336
CANADIAN JOURNAL OF ANESTHESIA
Clinical manifestations include symptoms of gastroin-
testinal hypermotility and vasomotor instability.
Symptoms such as nausea, vomiting, diarrhea, cuta-
neous flushing, hypertension, and hypotension are seen
antagonists, kallikrein inhibitors, and steroids among
3,4
others. However, octreotide appears to be the most
efficacious treatment for carcinoid syndrome reducing
14,15
symptoms in more than 70% of patients.
Serotonin
5
in about 80% of patients. Cardiac involvement, includ-
antagonists were used in the past with limited success
but may still have a role as a second line treatment if
octreotide therapy fails. Other pharmacological inter-
ventions suppressed symptoms only occasionally, and
ing pulmonic or tricuspid valve fibrosis and the occur-
rence of tachyarrhythmias, is seen in about 40% of
5
patients. Bronchospasm, hepatomegaly, and hyper-
3,5
14,15
glycemia are less common symptoms.
often resulted in significant side effects.
Orthotopic liver transplantation is a recent treat-
ment option for patients with extensive hepatic carci-
noid metastases and disabling symptoms. Although
still controversial as an indication, liver transplantation
appears to result in a prolonged disease-free interval
and a longer survival, as well as in a considerable pal-
The octreotide dosing regimen chosen for perioper-
ative management consisted of 50 µg and a 50 µg iv
injection prior to incision, followed by a continuous iv
infusion of 50 µg·hr , and additional 50 µg boluses to
treat episodes of hemodynamic instability. The outlined
–1
dosing regimen seems to be the best document-
8,9
13,16,17
liation of symptoms.
A recent multicentre study
ed.
However, the optimal dose of octreotide has
showed a five year survival rate of 69% in metastatic
carcinoid tumours . This is considerably higher than
not been studied systematically. Following these recom-
mendations, there were still acute increases in blood
pressure that appeared related to increased surgical
manipulation of the liver. However, such changes were
never threatening. On two instances, when the mean
arterial pressure (MAP) increased to 130 mmHg, it
returned to baseline within minutes after an additional
50 µg octreotide iv. Doses of either phentolamine or
esmolol were concomitantly administered and therefore
the reduction in blood pressure cannot solely be attrib-
uted to octreotide. Vasoactive drugs were co-adminis-
tered with octreotide to abolish the hypertension
quickly. There is at least one report indicating a delay of
several minutes before octreotide became fully effective
2
the five year survival rate of 25% after nontransplant
1
0
treatment.
Approximately 20 different mediators released from
carcinoid tumour cells are known. The most important
ones contributing to the carcinoid syndrome appear to
3
be serotonin, histamine, and the kinin peptides. In the
past, anesthetic management has focused on blocking
histamine and serotonin receptors and avoiding drugs
facilitating the release of mediators from tumour cells.
Drugs thought to trigger mediator release include the
opioids meperidine and morphine, the neuromuscular
relaxants atracurium and mivacurium, and the cate-
cholamines, including medications which induce their
release. The use of thiopental has been discouraged by
some because in vitro studies have demonstrated a dose
3
after intravenous administration.
The anhepatic and post-anhepatic phases were
uneventful. Contrasting with the pre-anhepatic phase,
the blood pressure did not show marked variations. The
exclusion of the liver from the systemic circulation dur-
ing the anhepatic phase may explain this. For the same
reason, epinephrine administration during the anhepat-
ic phase may have been safe. However, in the post-
anhepatic phase the transplanted liver may not have
been able to metabolize mediators from remaining
tumour cells draining into the portal circulation. For
this reason the octreotide infusion was continued
throughout surgery and into the intensive care unit stay.
Both crystalloid and colloid solutions (albumin 5%)
were used for intraoperative fluid resuscitation. The
use of albumin may be questioned by some because of
the potential risk of transmitting an infectious disease,
either viral or via prions. However, the use of heat pas-
teurized albumin has an excellent safety record.1
Currently, the concerns about transmitting an infec-
tious disease via albumin seem mainly theoretical.
Therefore, the use of albumin still seems appropriate
for selected cases.
3,4,11
dependent histamine release from skin mast cells.
However, thiopental triggered histamine release seems
1
1
to be of minimal importance in the clinical setting.
The use of succinylcholine has also been discouraged
because the increase in intra-abdominal pressure result-
ing from muscular fasciculations could potentially trig-
ger mediator release. A recent review showed no
evidence to support this view and we chose to use suc-
cinylcholine secondary to a potentially difficult airway
3
and for a rapid sequence intubation. There were no
adverse effects.
More recently, anesthetic management of carcinoid
syndrome has focused on preventing mediator release
from carcinoid tumour cells with the somatostatin
analogue octreotide. It has been suggested that the
use of octreotide renders the administration of drugs
previously used in the management of carcinoid syn-
8,19
12,13
drome superfluous.
These drugs were used to
block the action of mediators already released into the
circulation and included serotonin and histamine