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document
Pulse oximeter perfusion index as an early indicator of sympathectomy after epidural anesthesia . BACKGROUND The pulse oximeter perfusion index ( PI ) has been used to indicate sympathectomy-induced vasodilatation . We hypothesized that pulse oximeter PI provides an earlier and clearer indication of sympathectomy following epidural anesthesia than skin temperature and arterial pressure . METHODS Forty patients received lumbar epidural catheters . Patients were randomized to receive either 10 ml 0.5 % bupivacaine or 10 ml 0.25 % bupivacaine . PI in the toe , mean arterial pressure ( MAP ) and toe temperature were all assessed at baseline and at 5 , 10 and 20 min following epidural anesthesia . The effect of epidural anesthesia over time was assessed by repeated measures analysis of variance . Additionally , we defined clinically evident sympathectomy criteria ( a 100 % increase in the PI , a 15 % decrease in MAP and a 1 degrees C increase in toe temperature ) . The numbers of patients demonstrating these changes for each test were compared using the McNemar test for each time point . RESULTS Twenty-nine subjects had photoplethysmography signals that met a priori signal quality criteria for analysis . By 20 min , PI increased by 326 % , compared with a 10 % decrease and a 3 % increase in MAP and toe temperature , respectively . For PI 15/29 , 26/29 and 29/29 of the subjects met the sympathectomy criteria at 5 , 10 and 20 min , respectively , compared with 4/29 , 6/29 and 18/29 for MAP changes and 3/29 , 8/29 and 14/29 for toe temperature changes . CONCLUSIONS PI was an earlier , clearer and more sensitive indicator of the development of epidural-induced sympathectomy than either skin temperature or MAP .
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Intervention_Physical
lumbar epidural catheters
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Intervention_Pharmacological
receive either 10 ml 0.5 % bupivacaine
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Intervention_Pharmacological
10 ml 0.25 % bupivacaine
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Intervention_Pharmacological
epidural anesthesia
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Intervention_Pharmacological
epidural anesthesia
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Outcome_Physical
PI in the toe , mean arterial pressure ( MAP ) and toe temperature
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Outcome_Other
measures analysis of variance
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Outcome_Physical
clinically evident sympathectomy criteria ( a 100 % increase in the PI , a 15 % decrease in MAP and a 1 degrees C increase in toe temperature ) .
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Outcome_Other
McNemar test
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Outcome_Physical
photoplethysmography signals
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Outcome_Physical
PI
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Outcome_Physical
MAP and toe temperature
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Outcome_Physical
sympathectomy criteria
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Outcome_Physical
MAP
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Outcome_Physical
temperature changes
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Outcome_Physical
skin temperature
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Outcome_Physical
MAP
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Participant_Sample-size
Forty
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Participant_Sample-size
Twenty-nine