A Survey of Current HemodynamicManagementin the Cardiac Intensive Care Unit and ProposedStudy ProtocolRebekah E. Thomson1 Nawaf Al-Subaie1 S. Nick Fletcher1

1Department of Cardiothoracic Intensive Care, St. Georges HospitalsNHS Foundation Trust, London, United Kingdom

J Card Crit Care TSS 2017;1:14–17.

Address for correspondence Rebekah Thomson, BSc hons, MSc,Department of Cardiothoracic Intensive Care, Atkinson Morley Wing,St. Georges Hospital, Blackshaw Road, Tooting, London SW17 0QT,United Kingdom (e-mail: rebekah.thomson@nhs.net).

Introduction

More than 30,000 adult cardiac surgery procedures areperformed annually in the United Kingdom. Two-thirds ofthese cases are relatively low risk1 (isolated coronary arterybypass and isolated aortic valve) and should have a com-paratively low duration of intensive care and hospital of stay.Although the mortality for this group of patients remainslow,1 around 5% of patients go on to develop a surgical siteinfection postcardiac surgery and a further 20% of patientsdevelop acute kidney injury (AKI).2 Both these complicationrates could be reduced by adequate oxygen delivery3 andperfusion as suggested by the National Institute for Healthand Care Excellence (NICE) guidance.4,5

It is also suggested that thismorbidity is a strong indicatorof the quality of health care provided and reducing suchcomplications is paramount.6

There have been multiple studies investigating pharma-cologic agents to prevent complications such as AKI aftercardiac surgery, which have proved disappointing. However,interventions, in the immediate period following surgery, toensure adequate flow and perfusion pressure are key topreventing organ dysfunction and specifically AKI.2

NICE guidancewas issued to support the use of esophagealDoppler in major noncardiac surgery cases,5 and the evidenceforoptimizationofhemodynamicsperi- andpostoperatively isstrong. However, many of these studies have not included thecardiac surgery population, who also require intensive carepostoperatively. Few studies have suggested that protocol-driven therapy is of benefit in cardiac surgery,7 though thesestudies are heterogeneous in nature and have not influencedclinical practice so far.

The aim of the survey was to establish the role of currenthemodynamic postoperative practice in low-risk cardiac

Keywords

► hemodynamicmanagement

► cardiac intensive careunit

► cardiac surgery

Abstract Cardiac surgery is one of the few specialties that require postoperative admission to theintensive care unit (ICU) or an overnight intensive recovery routinely. Hemodynamicmanagement of patients following cardiac surgery varies throughout the United Kingdom.Postoperative factors suchas thedynamic changes inmyocardial contractility, vasodilation,and the possible structural alteration to the heart add to complexity to themanagement ofthose patients. Traditionalmethods to target cardiovascular support aremainly focused oncentral venous and systemic arterial pressure, in addition to surrogate markers of organperfusion such as lactate and urine output. Although overall mortality is low followingcardiac surgery, 0.8 to 3.1% depending on the type of cardiac surgery, there are associatedcomplications. Around 5% of patients develop a surgical site infection postcardiac surgeryand a further 20%of patients develop acute kidney injury, both of which could be avoidableby achieving hydration and adequate oxygen delivery. The purpose of this UK-based surveywas to better understand the current postoperative intensive care hemodynamicmanage-ment in patients following aortic valve and coronary artery surgery with a view to studyprotocol development.

DOI https://doi.org/10.1055/s-0037-1604336.ISSN 0000-0000.

Copyright © 2017 Official Publication ofThe Simulation Society (TSS), accreditedby International Society ofCardiovascular Ultrasound (ISCU)

SurveyTHIEME

14

surgery and to help form a trial design targeting such a groupof patients.

Methods

The survey was sent electronically to consultant members ofthe Association of Cardiothoracic Anaesthetists (ACTA) in36 UK cardiac surgical centers. The survey consisted of10 questions. The questions targeted current unit guidelines,local device preference for cardiac output monitoring, fluidadministration practice, and renoprotective strategies. Theauthors also established which clinical team (surgical, an-esthesia, intensive care) were responsible for patient careprovided in the immediate postoperative period and whichcenters would be willing to participate in a study assessingthe role of a protocol-guided hemodynamic managementstrategy. There were multiple responses from severalcenters; all responses were included in the analysis to takeaccount of individual clinician variation.

Results

A total of 44 responses from 21 out of the 36 centers werereceived. Only one respondent reported a system of proto-colized hemodynamic management, whereas six (14%)respondents had guidelines in place. Most responses(37, 84%) reported that patients were managed usingindividual clinician-directed care.

The intensive care team–directed patient care immedi-ately following surgerywas reported in 16 (36.3%) responses,whereas cardiac surgery and anesthesia had equal represen-tation in this survey (2, 4.5%). A shared postoperative caremodel was reported by 24 (54.6%) respondents.

The following parameters were most frequently used toguidefluid therapy (►Fig. 1): lactate 41 (93%), urine output 40(91%), central venouspressure39 (89%),meanarterialpressure32 (73%), and cardiac output 32 (73%). Some centers reportedstroke volume variance or “other” parameters (►Table 1).

The following monitoring technologies were used tomeasure cardiac output and guide fluid administration

(►Fig. 2): echocardiography in 42 (95%) respondents, pul-monary artery (PA) catheter in 36 (82%), PiCCO (PULSIONMedical Systems SE, Middlesex, United Kingdom) in 14(32%), Oesophageal Doppler (Deltex Medical, West Sussex,United Kingdom) in 7 (16%), and LiDCO (LiDCO Group PLC,London, United Kingdom) in 7 (16%).

The use of a cardiac output monitoring device is usually inresponse to some deterioration in clinical condition, for ex-ample hypotension or hyperlactemia. Although some devicesform a part of routine postoperative care, with PA cathetersused by 8 (22.2%) respondents,minimally invasive devices by 5(11.3%), and echocardiography by 19 (43%) respondents (justbelow half of all respondents with the skill) (►Table 2).

The survey inquired about the type of fluid used. Combi-nation fluid therapy is used in many centers: Crystalloid 72%(32), non–starch-based colloids 72% (32), starch-based col-loids 9% (4), and albumin 30% (13).

Patients with chronic kidney disease or elevated serumcreatinine preoperatively have an increased risk of AKI andfluid accumulation. We asked clinicians whether they use“renoprotective” strategies. Several centers ensure adequatehydration (two, 5%) and few use hemofiltration on cardiopul-monarybypass (n¼2, 5%). Somecenterspromotediuresiswithfrusemide (n ¼ 8, 18%), whereas others use dopamine (n ¼5,11.4%) and few use mannitol (n ¼2, 5%). Most clinicians whoresponded do not have a strategy in place or have routinepractice for prevention of AKI ormanagement of patientswithelevated serum creatinine preoperatively. Some units arerestrictive in intravenous fluid administration (n ¼ 5, 11.4%respondents) and some are more liberal.

Fig. 1 Parameters most frequently used to guide fluid therapy.

Table 1 Parameters used to guide fluid therapy

S. No. Parameters Mean %

1 Lactate 41 93

2 Urine output 40 91

3 Cardiac output 32 73

4 Central venous pressure 39 89

Journal of Cardiac Critical Care TSS Vol. 1 No. 1/2017

A Survey of Current Hemodynamic Management Thomson et al. 15

Forty-three (98%) respondents registered their interest ina multicenter randomized trial of protocolized managementof fluid therapy. Respondents were given the opportunity toexpress barriers to study participation; overall there was apositive response with supportive comments. However, anegative common theme that emerged was the influence ofthe other clinicians involved in the management of patientsand/or colleagues who had fixed ideas on postoperative fluidadministration.

Another potential barrier to study participation includedthe lack of confidence in certainminimally invasivemonitorsand the reliability of the measurements. Although validateddevices are available, clinicians with echocardiography skillsfelt that this is more consistent.

Discussion

The primary purpose of this survey was to take a snapshot ofcurrent UK practice and establish the need for a researchproposal in this area. It was also used to test receptivenessfor study center participation. The response rate was 58% so itwas not a complete reflection of all cardiac intensive care unit(ICU) practice in the United Kingdom. The authors found aconsiderable degree of heterogeneity in the intensive care-basedmanagementofpatients followingcardiac surgery in theUnitedKingdom. This survey reflects theopinion of consultantcardiac anesthetists and intensivists only, so it does not take

into account all the clinicians contributing to patient care.Cardiac anesthetists and intensivists, however, deliver themajority of postsurgical critical care in the United Kingdom.

Fluid therapy has been a hot topic for debate for the pastdecade,with controversyover the type of fluid that should beused for fluid resuscitation, specifically in the acute phase.Although centers varied widely, the authors concluded thatall centers used a crystalloid in addition to some center-specific colloids. The Cochrane Review (2013),8 which in-cluded trials conducted on cardiac surgical patients, showedno evidence to support the use of colloids over crystalloids.This review also demonstrated potential harm from the useof hydroxyethyl starch, so the authors were surprised to notethat four centers continued to use this fluid.

Theauthorswerealsokeen toestablish thenatureofcurrentpractice for the management of patients at high risk of devel-oping AKI. Practice showed considerable variability here withuse of several agents including furosemide and dopamine,neither of which have been demonstrated to be effective inprevention of kidney injury and may even cause harm.9 Theauthors suggest that this variability results from the absence ofgood evidence to inform clinical practice in these patients.

The results identified the potential of two ormore devicesused in each center. This approach might be explained byclinicians usingmultiple tools, such as echocardiographyandcardiac output devices, to establish cardiac function and theresponse to fluid. Despite wide availability of cardiac outputmonitoring devices, their use is not routine. Usage appears tobe reactive in response to signs of inadequate perfusionrather than a proactive strategy. This may be related tounfamiliarity, a lack of faith in their accuracy, invasiveness,or simply cost. There are validation studies for the use ofminimally invasive cardiac output devices in patients follow-ing cardiac surgery, but perhaps more work is required.10–12

Echocardiography is a routine practice in cardiothoracicICUs, and it offers important information to guide therapy,though its use is somewhat limited by the lack of continuousand validated parameters in this group of patients. In addition,

Fig. 2 Monitoring technologies used to measure cardiac output and guide fluid administration.

Table 2 Use of a cardiac output monitoring device

S. No. Device No. ofrespondents

%

1 Pulmonary artery(PA) catheter

8 22.2

2 Minimally invasivedevice

5 11.3

3 Echocardiography 19 43

Journal of Cardiac Critical Care TSS Vol. 1 No. 1/2017

A Survey of Current Hemodynamic Management Thomson et al.16

the experience and availability of a trained clinician is requiredfor the delivery of echocardiography, which is not alwayspossible. Transesophageal echocardiography (TEE) gives moredetailed views than transthoracic echo, but it is restricted in thelow-risk surgical patients because of the previous factors andrequirement for sedation. Although perioperative echocardio-graphy remains an important element in the care of the cardiacsurgery patient intraoperatively, it is not yet a practical alter-native for the postsurgical context. Minimally invasive cardiacoutput monitoring offers an objective measurement of fluidresponsiveness superior to traditional methods using arterialpressure and urine output.13 It can be used by trained nursingstaff and allows nurse led protocols to be implemented. Multi-ple single-center studies have demonstratedpositive outcomesand cost-effectiveness,14 though they have not influencedcurrent practice as yet.7,15,16

The potential risk of fluid overload, which causes manyclinicians to question the safety of such therapy, by using amethod aiming to maximize stroke volume/cardiac outputhas not been demonstrated. Similar volumes of fluids areadministered by delivering goal-directed therapy (GDT)versus standard therapy, which challenges this misconcep-tion.16 Having expert nurses to interpret data and clearguidelines to escalate to senior medical staff is essential topromote safety of such concepts. This survey strongly sup-ports a multicenter randomized controlled trial of proto-colized care to further inform the current practice.

Conclusion

There isa considerabledegreeofheterogeneity in the intensivecare-based hemodynamic management of patients followingcardiac surgery in the United Kingdom. Most clinicians havenot agreed to hemodynamic protocols or guidelines in place.We consider that this is the consequence of a lack of goodresearch evidence. This strengthens the argument for largetrials to guide hemodynamic management in such patients.

Authors’ ContributionsThe authors have contributed in conducting the surveyand toward the preparation and analysis the survey. Allthe authors have read the final version of the article andagree with its conclusions.

Conflict of InterestThere are no conflicts, contradictions, or ethical problemsbetween the authors concerning the content of the article.

References1 National Institute for Cardiovascular Outcomes Research (NICOR).

National Adult Cardiac Surgery Audit. Annual Report 2010–2011.University College London

2 Lamiere N, Van BiesenW, Hoste E, Vanholder R. The prevention ofacute kidney injury: an in depth narrative review Part 1: volumeresuscitation and avoidance of drug- and nephrotoxin-inducedAKI. NDT Plus 2008;1(06):392–402

3 Brienza N, Giglio MT, Marucci M, Fiore T. Does perioperativehemodynamic optimization protect renal function in surgicalpatients? A meta-analytic study. Crit Care Med 2009;37(06):2079–2090

4 National Institute of Clinical Excellence. CG74. Surgical SiteInfection: Prevention and Treatment of Surgical Site Infection.Manchester, UK: NICE; 2008

5 National Institute of Clinical Excellence. NICEMedical TechnologyGuidance (MTG3). CardioQ-ODM Oesophageal Doppler Monitor.Manchester, UK: NICE; 2011

6 de Vos M, GraafmansW, Keesman E, Westert G, van der Voort PH.Quality measurement at intensive care units: which indicatorsshould we use? J Crit Care 2007;22(04):267–274

7 Aya HD, Cecconi M, Hamilton M, Rhodes A. Goal-directed therapyin cardiac surgery: a systematic review and meta-analysis. Br JAnaesth 2013;110(04):510–517

8 Perel P, Roberts I, Ker K. Colloids versus crystalloids for fluidresuscitation in critically ill patients. Cochrane Database Syst Rev2013;2(02):CD000567

9 Lassnigg A, Donner E, Grubhofer G, Presterl E, Druml W, Hies-mayr M. Lack of renoprotective effects of dopamine andfurosemide during cardiac surgery. J Am Soc Nephrol 2000;11(01):97–104

10 Mora B, Ince I, Birkenberg B, et al. Validation of cardiac outputmeasurement with the LiDCO™ pulse contour system in patientswith impaired left ventricular function after cardiac surgery.Anaesthesia 2011;66(08):675–681

11 Hofer CK, Müller SM, Furrer L, Klaghofer R, Genoni M, Zollinger A.Stroke volume and pulse pressure variation for prediction of fluidresponsiveness in patients undergoing off-pump coronary arterybypass grafting. Chest 2005;128(02):848–854

12 McKendry M, McGloin H, Saberi D, Caudwell L, Brady AR, SingerM. Randomised controlled trial assessing the impact of anurse delivered, flow monitored protocol for optimisation ofcirculatory status after cardiac surgery. BMJ 2004;329(7460):258–262

13 Marik PE, BaramM, Vahid B. Does central venous pressure predictfluid responsiveness? A systematic review of the literature andthe tale of seven mares. Chest 2008;134(01):172–178

14 Ebm C, Cecconi M, Aya H, Geisen M, Rhodes A, Grounds M.Economic evaluation of early-goal directed therapy for high-risk surgical patients. Crit Care 2012;16(Suppl 1):198

15 Mythen MG, Webb AR. Perioperative plasma volume expansionreduces the incidence of gut mucosal hypoperfusion duringcardiac surgery. Arch Surg 1995;130(04):423–429

16 Thomson R, Meeran H, Valencia O, Al-Subaie N. Goal-directedtherapy after cardiac surgery and the incidence of acute kidneyinjury. J Crit Care 2014;29(06):997–1000

Journal of Cardiac Critical Care TSS Vol. 1 No. 1/2017

A Survey of Current Hemodynamic Management Thomson et al. 17