Resuscitation with hyperoncotic human albumin following
cardiovascular surgery
The advantages and risks of resuscitation with isooncotic albumin are
potentially of even greater significance when volume expansion is
achieved with hyperosmolar
albumin [45, 54]. Prospective studies performed in various ICU
settings have indicated that the volume-expanding effect of hyperosmolar
albumin is twice that of 5% human albumin [45, 55] with results
demonstrating a less positive fluid balance in patients resuscitated
with hyperoncotic albumin [43, 45, 55].
Similar investigations in patients following cardiac surgery had not
been performed until recently. In a prospective, sequential, open-label
study by Wigmore, et al., authors aimed to compare the effects of FBT
using 20% albumin (200mL bolus) versus crystalloid (500mL bolus) on
fluid balance, hemodynamic markers and clinical course in the ICU in a
cohort of post-cardiac patients (n=100) [20]. FBT was given in
response to clinical signs of hemodynamic instability or in response to
a low cardiac index (<2.2 L/min/m2)
[20]. Patients in the albumin group were noted to have a less
positive fluid balance in the first 24 hours (p=0.001), and required
fewer FBT compared to those in the crystalloid group (p<0.001)
[20]. Further, individuals in the concentrated albumin group
required vasopressors for a shorter period of time and had a shorter
length of ICU stay compared to their study counterparts (p =0.048)
[20]. Despite these findings, there was no appreciable difference
between the two groups in cardiac output (CO), mean arterial pressure
(MAP) or central venous pressure (CVP) following the first fluid bolus
[20]. Furthermore, this study showed no difference in mortality
between study groups [20].
In a smaller prospective observational study by Cutuli, et al., authors
investigated the effects of 20% albumin boluses on cardiac index (CI)
and MAP in a cohort of twenty post-cardiac patients [24]. Patients
included in this single center analysis were those admitted to the ICU
following an on-pump cardiovascular surgery, who were given a bolus of
20% albumin within the first twelve hours of ICU admission [24].
The clinical indications of when to administer FBT was similar to the
study conducted by Wigmore, et al [20, 24]. After the administration
of FBT, 55% of the study cohort demonstrated an appreciable increase in
MAP (>10%) [24]. This effect dissipated in nearly half
of the responders within 30 minutes of their FBT, returning to their MAP
baseline [24]. Interestingly, the impact FBT had on CI for the study
cohort varied from these results [24]. While only 25% of
participants had a significant increase in CI (>15%)
immediately after receiving hyperoncotic albumin, 25% of the cohort
demonstrated a delayed increase in CO, one that persisted beyond 30
minutes [24]. One explanation to these incongruent findings is the
notion that the effect of hyperoncotic albumin peaks at 30 minutes after
administration [24].
The parameters used when FBTs were given in these two analyses
highlights the individualized practice of fluid resuscitation in the
perioperative setting [12]. In a retrospective, non-interventional
descriptive study performed at a tertiary care medical center, Torbic,
et al. aimed to describe the prescribing practice of concentrated
albumin within the ICUs at their institution (n=2,066) [12]. During
the study period, the majority of the hyperoncotic albumin administered
within their institution occurred in the cardiovascular ICU (CVICU) in
patients following cardiac surgery (n=1509, 73%) [12]. In this
analysis, authors describe the medical conditions that may benefit from
the administration of human albumin, where the use of hyperosmotic
albumin is potentially superior to isooncotic albumin [12]. The
evidence-based indications include post-subarachnoid hemorrhage
vasospasm, large-volume paracentesis, spontaneous bacterial peritonitis
and hepatorenal syndrome [12, 56-58]. Based on these indications,
authors discussed the hyperosmolar albumin administration practices in
the CVICU, emphasizing the use of hypertonic albumin in response to
hypotension, low urine output or perceived hypovolemia to be
inappropriate and unsupported by the current literature [12]. From a
health care utilization standpoint, the authors also discuss the
enormous cost associated with the use of concentrated human albumin
[12].
In an effort to identify best practice and further delineate the
appropriateness of the routine administration of concentrated albumin,
Rabin, et al., studied the effect of restrictive albumin practices
following cardiac surgery over a thirteen month period [52]. During
this retrospective analysis, authors investigated the use of
hyperoncotic albumin in patients admitted to the CVICU following cardiac
surgery before and after institutional guidelines limiting the use of
albumin administration (n=1,401) [52]. Outcomes of interest included
the amount of albumin use, number of blood transfusions, ventilator free
days, mortality and length of hospital stay [52]. During the first
nine months of the study period, there were no restrictions in albumin
administration [52]. Following the implementation of the restrictive
guidelines, the use of albumin was limited to patients that required
more than three liters of crystalloids 24 hours after surgery [52].
Following the initiation of restrictive guidelines, authors found the
amount of hyperoncotic albumin given decreased from a mean of 280
monthly doses to a mean of 101 monthly doses (p <0.001)
[52]. This decrease in 180 albumin doses equated to more than
$45,000 saved per month [52]. Authors found no difference in
average length of stay, mortality, ventilator free days or number of
transfusions required between the two study period [52].