shara wy lee, kim s khaw, warwick d ngan kee michael tc ying, stella sy ho department of anaesthesia...
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Shara WY Lee, Kim S Khaw, Warwick D Ngan Kee
Michael TC Ying, Stella SY Ho
Department of Anaesthesia & Intensive CareDepartment of Diagnostic Radiology & Organ ImagingThe Chinese University of Hong Kong
Department of Health Technology & InformaticsThe Hong Kong Polytechnic University
Shara WY Lee, Kim S Khaw, Warwick D Ngan Kee
Michael TC Ying, Stella SY Ho
Department of Anaesthesia & Intensive CareDepartment of Diagnostic Radiology & Organ ImagingThe Chinese University of Hong Kong
Department of Health Technology & InformaticsThe Hong Kong Polytechnic University
A new method for detecting inferior vena cava compression in term parturients
Annual Scientific Meeting in Anaesthesiology 2006 – 18th ~ 19th November 2006 (HKCEC) 11
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Aortocaval Compression in Pregnancy
• Compression of abdominal aorta & inferior vena cava by the gravid uterus
• Positioning of parturient – to minimize haemodynamic disturbance
• Compression of abdominal aorta & inferior vena cava by the gravid uterus
• Positioning of parturient – to minimize haemodynamic disturbance
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Effects of inferior vena cava compression
Compensatory mechanisms:
Maternal Heart rate Systemic vascular resistance
Collateral circulation: azygous vein, vertebral plexus & epidural venous plexus
Compression of IVC by gravid uterus
Venous return to heart
Right atrial pressure / Preload / CO / SV
Uterine blood flow Fetal compromise
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Established methods to detect ACC
Directly:
• Angiography to visualize aortic compression
• Venography - Presence of collateral circulations
Azygous vein, vertebral plexus & epidural venous plexus
• Less invasive modalities
MRI, CT
Abdominal US scan
Directly:
• Angiography to visualize aortic compression
• Venography - Presence of collateral circulations
Azygous vein, vertebral plexus & epidural venous plexus
• Less invasive modalities
MRI, CT
Abdominal US scan
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Established methods to detect ACC
Indirectly:
• Detection of femoral / brachial hypotension
Gradient of BP femoral artery vs. BP brachial artery
BP femoral artery > BP brachial artery
• Haemodynamic disturbance
Cardiac Output
Compensatory mechanisms ( Heart rate and SVR)
Indirectly:
• Detection of femoral / brachial hypotension
Gradient of BP femoral artery vs. BP brachial artery
BP femoral artery > BP brachial artery
• Haemodynamic disturbance
Cardiac Output
Compensatory mechanisms ( Heart rate and SVR)
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Established methods to detect ACC
All the methods required complicated setupsAll the methods required complicated setups
No convenient and non-invasive bedside technique available to detect aortocaval compression
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Study Objective
To develop an easier bedside method for detecting inferior vena cava compression in parturients
We hypothesize that:
Observing for phasic blood flow in the femoral vein using ultrasound can be used to detect inferior vena cava compression in term parturients.
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Venous phasicity test - Principles
Presence of phasicityPresence of phasicity
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Venous phasicity test - Principles
Absence of phasicityAbsence of phasicity
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Methods
• Clinical Research Ethics Committee Approval
• Informed written consent
• 10 ASA I-II term parturients
• Before elective Caesarean section
• Clinical Research Ethics Committee Approval
• Informed written consent
• 10 ASA I-II term parturients
• Before elective Caesarean section
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Materials and Methods
• Philips HDI-3000 ultrasound unit (3-5MHz curvilinear
probe)
• Step 1: Direct insonation of abdominal aorta & IVC
Colour-flow ultrasound
• Step 2: Respiratory phasicity test of the femoral vein Colour spectral Doppler ultrasound
• Patient positioned on tilting table (0º, left 7.5º & 15º)
• Philips HDI-3000 ultrasound unit (3-5MHz curvilinear
probe)
• Step 1: Direct insonation of abdominal aorta & IVC
Colour-flow ultrasound
• Step 2: Respiratory phasicity test of the femoral vein Colour spectral Doppler ultrasound
• Patient positioned on tilting table (0º, left 7.5º & 15º)
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Femoral vein US Image
Colour-flow Colour-flow USUS
Aortic/IVC Aortic/IVC CompressionCompression
Doppler USDoppler USFemoral veinFemoral vein
Finometer Finometer NIBP & CO
PortapresPortapresDetects aortic compression
Dinamap Dinamap NIBP (Right arm)
DatexDatex NIBP (Right calf)NIBP (Right calf)
USCOM USCOM Cardiac Output
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Inferior vena cava
Abdominal aorta
Spine
Direct Abdominal scan of aorta / IVC
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Direct abdominal scan of aorta / IVC
Supine position 15 degrees tilt
Difference in size /colour-filling of vessel
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Phasicity test of femoral vein
• To study the changes after direct abdominal insonation of IVC
• Respiratory phasicity test (Spectral Doppler US) Quiet breathing Deep breathing Valsalva manoeuvre (15 cmH2O PEEP valve)
• To study the changes after direct abdominal insonation of IVC
• Respiratory phasicity test (Spectral Doppler US) Quiet breathing Deep breathing Valsalva manoeuvre (15 cmH2O PEEP valve)
Loss of phasicity Presence of IVC compressionLoss of phasicity Presence of IVC compression
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Quiet breathing
Supine position 15 degrees tilt
Difference in respiratory phasicity at different tilts
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Forced breathing
Presence of phasicity (No obstruction)
Absence of phasicity (IVC obstruction)
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Valsalva Manoeuvre
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Results:
Pos CO HR/SVR IVC NB FB VAL Status
Supine (n=3) IVC
compression
Lt 7.5º (n=3) IVC partial
compression
Supine (n=27) = / = / IVC patent
Supine (n=27) = / = / IVC patent
Lt 15º (n=30) = / = / IVC patent
HaemodynamicsHaemodynamics Patency / Phasicity testPatency / Phasicity test IVC statusIVC statusPosition
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Summary: Venous phasicity of femoral vein
• In patients with partial IVC compression Loss of phasicity during - Quiet breathing Phasicity restored - Deep breathing & Valsalva Minimal haemodynamic disturbance Increased respiratory phasicity at 15º
• In patients with complete IVC compression Loss of phasicity during - Quiet / Deep breathing & Valsalva More severe haemodynamic disturbance
• Effects of lateral tilts Phasicity restored during quiet breathing at 15º Direct abdominal scan at ~T9 – Improved IVC patency
• In patients with partial IVC compression Loss of phasicity during - Quiet breathing Phasicity restored - Deep breathing & Valsalva Minimal haemodynamic disturbance Increased respiratory phasicity at 15º
• In patients with complete IVC compression Loss of phasicity during - Quiet / Deep breathing & Valsalva More severe haemodynamic disturbance
• Effects of lateral tilts Phasicity restored during quiet breathing at 15º Direct abdominal scan at ~T9 – Improved IVC patency
2020
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Conclusions
• Venous phasicity test – Detection of IVC compression
• ? Superseed abdominal scan
• Limitations of direct abdominal scan:
Time consuming
View obstructed by fetus (Fetal orientation)
Inadequate penetration (Gravid uterus increases depth of IVC)
Open vessel ≠ Presence of flow
• Venous phasicity test – Detection of IVC compression
• ? Superseed abdominal scan
• Limitations of direct abdominal scan:
Time consuming
View obstructed by fetus (Fetal orientation)
Inadequate penetration (Gravid uterus increases depth of IVC)
Open vessel ≠ Presence of flow
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Conclusions
• Venous phasicity test:
Non-invasive, reproducible and convenient
Includes functional collateral circulation
Familiar anatomy – femoral catheters
Preliminary investigation shows feasibility
Further study to improve and modify present methodology
and confirm clinical utility
• Venous phasicity test:
Non-invasive, reproducible and convenient
Includes functional collateral circulation
Familiar anatomy – femoral catheters
Preliminary investigation shows feasibility
Further study to improve and modify present methodology
and confirm clinical utility
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- The End - Annual Scientific Meeting in
Anaesthesiology 2006
Shara WY Lee, Kim S Khaw, Warwick D Ngan Kee
Michael TC Ying, Stella SY Ho
Department of Anaesthesia & Intensive CareDepartment of Diagnostic Radiology & Organ ImagingThe Chinese University of Hong Kong
Department of Health Technology & InformaticsThe Hong Kong Polytechnic University
Shara WY Lee, Kim S Khaw, Warwick D Ngan Kee
Michael TC Ying, Stella SY Ho
Department of Anaesthesia & Intensive CareDepartment of Diagnostic Radiology & Organ ImagingThe Chinese University of Hong Kong
Department of Health Technology & InformaticsThe Hong Kong Polytechnic University 2323