Hemodynamic Monitoring
Goal = Balance
Fluid minimization --> Hypotension, Renal Failure, Anastamotic Leaks
Aggressive fluids --> Volume Overload, Hypoxia, Increased LOS
Key = Preload Responsiveness
As preload increases, stroke volume increases,
Frank-starling curve - increase preload, increase contractility
Once preload is maximized, increasing preload, causes congestion
With ventricular failure, stroke volume can't increase with preload causing congestion
Pulmonary Artery Catheter (PAC) - aka Swan-Ganz Catheter
Developed in 1970s
Initial use – guidance of post-MI therapy
Extended to other critical care applications
1996 - > 2 million sold/year
Left subclavian (or other central line) --> SVC --> R atrium --> R ventricle --> pulmonary artery --> pulmonary circulation
Measured by standard PAC: CVP, PAP, PAOP (PCWP), SvO2 (Intermittent), CO (measured by thermodilution)
Measured by specialized PAC: Continuous SvO2, COntinuous CO, RVEF
Derived: SVR (just based on other variables, not helpful), SV, PVR, RVEDV, DO2, VO2
PAOP or PCWP reflects pressure in the left atrium/left ventricle in diastole
PAC most helpful when there is an abnormality between SVC and pulmonary arteries (between where the CVC and SWAN are located) - chronic lung disease; pulmonary HTN; RV dysfunction; tricuspid or pulmonic valve dysfunction - otherwise CVP sufficient
1996 Observational Study:
No improvement with PAC, increased 30 day mortality in PAC group, some calls for moratorium on PACs, widespread calls for controlled trials
Summary of Randomized, Prospective Clinical Trials Comparing Pulmonary Artery Catheter (PAC) with Central Venous Pressure (CVP) Monitoring
Author: Pearson KS
Year: 1989
Population: "Low risk" pts undergoing cardiac or vascular surgery
Outcome: No difference in mortality or length of ICU stay, large difference in cost
Author: Tuman KJ
Year:1989
Population: Cardiac surgery pts
Outcome: No difference in mortality, length of ICU stay, significant noncardiac complications
Author: Isaakson IJ
Year:1990
Population: Aortic surgery patients
Outcome: No difference in mortality, length of ICU stay or length of hospital stay
Author: Joyce WP
Year: 1990
Population: Aortic surgery patients
Outcome: No difference in mortality or postoperative cardiac complications
Author: Bender JS
Year: 1997
Population: Vascular surgery patients
Outcome: No difference in mortality, length of ICU stay or length of hospital stay
Author: Valentine RJ
Year: 1998
Population:Aortic surgery patients
Outcome: No difference in length of ICU stay, higher incidence of postoperative complications in PAC group
Prospective Clinical Trial Comparing Pulmonary Artery Catheter (PAC) with Central Venous Pressure (CVP) Monitoring
Author: Sandham JD NEJM
Year:2003
Population: "High Risk" major surgery
Outcome: No difference in mortality, length of ICU stay, increased incidence of PE in PAC group, trend to increased line complications
Question - is there a subset of patients that may benefit from Swan-Ganz catheter? - probably yes but small and decreasing group of people
National Trauma Data Base Review supported these findings for majority of patients, increased moratlity in younger or mildly injured patients, decreased mortality in older more severely injured patients
Arizona Prospective PAC Experience
PAC - Indications
- Specific hemodynamic question
- Not answerable by clinical or noninvasive means and less invasive means (ie CVP) are less accurate with severe lung disease, pulmonary hypertension, tricuspid or pulmonary valve dysfunction, impaired RV performance
- Answer could change management
PAC - Complications (~15% incidence)
Central Access/Insertion Related -
Tip related vascular trauma - intimal injury/pseudoaneurysm formation, PA perforation, valve injury - NEVER ADVANCE UN-INFLATED BALLOON - fully inflate (1.5cc) balloon at 20 cm
Knotting of catheter - ~100 reported cases; result of coiling/looping in R ventricle & cinching down on withdrawl; avoid with slow, continuous advancement, stop if RV waveform persists for more than 20cm, withdraw slowly; majority retrievable by IR; large bow ties may require thoracotomy
PAC “Floating” Related -
Cardiac Arrhythmias - common occurrence – most self limited - get EKG beforehand
- 3% sustained ventricular arrhythmias - prepare to treat but no ppx lidocaine
- 5% RBBB - can precipitate full heart block if LBBB pre-existing; need expedient pacing capability if LBBB present; consider fluoro to guide if LBBB present
[
RBBB - RSR' (rabbit ears) in V1-3 with QRS > 0.11; Broad S in 1, avL, V5-6
LBBB - QRS duration >0.12 sec; lead V1 has a QS or a rS pattern and the downstroke of the S wave is swift and clean, Lead V6 has an R wave that may be notched at the top (no q wave and no S wave); V.A.T. may be >0.09sec, ST segment depressed, T wave inversion in V4-6
Complete heart block - disociation of p and qrs waves - transcutaneous pacing, atropine, if ineffective then epi or dopa and pacemaker
]
Usage/Maintenance Related -
PA Perforation - 0.2% incidence; 30-50% fatal; occurs during insertion or wedging; increased risk with pulmonary HTN, mitral valve disease, steroids, hypothermia; Hemoptysis, local infiltrate on CXR; deflate, pull back slightly, re-inflate and leave balloon up, control airway, toracotomy vs. angioembolization
PA Pseudoaneurysm - PA Perf that “walls off”; Forms immediately or over an interval (up to months); High risk of re-bleeding; High mortality (40-70%); Dx & Treat with Angio; Thoracotomy + Lobectomy for Angio failures
Pulmonary Infarction - result of prolonged balloon inflation, majority are asymptomatic
Thromboembolic Events - mural thrombi develop in ~30%, majority are not clinically significant, risk decreased with heparin bonding
Endocarditis - up to 2% incidence, pulmonic valve most commonly affected
Data Related -
West Zones
Zone 1 - top 3rd of the lung; not usually present, vent pressures can cause; Pa < PA > PV
Zone 2 - middle 3rd of the lung; Pa>PA>PV
Zone 3 - bottom 3rd of the lung; Pa>PA<PV; desired zone; almost always OK if PAC is below the L atrium
PAC Insertion
~20cm right atrium
~30cm right ventricle
~40cm PA
~50cm wedge
IJ - easy to float, easy to cannulate
Subclavian - Easy to float, easy to cannulate
Femoral - Easy to cannulate, fewer major complications, higher risk of infection, risk of DVT
Brachial R - Few major complications
Brachial L - safer if bleeding diathesis or coagulopathy; may be easiest in morbidly obese
Skin to RV
Ensure Introducer is fully seated
Put on Sheath
Hand off ports & Syringe
Flush all ports & Confirm reactivity
Insert to 20 cm the balloon up(1.5 ml)
RV to PA
Steady advance through ventricle - too slow --> arrhythmias, too fast or looping --> knotting
Look for diastolic pressure increase & dicrotic notch* signaling PA
Advance to Wedge - pressure decrease, lose dicrotic notch
Deflate - PA waveform should reappear
Troubleshooting
If < 1mL inflation yield wedge - too deep, pull back to avoid rupture
If fails to wedge or wedges only after 2-3 second delay --> advance
Secure sheath
Check CXR - tip should not be >5cm from midline
Pulsus Paradoxus: spontaneous ventilation --> dec intrathoracic pressure during inspiration --> inc cardiac distensibility --> dec LV emptying during systole --> dec CO --> dec SBP
Exaggeration (>10mm change in pressures) of this is seen in cardiac tamponade, pericardial effusion, tension PE, Severe lung dysfunction
Reverse Pulsus Paradoxus
Positive pressure ventilation --> inc intrathoracic pressure with inspiration --> inc external pressure on LV --> inc LV emptying during systole --> inc CO --> inc SBP
Effects of Positive Pressure Ventilation during Diastole --> dec R&L sided venous return --> dec cardiac filling --> dec CO --> dec SBP
Effects of PPV on CO are Dependent on Intravascular Volume Status
Adequately Volume-Resuscitated (CVP 8-15) - enhanced ventricular emptying in systole predominates and CO improves
Hypovolemic - impaired venous return in diastole predominates and CO suffers, increased variability in SV relative to ventilatory phase occurs
Pulse Pressure Variation (PPV) & Stroke Volume Variation (SVV)
Volume depleted patients have increased PPV & SVV
PPV & SVV can therefore predict “fluid responsiveness”
Goal SVV <10-15%
Accuracy of PPV & SVV
Benefits of Goal Directed Therapy with PPV or SVV in Surgical Patients
Decreased Complication Rate
Decreased LOS
Decreased need for Vent. Support
Only works in intubated patients
Doesn't work in patients with arrhythmias
Benefits of Cardiac Monitoring – Inconsistent Results
Swiss MC RCT 2006-07
388 HD unstable patients in initial 6hr of ICU
Randomized to continuous cardiac monitoring or “standard care”.
No difference in outcomes noted
Of note: avg ICU LOS = 2-3 days
Photoelectric Plethysmography
Changes in blood volume measurement measured by Pulse Ox.
Similar in accuracy as PPV & SVV but noninvasive.
Similar limitations (must be on vent, etc…)
Doppler method: Peak Aortic Flow Velocity ( PV)
Goal Directed Therapy Intraop.
May-Dec. ’08
80 French Large Abd OR Cases
Randomized to standard (12 cc/kg/hr LR)
Goal Directed (6 cc/kg/hr LR c prn boluses of 250 cc Hespan prn PV > 13%)
HD – Monitoring Conclusions
Little Level 1 Data
Trends & Individual Characteristics likely more important than absolute numbers
Decreasing invasiveness necessary
Intraop fluid management controversial but hypoperfusion & volume overload are bad