Respiratory insufficiency in bariatric patients

Transcription

1 Respiratory insufficiency in bariatric patients Special considerations or just more of the same? Weaning and rehabilation conference 6th November 2015

2 Definition of obesity Underweight BMI< 18 Normal weight BMI Overweight BMI > 25 Obesity BMI > 30 Morbid obesity BMI > 40 or comorbidities

3 Perspective Globally 1,9 billion are overweight (BMI>25) 600 mio are obese (BMI>30) Compared to 800 mio starving 20-30% of ICU patients have a BMI > 30 WHO 2015

4 Physiology in the obese Increased abdominal pressure and thoracic weight Reduced compliance worsened in suppine position and during sedation Changes in diaphragma Weight of heart Increased thoracic blood volume Increased FiO 2 Loss of muscle tone/power

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6 Physiology in the obese Reduction in end expiratory lung volumes Reduction in functional residual volume FRC: 2 liters at BMI 25; 1 liter at BMI 35 Reduction of EELV below closing capacity causes collapse of bronchioli Atelectasis impaired gas exchange, ie shunt and hypoxemia Compliance reduced: - 75 cmh2o at BMI 25; 50 at BMI 35

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8 Complications to mechanical ventilation Expiratory flow limitation: airway collapse (PEEPi) Prolonged expiration Increased incidence of asthma and bronchospasm VILI ventilator induced lung injury caused by repetetive opening and closing of og collapsed alveoli

9 Complications to anesthesia not ICU Postoperative complications 5 % in Morbidly obese are not increased (except 1 study) When Intubation is needed postoperatively, increased risk of ARDS (not mortality)

10 Ventilator strategy No evidence for particular ventilator mode KEEP THE LUNG OPEN Lowest FiO 2 to mantain physiologic oxygenation PEEP (10-15) after RM (up to cmh 2 O 6-8 secs) Sighs Vt? IBW 6-8 ml/kg The lung does not grow with increased Body Mass

11 From: Prevention of Atelectasis in Morbidly Obese Patients during General Anesthesia and Paralysis:A Computerized Tomography Study Anesthesiology. 2009;111(5): doi: /aln.0b013e3181b87edb Figure Legend: Fig. 3. Representative computerized tomography (CT). A CT scan 1 cm above the diaphragm in the three different groups at all four time points. Note the sustained effect of RM + PEEP and the transient effect of RM + ZEEP. PEEP = positive end-expiratory pressure; RM = recruitment maneuver; ZEEP = zero end-expiratory pressure. Date of download: 10/25/2015 Copyright 2015 American Society of Anesthesiologists. All rights reserved.

12 To PEEP or not to PEEP

13 Beware of hyperinflation Zimbabwe 2008

14 Co morbidities Obesity is correlated to a wide range of other diseases Anxiety depression Ischemic heart disease, hypertension COPD Diabetes mellitus Chronic inflammatory state Increased risk of acute kidney injury oedema

15 Special considerations Obesity hypoventilation Syndrome OHS PaCO 2 > 5,9 kpa (45 mmhg) + BMI > 30 Exclusion of other reasons for hypercapnia Malignant OHS When BMI > 40 Obesity supine death syndrome

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17 Prepare for extubation Minimal sedation Protocolized sedation and weaning Prevent neuromuscular weakness because of prolonged ventilation Treat prolonged expiration to avoid increased WOB and fatigue Optimize fluid status

18 Positioning Position in sitting or halfsitting Obesity supine death syndrome McKenzie Anesth Analg 1980 Jan; 59(1):81

19 Postextubation NIV could reduce respiratory insufficiency in terms of reduced LOS in ICU and hospital. Mortality reduction in patients with hypercapnia El Sohl; Eur Respir J 2006; Common reintubation what rate is acceptable

20 Outcomes Overweight is not related to increased mortality but Longer length of stay (LOS) 1,5 day and Ventilator 1 day Low BMI increases mortality! Moderately overweight (BMI 30-40) might have a lower mortality RR 0,86 (CI 0,81-0,91; p < 0,001) Akkinusi et al CCM Metaanalysis

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22 Special considerations Prevent or treat overt pain and anxiety A priori higher PEEP. Allow for longer expiration Prepare before mobilization and exercise Optimize blood pressure and cardiac output. Increase oxygen supply and ventilation if needed. Treat bronchospasm as needed. Evaluate thoroughly before weaning and extubation Consider NIV for postextubation profylaxis Especially with hypercapnia or for exercise

23 Key Points Generally same challenges in obese patients as those with normal weight. The obese patient with respiratory insufficiency has an increased risk of a more difficult weaning from the ventilator and thus longer time on mechanical ventilation We need to take precautions in order to avoid further complications. These are the same measures as in any other patient with difficult weaning Though a longer stay in the ICU the bariatric patient does not have an excess mortality (overweight might even be protective).

24 Thank you