Kristen L. Engle

Local Recurrence After Laparoscopic Radiofrequency Thermal Ablation of Hepatic Tumors

AbstractBackground: Since we first described laparoscopic radiofrequency ablation (LRFA) of liver tumors, several reports have documented technical and safety aspects of this procedure. Little is known, however, about the long-term follow-up of such patients. Methods: From January 1996 to February 1999, we performed LRFA on 250 liver tumors in 66 patients. Triphasic spiral computed tomographic scanning was obtained preoperatively and at 1 week, and every 3 months postoperatively. Lesion diameter was measured in the x- and y-axes and the volume estimated; 181 lesions in 43 patients for whom computed tomographic scans available were included in the study. The tumor types were as follows: 64 metastatic adenocarcinomas, 79 neuroendocrine metastases, 27 other metastases, and 11 primary liver tumors. Results: One week postoperatively, the ablated zone was larger than the original tumor in 178 of 181 lesions, which suggests ablation of the tumor and a margin of normal liver tissue. A progressive decline in lesion size was seen in 156 (88%) of 178 lesions, followed for at least 3 months (mean, 13.9 months; range, 4.9–37.8 months), which suggests resorption of the ablated tissue. Fourteen definite local treatment failures were apparent by increase in size and change in computed tomographic scan appearance, and eight lesions were scored as failures because of multifocal recurrence that encroached on ablated foci (22 total recurrences). Predictors of failure include lack of increased lesion size at 1 week (2 of 3 such lesions failed), adenocarcinoma or sarcoma (18 of 22 failures; P < .05), larger tumors (failures, M < 18cm3 vs. successes, M < 7cm3; P < .005) and vascular invasion on laparoscopic ultrasonography. By size criteria, 17 of 22 failures were apparent by 6 months. Energy delivered per gram of tissue was not significantly different (P < .45). Conclusions: LRFA has a 12% local failure rate, with larger adenocarcinomas and sarcomas at greatest risk. Failures occur early in follow-up, with most occurring by 6 months. LRFA seems to be a safe and effective treatment technique for patients with primary and metastatic liver malignancies.

Laparoscopic radiofrequency ablation of primary and metastaticliver tumors

AbstractBackground: Radiofrequency thermal ablation is a new technology for the local destruction of liver tumors. Since we first described laparoscopic radiofrequency ablation (LRFA) for the treatment of liver tumors, much has been learned about patient selection, laparoscopic ultrasound (LU) guided placement of the ablation catheter, monitoring of the ablation process, and patient follow-up. Methods: Since January 1996 we have performed LRFA of 250 tumors in 67 patients including 85 adenocarcinomas, 107 neuroendocrine tumors, 34 sarcomas, 1 melanoma, and 11 hepatomas. We used LU to guide placement of the ablation catheter and to monitor the ablation process. Most of the patients had two trocars (camera and laparoscopic ultrasound) with the 15-gauge ablation catheter (RITA Medical Systems, Mountain View, CA, USA) placed percutaneously. Results: The LRFA procedure was completed successfully in all patients, with 1 to 14 lesions per patient, ranging in size from 0.5 to 10 cm in diameter. The entire liver could be examined by LU via right subcostal ports. Criteria for successful ablation were 5-min ablation times at 100°C with 1-min cool-down temperatures of 60° to 70°C. Outgassing of dissolved nitrogen, monitored by ultrasound, was useful in confirming the zone of ablation. Intralesional color-flow Doppler, seen before ablation, was eliminated after ablation. Placement of the grounding pad closer to the lesion on the back rather than the thigh resulted in more efficient energy delivery to the tumor. Lesions larger than 3 cm in diameter required overlapping ablations to achieve a 1-cm margin of normal liver. Most patients required overnight hospitalization, with no coagulopathy or electrolyte disturbances noted. Conclusions: The LRFA procedure is a novel, minimally invasive technique for treatment of liver tumors that have failed conventional therapy. This study documents the technical aspects of targeting lesions and performing reproducible zones of ablation. Familiarity with these techniques should lead to more widespread application.

Use of CT Hounsfield unit density to identify ablated tumor after laparoscopic radiofrequency ablation of hepatic tumors.

AbstractBackground: When attempting to interpret CT scans after radiofrequency thermal ablation (RFA) of liver tumors, it is sometimes difficult to distinguish ablated from viable tumor tissue. Identification of the two types of tissue is specially problematic for lesions that are hypodense before ablation. The aim of this study was to determine whether quantitative Hounsfield unit (HU) density measurements can be used to document the lack of tumor perfusion and thereby identify ablated tissue. Methods: Liver spiral CT scans of 13 patients with 51 lesions undergoing laparoscopic RFA for metastatic liver tumors within a 2-year time period were reviewed. HU density of the lesions as well as normal liver were measured pre- and postoperatively in each CT phase (noncontrast, arterial, portovenous). Statistical analyses were performed using Students paired t-test and ANOVA. Results: Normal liver parenchyma, which was used as a control, showed a similar increase with contrast injection in both pre- and postprocedure CT scans (56.4 ± 2.4 vs 57.1 ± 2.4 HU, respectively; p= 0.3). In contrast, ablated liver lesions showed a preablation increase of 45.7 ± 3.4 HU but only a minimal postablation increase of 6.6 ± 0.7 HU (p < 0.0001). This was true for highly vascular tumors (neuroendocrine) as well as hypovascular ones (adenocarcinoma). Conclusions: This is the first study to define quantitative radiological criteria using HU density for the evaluation of ablated tissues. A lack of increase in HU density with contrast injection indicates necrotic tissue, whereas perfused tissue shows an increase in HU density. This technique can be used in the evaluation of patients undergoing RFA.

A critical analysis of intraoperative time utilization in laparoscopic cholecystectomy

Background: Time and efficiency analysis is a technique common in industry that is being applied to surgical procedures. The aim of this study is to analyze the time spent performing the component parts of laparoscopic adrenalectomy by both the lateral transabdominal and the posterior retroperitoneal approaches. Methods: Operational videotapes of 33 patients undergoing laparoscopic adrenalectomy (12 lateral, 21 posterior) were reviewed. The operation was divided into six steps: trocar entry, laparoscopic ultrasonography, exposure of the adrenal gland, dissection of the adrenal, extraction of specimen, and irrigation-aspiration. Time spent for each step and the relation with age, gender, body mass index (BMI), tumor size, side, and histology were assessed using Students t-test, Pearson correlation, and regression analysis. Results: Although tumor size was larger in the lateral compared to the posterior approach (5.5 vs 2.5 cm, p < 0.001), there was no difference between the groups regarding total operating time (116.1 vs 112.8 min). Most of the operating time was spent on dissection of the adrenal gland with both techniques (lateral, 60%; posterior, 66%). Exposure of the adrenal gland was longer in the lateral compared to the posterior approach (15.1 vs 5.8 min, respectively; p < 0.05). In the transabdominal technique, this step was longer on the right side than on the left (18.9 vs 11.4 min, respectively; p < 0.05). In the lateral approach, dissection time was dependent on tumor size (r = 0.90, p < 0.05) but not on BMI, whereas in the posterior approach both tumor size and BMI were positively correlated (r = 0.56 and r = 0.64, respectively). Conclusions: To our knowledge, this is the first study to apply time analysis techniques to laparoscopic adrenal surgery. Understanding the variables that affect operative time may influence the choice of the surgical approach in a given patient. This study also suggests that efforts to improve operative efficiency are best directed at the dissection of the adrenal.

Intraoperative thermal regulation in patients undergoing laparoscopic vs open surgical procedures

BackgroundAlthough perioperative hypothermia is a well-known consequence of general anesthesia, it has been hypothesized that laparoscopic surgery exacerbates hypothermia to a greater extent than open surgery. The aim of this study was to demonstrate that laparoscopic surgery does not represent an increased risk for hypothermia.MethodsA case-controlled retrospective study was conducted on 45 patients, 25 undergoing laparoscopic chole-cystectomy and 20 undergoing parathyroid surgery under endotracheal general anesthesia. Data were collected regarding age, sex, weight, height, American Society of Anesthesiologists (ASA) status, length of surgery, and anesthesia. In addition, we analyzed the type of intraoperative intravenous fluids, anesthetics and perioperative drugs, and temperature, blood pressure, and heart rate recordings during anesthesia.ResultsThere was no significant difference between the two groups with respect to age, sex, body mass index (BMI), ASA status, type or amount of intravenous fluids infused, length of anesthesia or surgery, changes in mean blood pressure, or heart rate. Core body temperatures in both groups decreased significantly over time (p < 0.001). However, the core body temperature changes at all measurement points and the rate of temperature drop were similar in both laparoscopic and parathyroidectomy groups (p > 0.05). There was no difference between the groups in terms of maximum drop in temperature (lowest temperature recorded vs baseline temperature) (1.1 ∓ 0.7 vs 1.0 ∓ 0.7°C, p > 0.05).ConclusionThis study demonstrates that patients who undergo laparoscopic and open procedures of similar duration under endotracheal general anesthesia have similar profiles in terms of perioperative hypothermia.

Erratum to: Laparoscopic management of a posterior mediastinal tumor mimicking an adrenal neoplasm

Background: Rarely, a posterior mediastinal mass may mimic an adrenal tumor on preoperative computed tomography (CT) scan. The intraoperative discovery that a mass thought to be associated with the adrenal gland actually is above the diaphragm in the posteroinferior mediastinum poses a challenge for the laparoscopic surgeon. Conversion to a thoracotomy or to videothoracoscopy incurs additional morbidity and risk for the patient. Materials and Methods: We describe a technique for the transdiaphragmatic removal of a benign mass from the posterior mediastinum. A posterior mediastinal tumor was detected during a laparoscopic procedure for a suspected right adrenal tumor. Frozen section proved benign, and the mass was resected laparoscopically via transdiaphragmatic access to the posterior mediastinum. Results: No complications were noted during or after surgery. The patient was ready for discharge from the hospital postoperative day 1. Conclusions: Transdiaphragmatic resection was used successfully instead of conversion to a thoracotomy or thoracoscopic procedure for a benign posterior mediastinal tumor found incidentally during laparoscopic surgery for a presumed adrenal lesion. This transdiaphragmatic approach can be applied to selected benign mediastinal masses.