Lactated Ringer's Versus 5% Human Albumin: A Double-Blinded, Randomized, Prospective Study in Cardiac Surgical Patients
Phase: PHASE2
Conditions: Hemodynamic Stability
Sponsor: William C. Oliver

 
 
 
 
 
 
 
Lactated Ringers versus 5% 
Human Albumin: A Double-
Blinded, Randomized, 
Prospective Study in Cardiac 
Surgical Patients 
NCT 02654782  
June 29, 2015 

 
 
June 29th, 2015 
Lactated Ringer’s versus 5% Human Albumin: 
A Double-Blinded, Randomized, Prospective Study in 
Cardiac Surgical Patients 
 
 
 
Principal Investigators: 
William C. Oliver, Jr., M.D.1; Gregory A. Nuttall, M.D.1;  
   
 
Erica D. Wittwer, M.D., Ph.D.2; David W. Barbara, M.D.2 
Co-investigators: 
 
Jennifer M. Levy, R.N.3; Mary E. Marienau, Ph.D., CRNA2;  
Amy Gnagey, APRN, CRNA4; Joseph A. Dearani, M.D.5; Hartzell 
V. Schaff, M.D.5 
 
 
1Professor, Department of Anesthesiology, Mayo Clinic College of Medicine 
2Assistant Professor, Department of Anesthesiology, Mayo Clinic College of Medicine 
3Nurse Anesthesia Program, Department of Anesthesiology, Mayo Clinic College of Medicine 
4Instructor, Department of Anesthesiology, Mayo Clinic College of Medicine 
5Professor, Division of Cardiovascular Surgery, Department of Surgery, Mayo Clinic College of 
Medicine 
 
 

 
 
 
ABSTRACT 
Following IRB approval and written informed patient consent, 40 elective, cardiac surgical 
patients will be randomized to two different fluid therapy regimens, 5% human albumin only or 
Lactated Ringer’s only, beginning in the intraoperative period and up to 6 hours in the intensive 
care unit. Providers and patients will be blinded to the fluid administered in the operating room 
and intensive care unit. The primary outcome measure will be the total volume of 5% human 
albumin or Lactated Ringer’s given during the study period to maintain specified hemodynamic 
guidelines. Hemodynamic instability will be defined according to each patient’s stipulated 
baseline parameters. Fluid will be administered at the request of providers in the operating room 
and intensive care unit in compliance with a perioperative fluid algorithm. Outcome measures of 
hemodynamic instability will include systolic and diastolic blood pressures; mean arterial 
pressure, central venous pressure, cardiac index, urine output, and vasopressor use. Alveolar-
arterial gradient will be assessed between the two choices of fluid to determine any relationship 
with fluid choice and duration of intubation in the intensive care unit. Blinding of the fluid 
therapy has not been done in this group of patients so detection of bias towards one of the fluids 
may be appreciated. 
 

 
 
I. SPECIFIC AIMS 
Specific Aim 1: 
To determine the ratio of 5% human albumin to Lactated Ringer’s (LR) by 
examining total fluid volume. 
Specific Aim 2: 
To determine whether or not patients will experience decreased vasopressor and 
blood product requirements as well as decreased time to extubation and length of 
intensive care unit (ICU) stay related to less total fluid volume and reduced 
alveolar-arterial (A-a) gradient. 
Specific Aim 3:  To determine which fluid, LR or 5% human albumin, is the ideal fluid to 
administer to cardiac surgical patients in order to maintain individual patient 
hemodynamic stability without fluid overload. 
Specific Aim 4:  To determine whether provider bias plays a role in choosing and administering 
fluid in the operating room (OR) and ICU.  
 
HYPOTHESIS 
Hypothesis 1:  
The individual total fluid volume will be less with 5% human albumin 
compared to LR in the perioperative cardiac surgical patient. 
Hypothesis 2:  
The A-a gradient with 5% human albumin compared to LR will be lower in 
the perioperative cardiac surgical patient.  
Hypothesis 3:  
Provider bias largely determines which fluid will be administered to 
perioperative cardiac surgical patients.                   

 
 
II. BACKGROUND AND SIGNIFICANCE 
There has been a great deal of research done on ideal fluid therapy in general populations as well 
as critically ill patients; however, ideal fluid therapy in the cardiac surgical patient has not been 
identified. There has been an extensive amount of debate regarding ideal fluid therapy dating 
back as far as 1977 for both medical and surgical patients.(1) Adequate fluid volume plays a 
major part in maintaining the necessary hemodynamics to prevent organ damage during cardiac 
surgery. Cardiopulmonary bypass (CPB) frequently causes an inflammatory response(2) that 
results in capillary leakage and interstitial edema. Other factors also contribute to a depletion of 
circulatory volume during surgery including hemorrhage, diuretics, and vasoactive drugs.(3) 
Fluids such as crystalloid and colloid have traditionally been given to meet volume replacement 
demands associated with cardiac surgery. Two commonly administered fluids for perioperative 
volume replacement associated with cardiac surgery are colloids (5% human albumin) and 
crystalloids (LR). 
Cardiac surgery patients initially present with a “shock-like” state shortly after an incision is 
made called the ebb phase. The ebb phase commences with initial peripheral vasoconstriction, a 
shifting of blood from the peripheral to major organs, and a reduced body temperature. Shortly 
after the ebb phase, the flow phase causes an improved cardiac index (CI), vasodilation, pyrexia, 
and an increase in capillary permeability. Considering the vasodilation and increase in capillary 
permeability, giving fluid during the flow phase can cause a pooling of fluid in the extravascular 
space. Destruction to the endothelial glycocalyx layer of the vasculature causes high 
transcapillary escape rates. Shedding of the endothelial glycocalyx layer seems to occur in 
cardiac surgery with and without CPB. With this physiology in mind, it would appear that there 
should be no difference between crystalloids and colloids in maintaining normovolemia.(4) It is 

 
 
known that the intravascular Starling forces are altered with the initiation of CPB. The increased 
hydrostatic pressures, generated from left ventricular dysfunction, and the decreased colloid 
oncotic pressures, resulting from hemodilution, combine to affect intravascular volume. This 
would suggest that fluid selection might have an impact on extravascular lung water, interstitial 
edema, and respiratory dysfunction following CPB and during the ICU period. 
A-a gradient is a simple but useful clinical measurement(5) that reflects the degree of 
ventilation/perfusion mismatch (V/Q).(6) There is a wide distribution of A-a gradient values. 
Alveolar gas exchange depends on a slightly unbalanced V/Q but with great capacity to recruit 
blood to adjust to very strenuous demands and maintain the V/Q so that the A-a gradient remains 
low.(7) In 1992, Moore et al. was able to decrease the A-a gradient in patients with congestive 
heart failure with only minimal oxygen supplementation and their exercise tolerance was 
significantly improved.(8) 
Many different crystalloid solutions are available to treat patients. All of them contain different 
osmolality and concentrations of electrolytes. Lactated Ringer’s is considered a full electrolyte 
crystalloid that relates highly to the composition of human plasma. Plasma volume is responsible 
for 4% of total body weight compared to the interstitium that is 16% of total body weight. 
Crystalloids are diffused evenly between the intravascular and extravascular spaces, so there is a 
large difference in the amount of crystalloid needed to maintain intravascular volume compared 
to colloids (4:1 ratio).(3) Considering the amount of crystalloid that may be required to replace 
blood loss, the patient is at an increased risk for substantial fluid accumulation in the 
extravascular compartments and fluid overload.(3) In contrast, Shaw et al.(4) has reported only a 
30% greater efficacy in boosting intravascular space with colloids compared to crystalloids in a 
1:1.2 to 1:1.4 ratio. The uncertainty regarding the amount of crystalloid necessary to replace 

 
 
ongoing blood loss to maintain effective circulating volume is a drawback for crystalloid 
resuscitation. Increased fluid in the extravascular space combined with CPB, anesthesia, 
hypothermia, medications, and transfusions could potentially lead to postoperative pulmonary 
edema and inadequate gas exchange.(9) A chart review conducted in 2009 of 41 major vascular 
surgery patients showed that when patients were given less than 3 liters of LR they had a 
decrease in time of mechanical ventilation and length of ICU stay.(10) Similarly cardiac surgery 
patients typically will be exposed to more than 3 liters of fluid in a case and in the immediate 
postoperative period. 
Albumin has long been considered the gold standard for volume expansion.(11) It is the most 
abundant protein in human plasma and accounts for 70% of oncotic pressure. Albumin is 
synthesized in the liver but is not stored anywhere if it were to be needed quickly.(12) Colloid 
solutions, in general, have a high molecular weight and leave the intravascular space slowly 
through capillary walls applying colloid-osmotic pressure and causing fluid to be retained within 
the intravascular space. Human albumin is also important for transporting calcium, magnesium, 
and medications.(3) Albumin administration as a volume expander has been criticized for its 
cost, availability, and the potential for disease transmission since it is obtained from human 
donors.(13) Some studies have been performed which showed detrimental effects associated with 
albumin. A well-known study to report adverse results with albumin is the systematic review 
conducted by the Cochrane Group in 1998. This review analyzed 30 randomized controlled 
trials. The results suggested a higher mortality rate in critically ill patients with 
hypoalbuminaemia, burns, and hypovolaemia from trauma or surgery.(14) In response to this 
review, the 2004 SAFE Trial showed no difference in mortality in critically ill patients when 
crystalloid and colloid were compared. This study was a significant milestone in treating 

 
 
critically ill patients and disproving detrimental effects of albumin; however, cardiac surgery 
patients were excluded from the study.(15)   
In 1992, a review article looking back as far as the 1970s, found that colloid solutions were the 
preferred fluid administered to postoperative cardiac surgical patients.(13) This article noted that 
colloids, in animal testing, do not readily pass through membranes leading to further volume 
expansion compared to crystalloids that tend to distribute according to compartment ions. Since 
sodium is primarily an extracellular cation, normal saline tends to distribute in extracellular 
compartments. A review of 79 randomized controlled trials in 2003 compared albumin to control 
regimens of crystalloids, artificial colloids, low-dose albumin, or no albumin.(16) The target 
indicators were ascites, burns, brain injuries, hypoalbuminaemia, cardiac surgery and non-
cardiac surgery. Fourteen of the 79 studies focused on volume expansion in the cardiac surgery 
patient. Albumin showed more favorable outcomes in these trials maintaining colloid oncotic 
pressure-pulmonary artery wedge pressure gradients at close to normal levels, less fluid 
requirements, and more successful hemodilution compared to crystalloids. In 2006 a prospective, 
blinded, randomized trial, looking at 90 minute filling pressure-guided fluid challenge after 
cardiac or major vascular surgery, favored albumin as the fluid of choice. Significantly more 
saline had to be infused in these patients in comparison with albumin. The patients that received 
albumin had an increase in colloid oncotic pressure as well as heart rate (HR), mean arterial 
pressure (MAP), CI, central venous pressure (CVP), pulmonary capillary wedge pressure 
(PCWP), global end-diastolic volume index, global ejection fraction, stroke volume index, and 
left ventricular stroke work.(17)  
Since the studies that have been done up to this time have not provided the level of evidence 
based results concerning optimal fluid therapy for perioperative cardiac surgical patients, 

 
 
healthcare providers may have developed an unfounded bias towards one fluid type or the other. 
A questionnaire completed by 270 physicians in Canada revealed that most selected colloids for 
treatment of oncotic pressure and blood loss. Crystalloids were chosen for their low cost, few 
side effects, and the belief that crystalloids contain most of what a patient needs.(18) In 1995, 24 
medical professionals were asked to participate in developing guidelines for using albumin, 
nonprotein colloids, and crystalloids based on current literature. The resulting guidelines 
included 12 indications for fluid administration. The cardiac surgery guidelines made crystalloids 
the fluid of choice for priming volume of CPB. It also suggested administration of nonprotein 
colloids used in conjunction with crystalloids if there was a concern for pulmonary edema. 
Crystalloids were considered first line approach postoperatively, followed by nonprotein 
colloids, and then albumin.(19) A criticism of this study was the number of healthcare 
professionals that participated in the study but were not specialists in cardiac surgery. 
Understanding the motivation of healthcare providers for selection of certain types of 
resuscitation fluids in cardiac surgery and the ICU could prove beneficial for future research. 
In January of 2015, a systematic review and meta-regression analysis of 48 studies related to the 
selection of crystalloid or colloid for fluid therapy was conducted.(1) Forty-three of the studies 
were randomized controlled trials. This review found that older studies used albumin in a ratio of 
4:1 over crystalloids. However, in cardiac surgery patients, the ratio of albumin was 3:1 over 
crystalloid. The colloid to crystalloid ratio varied in relation to the decade that the trial was 
conducted and not according to type and indication for fluid and patient population. There were 
many different endpoints in the study, but A-a gradient was not included. Overall, this systematic 
review of Cortes et al.(1) supports the idea of decreased fluid requirements when colloids are 
used. This study speculated that the reason for a decrease in the ratio between colloids and 

 
 
crystalloids over the years is that patients are receiving fluid treatment earlier than in the past. 
Furthermore, this study has shown an increase in albumin levels even if patients are exhibiting 
capillary permeability issues.  
Our study will look at crystalloid compared to albumin in relation to total fluid volume and A-a 
gradient in the both the intraoperative and postoperative periods. There is only one study(17) that 
reported the double-blinded administration of fluid after cardiac surgery for only a 90-minute 
period and noted the physiological changes. The bias associated with fluid administration in the 
past may adversely affect patient outcomes. Because the study is blinded, stronger 
recommendations may be formulated giving guidance to healthcare providers and possibly 
improving patient safety.  
 
III. PRELIMINARY DATA 
The investigators of this study have had prior experience performing blinded, randomized, 
prospective trials in cardiac surgical patients.(20-23) These studies involved successful blinding 
in difficult clinical situations. The cardiac surgical and ICU personnel have significant 
experience in the performance of these types of studies that require blinding. Several of the 
authors on this study are critical care physicians that work with the cardiac patients that will be 
enrolled.  
 
IV. RESEARCH DESIGN AND METHODS 
Sample-Size/Statistical Power Considerations 
From previous studies exploring differences in fluid requirements between crystalloids and 
albumin solutions(1) we anticipate that the distribution of fluid volume will likely be skewed, but 

 
 
the effect size (difference between groups in SD units) will be at least 1.0. In general, a sample-
size of N=40 (N=20 per group) will provide statistical power (two-tailed, alpha=0.05) of greater 
than 80% to detect a difference between groups of 1 SD. Therefore, a total sample-size of N=40 
is proposed. 
Data Analysis 
The current investigation utilizes a straightforward, randomized design. Unless otherwise 
specified, analyses will be performed using an intention-to-treat approach whereby subjects are 
analyzed according to randomized treatment. Data will be summarized using mean±SD or 
median (25th, 75th percentile) for continuous variables and frequency percentages for categorical 
variables. For the primary analysis, the total volume of study fluid (5% human albumin or LR) 
administered in the perioperative period and up to 6 hours after ICU admission will be compared 
between groups using the two-sample t-test or rank sum test. Additional analyses will be 
performed for secondary endpoints. For these analyses binary endpoints will be compared 
between groups using the Fisher’s exact test and continuous variables will be compared between 
groups using the two-sample t-test or rank sum test. Model assumptions for each analysis will be 
validated and transformations or nonparametric methods will be utilized as appropriate. In all 
cases, two-sided tests will be performed with p ≤ 0.05 used to denote statistical significance. 
Randomization  
Subjects will be randomized to one of two study groups using a randomization schedule prepared 
by the Division of Biostatistics. The randomization schedule will be generated using blocks of 
size 4 to ensure that after every 4th subject is enrolled an equal number of subjects are assigned 
to each fluid regimen. Using this randomization schedule, individual randomization cards will be 
created and placed in sealed envelopes labeled according to a sequentially assigned subject 

 
 
randomization number. At the time of randomization, a subject will be assigned the next 
sequential subject randomization number and the corresponding envelope will be opened to 
determine the treatment assignment.  
Patients 
Following IRB approval and written informed consent patients having elective cardiac surgery 
between the ages of 18 and 99 performed by Drs. Schaff and Dearani are eligible. Patients will 
not be excluded for taking aspirin, heparin, or warfarin preoperatively. Exclusionary criteria 
include: previous sternotomy, emergency surgery, combined procedures involving vascular or 
thoracic operations, congenital heart repair, hypothermic CPB < 28C; serum creatinine  1.5 
mg/dL, dialysis dependent renal failure, any neurologic injury or event within 30 days (including 
transient ischemic attack), cerebrovascular accident with significant residual neurologic deficit, 
pre-existing clotting disorder, platelet receptor GPIIb/IIIa antagonists medication received within 
48 hours, steroids, severe chronic obstructive pulmonary disease with FEV1 < 45% of predicted, 
home oxygen use, previous difficult intubation, acute normovolemic blood conservation 
techniques, primary liver disease with serum AST > 31 U/L, circulatory arrest, thrombolysis, left 
ventricular ejection fraction < 40%, intra-aortic balloon pumps, total hearts, ventricular assist 
devices, ongoing congestive heart failure, pregnant women, and adults lacking capacity to 
consent. Any patients initially enrolled in the study that end up with an intra-aortic balloon 
pump, left ventricular assist device, or on extracorporeal membrane oxygenation will be 
eliminated from the study.  
Patients will be maintained on their current preoperative medications until they arrive in the OR. 
The anesthetic induction will be fentanyl 1-4 mcg/kg, midazolam 0.025-0.05 mg/kg, rocuronium 
0.5-0.6 mg/kg and propofol 1-1.5 mg/kg. Anesthetic maintenance will be isoflurane 0.4-1.2% 

 
 
and fentanyl 2 mcg/kg/hr or sufentanil 0.5 mcg/kg/hr. With chest closure, the patient will be 
transitioned to propofol 15-50 mcg/kg/min or dexmedetomidine 0.2-0.7 mcg/kg/hr. An arterial 
catheter will be placed either radially or femorally to identify the blood pressure (BP) 
continuously and allow for sampling of blood for laboratory tests including arterial blood gases 
(ABGs). Central venous access and monitoring will be accomplished by the insertion of a 
pulmonary artery catheter in the internal jugular vein. Standard methods for patients undergoing 
cardiac surgery requiring CPB will include standard priming solution (crystalloid, mannitol 
12.5%), membrane oxygenator, non-pulsatile flow of 2.0-2.4 L/min/m2, MAP maintained during 
CPB between 50 and 90 mmHg, nasopharyngeal temperature between 28C and 37C, and 
conventional ultrafiltration to a volume of 27 ml/kg.(24) Packed red blood cells will be added to 
the priming volume if the patient's hemoglobin (Hgb) is estimated to be < 8.0 g/dL upon 
initiation of CPB. Packed red blood cells will also be given if the Hgb falls below 7.5 g/dL at any 
time during CPB. 
Group Designations 
Group A will receive LR and group B will receive 5% human albumin as the sole maintenance 
fluid and volume expander intraoperatively and for the initial 6 hours after admission to the ICU. 
All patients will be given fluid at the request of the healthcare provider in response to 
hemodynamic changes with help from the fluid algorithm in Figure 1. 
Blinding 
All medical personnel caring for the patient will be blinded to the identity of the fluid regimen 
used in the OR and ICU except for the study personnel administering the fluid. The study  staff 
will have institutional privileges and qualifications to administer fluids. . Funding is currently 
being pursued for study staff. Albumin, Lactated Ringer’s, and IV tubing for each fluid will be 

 
 
stocked in a cart that can only be accessed by the blinding staff. This cart will be concealed with 
a room divider from the OR and ICU staff. Intravenous pumps and tubing that contain the 
designated fluids will be concealed from the patient's medical providers by a large curtain and 
tubing covers. The blinding will prevent the medical providers (anesthesiologist, nurse 
anesthetist, surgeon, critical care physician, and nurse) from realizing the type or amount of fluid 
the patient has received. The healthcare providers will determine the rate and duration of fluid 
infusions aided by the fluid algorithm in Figure 1 while study personnel carry out the orders. The 
physicians will not be allowed to compare fluid amounts but only assess physiologic parameters 
to determine if further volume is required to treat the patient. The blinding may be broken at any 
time the physician caring for the patient believes it necessary for continuation of care. Blood 
products will be administered, without blinding, by the providers in the room as needed.  
Outcome Measures 
Total fluid administered indexed to weight will be the primary outcome measure, and the A-a 
gradient as a secondary measure will be determined from ABGs obtained after induction of 
anesthesia, after initiation of CPB, prior to separation of CPB, 10 minutes after protamine, upon 
admission to the ICU, and with extubation. Other outcome measures will include hemodynamic 
measurements: BP, MAP, CI, and CVP. Hemodynamic measurements will be obtained at the 
following times except for CI: sternotomy, post heparinization, 2 min after separation from CPB, 
10 min after protamine administration, 5 minutes after sternal closure, and immediately prior to 
transfer from OR. Hemodynamic measurements will also be obtained at 1 hour, 2 hours, 4 hours, 
and 6 hours after ICU admission. The CI will be obtained at the following times: 10 min after 
protamine, 5 min after sternal closure, 10 min after ICU arrival, 2 hours, and 6 hours after 
admission to the ICU. 

 
 
Ten minutes after protamine, the hemostatic condition of the surgical field will be classified as 
dry, moderate, or wet by the surgical and anesthesia staff. Packed red blood cells will be 
considered for a Hgb < 8.0 g/dL or if ischemia, hypotension, or rapid blood loss necessitate 
transfusion. Once in the ICU, PRBC cell salvage blood will be administered first before PRBC 
are given. The triggering hemoglobin is < 8.0 g/dL unless there are mitigating circumstances 
such as acute coronary ischemia or uncontrolled bleeding. Mediastinal chest tube drainage will 
be recorded hourly for 6 hours after ICU arrival. Upon arrival to the ICU, all neuromuscular 
blockade will be reversed. Sedation will be maintained with propofol or dexmedetomidine and a 
patient controlled analgesia pump will be started with a basal rate of 25 mcg/hr of fentanyl.  A 
standardized, initial ventilator setting and subsequent adjustment and ventilation weaning 
protocol is instituted for all patients shown in Figure 2. After determining the patient is stable 
from a hemodynamic and hematologic standpoint and there is no bleeding, the sedation will be 
weaned and eventually discontinued in conjunction with weaning of mechanical ventilation. The 
critical care provider, who is blinded to the subject’s group designation, is responsible for 
making the final decision regarding tracheal extubation.  
Primary Endpoint 
The primary endpoint will be the total fluid volume of 5% human albumin or LR administered in 
the perioperative period up to 6 hours in the ICU. 
Secondary Endpoint 
The secondary endpoint will be A-a gradient, which will be assessed with every ABG, in 
response to the administered volume expanders, 5% human albumin or LR.  
Tertiary Endpoint 

 
 
All providers in the room including the surgeon, anesthesiologist, nurse anesthetist, and nursing 
staff in the OR and ICU will be asked to fill out a survey on each patient regarding which type of 
fluid they feel the patient received during the patient’s care. The providers will only be able to 
look at hemodynamic monitoring trends of each patient to determine the type of fluid. They will 
be asked to provide a reason for choosing that particular fluid and will also be asked to talk to 
study staff if they feel blinding has been compromised. 
 
V. HUMAN SUBJECTS 
Detailed description: Subject Inclusion and Exclusion Criteria 
Adult male and non-pregnant female patients undergoing elective cardiac surgery at this facility 
between the ages of 18 and 99 years of age are eligible. Patients may also be receiving aspirin, 
heparin, or warfarin preoperatively. Exclusionary criteria include: previous sternotomy, 
emergency surgery, combined procedures involving vascular or thoracic operations, congenital 
heart repair, hypothermic CPB < 28C, serum creatinine  1.5 mg/dL, dialysis dependent renal 
failure, any neurologic injury or event within 30 days (including transient ischemic attack), 
cerebrovascular accident with significant residual neurologic deficit, severe chronic obstructive 
pulmonary disease with FEV1 < 45% of predicted, home oxygen use, previous difficult 
intubation, acute normovolemic blood conservation techniques, primary liver disease with serum 
AST > 31 U/L, circulatory arrest, thrombolysis, pre-existing clotting disorder, platelet receptor 
GPIIb/IIIa antagonists medication received within 48 hours, steroids, left ventricular ejection 
fraction < 40%, intra-aortic balloon pumps, ongoing congestive heart failure, ventricular assist 
devices, total hearts, pregnant women, and adults lacking capacity to consent. Any patients 

 
 
initially enrolled in the study that end up with an intra-aortic balloon pump, left ventricular assist 
device, or on extracorporeal membrane oxygenation will be eliminated from the study. 
Population: We will study 40 elective cardiac surgical patients to be randomized to 2 groups. 
Recruitment of patients: Patients will be recruited prior to surgery. 
Potential risks: All of the fluids in this study are FDA approved for this purpose. The potential risks 
of this study are inadequate or excessive fluid administration. The fluid administration will be under 
the direction of an experienced medical provider that minimizes the risk of over or under infusion of 
fluid. 
Protection:  Patient confidentiality will be rigorously maintained by use of secure files and 
elimination of patient identifiers (beyond a confidential code) on each record or sample. Qualified 
physicians will perform all invasive procedures for clinical purposes. Additionally, if serious 
complications occur the individuals will receive care from Mayo Clinic physicians who are experts in 
treatment of that particular complication. Finally, we will monitor all of our subjects and keep a 
detailed database of major and minor complications.   
Benefits:  No direct benefits to the participant. 
VI. GENDER/MINORITY MIX 
The gender and minority mix will reflect that of the cardiac surgical population. 
 
 

 
 
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