During perioperative period of a carcinoid tumor, the most important goals are to prevent the release of bioactive mediators (by avoiding triggering factors) and to perform an adequate management of an eventual carcinoid crisis (despite efforts to prevent it) [1
]. Additionally, our patient had a previous history of anaphylactic reaction which was not fully studied. Ideally, surgery should only be performed when this study is completed, but the risk evaluation should not delay urgent or cancer surgery, like the described case [4
]. In addition to the allergic reaction, we have considered the possibility of that episode being a carcinoid crisis as a first manifestation of carcinoid tumor, since many of the clinical features are shared by the two entities (hypotension, cutaneous flushing, bronchospasm, diarrhea [4
Over the last decades, several attempts have been made to prevent carcinoid crises by using certain drugs instead of others which provoke endogenous release of catecholamines
and histamines [7
]. Premedication with benzodiazepines and antihistamines is useful in reducing anxiety and preoperative stress [1
], but its administration may be controversial, since the release of histamine occurs more often with gastric carcinoids [3
]. Although steroids possibly do not avoid anaphylactic shock, they may reduce reactions caused by non-specific histamine release [4
]. However, the landmark of prophylaxis involves the administration of octreotide [7
] and it has been reported as an efficacious treatment of carcinoid syndrome [1
] by preventing mediators release and its effects [1
There are many recommendations for appropriate prophylactic use of octreotide concerning timing, duration, dose and patient selection. Some authors recommend a preoperative subcutaneous dose of 100 µg of octreotide and another 100 µg intravenously just before induction of anesthesia [3
]. On the other hand, others recommend a single preoperative dose of 150-500 µg of octreotide for symptomatic patients [7
]. Guidelines from the United Kingdom support prophylactic administration of somatostatin analogues
to prevent a potential crisis and recommend octreotide in a constant infusion of 50 µg/hr during 12 hr before and until 14-48 hr after surgical intervention for all patients with a functioning carcinoid tumor [8
]. The North American Neuroendocrine Tumor Society (NANETS) consensus guidelines recommend, in patients with suspected carcinoid syndrome who undergo major procedures, a preoperative bolus of octreotide 250-500 µg IV with extra doses available throughout the procedure [9
However, some considerations should be done to these recommendations: firstly, they are mostly based on cases reports; secondly, all recommendations are made concerning patients with carcinoid syndrome and thirdly, outcome data of the suggested regimens’ effectiveness is still not consistent. For example Kinney et al. [10
] performed a retrospectively study in a group of patients who were submitted to abdominal surgery for metastatic carcinoid tumors. They found an incidence of intraoperative complication of 11% among patients who did not receive intraoperative octreotide and of 0% among those who received at least one dose. However, it is not mentioned the percentage of patients who made preoperative octreotide. Among the 6 patients who only received preoperative octreotide alone, one (17%) had an intraoperative complication. Massimino et al. [7
] evaluated retrospectively the effectiveness of 500 µg prophylactic octreotide dose on preventing carcinoid crisis
in patients with carcinoid tumors (with and without carcinoid syndrome) undergoing abdominal surgeries. They found no correlations between the presence of carcinoid syndrome and intraoperative complications or carcinoid crisis; prophylactic octreotide therapy did not also show any correlation with intraoperative complications, indicating that a preoperative bolus would not prevent all intraoperative complications.
A recent meta-analysis for the prophylactic effectiveness of somatostatin analogues (SSTA) that included these two studies showed that perioperative carcinoid crisis was similar despite the prophylactic administration of SSTA, and therefore the prophylactic use of octreotide was not useful in preventing carcinoid crisis [11
]. However, authors alert to the use of the results with caution, seeing that the studies included were both retrospective and that the quality of evidence is questionably. Having all of this in mind octreotide was not given prophylactically in our case, but it was available in the operation room in case it was necessary.
There are many triggers in the intraoperative setting that can stimulate the release of carcinoid mediators: the use of histamine
releasing drugs, response to intubation, hypo and hypertension, insufficient analgesia and intraoperative tumor handling, among others [1
A balanced technique is the most common an aesthetic technique reported, although combined anesthesia has been used successfully for management of patients with carcinoid tumors [1
]. In our case, the patient had aortic valve prosthesis with obstruction, which is a clear contraindication to a neuraxial technique.
Considering the possibility of an allergic reaction to one of the drugs used in the previous anesthesia, we chose different drugs, as recommended in these situations [4
]. The drugs were chosen taking into account their potential to release histamine and the possibility of cross-reactions. Although thiopental has a potential to release histamine, the clinical experience has not been adverse [3
]. NMB agents have a high degree of cross-reactivity, 65% by skin testing [5
] and, if possible, should be avoided [4
], which was not our case. Remifentanil has a very little potential of histamine release [4
] and its infusion provides adequate analgesia with suppression of the intubation stimulus and a rapid titration in order to quickly meet the analgesic requirements during the surgery.
In our case, hypotension
may have several causes such as anesthetic drugs, aortic stenosis, and essential chronic hypertension and associated hemodynamic liability, release of carcinoid mediators, anaphylactic reaction and hypovolemia, among others. The hypotension should be promptly treated, because it can trigger itself the release of carcinoid mediators. However the treatment with sympathomimetic agents may even increase it [1
]. Along with fluid administration, IV octreotide is the most effective treatment described for hypotension associated with carcinoid tumor [1
]. In our case, by verifying the absence of response to fluid administration and phenylephrine and the onset of cutaneous flushing, we assumed facing the initial phase of a carcinoid crisis. Octreotide administration prevented its progression.