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document
A preliminary study of the optimal anesthesia positioning for the morbidly obese patient . BACKGROUND Hypoxemia during the induction of general anesthesia for the morbidly obese patient is a major concern of anesthesiologists . The etiology of this pathophysiological problem is multifactorial , and patient positioning may be a contributing factor . The present study was designed to identify optimal patient positioning for the induction of general anesthesia that minimizes the risk of hypoxemia in these patients . METHODS 26 morbidly obese patients ( body mass index-BMI 56 +/- 3 ) were randomly assigned to one of three positions for induction of anesthesia : 1 ) 30 degrees Reverse Trendelenburg ; 2 ) Supine-Horizontal ; 3 ) 30 degrees Back Up Fowler . Mask ventilation , full neuromuscular paralysis and direct laryngoscopy were performed . Any airway difficulties were noted . After endotracheal tube placement , subjects were ventilated for 5 minutes with 1 % isoflurane in a mixture of 50 % oxygen/50 % air and then disconnected from the ventilation circuit . The time required for capillary oxygen saturation ( SaO2 ) , as measured by pulse oximeter , to decline from 100 % to 92 % was noted and identified as the safe apnea period ( SAP ) . Ventilation was then immediately re-established . The lowest SaO2 after resuming ventilation and the time from that nadir to an SaO2 of 97 % were also recorded . RESULTS BMI and hip-waist ratios of patients in groups 1 , 2 and 3 did not significantly differ . There were no differences in airway difficulties between the different groups . The SAP in groups 1 , 2 and 3 was 178 +/- 55 , 123 +/- 24 and 153 +/- 63 seconds , respectively . The SaO2 of patients in the reverse Trendelenburg position dropped the least and took the shortest time to recover to 97 % . CONCLUSIONS In morbidly obese patients , the 30 degrees Reverse Trendelenburg position provided the longest SAP when compared to the 30 degrees Back Up Fowler and Horizontal-Supine positions . Since on induction of general anesthesia morbidly obese patients may be difficult to mask ventilate and/or intubate , this extra time may preclude adverse sequelae resulting from hypoxemia . Therefore , Reverse Trendelenburg is recommended as the optimal position for induction .
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Intervention_Physical
anesthesia positioning
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Intervention_Physical
30 degrees Reverse Trendelenburg
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Intervention_Physical
Supine-Horizontal
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Intervention_Physical
30 degrees Back Up Fowler
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Intervention_Physical
Mask ventilation , full neuromuscular paralysis and direct laryngoscopy
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Intervention_Pharmacological
1 % isoflurane in a mixture of 50 % oxygen/50 % air
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Intervention_Physical
Reverse Trendelenburg
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Intervention_Physical
Back Up Fowler
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Intervention_Physical
Horizontal-Supine
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Intervention_Physical
Reverse Trendelenburg
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Outcome_Physical
airway difficulties
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Outcome_Physical
time required for capillary oxygen saturation ( SaO2 )
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Outcome_Physical
safe apnea period ( SAP )
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Outcome_Physical
SaO2
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Outcome_Physical
BMI and hip-waist ratios of patients
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Outcome_Physical
airway difficulties
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Outcome_Physical
SAP
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Outcome_Physical
SaO2
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Outcome_Mental
position
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Outcome_Physical
time to recover
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Participant_Condition
morbidly obese patient .
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Participant_Condition
general anesthesia for the morbidly obese patient