The purpose of this study is to investigate whether dexamethasone as an adjuvant to ropivacaine for adductor canal block increases duration of the sensory block, when controlling for a systemic effect using a paired design and bilateral blocks. The investigators hypothesize that adding dexamethasone to ropivacaine will prolong block duration compared with ropivacaine + placebo.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
20
Adductor canal block, single bolus
Adductor canal block, single bolus
Department of Anaesthesia-Surgery-Intensive Care, Gentofte Hospital
Gentofte Municipality, Hellerup, Denmark
Difference in duration of sensory block between dexamethasone and placebo assessed as cold sensation with an alcohol swab
Duration is defined as time from block performance until recovery of cold sensation to an alcohol swab, assessed every hour post-block (and every half hour when pain scores during the tonic heat stimulation test is above 0, except at 2 and 3 hours post block where there will be a break and no assessments will be performed.
Time frame: 0-36 hours
Difference between dexamethasone and placebo in the duration of a sensory block assessed by pin-prick
Duration is defined as time from block performance until recovery of normal sensation, assessed on the hour post block (except at 2 and 3 hours post block where there will be a break and no assessments will be performed).
Time frame: 0-36 hours
Difference between dexamethasone and placebo in the duration of a sensory block assessed as maximum pain during a tonic heat stimulation test
Duration is defined as time from block performance until recovery of normal sensation, assessed on the hour post block (except at 2 and 3 hours post block where there will be a break and no assessments will be performed). Recovery of normal sensation is defined as VAS pain scores ± 10 mm of the pre-block value.
Time frame: 0-36 hours
Difference between dexamethasone and placebo in the duration of a sensory block assessed as warmth detection threshold
Duration is defined as time from block performance until recovery of normal sensation, assessed on the hour post block (except at 2 and 3 hours post block where there will be a break and no assessments will be performed and only assessed if pain scores during tonic heat stimulation is above 0 ). Recovery of normal sensation is defined as detection thresholds of ± 2 degrees C of the pre-block value.
Time frame: 0-36 hours
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Difference between dexamethasone and placebo in the duration of a sensory block assessed as heat pain detection threshold
Duration is defined as time from block performance until recovery of normal sensation, assessed on the hour post block (except at 2 and 3 hours post block where there will be a break and no assessments will be performed and only assessed if pain scores during tonic heat stimulation is above 0 ). Recovery of normal sensation is defined as detection thresholds of ± 2 degrees C of the pre-block value.
Time frame: 0-36 hours
Difference in maximum pain scores between dexamethasone and placebo during block and after recovery of normal sensation
Pain scores during a tonic heat stimulation will be compared at 4 h post block and 1 h after pain scores have returned to the pre-block values.
Time frame: 0-36 hours