APPROACH TO ASSESSMENT AND WEANING OFF THE MECHANICAL VENTILATOR AT THE BEDSIDE DR. MUNIRA DILAWER GHEEWALA

Mechanical Ventilation (MV) is a life supporting modality that is used in a significant number of patients in the ICU. Most of these MV patients get extubated readily. Around 20 % however, fail their first attempt at weaning. 40 % of the total duration of MV is spent in the weaning process.

Pulmonary Infections (VAP) GI bleeding Deep Venous Thrombosis Decubitus Ulcers Muscle wasting and weakness Barotrauma Tracheal Damage Others

1. The STRENGTH of the respiratory muscles 2. The LOAD on the respiratory muscles 3. The RESPIRATORY DRIVE to breathe

The relationship between the respiratory muscle strength and the respiratory load should be viewed as a balance

Reason for Intubation and the cause for ventilator dependency Posture Ambulation Psychological Factors Sleep Cycle and adequacy of Sleep

Rectifiable problems CNS : Mental status/Cognitive function/GCS/Sedation CVS : Myocardial Ischemia, Murmurs – contributing to failure and inappropriate gas exchange, Cardiac arrhythmias (causing hemodynamic compromise) RS : Pneumonia (CAP/VAP), Pneumothorax, COPD GI : Feeds, Constipation, Gross Ascites, Diarrhoea Neuro-muscular weakness Hemodynamic Instability on inotropic support Infection/ SIRS - Hyperthermia Nutrition : Malnourished, Overfed Tracheal Secretions Fluid balance Acid-base status Electrolyte disturbance (Mg, PO4, Ca,K) Drugs

Monitor – 1. heart rate : tachycardia, arrhythmias, ST-T changes (MI) 2. SPO2 – Low saturation indicative of inadequate ventilation 3. RR – tachypnea indicative of hyperventilation-- ?hyperthermia, underlying metabolic acidosis, pain.

Infusions and Equipments – 1. TPN – clue to feeding, refeeding 2. Inotropes – hemodynamic instability 3. Antibiotics – Infection, SIRS 4. Electrolyte infusions. 5. Inhaler/ Nebuliser 6. ICD – total drain, bubbling?

Ventilation – 1. Mode 2. Fio2 / PEEP /RR /TV 3. I:E ratio

Consciousness level, orientation (r/o sedatives, anaesthesia effect) Cough, Gag reflex Secretions Tracheostomised – s/o long ICU stay Chest wall trauma – flail segment, bruising Obese patient Purpura/ striae/ cushingoid appearance

Fever Cardiac status – murmurs, tachycardia RS – chest wall expansion, crepts, wheezing, conducted sounds, excessive secretions. Muscle strength Abdominal examination – distension, constipation, ascites, tolerating feeds? Nutrition – malnourished

T-PIECE trial SIMV PSV Newer modalities – Automatic Tube Compensation Proportional Assist Ventilation – Flow assist and Volume assist

Assess patient for readiness of weaning SPO2 > 92 % PEEP < 8 cm of H2O FiO2- < Minute Ventilation < 20 l/min Hemodynamic stability – HR >50/min & <140/min BP - >90 mm/hg & <180 mm /hg Patient initiates spontaneous inspiratory efforts Patient performs following simple commands a) Opens & close eyes b) Opens & close mouth c) Cough d) Performs forced vital capacity manoeuvre achieving double the baseline tidal volume

If Yes Begin a T-piece trial with/ without O2 and wait for 3 minutes, measure Rapid Shallow Breathing Index (RSBI) – RR(breaths/min)/TV IF RSBI < 105 – Continue T-piece trial and assess after 60 mins  RR < 35/min  Spo2 >92 %  Change in HR <20%  Change in BP <20%  Patient is not agitated  Patient coughs on command If No or if RSBI >105 or if assessment after 60 mins of T-piece trial does not comply with any of the criteria mentioned adjacent Resume appropriate ventilator settings and allow the patient to rest for the next 24 hours

Inform physician Prepare for extubation Keep NIV ready if needed Obtain verbal order for extubation or wait for physician to obtain bedside assessment and extubate

 Under evaluation and in trial phase  Has currently shown to reduce MV duration from 12 to 7.5 days and ICU stay from 15.5 to 12 days.  No adverse effects compared to physician controlled weaning