Intraoperative tumor lysis syndrome in a child with Wilms' tumor.

Tumor lysis syndrome in an onco-metabolic emergency resulting from massive lysis of rapidly proliferating malignant cells seen commonly in patients with hematological malignancies such as acute lymphocytic leukemia and Burkitt's lymphoma and is quite rare in solid tumors. Spontaneous development of tumor lysis has been described among other trigger factors such as corticosteroid therapy, anesthesia, tumor manipulation during surgery and pyrexia. We describe such a case in a 5-year-old boy posted for excision and staging of a massive Wilms' tumor who developed a hyperkalemic cardiac arrest during the procedure and its subsequent intraoperative and postoperative management. Intraoperative cardiac arrest is a stressful situation for both the anesthesiologist and the surgeon, more so when it involves a child. The aim of this report is to make the anesthesiologist aware of the possibility and occurrence of such a phenomenon in children and be adequately prepared for such an emergency.

INTRODUCTION

Tumor lysis syndrome (TLS) in an onco-metabolic emergency resulting from massive lysis of rapidly proliferating malignant cells seen more commonly in patients with hematological malignancies such as acute lymphocytic leukemia and Burkitt's lymphoma.[123] It is generally observed post or during chemotherapy in such patients. TLS is quite rare in solid tumors and very few cases have been described in literature.[4] We describe such a case in a 5-year-old boy posted for excision and staging of a massive Wilms' tumor who developed a hyperkalemic cardiac arrest during the procedure and its subsequent intraoperative and postoperative management. Intraoperative cardiac arrest is a stressful situation for both the anesthesiologist and the surgeon, more so when it involves a child. The aim of this report is to make the anesthesiologist aware of the possibility and occurrence of such a phenomenon in children and be adequately prepared for such an emergency.

CASE REPORT

A 5-year-old boy was referred to the Pediatric Surgery Department with complaints of a large mass in the abdomen for the past 4–5 months. There were no other associated complaints such as nausea, vomiting or abdominal pain. Preanesthetic evaluation revealed no previous surgeries or hospitalization, no medication, no history of any other chronic illness or associated congenital anomalies. Airway examination was normal. Per abdomen examination revealed a tense, distended, nontender abdomen wall with a large solid mass on palpation, which seemed to occupy most of the abdomen [Figure 1]. Radiological evaluation revealed a large 30 cm × 20 cm tumor arising from the right kidney with no intravascular extension. He was posted for excision and surgical staging of the tumor. Preoperative investigations revealed a normal hemogram and normal electrolytes. Renal function tests were also within normal limits.

Figure 1

Large distended abdomen with dilated veins

The patient was taken up for surgery after arranging adequate units of blood and taking informed high-risk consent from the parents. The child was taken into the operation theater (OT) after premedication with midazolam. After establishing basic monitoring and decompressing the stomach with a nasogastric tube, the patient was induced in a slight head up position to decrease respiratory embarrassment due to the abdominal mass. A central venous catheter was inserted into the right internal jugular vein anticipating a large amount of blood loss and fluid shifts.

The abdomen was then opened and revealed a large vascular mass arising from the right kidney [Figure 2]. The tumor was gradually dissected and removed over the next 1 h. Hemodynamic stability in terms of oxygenation and perfusion was maintained with isotonic crystalloids initially and later with packed red blood cells. There was no drastic hypotension noted and the operation seemed to progress uneventfully till the mass was removed from the abdomen. As the surgeons prepared to close the abdomen, suddenly a ventricular tachycardia (VT) rhythm was noted on the monitor, which was initially confused with electrocautery interference, but was confirmed after asking surgeons to stop. Absence of the carotid pulse confirmed a pulseless VT and chest compressions were started while the defibrillator was charged. The patient was revived with return of normal cardiac rhythm after 10 min of resuscitation following the pediatric advanced life support algorithm. He was given 3 DC shocks (2 J/kg), 2 doses of epinephrine (10 mcg/kg), and calcium gluconate (100 mg/kg). A femoral arterial blood gas (ABG) sample was sent while the surgeons rapidly closed the abdomen. The patient was urgently shifted to the Pediatric Intensive Care Unit (PICU). The blood gas sample revealed hyperkalemia (6.8 mEq/L) and hypocalcemia (7 mg/dl). The electrocardiogram (ECG) now showed a sine wave pattern. Anti hyperkalemic measures were instituted in the form of glucose insulin infusion over 10 min, salbutamol nebulization and soda bicarbonate (2 mmol/kg). The patient required inotropic support in the form of dopamine (10 mcg/kg/min) and norepinephrine (0.5 mcg/kg/min). Repeat sample of ABG revealed persistent hyperkalemia and the patient was planned to be put on urgent hemodialysis (HD). Due to hemodynamic instability and high inotropic requirement, the patient could not tolerate HD and arrested again in the PICU. He was transiently revived and the HD was stopped. However, due to resistant hyperkalemia, not at all responding to conventional modes of treatment, patient recurrently went into VT. After numerous attempts at resuscitation, the patient could not finally be revived and was declared after briefing and sensitizing the parents to the prognosis.

Figure 2

Intraoperative tumor arising from the right kidney

DISCUSSION

TLS is basically characterized by hyperkalemia, hyperphosphatemia and hyperuricemia, which has been described by Cairo and Bishop in their definition for both laboratory and clinical criteria.[14] Hyperphosphatemia and thus reciprocal hypocalcemia may lead to tetany and other potentially life-threatening complications. TLS may develop soon after the initiation of chemotherapy wherein large amount of uric acid released may lead to acute renal failure or death.[1]

TLS is known to conventionally occur in hematological malignancies with rapid cellular turnover rates, though in patients with solid cancers it may result due to some form of targeted therapy such as radiation, chemotherapy or hormonal therapy. Sometimes spontaneous development of TLS is also seen.[1] Other trigger factors of TLS include corticosteroid therapy, anesthesia, tumor manipulation during surgery and pyrexia.[567] The anesthesiologist will most likely not encounter such a case on a routine basis, as this emergency is usually described outside the OT, in wards and ICU, postchemo- or radio-therapy in hematological malignancies.

Basic treatment modalities are mainly preventive in high-risk patients, which include aggressive hydration therapy, hypouricemic drugs such as allopurinol and correction of preexisting electrolyte imbalances.[1] Such an altered biochemical profile along with a high tumor load can precipitate TLS during surgery. Drugs such as succinylcholine, which are known to cause metabolic derangements should also be used with caution or avoided, if possible.[8] None of the mentioned offending drugs were used during the case described.

Hyperkalemia is the most life-threatening manifestation of TLS and was also the main manifestation in the present case, which caused the cardiac arrest. Although reverted initially, the hyperkalemia which develops post tumor lysis is known to be resistant to conventional modes of therapy.[14] A case report described intraoperative cardiac arrest in a Wilms' tumor patient, but the etiology was mainly related to acute blood loss and hemodynamic instability.[9] Although the criteria for diagnosis of TLS could not be established because of lack of serum levels of phosphorus and uric acid and rapid downhill course postoperatively, which did not allow proper evaluation, there was strong suspicion for the same in view of no other apparent cause of hyperkalemia and hypocalcemia, which did not respond to anti hyperkalemia measures. Furthermore, there was significant surgical handling of a large bulky tumor. As this patient did not fall into the typical patient profile for tumor lysis, we did not suspect or anticipate this diagnosis preoperatively. It was only a retrospective diagnosis.

The anesthesiologist is the perioperative physician in the OT, and thus the leader of the resuscitation team. The surgeon as the primary physician must do a thorough preoperative evaluation, which is cross-checked during the preanesthetic check-up. Drugs and equipment of resuscitation should be checked and be on standby. During emergency, the anesthesiologist should assign specific roles to his team, take charge, and also include surgeons in the process.

A review of TLS in solid tumors describes cases reported mostly among lung, genitourinary, gastrointestinal and gynecological tumors, and prescribes routine assessment of lactate dehydrogenase, renal function, uric acid, phosphorus and potassium in high-risk patients such as those with advanced or metastatic disease or those undergoing presurgery chemo- or radio-therapy.[4] Very few cases if at all have been described in childhood tumors such as Wilms' tumor. Further studies and reviews, separate diagnostic criteria for pediatric age group, and awareness and preparedness for such a complication would be prudent.

CONCLUSION

TLS is an established entity in hematological malignancies with known trigger factors. TLS in solid tumors are reported to be very few in literature. Though a remote possibility, its occurrence in large bulky tumors of pediatric age group should be borne in mind while anesthetizing such patients. The anesthesiologist should be aware of the risk factors for intraoperative tumor lysis, keep a close watch on the ECG and persuade the surgeon for minimal tumor manipulation. Drugs for cardiac resuscitation including defibrillation and facilities for postoperative ICU care should also be available.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest