Cognitive outcome and CABG surgery: a case of the

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Cognitive outcome and CABG surgery: a case of the
NeSECC UPTODATE 2012 nr. 1; p.20
Cognitive outcome and CABG surgery: a case of the Emperor’s
new clothes?
Dr. D. van Dijk
University Medical
Center Utrecht,
The Netherlands,
[email protected]
“The Emperor’s New Clothes” is a short
tale by Hans Christian Andersen about
an Emperor who cares for nothing but his
wardrobe. He hires two weavers who promise him the finest suit of clothes from a
fabric invisible to anyone who is unfit for
his position or “just hopelessly stupid”.
The Emperor cannot see the cloth himself,
but pretends that he can for fear of appearing unfit for his position or stupid, and
his ministers do the same. When finally
the Emperor parades before his subjects
in his new clothes, a little boy cries out,
“But he isn’t wearing anything at all!” The
Emperor cringes, suspecting the assertion
is true, but holds himself up proudly and
continues the procession.
Many researchers including myself have
studied postoperative cognitive decline
(POCD) following coronary artery bypass grafting (CABG) for years. During
three decades we have obtained funding
to set up psychometric test facilities and
assess cognitive performance in thousands of CABG patients. POCD is diagnosed when patients have a lower psychometric test performance after their
surgery, than before. Again and again we
found alarming incidences of POCD, not
only in the first weeks after CABG, but
also during long-term follow-up. Not surprising, we have been able to publish this
disturbing finding in prestigious journals
and newspapers.1
We have always attributed the high incidence of POCD after cardiac surgery
to the use of cardiopulmonary bypass
(CPB). This seems reasonable because several studies have demonstrated potentially harmful side effects of CPB on the
brain. This includes cerebral micro em-
boli during CPB and cerebral edema after
CPB. Over the last 8 years, however, randomized trials have compared cognitive
outcomes after off-pump versus on-pump
CABG. Surprisingly, these trials failed to
show a clear benefit of avoiding CPB on
the incidence of POCD.
The little boy who cried out, “But he isn’t
wearing anything at all!” is Dr Lars Rasmussen, who assessed the reliability of
definitions of POCD.2 Dr Rasmussen
administered a baseline and a followup psychometric test battery to healthy
volunteers, with a time interval of three
months. He applied the most commonly
used definition of POCD to the test results, and found that according to this definition, 29 percent of the volunteers had
cognitive decline, three months after their
baseline assessment. Apparently there is
substantial natural variation in psychometric test performance and in contrast
to what we thought, it is very difficult to
distinguish true cognitive decline from
random variation in test performance.
Although many people now suggest that
the Emperor’s new clothes in fact did not
exist at all, we are still uncertain about
POCD. How can we ignore the many
transcranial Doppler studies showing
NeSECC UPTODATE 2012 nr. 1; p.21
hundreds of emboli during CPB, or the
post-mortem examinations of the brains
of CABG patients, also revealing evidence
of cerebral emboli? And how can we close
our eyes to the patients who are unable to
return to employment after their CABG
because of mental problems.
References
1. Newman MF,
2.
et al. Longitudinal assessment of
neurocognitive function after coronary artery bypass surgery. N Engl J Med 2001;344:395-402.
Rasmussen LS, et al. The assessment of postoperative cognitive function. Acta Anaesthesiol Scand
2001; 45: 275—89.
What we know, however, is that the incidence of true POCD is much lower than
we always thought, and that presence of
advanced age and atherosclerotic disease
are more important determinants of longterm POCD than the use of CPB.
Hemolyse bij het gebruik van drie verschillende centrifugaalpompen binnen ECLS setting
Hemolyse is een verschijnsel waarbij o.a.
mechanische krachten van de centrifugaalpomp de erytrocyten laten desintegreren. Dit verschijnsel treedt op tijdens
het gebruikmaken van ECLS, waarbinnen de centrifugaalpomp een essentieel
onderdeel vormt.
In dit onderzoek worden drie verschillende centrifugaalpompen met elkaar
vergeleken; Sorin RevOlution, Medtronic
BPX80 en Maquet Rotaflow.
Simultaan zijn drie, op de centrifugaalpomp na, identieke ECLS systemen opgestart en hebben voor een periode van
vijf dagen onder gelijke omstandigheden
gecirculeerd. Alle drie systemen bevatten
een gelijk hoeveelheid prime van een gelijke samenstelling, bestaande uit volbloed
aangevuld met erytrocytenconcentraat.
Het hier genoemde experiment is in triplo uitgevoerd. De mate van hemolyse is
gemeten aan de hand van hemolytische
index, lactaatdehydrogenase (LDH) en
kalium (K+).
Er zijn geen significante verschillen meetbaar tussen de Sorin RevOlution, de Medtronic BPX80 en de Maquet Rotaflow op
basis van p>0.05 significantie voor de hemolytische index, LDH en K+.
A. Abbas EKP
LUMC, Leiden