Asthma is characterized by airway obstruction, inflammation and hyperresponsiveness. Common symptoms include shortness of breath, wheezing, cough and sputum production. Preoperative assessment of asthma patients focuses on disease severity, medication effectiveness and potential need for additional therapy. During anesthesia, airway reflexes must be suppressed to prevent bronchospasm from mechanical ventilation. Treatment of acute exacerbations includes oxygen, bronchodilators, steroids, aminophylline and mechanical ventilation if needed. Precautions are taken intraoperatively and postoperatively to prevent bronchospasm.

1. ASTHMA AND ANESTHESIA
DR.SUNDAS AFTAB

2. ASTHMA
CHARACTERIZED BY:
• AIRWAY OUTFLOW OBSTRUCTION
• AIRWAY INFLAMMATION(BRONCHIAL WALL INFLAMMATION)
• AIRWAY HYPERRESPONSIVENESS

3. SYMPTOMS
SYMPTOMS OF ASTHMA ARE MOST FREQUENTLY A COMBINATION OF
• SHORTNESS OF BREATH,
• WHEEZE,
• COUGH, AND SPUTUM PRODUCTION.
• AIR HUNGER
• THERE ARE OFTEN SPECIFIC TRIGGER FACTORS (EXERCISE OR ALLERGY) WHICH
PRECIPITATE SYMPTOMS. POOR CONTROL OFTEN RESULTS IN SYMPTOMS BEING
WORSE AT NIGHT.

4. SIGNS
• INSPECTION
• PALPATION
• PERCUSSION
• AUSCULTATION
CENTRAL MEDIASTINUM
VOCAL FREMITUS DECREASED(AIR
RETAINED)
HYPERRESONANCE
RONCHI(I & E : BIPHASIC)

5. PATHOPHYSIOLOGY

8. INVESTIGATIONS
• CXR: M/C NORMAL,HYPERINFLATION RESULTS IN FLATTENED
DIAPHRAGM,SMALL APPEARING HEART AND HYPERLUCENT LUNG
FIELD
• ECG : MAY SHOW RIGHT VENTRICULAR STRAIN (ST SEGMENT
CHANGES,RT. AXIX DEVIATION,RBBB) DURING ASTHMATIC
ATTACK
• PFT : REVERSIBLE OBSTRUCTIVE DISEASE (DISTINGUISH IT FROM
COPD) INCREASE IN FEV1BY >15% FROM BASELINE AFTER
BETA AGONIST INHALER
• NO BREATH TEST : NORMALLY <25 PPB ASTHMA >50PPB
• ABG : TYPE 1 RESPIRATORY FAILURE >TYPE 2 RESPIRATORY
FAILURE
ALVEOLAR HYPOXIAHYPERVENTILATION PACO2(RESP
ALKALOSIS)

9. PREOPERATIVE ASSESSMENT
• DISEASE SEVERITY
• EFFECTIVENESS OF CURRENT MEDICATIONS
• POTENTIAL NEED FOR ADDITIONAL THERAPY BEFORE SURGERY
THE GOAL IS TO FORMULATE PLAN TO PREVENT OR BLUNT
EXPIRATORY FLOW OBSTRUCTION
CLINICAL HISTORY:
• 1. AGE OF ONSET
• 2. TRIGGERING EVENTS
• 3. HOSPITALIZATION FOR ASTHMA (FREQUENCY OF EMERGENCY VISITS & NEED FOR INTUBATION AND
MECHANICAL VENTILATION)
• 4. ALLERGIES
• 5. COUGH
• 6. SPUTUM CHARACTERISTICS
• 7. CURRENT MEDICARIONS 8. ANESTHETIC HISTORY

10. • PHYSICAL EXAM.: GENERAL APPEARANCE, USE OF ACCESSORY MS. OF RESP.
• AUSCULTATION: WHEEZING/ CREPITATIONS
• BLOOD EOSINOPHIL COUNTS OFTEN PARALLEL WITH DEGREE OF AIRWAY
INFLAMMATION
• AIRWAY HYPERACTIVITY PROVIDES AN INDIRECT ASSESSMENT OF CURRENT
STATUS OF DISEASE
• PFT: FEV1 (BEFORE AND AFTER BD THERAPY)
• RISK FACTOR FOR PERIOPERATIVE COMPLICATIONS
• 1) FEV1 <70%
• 2) FEV1/ FVC <65% OF PREDICTED VALUE

11. PREOPERATIVE THERAPY
CHEST PHYSIOTHERAPY ANTIBIOTIC THERAPY BRONCHODILATOR THERAPY
• THESE CAN IMPROVE REVERSIBLE COMPONENTS OF ASTHMA
• ANTICHOLINERGICS ARE INDIVIDUALIZED AS THEY CAN INCREASE VISCOSITY OF
SECRETIONS IN SELECTED PATIENTS PREOPERATIVE COURSE OF ORAL
CORTICOSTEROIDS MAY BE USEFUL
• ABG: INDICATED IF THERE IS INADEQUACY OF OXYGENATION OR VENTILATION.
• PATIENTS SHOULD BE FREE OF WHEEZING AND SHOULD HAVE PEFR >80% OR
PATIENTS PERSONAL BEST VALUE BEFORE SURGERY

12. INTRAOPERATIVELY:
• DURING INDUCTION AND MAINTAINANCE OF ANAESTHESIA : AIRWAY
REFLEXES MUST BE SUPPRESSED TO AVOID BRONCHOCONSTRICTION IN
RESPONSE TO MECHANICAL VENTILATION OF HYPERACTIVE AIRWAYS.
• STIMULI WHICH DO NOT EVOKE RESPONSE CAN PROVOKE LIFETHREATENENING
BRONCHOCONSTRICTION IN PATIENTS WITH ASTHMA

13. GENERAL ANESTHESIA
INDUCTION:
1. MOST OFTEN ACCOMPLISHED WITH IV INDUCTION AGENT
2. PROPOFOL > THIOPENTONE ( THIOPENTONE ITSELF DOESN’T CAUSE
BRONCHOSPASM BUT INADEQUATELY SUPPRESSES AIRWAY REFLEXES SO ET
INTUBATION CAN CAUSE BRONCHOSPASM)
3. KETAMINE PRODUCES BRONCHIAL SMOOTH MS. RELAXATION & DECREASES
AIRWAY RESISTANCE ESP. IN ACTIVELY WHEEZING PATIENTS BUT CAN INCREASE
AIRWAY SECRETIONS, CAN CAUSE TACHYCARDIA,HTN AND INCREASE PULMONARY
VASCULAR RESISTANCE

14. MAINTENANCE:
• GOAL IS TO ESTABLISH DEPTH OF ANESTHESIA SUFFICIENT TO DECREASE AIRWAY
REFLEXES SO THAT BRONCHOSPASM IS NOT PPT.
• SEVOFLURANE /HALOTHANE LESS PUNGENT LESS COUGHNING LESS
BRONCHOSPASM
• AN ALTERNATIVE TO DECREASE AIRWAY REFLEXES IS IV OR INTRATRACHEAL
INJECTION OF LIDOCAINE (1-1.5MG/KG) 1-3 MINUTES BEFORE ET INTUBATION
• OPIOIDS DECREASE AIRWAY REFLEXES AND HELP TO ACHIEVE DEEP ANESTHESIA
REMIFENTANYL –ULTRASHORT ACTING AND DOES NOT ACCUMULATE
CONTINUOUS INFUSION 0.05- 1 MG/KG

15. • INSERTION OF LMA IS LESS LIKELY TO CAUSE BC THAN INSERTION OF ETT
• LMA IS BETTER IF PATIENT IS NOT AT RISK OF ASPIRATION
• INTRAOPERATIVELY DESIRABLE LEVEL OF ARTERIAL OXYGENATION AND CO2
REMOVAL IS PROVIDED BY MECHANICAL VENTILATION
• SLOW INSPIRATORY FLOW RATES A) OPTIMAL DISTRIBUTION OF VENTILATION
RELATIVE TO PERFUSION B) SUFFICIENT TIME OF EXHALATION PREVENTS
AIR TRAPPING
• HUMIDIFICATION AND WARMING OF INSPIRED GASES MAY BE ESPECIALLY USEFUL
IN PATIENTS WITH EXERCISE INDUCED ASTHMA
• LIBERAL ADMINISTRATION OF FLUID ADEQUATE HYDRATION- LESS VISCOUS
AIRWAY SECRETIONS REMOVED EASILY
• SKELETAL MUSCLE RELAXANTS WITH NDMR
• DRUGS WITH LIMITED ABILITY TO RELEASE HISTAMINE SHOULD BE SELECTED

16. • AT THE END OF SURGERY REMOVAL OF ETT WHILE ANESTHESIA IS STILL
SUFFICIENT TO SUPPRESS HYPERACTIVE AIRWAY REFLEXES IS PREFERRED KNOWN
AS “ DEEP EXTUBATION”
WHEN ABOVE IS NOT POSSIBLE THEN INTRAVENOUS LIDOCAINE OR
PRETREATMENT WITH BD IS CONSIDERED.

17. ACUTE SEVERE BRONCHIAL ASTHMA:
4 RESPIRATORY SIGNS 2 CARDIAC SIGNS
• RR> 24 / MIN - HR> 120/MIN
• SILENT CHEST - PULSUS PARADOXUS
• PRESENCE OF CYANOSIS
• UNABLE TO COMPLETE SENTENCE

18. TREATMENT OF ACUTE EXACCERBATION:
• OXYGEN INHALALTION UPTO 6 LITRES/MIN + SHORT ACTING BD SHORT
ACTING BETA AGONIST (SALBUTAMOL)
• SHORT ACTING ANTICHOLINERGIC (IPRATROPIUM)
• IV AMINOPHYLLINE BOLUS (6MG/KG) F/B INFUSION1MG/KG/HR)
• MUSCLE RELAXANT MGSO4 1-2 GM OVER 20 MINS.
• MECHANICAL VENTILATION
• G A (HALOTHANE)

19. MANAGEMENT OF ANAESTHESIA
• BRONCHOSPASM 0.2 % - 4.2% OF ALL PROCEDURES INVOLVING G.A. PERFORMED
IN ASTHMATIC PATIENTS
• FACTORS PREDICTING IT: 1. TYPE OF SURGERY (UPPER ABDOMEN & THORACIC) 2.
PROXIMITY OF MOST RECENT ASTHMATIC ATTACK
PATHOLOGICAL MECHANISMS INVOLVED: MAY BE BY G.A. OR DIRECT MECHANISMS
1. DEPRESSION OF COUGH REFLEX
2. IMPAIRMENT OF MUCOCILIARY CLEARANCE
3. REDUCTION OF PALATOPHARYNGEAL MUSCLE TONE INCREASE AIRWAY
RESISTANCE
4. DEPRESSION OF DIAPHRAGMATIC FUNCTION
5. INCREASE IN AMOUNT OF FLUID IN AIRWAY WALL

20. DIRECT AIRWAY STIMULATION BY:
1. ENDOTRACHEAL INTUBATION
2. PARASYMPATHETIC SYSTEM ACTIVATION
3. RELEASE OF NEUROTRANSMITTERS OF PAIN ( SUBSTANCE P & NEUROKININS)

21. TREATMENT

22. D/DS
• THE DIFFERENTIAL DIAGNOSIS OF WHEEZING IN CHILDREN IS EXTENSIVE AND INCLUDES:
• ASTHMA,
• FOREIGN BODY
• BRONCHIOLITIS
• INHALATIONAL INJURY
• PNEUMOTHORAX
• ENDOBRONCHIAL INTUBATION
• HERNIATED ENDOTRACHEAL TUBE CUFF
• CARDIAC FAILURE, CYSTIC FIBROSIS, SICKLE CELL DISEASE, RECURRENT ASPIRATION, MEDIASTINAL
MASS, TRACHEOMALACIA, VASCULAR RING, TRACHEAL WEB/STENOSIS, BRONCHIAL STENOSIS AND
ROUNDWORM INFESTATION