHOSPASM

ANATOMY

Arterial supply: Right , one Bronchial Artery from 3rd posterior intercostal artery. Left , two Bronchial Arteries from descending thoracic aorta.Venous drainage: mostly from pulmonary veins, from bronchial veins.Lymphatic drainage : Interbronchial LN Tracheobronchial LN Bronchomediastinal LN

INNERVATION OF BRONCHIPARASYMPATHETIC NERVOUS SYSTEM

SYMPATHETIC ADRENERGIC SYSYTEM

NON ADRENERGIC NON CHOLINERGIC SYSTEM

PARASYMPATHETIC

PREGANGLIONIC FIBRES FROM VAGUSPOST GANGLIONIC FIBRES IN AIRWAYSACHM3

BRONCHO-CONSTRICTIONANTI CHOLINERGICS

SYMPATHETIC T2 T4 ganglia of sympathetic trunk .

ADERENERGICAlpha receptors : clinically insignificant

BETA 2 RECEPTORS

Beta 2 receptorscAMPCa efflux and into SRG proteins Adenylate cyclaseBRONCHIAL RELAXATIONATP

NON ADRENERGIC NON CHOLINERGIC SYSTEMEXCITATORY : SUBSTANCE P, NEUROKININ A.

INHIBITORY: VIP & NO

During the induction phase Airway irritationAnaphylaxis Misplacement of ETTAspiration of gastric contents Pulmonary edemaUnknown, possibly allergy.

Intra operative bronchospasmAllergyAspirationAcute exacerbation of asthmaAirway irritation

During ExtubationPulmonary edemaAnaphylaxis/allergy Inadvertent extubationExtubation spasmAspirationUnilateral bronchospasm and pulmonary edema (cause not determined)

CAUSES OF BRONCHOSPASMNon allergic mechanism: Mechanical factors Pharmacological factors: via histamine releasing drugs.

Non allergic mechanism: by nonspecific stimuli (by ETT or Suction catheter)Hyper reactive airway: Asthma, chronic smoker, COPD, URTI.

Immediate hypersensitivity: ALLERGY Ig E mediated Anaphylaxis Anaphylactoid: Non immune mechanism.

Drugs causing bronchospasm: Adenosine, Non selective beta blockers ( propanolol, timolol, nadolol, pindolol, alprenolol,oxprenolol)

Mechanical obstruction due to kinking, secretions, overinflation of tracheal tube cuffLaryngospasm Esophageal intubationInadequate depth of AnesthesiaEndobronchial intubationObstruction of tube by foreign bodyPulmonary aspirationPulmonary edemaPulonary embolusPneumothorax Extreme Head down position & bowel packing.

DIFFERENTIAL DIAGNOSIS

BRONCHOSPASMLARYNGOSPASMExpiratory and accompained by a wheeze or croupInspiratory usually accompained by a stridorAccessory muscles of respiration Indrawing of the intercostals suprasternal notch presentExpiration is prolongedNot prolongedCyanosis is slow to developDevelops rapidly

PATHOPHYSIOLOGYExaggerated bronchoconstrictor response to trigger - airway edema , increased secretions, smooth muscle contraction.

Airway inflammation increases bronchial hyper responsiveness.

Anaphylaxis: release HISTAMINE, ECF, LEUKOTRIENES C4 D4 E4, PGD2 and KININS

ANESTHETIC AGENTSINDUCTION AGENTS: BARBITUARATES, ETOMIDATE, PROPOFOLLOCAL ANESTHETICS: ESTER GROUPMUSCLE RELAXANTS: Sch, GALLAMINE, d-TUBOCURARUNE, METOCURINE, PANCURONIUM, VECURONIUM, ATRACURIUM, MIVA , DOXACURIUMOPIODS: MEPERIDINE,MORPHINE, FENTANYL. OTHER AGENTSANTIBIOTICS, BLOOD PRODUCTS, DRUG PRESERVATIVES, FRUSEMIDE, INSULIN, MANNITOL, NSAIDS, PROTAMINE, RADIOCONTRAST DYES, LATEX, GRAFTS, VIT K, COLLOIDS

Signs and symptomsRash

Increased peak airway pressure during IPPV

Wheeze(Expiratory)/ silent chest

Hypotension due to development of auto PEEP.

Falling oxygen saturation

Increased ET CO2

Capnography change: sharkfin appearance

Auto PEEP/ Intrinsic PEEP?

Accumulation of air in alveoli if breath is delivered before complete exhalation of previous breath Positive airway pressure at the end of Expiration.

Over expansion of lungs leading to dynamic hyperinflation of lungs. HYPOTENSIONTreated by increasing expiratory time.

Other causes of auto PEEPMucus plugging of airwaysLarge Minute VentilationBlock in expiratory limb of breathing circuitSmaller ETT with inadequate expiratory time.

DIAGNOSIS by APNEA TEST for 30sec.

Anesthetic management Preoperative assessmentFor COPD: stop smoking, infection control, chest physiotherapy, use of bronchodilators and steroids.

All patients should be counselled and encouraged to stop smoking preoperatively. Six to eight weeks of abstinence before surgery significantly reduces the risk of respiratory complications including bronchospasm.

Evaluate the patients asthma over the past half year.

Improve lung function to predicted values before surgery, possibly with short course of oral steroids.

Give patients who have received steroids for longer than 2 weeks 100 mg hydrocortisone TID iv. Taper within 24hrs.

URTI in children increases the risk of bronchospasm and so it may be necessary to postpone surgery. The complete resolution of symptoms (approximately 2 weeks) correlates well with a decreased incidence of airway hyper reactivity.

Pretreatment with an inhaled/nebulised beta agonist, 30 minutes prior to surgery, induction of anaesthesia with propofol and adequate depth of anaesthesia before airway instrumentation reduces the risk of bronchospasm.

Regional v/s General??Instrumentation of airway is the main trigger for wheezing during anesthesia.

LMA cause less airway resistance increase than ETT.

RA is ideal for reactive airway disease.

On suspecting bronchospasm

Switch to 100% oxygen

Ventilate by hand

Stop stimulation / surgery

Consider allergy / anaphylaxis; stop administration of suspected drugs / colloid / blood products

Thorough ETT suction after deepening of anesthesia.

Immediate management; prevent hypoxia & reverse bronchoconstriction

Deepen anaesthesia

If ventilation through ETT difficult/impossible, check tube position and exclude blocked/misplaced tube.

If necessary eliminate breathing circuit occlusion by using self-inflating bag In non-intubated patients exclude laryngospasm and consider aspiration DRUG THERAPY

PHARMOCOLOGYBeta 2 agonistsCalcium sensitivity and ca infuxMyosin light chain kinaseBRONCHOCONSTRICTIONAchVagus histaminecGMPG proteins Adenylate cyclasecAMP

Cholinergic antagonists

Phospholipase C & IP3

DRUGS ACTING ON ANSSYSTEMIC ADRENERGIC AGONISTINHALED ADRENERGIC AGONISTS TERBUTALINE SHORT ACTING EPINEPHRINEALBUTEROL, LEVALBUTEROL ALBUTEROLMETAPROTERENOL, PIRBUTEROL LONG ACTINGSALMETEROL, FORMOTEROL,ARFORMOTEROL

INHALED CHOLINERGIC ANTAGONISTSSYSTEMIC CHOLINERGIC ANTAGONISTSSHORT ACTING: IPRATRROPIUMATROPINELONG ACTING: TIOTROPIUMSCOPOLAMINEGLYCOPYRROLATE

PHARMACOLOGIC INFLUENCE ON INFLAMMATIONINHALED CORTICOSTEROIDSLEUKOTRIENE MODIFIERSMAST CELL STABILIZERSMETHYLXANTHINESMONOTHERAPYANTAGONISTS:BECLOMETHASONE, BUDESONIDE, MONTELUKAST, ZAFIRLUKAST, PRANLUKASTCROMOLYNSODIUMNEDOCROMILTHEOPHYLLINE,AMINOPHYLLINECICLESONIDE, FLUNISOLIDE, FLUTICASONE ,MOMETASONE, TRIAMCINALONE INHIBITORS:ZILEUTON

COMBINATION THERAPYBUDESONIDE/ FORMOTEROLFLUTICASONE/ SALMETEROL

Glucocorticoid receptor alpha of airway epithelial cells is target of ICS.

Interact with transcription factors responsible for pro inflammatory mediators.

Arachidonic acid is converted into Leukotrienes via the 5- lipoxygenase pathway.

Leukotrienes C4, D4, E4 causes bronchoconstriction, tissue edema, eosinophil migration and increased airway secretion.

METHYLXANTHINES AMINOPHYLLINE: inhibitor of phosphodiesterase :increases cAMP and cGMPAdenosine receptorA1 A2 antagonism causing inhibition of release of histamine and leukotrienes.Activates histone deacetylase reducing expression of inflammatory genes..DOSE: 6mg/kg bolus fb infusion 1mg/kg/hr.

LOW THERAPEUTIC INDEX : 20mg/L Side effects: arrythmias and seizures.

ANESTHETICS WITH BRONCHODILATIONVOLATILE ANESTHETICSINTRAVENOUS ANESTHETICSISOFLURANEPROPOFOLSEVOFLURANEKETAMINEHALOTHANEMIDAZOLAM

Blockade of T-type voltage dependent calcium channels on distal airway smooth muscles.

Decreases intracellular calcium by decreasing sensitivity of calcium mediated by Protein kinase C and also increase in cAMP.

Other agentsAntihistamines : allergen induced broncho-constriction

Magnesium sulfate.

1st line Drug therapy

Salbutamol MDI: 6-8 puffs, 100micrograms per puff, repeat as necessary.Nebulisation : 5mg repeat as necessary.Intravenous: 250 mcg slow iv followed by 5mcg/min upto 20 mcg/min.

2nd line of therapy Ipratropium bromide : 0.5 mg nebulization 6th hourly.Magnesium sulfate : 50mg/kg iv over 2min upto 2grams.Hydrocortisone: 200mg iv 6th hourly.Ketamine: bolus of 10-20 mg fb infusion 1-3mg/kg/hr.Aminophylline: 6mg/kg bolus fb infusion 1mg/kg/hr.Chlorphenaramine : 10mg slow iv. Epinephrine : neb 5ml of 1:1000 iv 10mcg to 100mcg titrated acc to response

REFERENCESSTOELTINGS PHARMACOLOGY AND PHYSIOLOGY- 5TH EDITION.BARASH CLINICAL ANESTHESIA : 7TH EDITION.MILLERS ANESTHESIA : 7TH EDITION.

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