CSC Review Course: SELECTION OF CONDUITS

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CSC Review Course SELECTION OF CONDUITS

• Lynn McGugan Clark MSN, ACNP
• Duke University

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CABG
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Incisions

• Median sternotomy
• Partial sternotomy
• L or R thoracotomy

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CABG

• Internal Thoracic Artery
• No vaso vasorum
• Lamina inhibits hyperplasia
• Few smooth muscle cells - little vasoreactivity
• Produces lots of prostacyclin (vasodilator and
  platelet inhibitor) and nitric oxide
  (vasodilator)
• Recommended for use when possible
• High output, pedicaled arterial graft improves
  early and late outcomes

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Harvesting of the IMA/ITA

• Asymmetric sternal retractor placed
• Elevate the hemisternum
• No excessive traction
• Tidal volume decreased, pleural space opened
• Moistened laparotomy pad placed on the lung
  surface to keep it away from the field
• Push parietal pleura away from the endothoracic
  fascia and not enter pleural space

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• ITA pedicle separated from the chest wall
• Metal clips used to secure the larger branches
• Pedicle can be harvested from the level of the
  subclavian vein down to the bifurcation of the
  superior epigastric and musculophrenic arteries
• After heparinization pedicle is divided distally
  and flow is assessed

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Harvesting of the IMA/ITA

• Wrapped/doused with papaverine
• Cut with fine scissors 5-10 mm at distal edge to
  create a hood for sewing
• If injured, can be used as a free graft
• Phrenic nerve close to superior aspect

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• Can be skeletonized
• Surrounding muscle, fascia, vein removed
• Advantages increased length, improved ability
  to identify spasm, facilitation of sequential
  anastomoses, increased preservation of sternal
  blood supply
• Disadvantages increased harvest time, spasm,
  and likelihood of injury

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Bilateral IMA Grafts

• LIMA
• Most commonly to LAD, occasionally the circumflex
• RIMA
• To RCA or a branch circumflex LAD free graft

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• Complications
• Changes in chest wall mechanics that mimic
  restrictive lung disease
• Not recommended in COPD patients
• Increases risk of sternal wound complications
• Not recommended in obese or diabetic patients

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• Advantages
• Moderate increase in survival, decrease in
  ischemic events with 2 IMA grafts
• Perhaps not in females

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Radial Artery Grafts

• Highly vasoreactive
• Thick medial layer
• Improved patency rates compared to veins
• Evaluated by ultrasound or Allens test
• Non-dominant arm usually used

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• Taken either by longitudinal incision or
  endoscopically
• Dissected from 1 cm below the ulnar radial
  bifurcation to level of wrist crease
• Avoid superficial radial nerve
• Results in dorsal thenar numbness
• Avoid lateral antebrachial cutaneous nerve
• Results in forearm numbness if damaged

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• Complications
• Paraesthesias/numbness occur transiently in 25
  to 50, persist in 5-10
• Spasm

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Gastroepiploic Artery

• Lies along greater curvature of stomach
• Used in reoperative situations when no other
  suitable conduits are available
• Contraindications gastric surgery, documented
  mesenteric vascular insufficiency, IR therapies
  of the vessel, previous abdominal surgery
  (relative)
• Nasogastric decompression
• Extend sternotomy incision

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Gastroepiploic Artery

• Stomach retracted, artery dissected from omentum
• Surgical clips placed to control branches
• Dissected to duodenum
• Coronary target and size of the left lateral
  segment of the liver usually determine the route
• Most commonly supplies the R coronary system, can
  be used for LAD and distal circumflex, depending
  on length

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Other Arterial Conduits

• Internal Epigastric
• Ulnar
• Left Gastric
• Splenic
• Thoracodorsal
• Lateral Femoral Circumflex

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Greater Saphenous Vein Conduits

• ADVANTAGES
• Available
• Accessible
• Easy to harvest
• Reliable
• Resistant to spasm
• Versatile

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Disadvantages SVG

• Lower patency rates
• Size mismatch
• Inadequate length
• Varicosity
• Sclerosis
• Leg healing issues
• Poor compliance after arterialization
• Prone to atherosclerosis

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SVG Harvest

• Depends of length of target
• Open
• Tissue dissected away from vein, branches
  ligated, ligated proximally and distally
• Bridged
• Endoscopic
• Branches are divided and ligated once the vein is
  explanted

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• Location
• Patients with PVD should have upper thigh harvest
• Vein cannulated, pressurized, extra branches
  ligated and stored in heparin
• Complications Injury to nerves (tingling
  hyperesthesia)
• Patency rates may be related to endothelial
  damage during harvest

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Other Conduits

• Lesser saphenous vein
• Cephalic vein
• Cryopreserved human veins
• Bovine sacral artery
• Autologous endothelialized vein allografts
• Synthetic

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Process

• Anastomosis sequence
• Distal first
• Most ischemic to least ischemic
• LIMA last to avoid tension and injury

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• Distal Target Selection
• Visual inspection, epicardial exam
• Proximal enough to provide largest sized target
• Distal enough to avoid diseased region
• Avoid regions of branching and bifucations
• May need to dissect overlying tissue
  (knife/electrocautery)

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• Arteriotomy
• Thin purple strip usually present down center of
  artery usually indicates area free of disease
• Incision extended with fine scissors about 5 mm

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Process

• Sewing Technique
• Surgeon specific
• Sequential Grafting
• Allows arterial flow to more than one target
• Two sites are dependent on one conduit
• Distal done before proximal
• Aortotomy
• Incision, punch, conduit length identified

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OPCAB
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OPCAB

• Median sternotomy most common
• Anterior thoracotomy for LAD
• Lateral thoracotomy for marginal vessel access
• Hard to convert to conventional bypass with
  incisions other than sternotomy
• Partial sternotomies have not been shown to
  reduce pain or morbidity post-op

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OPCAB

• Special retractors with suction devices and
  stabilizers
• Pericardium opened with wide inverted T
  incision
• If heart hypertrophic, often incise right pleura
  and pericardium over to phrenic nerve to allow
  heart to move into right chest so that lateral
  vessels exposed
• Risk for phrenic nerve injury
• Grafts prepared before heart manipulated to
  reduce time spent in non-anatomic position

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OPCAB

• 2-4 deep pericardial traction sutures elevate and
  rotate the heart by placing traction on and
  distorting the pericardial well
• Injury to phrenic nerve, lung or pulmonary veins
• Suction devices allow heart to be moved into
  correct position
• Fork or suction type stabilizers immobilize
  target vessel for anastomosis

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• Patient placed in Trendelenburg, towards surgeon
• ?CO by increasing venous return
• Right side allows gravity to provide better view
  of lateral, posterior and inferior walls

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OPCAB

• Collateralized vessels done before
  collateralizing vessels
• LAD usually done first revascularizes septum
  and anterior wall prior to other procedures
• Limits amount of myocardium made ischemic
• Easiest vessels grafted first
• RCA can be problematic
• Proximal occlusion causes AV node ischemia
• Pacing wires placed early

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• Proximal anastomosis done by partial occlusion
  clamp on depressurized aorta
• Scanned first for diseased areas that should be
  avoided

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OPCAB

• Two RCT have shown no mortality benefit
• Small, underpowered
• Reduction in post operative morbidity
• Observational studies
• Magee et al. (2002)
• Reduced mortality, post op MI, reoperation, blood
  transfusions, prolonged ventilation, renal
  failure

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• Puskas, et al. (2001)
• Mortality approximately 1
• Stroke 1.5
• MI 1
• No difference from matched CPB patients

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OPCAB Advantages

• Graft patency equal to conventional surgery
• Less adverse neurologic outcomes
• No emboli from cross clamping aorta
• No gas or particle emboli from extracorporeal
  circuit
• Cleveland et al. (2001) 1.25 vs. 1.99 CVA
  rate (Plt 0.001)
• Iaco et al. (1999) 0.8 vs. 6.9 (Plt0.05)

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• Decreased inflammatory response
• Decreased complement C3a, elastase, IL-8, TNF-a,
  E-selectin
• Decreased SIRS

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OPCAB Advantages

• Decreased myocardial injury and infarction
• Decreased blood transfusions
• Less blood loss perioperatively
• Decreased renal dysfunction
• Magee 0.87 vs. 2.75 (p0.036)
• Sabik 0 vs. 1.5 (p0.03)
• Cleveland 3.85 vs. 4.26 (p0.036)

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• Decreased LOS
• 6 days vs. 7 days
• Decreased complications, intubation time, ICU LOS
• Decreased cost

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OPCAB Complications

• Aortic dissection
• Partial occlusion clamp placed on distended
  pulsatile aorta
• Increased mortality if conversion to conventional
  bypass needed
• 15 (Bertolino, et al. 1999)

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• Increased thromboembolic complications
• DVT, PE, early graft occlusion
• Increased antiplatelet therapy early
  post-operatively

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MAZE PROCEDURE
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MAZE Procedure

• Interruption of macro-reentry circuits by
  cryolesions or surgical incisions
• Atria can not fibrillate if circuits interrupted
• Pulmonary veins are completely isolated, both
  appendages removed
• Indication Intolerance of arrhythmia and
  failure of drug therapy
• The larger the atria, the less chance of success
• 98 successful, 99 when drug therapy added

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Complications

• A-fib/A-flutter occurs in 1/3 of patients
• Re-entry circuits are smaller in the first few
  weeks post op related to catecholamines,
  pericarditis, atrial irritability
• Perioperative neurological complication rate less
  than 1 Post-op less than 0.1 per year
• Discovery of SSS requiring PPM
• Failure of procedure
• LA dysfunction

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MAZE Procedure

• Cox maze III procedure (slight adjustments from
  Cox I and II, done since 1988)
• Based on the theory that AF results from multiple
  macroreentry circuits in the atria
• Indications
• Drug intolerance
• Arrhythmia intolerance
• Recurrent embolic events

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• With CPB, maze-like series of incisions or
  lesions created in both atria to prevent the
  formation of these circuits
• Pulmonary veins are completely isolated
• Both appendages are removed
• Mortality rate 2
• 50 more MAZE patients are free from A-fib at 3
  years than control patients
• Anticoagulate and give antiarrhythmics for 3
  months post-op even if in SR
• Complications Discovery of SSS requiring PPM,
  failure of procedure, LA dysfunction

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Minimally Invasive MAZE

• 7-cm incision right anterior 4th ICS using
  cryolesions instead of surgical incisions
• LAA not removed, closed from inside

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• Advantages
• Earlier extubation
• Shorter ICU stays hospitalizations
• Quicker rehab and return to previous function
• Decreased need for postoperative pacemakers (6
  versus 17 following median sternotomy)
• Decreased perioperative A-fib (22 versus 37
  with median sternotomy)

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MAZE Incisions
http//www.sts.org/images/mazeincisions.gif
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MITRAL VALVE SURGERY
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Mitral Valve Repair vs. Replacement

• Depends on extent of pathology and experience of
  surgeon
• Repair preserves subvalvular complex
• Chordae and papillary muscles
• Maintains optimal post-op LV geometry and
  contractile function
• Prolapse repair if prolapse generalized

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• Rheumatic repair if no calcium deposits on
  leaflets and chordae and papillary length is
  normal
• Ischemic repair if papillary muscle length
  normal, no scarring or rupture of papillary
  muscles or chordae
• Endocarditis no repair if leaflets or
  subvalvular mechanisms are destroyed or annular
  abcess present

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Mitral Regurgitation

• Mitral prolapse, ischemia, endocarditis,
  ruptured/elongated chordae, rheumatic fever,
  annular calcification
• Leaflet retraction from fibrosis or calcification
  Annular dilation (LV dilation)
• Chordal abnomalities (rupture, shortening,
  elongation)
• Papillary muscle dysfunction
• Leaflet perforation (endocarditis)

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Mitral Regurgitation

• Indication for surgery 3 to 4 MR with
  symptoms LV dysfunction, increased LVEDV and
  LVESV
• EF poor indicator of LV function in patients with
  MR (preserved because of regurgitant flow)
• Measurements of LVESV evaluate LV status better

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Hemodynamics

• Depends on compliance of LA
• Acute MR increases LA pressures which can cause
  acute pulmonary edema
• Chronic MR gives time to adapt to higher LA
  pressures
• Regurgitation into LA reduces forward flow
• LV mass increases (myocytes lengthen, reduced
  myofibril content, spherical remodeling)
• LVESV is less dependent on LV preload than EF,
  CO, SV, SW and is better used as a measure of LV
  systolic function

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Mitral Repair Procedure

• Pericardium opened
• CPB via SVC and IVC
• Antegrade and retrograde cannulation
• Right heart elevated
• Tourniquet applied around IVC with traction
  towards feet
• LA not manipulated until aortic cross clamp
  applied

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• LA incised parallel to interatrial groove behind
  SVC and below IVC retractor applied
• Papillary muscle exposure
• RVOT pressure to expose anterolateral commissure
• Diaphragmatic surface of LV manipulated to see
  posteromedial muscle

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• Valve evaluated
• Annulus for dilation/deformity
• Leaflets and motion
• Normal (type I)
• Prolapsed (type II)
• Restricted (type III)
• Perforated
• Chordae (length, thickening,, fusion, rupture)
• Papillary muscles (elongation, rupture)

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Mitral Valve Repair Procedures

• Quadrangular
• Posterior leaflet with elongated/ruptured IDd,
  resected, annulus closed, leaflet edges sutured
• Sliding Leaflet
• Prevents LVOT from SAM
• Used in patients with excess leaflet tissue
• Chordal transfer
• For anterior leaflet prolapse
• Part of posterior leaflet chordae transferred to
  anterior leaflet, attached with suture

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• Chordal shortening
• Chordal replacement with PTFE suture
• Annuloplasty
• Decreases size of annulus, prevents further
  dilation
• Increases leaflet coaptation
• Debridement for calcification
• Alfieri stitch
• Free edge of posterior leaflet sutures to
  prolapsed anterior leaflet

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Alternative Approaches

• Right anterolateral thoracotomy
• Appropriate for previous sternotomy
• CPB via peripheral circulation
• LA incision to expose MV during VF
• Transseptal
• Appropriate for small LA or in reoperations
• RA opened, septum incised to dome of LA
• Increases chance of junctional rhythm related to
  artery to sinus node dissection

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Mitral Regurgitation

• Post-op outcomes
• Increased forward SV with lower total SV, smaller
  LVEDV, regression of LV hypertrophy

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Mitral Valve Surgery Indications

• Mitral Stenosis
• Rheumatic fever (history available only in 50 of
  patients)
• Fusion of the valve leaflets at the commissures
• Shortening and fusion of cordae tendonae

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• Thickening of the leaflets
• Stiffening
• Contraction
• Calcification
• Mean valve area usually less than 1 cm²
  (critical)

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Indications for Mitral Valve Surgery

• Mitral Stenosis
• Etiology rheumatic fever, annulus or leaflet
  calcification, congenital deformitites, malignant
  carcinoid syndrome, neoplasm, LA thrombus,
  vegetations, metabolic diseases, previous MV sx

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• Hemodynamics Average LA pressure 15-20 mmHg at
  rest, transvalvular gradient 10-15 mmHg, A-fib
  detrimental CO decreased related to decreased SV
  to LV
• Flow through valve related to cardiac output and
  HR
• A-fib related to age and large left atrial size
• Left atrial HTN pulmonary vasoconstriction
  
• increased PVR
• Stoke rate 20

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Mitral Stenosis

• Outcomes related to clinical impairment
• 67 to 90 of MVR or open commissurotomy are alive
  at 10 years
• Higher risk with severe PHTN and RHF

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Indications for Mitral Valve Surgery

• Endocarditis
• Perforation of leaflets
• Destruction of chordae

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Mechanical vs. Prosthetic

• More common worldwide
• Young age to avoid reoperation
• Any patient wants to minimize risk of reoperation
• Any condition requiring long term anticoagulation
• ESRD
• St. Judes bi-leaflet valve is most commonly used
  (easy to insert and has good hemodynamic
  characteristics)

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Mechanical vs. Prosthetic

• More common in US
• Valves deteriorate slower in older patients good
  for older patients in SR
• Young women who wish to become pregnant
• Structural valve degeneration is most common
  drawback
• Mitral valves less durable than aortic
• If anticoagulation needs to be avoided
• GIB history or high risk lifestyle

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Prosthetic Mitral Valve Porcine

• Porcine aortic valve leaflets on a silicone
  sewing ring
• Decreases diastolic pressure gradients and
  turbulence
• Should be avoided in mitral position in patients
  with small LV to reduce LVOT obstruction caused
  by large struts

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Prosthetic Mitral Valve Pericardial

• CE valve uses bovine pericardium (preserved with
  glutaralderhyde)
• Maximize the use of the flow area minimal
  flow resistance

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Post Operative Care of Mitral Valve Patients

• Cachexia
• Require longer ventilatory support related to
  decreased respiratory muscle strength
• Aggressive nutritional support
• Trach quickly (by the end of the first week) to
  reduce ventilatory dead space and facilitate
  faster weaning
• Warfarin started POD 2 with 80-150 mg ASA

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AORTIC VALVE SURGERY
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Indications for Aortic Valve Surgery

• Aortic Stenosis (AHA/ACC Guidelines)
• Symptomatic patients with severe AS
• Patients with severe or moderate AS having CABG,
  aortic surgery or other valve surgery

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• Asymptomatic patients with severe AS and
• LV dysfunction
• Abnormal response to exercise
• VT
• LVH gt 15 mm
• Valve area lt 0.6 cm
• Prevention of sudden cardiac death

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Indications

• Aortic Regurgitation
• NYHA functional class III or IV symptoms and
  preserved LV systolic function (EF greater than
  50)
• NYHA class II with EF greater than 50 with LV
  dilation or declining EF at rest on serial
  studies or declining effort tolerance on exercise
  testing
• Canadian Cardiovascular Society functional class
  II or greater angina with or without CAD

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• Asymptomatic or symptomatic patients with mild to
  moderate LV dysfunction at rest (ejection
  fraction 25 to 50)
• Patients undergoing coronary artery bypass
  surgery or surgery on the aorta or other heart
  valves
• Patients with NYHA functional class II symptoms
  and preserved LV systolic function (ejection
  fraction greater than 50 at rest) with stable LV
  size and systolic function on serial studies and
  stable exercise tolerance

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Indications

• Aortic Regurgitation
• Asymptomatic patients with normal LV systolic
  function (EF greater than 50) but with severe LV
  dilatation (end-diastolic dimension greater than
  75 mm or end-systolic dimension greater than 55
  mm)
• Patients with severe LV dysfunction (EF less than
  25)

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• Asymptomatic patients with normal systolic
  function at rest and progressive LV dilatation
  when the degree of dilatation is moderately
  severe (end-diastolic dimension 7075 mm,
  end-systolic dimension 5055 mm)
• Asymptomatic patients with normal systolic
  function at rest but with decline in ejection
  fraction during exercise radionuclide angiography
  or stress echocardiography
• Asymptomatic patients with normal systolic
  function at rest and LV dilatation when degree of
  dilatation is not severe (end diastolic dimension
  less than 70 mm, end-systolic dimension less than
  50 mm)

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Indications

• Endocarditis
• Prosthetic Valve
• All cases of early (less than 60 days
  post-implantation) prosthetic endocarditis
• Concomitant heart failure and valvular
  dysfunction.
• Paravalvular leak or partial dehiscence
• Even in a stable patient, particularly if more
  than 40 of the valve annular circumference is
  involved

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• Presence of a new conduction defect, abscess,
  aneurysm, or fistula mandates operative
  management
• All fungal infections and those caused by the
  most virulent strains of Staphylococcus aureus,
  Serratia marcescens, and Pseudomonas aeruginosa
  (organisms are highly invasive and antibiotic
  therapy is generally ineffective)

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• Any case of persistent bacteremia despite a
  maximum of 5 days of appropriate antibiotic
  therapy and no other source of infection
• Vegetations larger than 10 mm (not well
  penetrated by antibiotics)
• Multiple systemic emboli

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Prosthetic Aortic Valve Types Allograft

• Beating heart/cadaveric donors
• Last up to 10 years
• HLA matching avoids rejection
• Low transvalvular gradients
• Low risk of thromboembolism infection
• Possibly cause regression of LV muscle mass

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• Used for patient with active endocarditis who
  are 30 to 60 years old, with a 10-year life
  expectancy who cannot be anticoagulated who have
  small aortic annuli or who require replacement of
  the valve and root
• Avoid in patients who have a heavily calcified,
  noncompliant aortic root and patients less than
  20 years old

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Aortic Valve Types Pulmonary Autograft

• Advantages
• Freedom from thromboembolism without need for
  anticoagulation improved hemodynamics through
  the valve orifice without obstruction or
  turbulence growth of the autograft with time
  assumption that replacement with living
  autologous tissue is preferential

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• Contraindications
• Pulmonary valve disease, congenitally abnormal
  pulmonary valves (e.g., bicuspid or
  quadricuspid), Marfan syndrome, unusual coronary
  artery anatomy, and severe coexisting autoimmune
  disease
• Long CPB time
• Risk for AI is only 1.5

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Procedure

• RA cannula for venous return, aortic cannula for
  systemic perfusion
• Vent cannula in R superior pulmonary vein
• High potassium blood given via ascending aorta to
  achieve diastolic arrest
• Retrograde cardioplegia good if AR or severe
  CAD
• Continuous oxygenated blood via coronary ostia
  after aorta opened

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• Difficult to protect RV with retrograde
  cardioplegia
• Anterior aortic root exposed to LCA prior to
  cardioplegia
• Aorta opened above RCA to sinus of Valsalva

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Types of Aortic Valve Prostheses

• Mechanical
• Should be placed in patients with absolute
  requirement for anticoagulation
• Less structural deterioration
• More bleeding complications
• Equal to bioprosthetic valve rate of thrombosis,
  if anticoagulated adequately
• ESRD patients have higher risk for structural
  deterioration

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• Bioprosthetic
• Reoperation for deterioration more common
• 70 years and older

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Procedure

• Valve excised
• Sponge placed in outflow area to catch debris
• Decalcification needed to seat prothesis well
• Bundle of His right below right and noncoronary
  cusp
• Anterior leaflet of MV continuous with left
  aortic valve cusp
• Can be repaired with pericardial patch

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• Sized with valve sizer
• Sutured with 12-16 interupted sutures /-
  pledgets
• LA, LV and aorta are de-aired before aortotomy
  suture tied (heart filled with blood, pulmonary
  vein vent closed, lungs inflated, cross clamp
  opened partially)
• 21-gauge needed used to aspirate LV apex and LA
  dome

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Post Operative Care

• Consider LV changes present preoperatively
• AS causes concentric LVH
• AR causes increased LVEDV and eccentric
  hypertrophy
• Dilated LV may require volume
• LVH, noncompliant ventricle in AS dependent on
  preload for filling
• Filling pressures 15-18 mmHg

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• If severe LVH, SAM may occur
• Beta-blockers may help to decrease inotropy
• SR important
• 1/3 CO from atrial contraction
• CHB occurs 3-5
• Suture placement or injury from aggressive
  debridement near conduction system
• Vasodilation common in patients with AR

96

• Goal INR 2.5 for low risk patients 3.0 for high
  risk patients
• Started on POD 2
• Older caged ball valves goals 3.5 to 4.5 related
  to higher risk of thrombosis
• Low CO present in 10
• AVSP helpful

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TRICUSPID VALVE SURGERY
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Tricuspid Valve Disorders

• Tricuspid Stenosis
• Etiology RHD
• Tricuspid Regurgitation
• Etiology MV disease, Eisenmengers Syndrome,
  primary pulmonary hypertension, RV infarct,
  Marfans syndrome, chest trauma, IVDA, CM, RHD,
  carcinoid syndrome

99

• Annular dilation
• Wall motion abnormalities
• Chordae enlongation or rupture
• Papillary muscle dysfunction
• Leaflet perforation

100
Repair vs. Replacement

• Pulmonary hypertension
• RV dilatation and systolic function
• Size of the right atrium

101

• Repair
• Plicate posterior leaflet annulus
  (bicuspidization)
• Partial purse string reduction of anterior and
  posterior leaflet annulus
• Rigid/flexible rings/bands
• Minimal RA enlargement and 1-2 TR will usually
  resolve after surgery on L sided valves
• Can be done via sternotomy or R thoracotomy
• Complications AV blocks

102
Tricuspid Valve Disorders

• Endocarditis
• Prothestic replacement/repair/excision
• TV excised if no PHTN and extensive infection
• Blood flows passively
• Valve replacement can be done later

103
Type of Valve Inserted

• Age, anticoagulation, social issues
• Biologic valve preferred
• Previous reports of thrombosis with mechanical
  valves (cage-ball and tilting disc types)
• Longer freedom from structural valve dysfunction
  for bioprostehetic valves in tricuspid position

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AORTIC SURGERY
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Aortic Dissection
http//www.massgeneral.org/tac/images/a_dissection
.gif
106
Aortic Dissection
Green Kron, 2003
107
Aortic Dissection

• Etiology
• Degenerative medial tissue, intramural hematoma

108
Risk Factors

• HTN, connective tissue disorders (Ehlers-Danlos
  syndrome, Marfan disease, Turner's syndrome),
  cystic medial disease of aorta, aortitis,
  iatrogenic, Atherosclerosis, thoracic aortic
  aneurysm, bicuspid aortic valve, trauma,
  pharmacologic , coarctation of aorta,
  hypervolemia (pregnancy), congenital aortic
  stenosis, polycystic kidney disease,
  pheochromocytoma, Sheehan's syndrome, Cushing's
  syndrome, cocaine abuse, giant cell arteritis,
  3rd trimester of pregnancy

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Signs and Symptoms
Klompas, JAMA, 2002 p. 2262-72.
110
Aortic Dissection

• Diagnostic Studies
• ECG, CXR, TEE, CT scan
• CBC, electrolytes, cardiac enzymes, type and
  screen, HFT, lactic acid

111

• Management
• Avoid procedures that cause HTN (Foley while
  awake)
• Measure BP in both arms
• SBP goal 90-110mmHg
• Decrease aortic wall stress
• Beta-blocker /- SNP

112

• HR control 60-70 bpm
• Narcotics for pain
• Anti-impulse therapy
• Minimize the rate of rise of aortic pressure to
  decrease rate of dissection propagation
• SNP/esmolol

113
Aortic Dissection

• Operative Indications
• Free aortic rupture
• Acute aortic expansion
• Malperfusion
• Pain/progression of dissection despite maximal
  medical management
• Failure to control HTN
• Type A (unless very high risk)
• Stroke or acute paralysis is NOT a
  contraindication

114
Aortic Dissection
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Outcome

• Type A
• Presence of 1 of the following (hypotension,
  myocardial or mesenteric ischemia, ARF or
  neurological deficits) increases in-hospital
  mortality 33 vs. 12, P 0.0001
• Survival at 1 yr 67
• Survival at 5 years 55
• Survival at 10 years 37

116
Outcome

• Type B
• Medical management no complications 10
  mortality
• 3 yr survival rate with endovascular repair 76
• 3 yr survival rate with medical management 77
• 3 yr survival rate with open surgical repair
  83

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Thoracic Aortic Aneurysms

• Ascending result from medial degeneration
• Descending/arch/thoracoabdominal result from
  atherosclerosis
• Can result from chronic dissections

118

• Indications for surgery of ascending aneurysms
• Symptomatic
• Expanding
• Greater than 5 cm with Marfans syndrome
• Greater than 5.5 cm without Marfans syndrome
• Greater than 4.5 cm if also operating for AS/AR
• Acute type A
• Mycotic aneurysms

119

• Indications for surgery on arch aneurysms
• Ascending aneurysms that require surgery and also
  extend to the arch
• Acute arch dissections with intimal tear or
  evidence of arch expansion or rupture
• Greater than 5-6 cm in diameter

120

• Indications for surgery on descending
• aneurysms
• Symptomatic
• Size greater than 6.5 cm in diameter
• Complicated acute type B dissections

121
Thoracic Aneurysm Management

• Coronary angiography done before surgery
• Ascending
• Myocardial perfusion stress imaging
• Neurological exam

122

• Optimize pulmonary status
• Concurrent COPD
• Lung manipulation during OR
• Transfusion requirement
• Optimize renal function
• After angiography
• Allow to return to baseline before surgery

123
Operative Procedures

• Ascending Repair
• Supracoronary graft placement
• If sinuses not involved
• Bentall (valved conduit)
• Marfans
• Valve-Sparing operation
• Depends on pathophysiology and location
• CPB

124

• DHCA (18 ?C) may be required depending on
  location of distal anastomosis
• Thiopental/pentobarbitol
• Pack head in ice
• Methylprednisolone
• Continuous retrograde perfusion
• Antegrade cerebral perfusion via axillary artery
  cannulation after arch vessels attached

125
Operative Procedures

• Transverse Arch
• Hemiarch
• Ascending and proximal arch involvement
• Brachiocephalic vessels remain attached to native
  aorta
• Extended repair
• Interposition graft, reimplantation of
  brachiocephalic island

126

• Trifurcation graft with individual anastomoses to
  arch vessels
• Distal arch repair
• Left thoracotomy /- CPB
• Elephant trunk
• If future operations thought to be needed, graft
  material left dangling from distal anastomosis

127
Operative Procedures

• Descending Thoracic Aorta
• Graft replacement with intercostal reimplantation
• Left thoracotomy/thoracoabdominal incision
• One lung ventilation

128

• Spinal cord ischemia protection
• CSF drainage
• Shunting
• Medications
• Partial femorofemoral bypass/ left heart
  bypass/circulatory arrest
• Right radial and right femoral arterial lines

129
Endovascular Repair of Aortic Disease

• Used for dissections, aneurysms, ulcers and
  hematomas
• Descending Aorta
• Landing zones for stents available, straight
  segments, no critical side braches to obliterate
• Femoral and iliac arteries need to be certain size

130

• Endoleaks most common complication
• Type I Occur at proximal or distal attachment
  sites
• Type II Communication between a branch vessel
  and excluded aneurysm sac
• Type III Originate in mid graft sections,
  caused by graft to graft overlaps or graft
  leakage
• Type IV increase in size of aneurysm sac

131
Endovascular Repair of Descending Thoracic Aortic
Dissections

• Surgical repair indicated for patients
• Presenting with complications (including
  intractable pain)
• Rapid expansion to a diameter greater than 4.5 -5
  cm
• Malperfusion syndromes
• Leak or impending rupture

132
Complications of Endovascular Stent Placement

• Perforation of false lumen outer layer
• False aneurysm formation
• Graft erosion
• Device migration

133
POSTOPERATIVE MANAGEMENT
134
Recovery From Anesthesia

• Agents
• Induction agents
• Relax muscles and cause unconsciousness provide
  no analgesia
• Anxiolytics
• Amnestics

135

• Muscle Relaxants
• Minimize movement and shivering during
  hypothermia
• Decrease paraspinal muscle pain post-op related
  to sternal retraction
• Inhalational anesthetics

136
Recovery from Anesthesia

• Bispectral electroencephalograhic monitoring used
  to minimize amount of anesthesia given
• Goal level 55-60
• Useful during CPB related to hemodilution
• Short acting narcotics
• Sufentanil (1/2 life 20-40 minutes)
• Remifentanil (1/2 life 3-4 minutes)
• Allows early extubation

137
Recovery From Anesthesia

• Analgesia and sedation
• Propofol or sedation until stable and
  neuromuscular agents no longer present
• Determine time of last dose and agent given
• Aggressive magnesium supplementation in OR
  potentiates neuromuscular blockade
• Need analgesia if not given prior to leaving OR
  and only propofol is used for sedation

138

• Hemodynamic Support
• Myocardial function temporarily depressed
• Serial assessments needed maintain adequate
  tissue perfusion
• Fluid resuscitation
• Capillary leak after CPB
• Peripheral vasoconstriction masks hypovolemia
• Hypotension is a late sign of hypovolemia
• Filling pressures will decrease initially

139
Volume Management

• Fluid initially extravascular low filling
  pressures common
• Preload initially decreased by
• Complement activation from CPB
• Serum proteins that lyse cells and bacteria
• Activated mast cells result in histamine release
  capillary permeability increased, third
  spacing

140

• Vasodilation
• Hemodilution from CPB
• Capillary leak related to decreased oncotic
  pressure
• Diuresis
• Diuretics started in OR
• Osmotic diuresis related to CPB
• Bleeding

141
Volume Management

• Filling pressures in the early post-op period
  need careful interpretation
• PAD and PCWP do not correlate well with LVEDV
• Patients with stiff ventricles may require higher
  filling pressures to achieve adequate filling
• Filling pressures are the first sign of
  hypovolemia
• Tachycardia, decreased CO and hypotension are
  late signs

142

• Volume replacement needs to be more than the
  total of the losses (urine/blood output)
• Too much fluid, or too rapid administration may
  distend RV and cause TR and RHF
• Fluids mobilize on POD 1-3
• May result in hypervolemia and pulmonary edema

143
Volume Management

• Goals
• Maintain intravascular volume for adequate
  circulation
• Prevent overload that increases organ edema
• Total body overload of salt and water after CPB
• Aggressive diuresis needed after hemodynamics
  stabilized
• Capillary leak from CPB

144

• Vasoconstriction masks intervascular hypovolemia
• Diuresis occurs in patients with normal renal
  function after CPB
• Volume needed to offset capillary leak and
  vasodilation
• PHTN diuresis used to reduce interstitial
  pulmonary fluid

145
Volume Management

• PRBC
• Increases risk of multi-organ dysfunction
• Suppresses immune system
• Costly
• Infection

146

• Blood Conservation Strategies
• Autologous donation
• Preoperative multivitamins, iron, and
  erythropoietin
• Pre-bypass hemodilution and blood storage
• Platelet harvest devices
• Antifibrinolytics (epsilon-aminocaproic acid and
  aprotinin)

147
Electrolyte Replacement

• K may be elevated post CPB from cardioplegia
• Diuresis occurs after CPB in patients with normal
  renal function leading to hypokalemia
• K kept 4 - 4.5
• Greater than 4.5 if arrhythmias problematic
• Magnesium
• Ca

148
Chest Tubes

• Hard/Blake
• Comparable drainage efficiency
• Blake drains more comfortable
• Connected to 20 cm H20 plus wall suction
• Milked/stripped to prevent blood clots within
• No patency advantage to one method
  (milking/stripping/folding/tapping) over another
• Stripping creates up to -300 mmHg
• May increase bleeding/painful

149

• Suctioning with endotracheal suction catheters
  may introduce infection
• Removed when less than 100 mL/8 hrs
• Prolonged duration may increase output and does
  not prevent development of effusions
• Mediastinal tubes always removed off suction
• CXR after removal of pleural tubes to r/o
  pneumothorax

150
Chest Tubes

• Pneumothorax
• May be caused by placement of sternal wires
• If present post op and patient is to remain on
  positive pressure ventilation, a CT should be
  placed
• Air leak may represent loose connections or
  damage to lung parenchyma
• Should not be removed while air leak present

151

• Small PTX (less than 20) can be managed with
  serial CXR evaluation
• Subcutaneous emphysema occurs when air exits
  under positive pressure where pleura has been
  damaged
• May be from emphysematous bleb rupture or pleural
  injury
• Happens most often after chest tubes are removed
• Treatment Unkink tubes or place a new tube

152
Chest Tubes

• Pleural Effusion
• Most common when IMA taken down from blood and
  fluid oozing from chest wall
• Blood can spill over from pericardial space
• Right effusion usually related to volume overload
• Leaving Blake drain in pleural cavity for several
  days lowers rate of late pleural effusions
• Post pericardiotomy syndrome

153
Autotransfusion

• Reinfused via 20-40 micron filter
• Low levels of platelets, fibrinogen and factor
  VIII, high levels of fibrin split products
• Volume expander
• Not cost effective if less than 250 mL
• Greater than 1 liter may potentiate coagulopathy

154
Glycemic Control

• CPB Effects
• Impaired glucose transport and utilization
• Insulin binds to oxygenator tubing
• Increased catecholamines
• Hypothermia causes low pancreatic insulin
  secretion and impairs ability to metabolize
  insulin

155
Hyperglycemia greater than 200 mg/dL

• Risk factors
• Pre-existing diabetes
• Infusions of catecholamine/vasopressors
• Glucocorticoid therapy
• Pancreatitis
• Sepsis
• Hypothermia
• Hypoxemia
• Insulin resistance
• Age

156
Glycemic Control

• Stress induced hyperglycemia common in critically
  ill patients, even if glucose previously well
  controlled
• Risk factors
• Increased excess counterregulatory hormones
• Overproduction of cytokines
• Inhibition of elevated free fatty acids
• TPN

157
Glycemic Control

• Pre-op insulin drip for hyperglycemic patients
• Insulin drip started intraoperatively for glucose
  greater than 150 mg/dl
• Insulin metabolism altered in hypothermia
• Endogenous and intravenous catecholamines
  increase glucose production
• Titration protocol used on admission to ICU and
  until POD 2

158
Effects of Hyperglycemia

• Increased incidence of post-op wound infections
  diabetic and non-diabetic
• Glucose exerts a large amount of osmotic pressure
  can lead to cellular dehydration and excessive
  loss of fluids and electrolytes (risk of
  postoperative infection is halved by aggressive
  glucose management) Goal 100-150 mg/dl
• Patients on high dose epinephrine may require
  additional bolus doses of insulin to decrease
  blood glucose

159
Incision Management and Assessment

• OR dressings stay in place x 48 hours
• After 48 hours cleanse incisions, CT, JP (Blake
  drain) sites
• Apply sterile gloves
• Apply normal saline to 4x4 gauze, squeeze gauze
  to remove excess, and then cleanse areas

160

• Leave incisions open to air
• Reapply dressing to incisions PRN based on
  drainage
• Change CT dressings daily
• Ace wrap legs and arms
• Rewrap in ICU once coags are corrected
• Remove at 24 hours post-op

161
Incision Management and Assessment

• Surgical Site Infection Prevention Protocol
• 24 hours after all tubes removed, chlorhexidine
  scrub to incision lines
• Assess sternal stability (firm pressure over
  chest incision while patient turns his head from
  side to side and coughs)
• Females bra supports breasts reduces tension
  on sternal incision

162

• Leg incisions
• Elevate legs - harvested leg vein edematous due
  to disruption of lymphatic channels with surgical
  manipulation
• Monitor closely for signs of infection
• Explain normal appearance of endoscopic harvest
  sites reddened and bruised along harvest lines

163
Ventilator Weaning

• CPB
• Emboli gas, fibrin, fat, cells, biologic
  debris
• Activates complement, contact, coagulation and
  fibrinolytic systems
• Activates leukocytes, monocytes, platelets and
  endothelial cells

164

• Side effects
• Increased FRC
• Shunting (increased alveolar-arterial oxygen
  gradient)
• Ventilation perfusion mismatch
• Microatelectasis
• Endothelial cell swelling
• Increased total body and lung fluid

165
Ventilator Weaning

• Goal wean from mechanical ventilation and high
  02 concentrations quickly
• Ensure adequate spontaneous ventilation, airway
  protection and satisfactory oxygenation
• Initial assessment
• lung auscultation (air exchange in both lungs)
• ABG
• CXR (edema, OETT position, effusions, PTX)

166
Ventilator Management

• Watch Sp02 and ETCO2 for trends
• Determine how ETC02 correlates with PaC02 on ABG
• Begin weaning when
• Temperature greater than 36 degree Celsius
• CT output less than 100 ml/hr
• Patient awake with spontaneous respiratory effort
• Neurologically intact
• Metabolic acidosis corrected

167
Ventilator Weaning

• Common Problems
• LLL atelectasis/infiltrates
• Pain, sedation, supine position, hesitancy to
  cough, general weakness
• Phrenic nerve injury
• Preoperative lung dysfunction
• Persistent left ventricular failure
• Excessive pain

168
Ventilator Weaning

• Goal Pa02 80-100 mmHg
• Goal PaC02 35-45 mmHg
• Normal pH 7.3 to 7.5
• Higher TV with lower rates reduce atelectasis
• PEEP maintains lung volumes and prevents
  atelectasis

169

• Typical settings
• Minute volume 120 ml/kg/min
• TV 15 mL/kg
• Rate 8 bpm
• PEEP 5 cm H20
• Fi02 lowered quickly to 50 or less

170
Ventilator Weaning

• ABG criteria
• Pa02 greater than 80 with Fi02 less than 0.5
• pH greater than 7.35
• PaC02 less than 45 mmHg

171

• Ventilatory criteria
• Vital Capacity (VC) greater than 15 ml/kg
• Negative inspiratory force (NIF) greater than 20
• fVT ratio less than 105
• Clinical criteria
• Alert, awake
• No bleeding, hemodynamically stable/no
  dysrhythmias

172
Ventilator Weaning

• Long Term
• Endurance training for respiratory muscles
• SBT daily for 30 min to 2 hours or failure
• Use T-piece, PS ventilation(5-6 cm) or CPAP

173

• Failure
• Unstable ABG
• Unstable hemodynamics
• Unstable ventilatory pattern
• Deterioration of mental status
• Worsening discomfort
• Diaphoresis
• Increased work of breathing

174
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