Adrenal incidentaloma: Anesthetic management, the challenge and the outcome.

Adrenal incidentalomas is a term increasingly used now and applied to any adrenal mass that is found incidentally on an imaging of a patient with complaints not related to adrenal pathology. This case report presents a patient with incidental adrenal mass that was evaluated according to proposed recommendations and planned for robotic-assisted laparoscopic adrenalectomy. There is increasing number of literatures on the advantages of robotic surgery for adrenal resection; however, there is controversy regarding the hemodynamic stability of patients during these procedures especially with patient suspected to have pheochromocytoma. We included literature reviews on the role of robotics and use of laparoscopy for adrenalectomy and the anesthetic considerations in these procedures aiming to raise awareness and draw attention to this increasingly emerging disease entity.

INTRODUCTION

Adrenal incidentaloma is a term applied to an incidentally discovered adrenal mass on imaging performed for reasons unrelated to adrenal pathology.[1] Its prevalence is rising because of the big volume of radiologic explorations that are done every day. Its frequency in United States is estimated to be 2-9% of autopsies and 1-10% of CT scans and MRIs detect masses of 5 mm or more.[2] It was reported in one study that the overall prevalence of adrenal lesions among the contemporary CT scans with high resolution was 4.4%, and that of benign adrenal masses was 4.2%.[3] They are a cluster of different pathologies, the majority of which are benign and nonfunctioning adrenal adenomas. However, mild hormonal alterations as well as metabolic abnormalities may be present in patients with adrenal incidentalomas. Thus, multidisciplinary approach with biochemical and radiologic evaluation is needed to characterize lesions and identify patient at high risk for hormonal or malignant evolution.[4]

Laparoscopic adrenalectomy has become the standard approach in the management of adrenal mass. This technique is minimally invasive and has the advantage of decreasing convalesces, less postoperative pain, and blood loss with improved cosmesis. Robotic-assisted laparoscopic adrenalectomy has been emerging as another modality less than a decade ago, and it is gaining increased acceptance among urologic community but it has been questioned concerning increased morbidity and negative hemodynamic sequelae especially in the management of pheochromocytoma.

In this case, patient presented with incidental adrenal mass that was considered nonfunctioning adrenal tumor and she was scheduled for Robotic adrenalectomy but she developed hypertensive crisis intraoperatively and surgery was converted into open adrenalectomy and patient was stabilized till end of operation. This case serves to emphasize the importance of being well prepared for such unexpected occurrences and the need for good communication and collaboration between urologic surgeons, endocrinologists, and the anesthesiologist in the management of adrenal incidentalomas. As well as to give highlights on the advantages and drawbacks of using robotic surgery.

CASE REPORT

A female, 54 years of age, presented with complaint of vague abdominal pain with nausea and general fatigue, was found incidentally to have right adrenal mass on ultrasonography. CT scan of abdomen confirmed the presence of the mass and laboratory studies were done and it was normal as shown in Table 1 and 2. Patient had no history of hypertension, diabetes, or symptoms of catecholamine excess secretion and the mass considered nonfunctioning and patient was scheduled for robotic-assisted laparoscopic adrenalectomy.

Table 1

Preoperative biochemical and hormonal tests results

Table 2

Complete blood count result

Preoperative

History

She had no history of hypertension, diabetes or cardiovascular disease, had no allergies and not taking any regular medications.

Physical examination

On examination patient was conscious, comfortable, looks quite obese (body weight 91.3 kg, BMI: 36.5), vital signs were normal. Preoperative evaluation of ASA is classified as 1, airway assessment of Mallampati 2, and good mouth opening with appropriate neck motion. Cardiovascular and respiratory are clinically free and rest of examination is unremarkable.

Electrocardiogram

Showed evidence of RBBB that considered insignificant.

Laboratory investigations

Included biochemical and initial hormonal studies with complete blood count, results were within normal or not conclusive.

Imaging

CT abdomen reported large poorly defined lesion, homogenous, enhanced on the right suprarenal gland measuring (8.9 × 7.4 × 6 cm), compressing inferior surface of liver and upper pole of right kidney [Figure 1].

Figure 1

CT abdomen reported large poorly defined lesion, homogenous, enhanced on the right suprarenal gland measuring (8.9 × 7.4 × 6 cm), compressing inferior surface of liver and upper pole of right kidney

Reviewing the preoperative vital signs chart of the patient since admission confirmed that the patient had no persistent or episodic increase in blood pressure. Also, diabetic monitoring failed to show evidence of hyperglycemia [Figure 2].

Figure 2

Preoperative vital signs chart

Intraoperative

In the operating room, ASA standard monitoring were connected, patient preoxygenated with 100% O2 by face mask followed by induction of anesthesia using Fentanyl 100 mcg, propofol 200 mg, and cisatracurium 10 mg. Mask ventilation and intubation were easy. Inhaled sevoflurane 3.5% was used initially. Suddenly patient BP started to rise reaching 230/160 responded to single dose of labetalol 5 mg and BP start to lower. Right radial arterial line inserted with arterial blood pressure monitoring was connected, and also right internal jugular central line with central venous pressure monitoring. Two peripheral intravenous accesses established with 14G catheter in both hands. Anesthesia was maintained with sevoflurane 2.5% in oxygen and air and cisatracurium infusion to maintain muscle paralysis at an initial rate of 10 mg/h. Phenylephrine and nitroglycerine infusions were kept standby, with ephedrine, and adrenaline and noradrenaline infusions were readily available to use in the case of emergency. Intravenous fluids set on both peripheral lines at total rate of 200 ml/h. The patient was positioned in left lateral position with pressure points padded. Operation started with setting up the Da Vinci Robotic surgical system, 5 mg morphine with 100 mcg fentanyl given at time of incisions. Patient BP was stable during that time within the accepted range. With the duration of 1.5 h after incision BP started to rise to 155/110 controlled with 100 mcg nitroglycerine, but BP kept fluctuating with manipulation of the mass and shooting to >200/160 and crisis not responded to antihypertensives given (labetalol boluses and nitroglycerine infusion) based on that and after 3 h from incision robotic converted to an open surgery. There was difficulty in resecting the tumor and controlling the venous drainage of the gland until 2 h after opening with variable fluctuations of BP [Figure 3].

Figure 3

Intraoperative blood pressure fluctuation

The arterial blood gas ABG analysis based on the baseline values after conversion into open showed derangement [Table 3], with decrease in the arterial partial pressure of O2 from 142 to 71.3 mmHg and evidence of metabolic acidosis.

Table 3

Intraoperative arterial blood gas results

Urine output was satisfactory at a rate of 0.5-0.75 ml/kg/h. Central venous pressure CVP slowly increased from 10 cm H2O at the beginning of operation to 23 cm H2O before conversion into open surgery to decline back to the initial value. Peak airway pressure did not exceed 30 cm H2O throughout the procedure. The following ABG showed improvement after oxygenation and 100 ml 8.4% sodium bicarbonate. Patient was started on insulin infusion of 20 U/h because of hyperglycemia (blood sugar result of 18.4 mmol/L).

Blood pressure continued to fluctuate with manipulation of the mass, and when the tumor was removed blood pressure dropped to hypotensive levels but stabilized with initiation of noradrenaline and adrenaline infusions at a rate of 0.3 and 0.1 mcg/kg/min, respectively. She received two units of packed red blood cells started after 1 h of opening and four units of fresh frozen plasma throughout the procedure. After 3 h of conversion into open surgery, operation ended. Patient was hemodynamically stable on continued vasopressors, blood loss estimated to be 1.5 L, total fluids given about 5 L, and total urine output 1.2 L.

Patient was awakened and could be extubated uneventfully, and she was transferred fully in conscious state to the surgical ICU.

Postoperative

On admission to the surgical ICU, patient had a blood pressure of 80/50 with MAP of 61 with HR of 80 bpm. She was kept on vasopressors (noradrenaline and adrenaline 0.2-0.15 mcg/kg/min, respectively). In addition, her blood pressure was maintained on the acceptable range. Eight hours later, she developed hypotension with BP of 70/50 and vasopressor doses doubled but BP not raised. It was noted that patient had bleeding in the drain estimated about 715 mL, with drop in the Hb of patient to 5.07 g/ dl, and decrease in the platelet count and prolonged coagulation profile, so resuscitation was started with blood transfusion (six units PRBC, six units platelets, ten units FFP). Intrabdominal bleeding was suspected but could not be confirmed due to unstable general condition of the patient. Patient's general condition was stabilized with these conservative measures. Vasopressors could be withdrawn after 2 days and she was discharged from the ICU to the ward on fifth day postoperatively with good general condition.

The pathology report of the mass came back with a result confirming the mass as benign adrenocortical adenoma. Patient was discharged after 1 week of the procedure to be followed at the outpatient clinic.

DISCUSSION

Adrenal incidentalomas are clinically silent adrenal masses that are discovered incidentally during diagnostic testing for clinical conditions unrelated to suspicion of adrenal disease.[5] Adrenal incidentalomas constitute an emerging clinical entity due to the increased use of abdominal imaging for diagnostic purposes. Most often, it consists of benign-nonfunctioning lesions. The two main concerns with regard to an adrenal incidentalomas are whether it is hormonally active or malignant.[6] These questions must be addressed when evaluating adrenal incidentalomas.

Although, in general, the majority of adrenal incidentalomas are nonhypersecretory adenomas, hormonal screening evaluation can reveal a significant number of cases of clinically unsuspected hormone-secreting adrenal tumors.[7] So a careful personal and family history, review of systems, and physical examination should be performed in all patients.

Screening for pheochromocytoma is mandatory in all cases because of this condition's high rates of morbidity and mortality, as well as because of its unpredictable course. It is completely asymptomatic in up to 15% of cases.[8]

The adrenal tumor size has been used to differentiate between benign and malignant adrenal masses. Risk of malignancy increases with the adrenal tumor size, cutoff values ranging from 4 to 6 cm have been proposed by different clinicians for surgical resection of adrenal masses.[9]

Nowadays, the role of surgery in the treatment of adrenal incidentalomas, considering their biologic behavior, is still debated. Surgery is mandatory in cases of hyperfunctioning adrenal masses, in the presence of suspect radiological malignancy, and when the maximum diameter is 4 cm or more.[10]

Laparoscopic adrenal surgery has significantly improved during the last years. Thus, at the moment it is possible to define such technique as the therapeutic “gold standard” option in the treatment of the adrenal tumors. However, some doubts are still remaining concerning the feasibility of laparoscopic adrenalectomy in the case of malignant adrenal tumors, hyper-vascular tumors (pheochromocytoma), and indeterminate incidentaloma.[11]

In recent years, as robotic surgery has become more prevalent, the indications for its use have come to encompass a wider variety of procedures, including adrenalectomy. The first robotic adrenalectomy in a human was reported in 2001 by Horgan and Vanuno among series of 34 robotic-assisted general surgery procedures.[12]

Opera-tive time is commonly longer in robotic trials due to being performed prior understanding the efficient sys-tem setup. System docking times have been reported to be up to 35 min, but with experienced teams, docking should be completed in about 5 min-.[13]

Surveys of robotic general surgeons are limited due to the small numbers of high volume users, but most surgeons feel that the learning curve of surgical robotics in general surgery is mainly due to the setup and docking of the system.

The reported conversion rates of robotic surgery to standard laparoscopy in most of the studies reviewed is very low or absent.

Brunaud et al.,[14] suggest that robotic adrenalectomy evaluation should be performed to minimize learning curve effects. Even when using a robotic system, several factors remain important in determining operative time (side, experience, and assistant's skill). Difficult patients (obese patients and/or those with large tumor) seem to be good candidates of unilateral robotic adrenalectomy. Other potential advantages that still need to be evaluated are perioperative hemodynamic modifications in patients with pheochromocytoma and ergonomics for the surgeon.

The use of robots in surgery is likely to increase because of enhanced precision and control. Anesthesiologists need to be aware of this fast-changing field and how it affects anesthetic techniques and their delivery. As surgeons gain expertise with robotically assisted surgery, operative times are expected to decrease dramatically to the point of traditional open surgery. The inability to move the patient while the robot is engaged with the patient is a challenge when attempting to alter cardiac filling pressures by gravity, causing pharmacologic agents to be used more often. Anesthesiologists have experienced working in locations that are remote from the patient's airway. It should come as no surprise that robotically assisted surgery of the upper body also presents that challenge. Improved monitoring methods are needed to make remote anesthesia safe and practical. Perhaps the “minimally invasive” revolution will advocate earlier patient recovery and the increased implementation of regional anesthetic techniques. The extent of the surgical stress response may be attenuated, ultimately minimizing the inflammatory response.[15]

Robotics is increasingly used in the urological procedure; as adrenal masses findings are raising with increasing volume of radiological imaging there is raising orientation toward treating these tumors with the robotic approach. It is considered that adrenal surgery should be performed by the urologist, because it is the medical specialty that knows the best this anatomical region.[16]

The anesthetic considerations applied for laparoscopic surgery are also applied for robotic-assisted cases with added special consideration to the use of robotic during procedure. There is no certain published anesthetic approach in managing patients with adrenal incidentalomas that can be applied to all patient, most of the patients have clinical pictures that cannot be attributed solely to the adrenal pathology until imaging findings suggest the mass to be the cause for the presentation of the patient.

With the age range patients present with adrenal incidentalomas, it is not unusual for these patients to have co-morbidities such as hypertension and/or diabetes mellitus. This usually presents a challenge to the anesthetist regarding how to best manage these patients preoperatively and perioperatively, and the conflicting issue is when some patients are totally asymptomatic and have no symptoms or signs of adrenal dysfunction whether to manage them as nonfunctioning tumor especially with normal biochemical studies or to manage them as probable suspected pathology such as Cushing's disease or pheochromocytoma.

The preoperative assessment is usually the standard assessment with special attention to the history and physical signs of the patient regarding symptoms and signs of cortisol or catecholamines excess secretion. The biochemical studies are of paramount importance to decide if the tumor is functioning or not that has an implication on the anesthetic plan of the patient. Endocrinologists must be incorporated in the management of these patients. Patients with hypertension suspected to be secondary to pheochromocytoma should be treated and premedicated with alpha blockers.

The conduct of anesthesia in robotic surgery is with standard induction and airway control with the tracheal tube. Full routine monitoring including core temperature measurement should be applied. The arterial line or central access is not mandatory, unless patient has co-morbidities. A large bore cannula is usual as establishing further i.v. access once the procedure has started is difficult. As the procedure may be prolonged, it is sensible to use a volatile agent for maintenance with a favorable recovery profile, for example, desflurane or sevoflurane. Many institutions choose to run a background infusion of remifentanil. The patient must remain paralyzed until the robot is undocked at the end of the procedure, usually with a continuous infusion of a nondepolarizing neuromuscular blocking agent. It is important that the anesthetist is especially rigorous in ensuring that there is no pressure in vulnerable areas, especially the elbows, axilla, back, and shoulders.[17]

The position of the tracheal tube should be checked regularly. There are reports of airway obstruction during insufflation of the pneumoperitoneum, secondary to tracheal tube migration resulting from physical movement of the diaphragm and mediastinum by the pneumoperitoneum. The physiological effects of pneumoperitoneum are numerous and can be severe. It is not uncommon for the patient to experience cardiovascular instability and hypoxaemia on carbon dioxide insufflation of the peritoneum and it is important to exclude other causes such as tracheal tube migration. If the patient remains haemodynamically unstable or hypoxaemia is resistant to application of PEEP, the operation may have to be abandoned or converted to an open procedure. End-tidal carbon dioxide should be maintained at normal levels to reduce the risk of further potentially catastrophic increases in cerebral blood volume and intracranial pressure.[17]

The robot itself introduces complexities that must be considered. It is an extremely heavy and bulky piece of equipment. The theatre can become very cramped with the addition of the surgical console, video tower, and robot cart. The arrangement of the equipment should be established and practiced in advance at institutions using a robot for the first time.[17]

When the robot is docked in position and the instrument and camera inserted through the laparoscopic ports, the robotic arms have little natural elasticity. Therefore, it is critical that the patient remains absolutely still, otherwise tearing could occur at the laparoscopic port sites. The table position must not be moved under any circumstances unless the surgical instruments are disengaged. In addition, patient coughing could cause serious injury and must be avoided with continuous muscle relaxation.[17]

Finally, the bulk of the robot is positioned over the abdomen and chest. Although the incidence of airway or serious cardiovascular events are no greater in robot-assisted surgery, if they do occur, the position of the robot will interfere with effective cardiopulmonary resuscitation and airway interventions. The theatre team should practice and be familiar with an emergency drill for the removal of the robotic cart.[17]

The successful use of the robot to assist in surgery depends upon excellent communication between all members of the theatre team. The surgeon sits behind a console, away from the site of operation, but must communicate effectively with both anesthetic staff and his operative assistant at the patients’ bedside. The loss of eye contact can have a dramatic effect on the quality of communication and special care must be taken to ensure that transfer of information is precise and clear. This is aided by the addition of audio speakers to the video tower that transmit the operating surgeon's voice.[17]

When the robot's arms have been removed from the patient, neuromuscular block may be reversed.

The postoperative course is usually uneventful. The incidence of complications is low. Blood transfusion is not normally required as intraoperative blood loss is very low, but significant hemorrhage may be insidious and the patient should be carefully monitored in the immediate postoperative period. Multimodal analgesic agents including acetaminophen and nonsteroidal antiinflammatory drugs (if there are no contraindications) should be administered. A small percentage of patients require opioids.[17]

The patient presentation reported in this case can serve as template for the scheme of management of patients with adrenal incidentalomas. She was incidentally found to have adrenal mass and was asymptomatic with near normal biochemical and hormonal studies; her age is typical for the presentation of adrenal mass. Patient was considered obese with BMI of 36, the association between obesity and nonsecreting adrenal incidentalomas has never been proven, but it is demonstrated in one study[18] a strong association between obesity and incidentally discovered nonfunctioning adrenal masses.

Although a study reported that patients with nonfunctioning adrenal incidentalomas exhibit higher fasting glucose with insulin resistance and dyslipidemia as part of the metabolic syndrome,[19] this patient had nearly normal blood glucose and diabetic monitoring did not show results of high blood sugar necessitating insulin administration. However, intraoperatively she developed hyperglycemia and needed insulin infusion to control it and this could be part of stress response and glycogenolysis or due to release of cortisol hormones from the mass during manipulation.

This patient did not receive any antihypertensives as preoperative medications because she had no hypertension or symptoms of catecholamine secretion, and her biochemical tests and hormonal results did not give any clue that this patient could have secreting mass. In spite of that the intraoperative plan takes into account the high possibility of occurrence of hypertensive crisis and other events. For these reasons patient had the arterial and central line in place with emergency drugs ready and handy.

Patient with adrenal masses suspected to be pheochromocytoma represent the greatest challenge for the anesthetist in the perioperative management. There have been several studies on how to best manage these patients with various anesthetic techniques. However, manipulation of the tumor during open surgery, with its hemodynamic responses, may be inevitable but can usually be of short duration. Laparoscopic excision of pheochromocytoma requires persistent tissue traction and diathermy or ultrasound coagulation that may cause sustained hemodynamic consequences of at least the same severity as may be expected during open surgery, but for a rather longer period of time. Laparoscopic surgery may prove too difficult, requiring open surgery on the same occasion or subsequent.[20] Patient reported in this case showed severe hemodynamic instability with hypertensive crisis that risk the whole outcome of the procedure and increased its risk of morbidity. The decision to convert the robotic surgery into open was taken in this case to minimize the adverse outcome that could result from the prolonged operative time with the robotic manipulation and resection of the mass with the anticipated difficulty to ligate the venous drainage of the big adrenal mass. Patient was adversely affected hemodynamically and metabolically with the time consumed and the nature of the surgery adding to that the effect of hormones released with manipulation of the mass.

With vigilant efforts and vigorous attempts patient could be stabilized till end of procedure and successfully extubated and shifted on inotropes to the surgical ICU.

Although this patient's tumor behaved as intraoperative pheochromocytoma excision, the preoperative laboratory studies did not give that impression with clinical presentation, the pitfall was the late catecholamine studies results that was sent outside the laboratory; based only on clinical presentation it was decided to proceed with the procedure. The results of catecholamines came late supporting the diagnosis of secreting adrenal mass that could be a pheochromocytoma, but the postoperative pathological diagnosis supports the finding of adrenocortical adenoma that is the most common pathological finding among adrenal incidentalomas.

In conclusion, incidental adrenal masses will continue to rise demanding the need to establish a protocol approaching these patients to reach the optimum outcome in managing adrenal incidentalomas. It is mandatory that the endocrinologist as well as the urologist and anesthesiologist reach an understanding of the nature and pathophysiology of the adrenal incidentalomas and be incorporated in taking the decisions as how best to manage such patients and tailored the plan according to the patient's situation. It can be implied here in this case report that the tumor size should not be the primary factor in determining the adrenalectomy approach with robotic assistance. In this case, robotic surgery appeared to be unsafe for the patient individual situation and ineffective in resecting the mass with increase in the operative time and risk of the mortality and morbidity. We suggest further prospective or case control studies regarding the use of robotics in urological or other specialized procedures and to monitor the hemodynamic response during these procedures.