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GDT

Goal Directed Therapy

Major surgery imposes an increased metabolic demand to which the patient’s normal physiological response should be to maintain an adequate blood pressure, cardiac output and oxygen delivery. Surgery patients that are unable to balance oxygen delivery and consumption develop a peri-operative oxygen debt that increases the risk of surgical complications and death.

Uncorrected fluid shifts and blood loss during surgery, may lead to the patient being subjected to periods of inadequate oxygen delivery. The oxygen debt incurred in, or before, surgery may be added to by an on-going oxygen delivery / consumption mismatch in the post-operative period. Such an accumulating dysoxia can result in a significant peri-operative metabolic imbalance leading to major organ dysfunction, post-operative morbidity and – in extremis - death. In contrast, protocol led interventions (goal directed therapy or GDT) to maximize flow-related hemodynamic variables during surgery (see review by: Lees, Hamilton and Rhodes, 2009; Hamilton et al., 2011), during surgery and post operatively (Lobo et al., 2011), or simply targeting oxygen delivery after surgery (Pearce et al., 2005), have all significantly reduced hospital stay and complications. Accordingly, it is gradually becoming accepted that the avoidance of dysoxia/oxygen debt in surgery, or if incurred, the early and rapid repayment of such a debt will make a significant impact on clinical outcomes and length of stay.

A comprehensive approach to improved outcome in moderate to major risk surgery patients should be capable of allowing hemodynamic optimization across the whole peri-operative period. This includes both implementation of an intra-operative protocol to avoid oxygen debt and, for the more at-risk patients/operations, a continuing clinical pathway that can provide accelerated repayment of the oxygen debt in the ICU. This “peri-operative”approach to GDT has been proposed in a paper from Lees, Hamilton and Rhodes (2009). They conclude that starting GDT at any time in the peri-operative period is useful, but there is strong evidence for the provision of advanced hemodynamic monitoring ie fluid and stroke volume optimisation in surgery and for oxygen delivery targeting in the ICU.

LiDCO believes that the widespread adoption of this new approach to high risk surgery patients will be helped by improvements in the design of the hemodynamic monitor – see O’Brien 2007 for company history and strategy. A technology that is simple to use and designed to implement a full peri-operative GDT strategy is preferred. Significant technology changes were needed, in order to make such practice accessible and achievable beyond the existing enthusiastic ‘early adopter’ group of physicians. The bulk of mainstream users require simpler, more intuitive technology. LiDCO’s monitors (Plus and Rapid) have been specifically designed to facilitate the intra-operative hemodynamic optimization of fluids and stroke volume and, when necessary, the GDT resuscitation (through increased oxygen delivery) of the surgery patient in the ICU. Particular care has been given to simplifying the monitor setup, particularly for surgical use and making the graphical user interface (GUI) more intuitive and consistent through the clinical pathway and locations of use. Patients that could benefit from this technology include both the arterial line and non-arterial line patient. These patients represent a large group and include: colorectal cancer, fractured neck of femur, major joint replacement, renal transplantation, bariatric surgery and urological procedures. LiDCO have also recently introduced the option of monitoring fluids and hemodynamic variables with a continuous non-invasive blood pressure technology. High-risk surgery patients can now be hemodynamically monitored without insertion of a catheter into an artery or probe into the oesophagus.

The LiDCOrapid screen / graphical user interface design

Peri Operative

Case Study – an example from the LiDCOrapid design evaluation phase – comments were from a consultant anesthetist in the beta site trial testing of the GUI:

“A 67 year old male with history of smoking-related emphysema surgery required for hemi hepatectomy of the right lobe of the liver. The surgeon requested that the anesthetist keep the patient dry (hypovolemic) during the first part of the operation – the hepatic resection period to avoid excessive bleeding, so no fluids were given until after the hepatectomy was finished. There was no cross clamp during this procedure and the blood loss was minimal at 200ml, plus 100ml of urine output. Total procedure time was less than 3hrs and the total abdominal exposure time was 2.5hrs. Initial pressure support was via phenylephrine bolus which was followed by a noradrenaline infusion (between 1 and 2 ml/hr of a 4mcg/50ml infusion). Hemoglobin remained high at 15-16g/dL with no evidence of dilution from fluid challenges. The estimated fluid required to rehydrate the patient based on observed and sensible losses was 3.0 to 4.0l. Following the liver resection the total fluid volume given to recover normovolemia was only 1.5 litres of crystaloid and 500 ml of colloid (gelofusion). This smaller amount of fluid (1 – 2 litres less than anticipated) significantly improved the stroke volume. The preload response parameters of SVV% and PPV% reduced well - back to target levels. Therefore between 1 and 2 litres of fluid were not given based on the use of the LiDCOrapid’s dynamic preload responsiveness parameters and user interface help with the maximization of stroke volume.”

LiDCOplus Screens – designed for GDT hemodynamic target setting and monitoring

LiDCOplus Screens - designed for GDT hemodynamic target setting and monitoring
LiDCOplus Screens for ICU GDT
Graph Screen Chart Screen Trend Screen
Graph Screen
sets targets for MAP & CO/DO21
Chart Screen
target is set at midline
Trend Screen
observation of patient over time

The LiDCOplus monitor was designed to be used by both nurses and clinicians in the ICU environment. The monitor has a bigger screen than the LiDCOrapid, because there is a requirement in the ICU for the screen to be visible from a greater distance. The LiDCOplus monitor can be used for fluid management and stroke volume optimisation as per the LiDCOrapid. However, the LiDCOplus monitor can also be calibrated by the lithium dilution method. This lithium dilution calibration can be made with a peripheral vein injection – thereby avoids insertion of a pulmonary artery or central venous catheter. Lithium dilution is a highly accurate and independent measure of blood flow and allows the setting and auditing of oxygen delivery targets with the required/ necessary high degree of precision. Targeting and maintaining oxygen delivery levels post operatively in the ICU using the LiDCOplus has been associated with a mean 12 day reduction in LOS (Pearce et al., 2005) and £4,800 saving per patient treated. Specific screens have been designed to make both the setting and checking that the patient is achieving hemodynamic targets as simple as possible.

Data from either LiDCO monitor can be downloaded to a USB memory stick and then reviewed off line for clinical audit and training purposes (LiDCOview software). A data record from a patient that had an abdominal aortic aneurysm repair is shown as an example below. Both the intra operative and 24 hrs post operative periods are shown. Audit reports can be run from the software quantifying hemodynamic performance vs the set targets.

LiDCO’s Clinical Audit Software - LiDCOview

LiDCOview Peri-Operative Optimisation

Summary of the LiDCO Monitors’ Performance Characteristics *

Criteria LiDCOrapid LiDCOrapid
with Non Invasive Blood Pressure
LiDCOplus
Fluid management
Responsiveness Yes (SVV%/PPV%) Yes (SVV%/PPV%) Yes (PPV%, SVV & SPV)
Fluid/other response Yes – SV response event screen Yes – SV response event screen Yes – SV response event screen
 
Practicability
Accurate Yes – nomogram calibrated Yes – nomogram calibrated Yes very – calibrated (lithium)
Precise Yes – trends SV/CO Yes - trends SV/CO Yes - trends SV/CO
Invasiveness Existing radial arterial line. Non invasive NIBP cuff Existing radial arterial line. + venous access
Beat to beat Yes Yes Yes
Signal stability Good Good Good
Follows fluid changes Yes Yes Yes
Follows trends in SV Yes Yes Yes
Follows trends in SV without readjustments Yes Yes Yes
 
Easy
Set-Up skill Easy (once art line placed) V. Easy – no art line Moderate requires calibration
Set-Up time < 5 mins(once art line placed) < 5 mins 5 to 10 mins (once lines in place)
Interpretation level Moderate/easy Moderate/easy Moderate/easy
 
Perioperative Use
Pre-op No unless art line in place Yes No unless art line in place
Intra-op Yes Yes Yes – but Rapid preferred
Post- op Yes Yes Yes – particularly if DO2I targeted

* This table was modified from the monitor comparison table format suggested by Bundgaard-Nielsen / Kehlet group in Copenhagen (see Bundgaard-Nielsen et al., 2007)

References:

1. Bundgaard-Nielsen M, Holte K, Secher H, Kehlet H Monitoring of peri-operative fluid administration by individualized goal-directed therapy. Acta Anaesthesiologica Scandinavica 2007 doi: 10.1111/j.1399-6576.2006.01221.x

2. Lobo S et al (2011) Restrictive strategy of intraoperative fluid maintenance during optimization of oxygen delivery decreases major complications after high risk surgery. Critical Care vol 15: R226 doi:10.1186/cc10466

3. O’Brien T, LiDCO - From the laboratory to protocolized goal directed therapy. Annual Reviews in Control 2007 31, 303 -310

4. Lees N, Hamilton M, Rhodes A. Clinical review: Goal-directed therapy in high risk surgical patients Critical Care 2009, 13:231 (doi:10.1186/cc8039)

5. Hamilton M, Cecconi M, Rhodes A. (2011) A systematic review and meta-analysis on the use of pre emptive hemodynamic intervention to improve postoperative outcomes in moderate and high risk surgical patients. Anesthesia and Analgesia June vol. 112:(6) 1392 -1402

6. Pearse R, Dawson D, Fawcett J, Rhodes A, Grounds RM, Bennett ED (2005) Early goal-directed therapy after major surgery reduces complications and duration of hospital stay. A randomised, controlled trial. Crit Care 9 (6) 687-693