Agenda. Mechanical Ventilation in Morbidly Obese Patients. Paolo Pelosi. ESPCOP, Ostend, Belgium Saturday, November 14, 2009.

Transcription

1 Mechanical Ventilation in Morbidly Obese Patients t Paolo Pelosi Department of Ambient, Health and Safety University of Insubria - Varese, ITALY ppelosi@hotmail.com ESPCOP, Ostend, Belgium Saturday, November 14, 2009 Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions 1

2 Obese s Grave (III sec. B.C.) Son of Velthur ( The Rich Man ) IAP is the main determinant of lung volume Damia, Br J Anaesth 1988; 60: ; Pelosi, Anesthesiology 1999; 91: IAP: Normals 7 cmh 2 O - Obese 18 cmh 2 O LUNG VOLUME (ml) * * p < 0.01 vs Before induction * 0 Before After After After Skin Induction Induction Laparotomy Incision Closure 2

3 Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions Lung volume as a function of obesity Pelosi P et al. Anesth Analg Sep;87(3):

4 Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions Modified from Netter FH, Masson

5 Airway closure during mechanical ventilation Hedenstierna et al Anesthesiology 1976; 44: Pelosi et al Anesthesiology 1999; 91: Obese Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions 5

6 Oxygenation as a function of obesity Pelosi P et al. Anesth Analg Sep;87(3): Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions 6

7 Compliance of the respiratory system vs BMI Pelosi P et al. Anesth Analg Sep;87(3): Lung and Chest wall mechanics are impaired in obese Pelosi P et al Chest 1996; 109:

8 IAP and chest wall mechanics in obese Pelosi et al. Anesthesiology 1999; 91: Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions 8

9 Respiratory resistance vs BMI Pelosi P et al. Anesth Analg Sep;87(3): Airway Resistance is increased in obese Pelosi et al. J. Appl. Physiol. 82(3): ,

10 Lung and Chest wall Resistance in Obesity Pelosi P et al Chest 1996; 109: V'aw ml/s Vol ml Paw cmh2o Pplat 30 PEEPtot Time (s) 10

11 Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions What to do? Airway closure - Low Tidal Volume (<10 ml/kg PBW) - PEEP (to raise EELV) Atelectasis - PEEP - Recruitment - Avoid high F I O 2 (<0.8) 11

12 Large tidal volume does not improve oxygenation in obese Bardoczky et al. Anesth Analg 1995; 81: ml / kg IBW Recruitment Maneuvres in anesthesia Pelosi P et al Crit Care, Mosby, Philadelphia, 2006; ICM 2003,29:218 CCM 2001, 1255:

13 PEEP improves repiratory function in obese but not in normal subjects Pelosi et al. Anesthesiology 1999; 91: Prevention of Atelectasis in Morbidly Obese Patients during General Anesthesia and Paralysis Anesthesiology 2009; 111:

14 Prevention of Atelectasis in Morbidly Obese Patients during General Anesthesia and Paralysis Anesthesiology 2009; 111: Prevention of Atelectasis in Morbidly Obese Patients during General Anesthesia and Paralysis Anesthesiology 2009; 111: F R C (L) CT 5 28LNon 2.8 L Aerated Tissue (+ 20%) Poory Aerated Tissue (+ 70%) % 1.6 L Awake Anaesthesia-Paralysis 14

15 Prevention of Atelectasis in Morbidly Obese Patients during General Anesthesia and Paralysis Anesthesiology 2009; 111: Prevention of Atelectasis in Morbidly Obese Patients during General Anesthesia and Paralysis Anesthesiology 2009; 111:

16 Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions Prone position does not affect respiratory function in obese Pelosi, Anesth Analg 1995;80: ; Pelosi, Anesth Analg 1996;83; * p < 0.01 supine vs prone supine 4 prone * * * * normal obese normal obese FRC PaO

17 Beach chair position and PEEP improve respiratory function in obese patients during PNP and general anesthesia Valenza et al Anesthesiology 2007; 107: Recruitment Maneuver and PEEP are not effective during laparoscopic bariatric surgery Whalen et al Anesth Analg 2006;102: Vasopressors treatments were larger in RM/PEEP group The effects of RM/PEEP were promptly dissipated in the immediate postoperative period 17

18 Intraoperative Ventilatory Strategies for Prevention of Pulmonary Atelectasis in Obese Patients Undergoing Laparoscopic Bariatric Surgery Talab HF et al Anesth Analg 2009;109: Alveolar-to-arterial oxygen gradient (mm Hg), 22 pts per group Introduction Agenda Effects of GA on respiratory function in morbidly obese patients: - Lung volume - Atelectasis and airway closure - Gas-Exchange - Respiratory compliance - Respiratory resistance Effects of Recruitment and PEEP Prone Position/Laparoscopic surgery Conclusions 18

19 Tidal volume in obese in operating room? 423/2961 obese patients : 16 % VT measured Vt/Kg en ml/ /Kg BMI < 18 Kg/m² 2BMI : Kg/m² 3BMI : Kg/m² 4BMI : Kg/m² 5BMI > 35 Kg/m² 5 4 Répartition des Vt/Kg Vt/Kg (ml/kg) de POIDS MESURE en fonction des classes de BMI 13 VT Calculated Ideal Body Weight (IBW) Vt/Kg de PIT en ml/kg Répartiton Vt/Kg des théorique Vt/Kg de (ml/kg) POIDS IDEAL en fonction des classes de BMI 1BMI < 18 Kg/m² 2BMI : Kg/m² 3BMI : Kg/m² 4BMI : Kg/m² 5BMI > 35 Kg/m² Description of anesthesia practice of ventilatory management during general anesthesia in operating room Prospective multicenter observational French study: 2961 patients from 49 anesthesia departments RECRUITMENT (RM) PEEP 100% 90% 100% 80% 90% 80% 70% 60% Recrutement Pas de recrutement 70% 60% 50% 40% 30% 20% PEP > 10 cmh2o PEP 5-9 cmh2o PEP 1-4 cmh20 PEP 0 50% (n=2075) BMI < 30 (n=311) BMI > 30 PEEP and RM are rarely used, whatever the type of surgery 10% 0% BMI < 18 BMI BMI BMI BMI>35 19

20 Which ventilation setting in obese patients during general anesthesia? Shultz MJ et al Anesthesiology 2007; 106; Pelosi and Negrini Curr Opin Crit Care Feb;14(1):16-21 Tidal Volume < 10 ml/kg PBW Increase RR to control pha/paco 2 Plateau Pressure < cmh 2 O PEEP > 5 cmh 2 O RM 30 cmh 2 O 5 s - PC Monitor Paw-Time/Check PEEPi Thou seest I have more flesh than another man, and therefore more frailty King Henry the Fourth, Part I - Act III. Scene III Thanks! National Audit Office Tackling Obesity in England HC220 February