Limb occlusion pressure (LOP) and arterial occlusion pressure (AOP) are the terms that mean the lowest tourniquet pressure required to stop the arterial blood flow into the limb distal to the cuff. LOP can be determined manually or automatically by slow cuff inflation until disapper of pulsation with Doppler flow-meter or pulse oximeter
The advantages of the tourniquet during upper or lower limb procedures are providing bloodless operative field and so less intra-operative blood lossIt has been reported that using the lowest effective inflation pressure minimize tourniquet induced nerve injury .). Limb occlusion pressure (LOP) and arterial occlusion pressure (AOP) are the terms that mean the lowest tourniquet pressure required to stop the arterial blood flow into the limb distal to the cuff. LOP can be determined manually or automatically by slow cuff inflation until disapper of pulsation with Doppler flowmeter or pulse oximeter .AOP can be estimated by a formula (AOP = \[SBP + 10\]/KTP) using patient's systolic blood pressure (SBP) and tissue padding coefficient (KTP) values. In both methods, addition of a safety margin to LOP or AOP is recommended for potential hemodynamic fluctuations during surgery
Study Type
OBSERVATIONAL
Enrollment
20
The patients will receive induced hypotensive anaesthesia and the tourniquet pressure will be based on the AOP.the tourniquet pressure will be determined based on the AOP which will be determined by the estimation formula (AOP=\[SBP+10\]/KTP) . The calculation is based on using initial SBP and tissue padding coefficient values , according to limb circumferences of the patient.After calculation of AOP, tourniquet pressures will be determined by adding a safety margin of 20 mmHg to AOP values(tourniquet pressure=AOP+20 mmHg).
: using the ultrasound Doppler technique and the tourniquet will be inflated until the arterial pulsations disappear at the side of the operation. This pressure will be recorded as LOP.using the ultrasound Doppler technique and the tourniquet will be inflated until the arterial pulsations disappear at the side of the operation. This pressure will be recorded as LOP .the tourniquet cuff will be inflated to the pressure according to theguidelines of the Association of Perioperative Registered Nurses(AORN) which recommends that a safety margin of 40 mmHg should be added for AOP below 130 mmHg, 60 mmHg for AOP between 131 mmHg and 190 mmHg, and 80 mmHg for AOP above 190 mmHg for adult patients
Beni-Suef University Hospital
Banī Suwayf, Egypt
RECRUITINGTourniquet inflation pressure
the tourniquet inflation pressure will be determined based on the Arterial occlusion pressure or the limb occlusion pressure
Time frame: tourniquet inflation pressures will be recorded at 0, 5, 15, 30, 60, and 120 min.
time required to set the tourniquet inflation pressures
Time needed to estimate AOP or to determine LOP and set the tourniquet cuff pressure.
Time frame: one minute before inflation of the tourniquet cuff
tourniquet performance
tourniquet performance as determined by the quality of bloodless surgical field.
Time frame: at the middle and end of surgery
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