Joel R. Lopes Jr., M.D. Director Trauma/Critical Care Anesthesia Department Of Anesthesiology Boston...
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Transcript of Joel R. Lopes Jr., M.D. Director Trauma/Critical Care Anesthesia Department Of Anesthesiology Boston...
Joel R. Lopes Jr., M.D.
Director Trauma/Critical Care Anesthesia
Department Of Anesthesiology
Boston University Medical Center
Mechanical Properties of the respiratory Mechanical Properties of the respiratory System in Morbidly Obese patientsSystem in Morbidly Obese patients
Decreased Functional Decreased Functional residual capacityresidual capacity
Increased Intra-abdominal Increased Intra-abdominal PressurePressure
Increased Alveolar-arterial Increased Alveolar-arterial Oxygenation gradientOxygenation gradient
Supine Position under General AnesthesiaSupine Position under General Anesthesia HYPOXEMIAHYPOXEMIA
FRC FRC << Closing Capacity Closing Capacity Unopposed Intra-Abdominal PressureUnopposed Intra-Abdominal Pressure
Options for VentilationOptions for Ventilation
P.E.E.P.P.E.E.P. Tidal VolumeTidal Volume Respiratory RateRespiratory Rate
P.E.E.P.P.E.E.P.
Maintain the highest mean Maintain the highest mean PaO2 intraOpPaO2 intraOp
NOT sustained postOpNOT sustained postOp
?benefits in the Morbidly ?benefits in the Morbidly ObeseObese
Yakaitis RW Anesth Analg 1975;54:427-32
““Does PEEP Improve Intraoperative Arterial Does PEEP Improve Intraoperative Arterial Oxygenation in Grossly Obese Patients?”Oxygenation in Grossly Obese Patients?”
Constant Tidal Volume = 1000-1200ccConstant Tidal Volume = 1000-1200cc Respiratory Rate = 9–12/minRespiratory Rate = 9–12/min PEEP = 10 – 12cm H2OPEEP = 10 – 12cm H2O
ABG analysis 5 minutes before and at 2, 4, 20, and 30 minutes following discontinuation of PEEP
Salem MR Anesth 1978:48:280-81
Effects of Discontinuing PEEP on A-a pO2Effects of Discontinuing PEEP on A-a pO2
300
320
340
360
380
B 2 5 20 30
Time
A-a
pO
2 G
radi
ent
Salem MR Anesth 48:281,1978
DiscontinuationDiscontinuation of PEEP resulted in of PEEP resulted in significant increase in Arterial O2 tensionsignificant increase in Arterial O2 tension
high Tidal Volumeshigh Tidal Volumes Redistribution of Pulmonary Blood flowRedistribution of Pulmonary Blood flow Increased intrathoracic pressIncreased intrathoracic press
Gas Exchange at Different PEEP levelsGas Exchange at Different PEEP levels
0cm H2O0cm H2O 10cm H2O10cm H2O 0cm H2O0cm H2O 10cm H2O10cm H2OPaO2PaO2 (mmHg)(mmHg) 218 218 ++ 47 47
215 215 ++ 47 47 110 110 ++ 29 29130 130 ++ 28 28
Diff (A-a)O2Diff (A-a)O2 (mmHg)(mmHg)
110 110 ++ 45 45113 113 ++ 86 86
208 208 ++ 30 30187 187 ++ 30 30
PaCO2PaCO2 (mmHg)(mmHg) 28.4 28.4 ++ 3.1 3.1
27.8 27.8 ++ 5.7 5.737.8 37.8 ++ 6.8 6.8
39.4 39.4 ++ 4.9 4.9
Normal Obese
Pelosi P Anesth:1999:91,1228
0 cm H2O0 cm H2O 10cm H2O10cm H2O 0cm H2O0cm H2O 10cm H2O10cm H2O
Intra Abd PressIntra Abd Press 9 9 ++ 2.4 2.4 18.8 18.8 ++ 7.8 7.8
End Exp VolEnd Exp Vol 2.15 2.15 ++ 0.58 0.58 2.75 2.75 ++ 0.59 0.59 0.58 0.58 ++ 0.17 0.17 1.03 1.03 ++ 0.28 0.28
ElastanceElastance
Resp SystemResp System
16.39 16.39 ++ 3.6 3.6 15.68 15.68 ++ 3.23 3.23 26.8 26.8 ++ 4.2 4.2 18.54 18.54 ++ 3.06 3.06
Obese
IntraAbd Press, Lung Volume, and Elastance at different Levels of PEEP
Pelosi P Anesth 1999:91;1225
Normal
Rev. Trendelenburg effect on Pao2Rev. Trendelenburg effect on Pao2
IntubationIntubation LaparotomyLaparotomy RetractorsRetractors Rev TBurgRev TBurg
P(A-a)O2P(A-a)O2 132 132 ++ 60 60 162 162 ++ 69 69 207 207 ++ 33 33 159 159 ++ 63 63
PaO2PaO2 177 177 ++ 68 68 152 152 ++ 52 52 115 115 ++ 41 41 156 156 ++ 55 55
Paw Paw peakpeak 3 3 ++ 6 6 30 30 ++ 5 5 31 31 ++ 2 2 26 26 ++ 3 3
C C tottot 32 32 ++ 5 5 31 31 ++ 6 6 32 32 ++ 5 5 41 41 ++ 5 5
Perilli V Anesth Analg 2000;91:1520-3
……Morbid Obesity, Pneumoperitoneum, and Posture on Morbid Obesity, Pneumoperitoneum, and Posture on Respiratory Mechanics and Oxygenation During LaparoscopyRespiratory Mechanics and Oxygenation During Laparoscopy
15
25
35
45
55
65
nl wtMO
Sprung J.Anesth Analg 2002;94:1345-50
Static Compliance
Pneumoperitoneum,
Effect of Tidal Volume and Respiratory Rate on Effect of Tidal Volume and Respiratory Rate on Respiratory Mechanics During Laparoscopy…Respiratory Mechanics During Laparoscopy…
600-700ml600-700ml 10 bpm10 bpm
1200-1400ml1200-1400ml 10 bpm10 bpm
600-700ml600-700ml 20 bpm20 bpm
Baseline
Double Vt
Double RR
Tidal Volume Resp Rate
Sprung J Anesth Analg 2003;97:268-74
Static Compliance in Normal Weight PatientsStatic Compliance in Normal Weight Patients
20
30
40
50
60
70
80
Baseline
Double Vt
Double RR
Pneumoperitoneum
Sprung J Anesth Analg 2003;97:268-74
Static Compliance in Morbidly Obese PatientsStatic Compliance in Morbidly Obese Patients
10
20
30
40
50
60
70
Baseline
Double Vt
Double RR
Pneumoperitoneum
Sprung J Anesth Analg 2003;97:268-74
Effect of Weight, Position, and Pneumoperitoneum on Effect of Weight, Position, and Pneumoperitoneum on Alveolar-arterial difference in O2 tensionAlveolar-arterial difference in O2 tension
40
60
80
100
120
140
160S
up
ine
Tre
nd
Rev
Tre
nd
Su
pin
e
Tre
nd
Rev
Tre
nd
Baseline
Double Vt
Double RR
Baseline
Double Vt
Double RR
Pneumoperitoneum
A-aDO2 mmHg
Sprung J Anesth Analg 2003;97:268-74
mo
nw