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Biomedical subjects

M Sinanan

Publications and source records attributed to M Sinanan.

17 recordsLinked to original sources
PubMed2001

Common bile duct injury during laparoscopic cholecystectomy and the use of intraoperative cholangiography: adverse outcome or preventable error?

BACKGROUND: Common bile duct (CBD) injury is a serious complication of laparoscopic cholecystectomy (LC). Predictors of this adverse outcome have not been well documented. HYPOTHESIS: Surgeon experience and the use of intraoperative cholangiography (IOC) are associated with a decreased rate of major CBD injury during LC. DESIGN: A retrospective population-based cohort study. SETTING: Washington State hospital discharge database reports from 1991 through 1998. PATIENTS: Discharge reports were searched for International Classification of Diseases, Ninth Revision, procedure codes consistent with LC and then evaluated for procedure codes for CBD repair and reconstruction within 90 days of LC. MAIN OUTCOME MEASURE: The rate of CBD injury in patients undergoing LC based on the surgeon's experience and IOC use. RESULTS: In all, 30 630 LCs and 76 major CBD injuries (2.5/1000 operations) were identified in this analysis. There were no significant differences between injured and noninjured patients in demographics, disease, payer status, or hospital variables. A CBD injury occurred in 3.2 of 1000 LCs in the early case order of surgeons compared with 1.7 per 1000 at later points (P = .01) (relative risk, 1.81; 95% confidence interval, 1.44-2.88). The rate of injury in LCs performed without IOC was 3.3 per 1000 compared with 2.0 per 1000 in LCs with IOC (P = .02) (relative risk, 1.7; 95% confidence interval, 1.1-2.6). Surgeon's experience and IOC use were independent predictors of injury. CONCLUSIONS: The rate of CBD injury is significantly lower when IOC is used. This effect is magnified during the early experience of surgeons. Systematic use of IOC may significantly reduce the rate of CBD injury.

Cholangiography↗
PubMed2001

Effects of geared motor characteristics on tactile perception of tissue stiffness.

Endoscopic haptic surgical devices have shown promise in addressing the loss of tactile sensation associated with minimally invasive surgery. However, these devices must be capable of generating forces and torques similar to those applied on the tissue with a standard endoscopic tool. Geared motors are a possible solution for actuation; however, they possess mechanical characteristics that could potentially interfere with tactile perception of tissue qualities. The aim of the current research was to determine how the characteristics of a geared motor suitable for a haptic surgical device affect a user's perception of stiffness. The experiment involved six blindfolded subjects who were asked to discriminate the stiffness of six distinct silicone rubber samples whose mechanical properties are similar to those of soft tissue. Using a novel testing device whose dimensions approximated those of an endoscopic grasper, each subject palpated 30 permutations of sample pairs for each of three types of mechanical loads; the motor (friction and inertia), a flywheel (with the same inertia as motor), and a control (no significant mechanical interference). One factor ANOVA of the error scores and palpation time showed that no significant difference existed among error scores, but mean palpation time for the control was significantly less than for the other two methods. These results indicated that the mechanical characteristics of a geared motor chosen for application in a haptic surgical device did not interfere with the subjects' perception of the silicone samples' stiffness, but these characteristics may significantly affect the energy expenditure and time required for tissue palpation. Therefore, before geared motors can be considered for use in haptic surgical devices, consideration should be given to factors such as palpation speed and fatigue.

Biomechanical Phenomena↗
PubMed2001

Objective laparoscopic skills assessments of surgical residents using Hidden Markov Models based on haptic information and tool/tissue interactions.

UNLABELLED: Laparoscopic surgical skills evaluation of surgery residents is usually a subjective process, carried out in the operating room by senior surgeons. By its nature, this process is performed using fuzzy criteria. The objective of the current study was to develop and assess an objective laparoscopic surgical skill scale using Hidden Markov Models (HMM) based on haptic information, tool/tissue interactions and visual task decomposition. METHODS: Eight subjects (six surgical trainees: first year surgical residents 2 x R1, third year surgical residents 2 x R3 fifth year surgical residents 2 x R5; and two expert laparoscopic surgeons: 2 x ES) performed laparoscopic cholecystectomy following a specific 7 steps protocol on a pig. An instrumented laparoscopic grasper equipped with a three-axis force/torque sensor located at the proximal end with an additional force sensor located on the handle, was used to measure the forces and torques. The hand/tool interface force/torque data was synchronized with a video of the tool operative maneuvers. A synthesis of frame-by-frame video analysis was used to define 14 different types of tool/tissue interactions, each one associated with unique force/torque (F/T) signatures. HMMs were developed for each subject representing the surgical skills by defining the various tool/tissue interactions as states and the associated F/T signatures as observations. The statistical distance between the HMMs representing residents at different levels of their training and the HMMs of expert surgeons were calculated in order to generate a learning curve of selected steps during laparoscopic cholecystectomy. RESULTS: Comparison of HMM's between groups showed significant differences between all skill levels, supporting the objective definition of a learning curve. The major differences between skill levels were: (i) magnitudes of F/T applied (ii) types of tool/tissue interactions used and the transition between them and (iii) time intervals spent in each tool/tissue interaction and the overall completion time. The objective HMM analysis showed that the greatest difference in performance was between R1 and R3 groups and then decreased as the level of expertise increased, suggesting that significant laparoscopic surgical capability develops between the first and the third years of their residency training. The power of the methodology using HMM for objective surgical skill assessment arises from the fact that it compiles enormous amount of data regarding different aspects of surgical skill into a very compact model that can be translated into a single number representing the distance from expert performance. Moreover, the methodology is not limited to in-vivo condition as demonstrated in the current study. It can be extended to other modalities such as measuring performance in surgical simulators and robotic systems.

Animals↗
PubMed2000

Skills evaluation in minimally invasive surgery using force/torque signatures.

BACKGROUND: One of the more difficult tasks in surgical education is to teach the optimal application of instrument forces and torques necessary to facilitate the conduct of an operation. For laparoscopic surgery, this type of training has traditionally taken place in the operating room, reducing operating room efficiency and potentially affecting the safe conduct of the operation. The objective of the current study was to measure and compare forces and torques (F/T) applied at the tool/hand interface generated during laparoscopic surgery by novice (NS) and experienced (ES) surgeons using an instrumented laparoscopic grasper and to use this data for evaluating the skill level. METHODS: Ten surgeons (five-NS, five-ES) performed a cholecystectomy and Nissen fundoplication in a porcine model. An instrumented laparoscopic grasper with interchangeable standard surgical tips equipped with a three-axis F/T sensor located at the proximal end of the grasper tube was used to measure the F/T at the hand/tool interface. In addition, one axis force sensor located at the grasper's handle was used to measure the grasping force. F/T data synchronized with visual view of the tool operative maneuvers were collected simultaneously via a novel graphic user interface incorporated picture-in-picture video technology. Subsequent frame-by-frame video analysis of the operation allowed a definition of states associated with different tool/tissue interactions within each step of the operation. F/T measured within each state were further analyzed using vector quantization (VQ). The VQ analysis defines characteristic sets of F/T in the database that were defined as F/T signature. RESULTS: The magnitude of F/T applied by NS and ES were significantly different (p < 0.05) and varied based on the task being performed. Higher F/T magnitudes were applied by NS than by ES when performing tissue manipulation, whereas lower F/T magnitudes were applied by NS than by ES during tissue dissection. Furthermore, the time to complete the surgical procedure was longer for NS by a factor of 1.5-4.8 when compared to the time for ES. State analysis suggests that most of this time is consumed in an [idle] state, in which movements of the surgeon make no tissue contact. CONCLUSIONS: Preliminary data suggest that F/T magnitudes associated with the tool/tissue interactions provide an objective means of distinguishing novices from skilled surgeons. Clinical F/T analysis using the proposed technology and methodology may be helpful in training, developing surgical simulators, and measuring technical proficiency during laparoscopic surgery.

Cholecystectomy, Laparoscopic↗
PubMed2000

Formula for surgical practice resuscitation in an academic medical center.

BACKGROUND: Managing patient referrals for surgical consultation in an academic practice has traditionally emphasized clinical rather than service expertise. However, assuring both efficiency and accuracy in the initial consultation have become critical early measures of quality care. METHODS: In partnership with the academic medical center administration, current practice was analyzed. Performance and communication standards were established around an ideal patient experience. A new ambulatory consultation process was developed; and flowcharting methods for resource allocation, statistical process control, and pre-visit data collection were used to reduce patient administrative time. Automated referral reports engaged referring physicians throughout the consultation. RESULTS: Accurate insurance and referral authorization have been provided for all patients, including the 4% who are underinsured. Patient, provider, and referring physician satisfaction has increased significantly. Staff time investment has progressively declined from 52 +/- 11 (95% confidence) minutes to 34 +/- 10 minutes for most patients. Realignment of tasks has reduced the administrative time spent by the patient by 32% without compromising clinical time. New patient volume increased by 29% per year, maintaining regional market share. CONCLUSIONS: Expertise in the process of consultation delivery is feasible and will be increasingly critical to the survival of academic surgical practice in a competitive market.

Academic Medical Centers↗
PubMed2000

Laparoscopic surgical simulator and port placement study.

We have developed a virtual laparoscopic surgical simulator and gathered data during student trial runs. The students performed simulated surgical dissections from 3 pairs of port positions with angles between the cutting and grasping instruments set to 60, 90, and 120 degrees. Preliminary data indicates improved performance at the 90 degree angle. Study updates can be found at http:¿www.hitl.washington.edu/research/lss

Cholecystectomy, Laparoscopic↗
PubMed2000

Hidden Markov models of minimally invasive surgery.

A crucial process in surgical education is to evaluate the level of surgical skills. For laparoscopic surgery, skill evaluation is traditionally preformed subjectively by experts grading a video of a procedure performed by a student. By its nature, this process is preformed using fuzzy criteria. The objective of the current study was to develop and assess a skill scale using Discrete Hidden Markov Models (DHMM). Ten surgeons (5 Novice Surgeons--NS; 5 Expert Surgeons--ES) performed a cholecystectomy and Nissen fundoplication in a porcine model. An instrumented laparoscopic grasper equipped with a three-axis force/torque sensor was used to measure the forces/torques at the hand/tool interface synchronized with a video of the tool operative maneuvers. A synthesis of frame-by-frame video analysis and a vector quantization algorithm, defined force/torque signatures for 14 types of tool/tissue interactions. From each step of the surgical procedures, two DHMM were developed representing the performance of 3 surgeons randomly selected from the 5 in the ES and NS groups. The data obtained by the remaining 2 surgeons in each group were used for evaluating the performance scale. The final result was a surgical performance index which represented a ratio of statistical similarity between the examined surgeon's DHMM and the DHMM of NS and ES. The difference between the performance index value, for a surgeon under study, and the NS/ES boundary, was considered to indicate the level of expertise in the surgeon's own group. Using this index, 87.5% of the surgical procedures were correctly classified into the NS and ES groups. The 12.5% of the procedures that were misclassified were preformed by the ES and classified as NS. However, in these cases the performance index values were very close to the NS/ES boundary. Preliminary data suggest that a performance index based on DHMM and force/torque signatures provides an objective means of distinguishing NS from ES. In addition this methodology can be further applied to evaluate haptic virtual reality surgical simulators for improving realism in surgical education.

Animals↗
PubMed1999

Surgeon-tool force/torque signatures--evaluation of surgical skills in minimally invasive surgery.

The best method of training for laparoscopic surgical skills is controversial. Some advocate observation in the operating room, while others promote animal and simulated models or a combination of surgical related tasks. The mode of proficiency evaluation common to all of these methods has been subjective evaluation by a skilled surgeon. In order to define an objective means of evaluating performance, an instrumented laparoscopic grasper was developed measuring the force/torque at the surgeon hand/tool interface. The measured database demonstrated substantial differences between experienced and novice surgeon groups. Analyzing forces and torques combined with the state transition during surgical procedures allows an objective measurement of skill in MIS. Teaching the novice surgeon to limit excessive loads and improve movement efficiency during surgical procedures can potentially result in less injury to soft tissues and less wasted time during laparoscopic surgery. Moreover the force/torque database measured in this study may be used for developing realistic virtual reality simulators and optimization of medical robots performance.

Algorithms↗
PubMed1998

Percutaneous CT-guided catheter drainage of infected acute necrotizing pancreatitis: techniques and results.

OBJECTIVE: The objective of this paper was to assess the safety and efficacy of percutaneous catheter drainage for initial treatment of infected acute necrotizing pancreatitis. MATERIALS AND METHODS: Thirty-four patients with acute necrotizing pancreatitis shown with contrast-enhanced CT were treated for sepsis with percutaneous catheter drainage. Extent of necrosis was less than 30% in 10 cases, 30-50% in 10 cases, and greater than 50% in 14 cases. Fourteen patients had central necrosis. Eighteen patients were critically ill with multiorgan failure. RESULTS: Sixteen (47%) of the 34 patients were cured with only percutaneous catheter drainage, including four (29%) of the 14 patients with central gland necrosis and 12 (60%) of the 20 with body-tail necrosis. Sepsis was controlled (defervescence of fever and return of WBC to normal) in an additional nine patients, allowing elective pancreatic surgery for control of pancreatic duct fistula. Eight patients failed to show clinical improvement after drainage and required necrosectomy. No patient experienced catheter-related complications. Mortality was 12% (all four deaths occurred after necrosectomy because of multiorgan failure). CONCLUSION: Percutaneous catheter drainage is a safe and effective technique for treating infected acute necrotizing pancreatitis. Overall, sepsis was controlled in 74% of patients, permitting elective surgery for treatment of pancreatic fistula, and 47% of patients were cured with no surgery required. No catheter-related complications occurred.

Adult↗
PubMed1998

Computerized endoscopic surgical grasper.

We report a computerized endoscopic surgical grasper with computer control and a force feedback (haptic) user interface. The system uses standard unmodified grasper shafts and tips. The device can control grasping forces either by direct surgeon control, via teleoperation, or under software control. In this paper, we test an automated palpation function in which the grasper measures mechanical properties of the grasped tissue by applying a programmed series of squeezes. Experimental results show the ability to discriminate between the normal tissues of small bowel, lung, spleen, liver, colon, and stomach. We anticipate applications in telesurgery, clinical endoscopic surgery, surgical training, and research.

Endoscopes↗
PubMed1997

Use of laparoscopic techniques improves outcome from adrenalectomy.

BACKGROUND: Laparoscopic adrenalectomy is a promising alternative to open approaches but safety and efficacy remain unproven. METHODS: A recent experience with laparoscopic adrenalectomy at the University of Washington was analyzed for efficacy, complications, evolution of technical steps, and clinical outcome. RESULTS: Nineteen adrenalectomies were performed in 16 patients with a mean age of 52 years. Indications included pheochromocytoma (4), functional adenoma (12), and uncontrolled Cushing's disease (3). All patients had computed tomography scans. Meta-iodo-benzyl-guanidine (MIBG) or iodocholesterol scans were done in selected patients. Three patients had bilateral procedures, 7 were on the left and 6 on the right, all via a transperitoneal flank approach. There were no conversions and all procedures were successful. Complications included subcapsular liver hematomas (2), one transfusion, and a bleeding port site requiring repeat laparoscopy. Except for 1 patient with COPD, the mean length of stay was 2.9 days. CONCLUSIONS: Laparoscopic adrenalectomy in appropriate patients is safe and effective. For endocrine surgeons with advanced laparoscopic skills, it should be considered a new standard therapy for benign adrenal tumors.

Adenoma↗
PubMed1996

Systematic use of gastric fundoplication in laparoscopic repair of paraesophageal hernias.

BACKGROUND: Early surgical treatment has been recommended in patients with paraesophageal hiatal hernias. Recently, the laparoscopic approach has emerged as an ideal way to perform the operation. But whether or not an antireflux procedure should be done remains controversial. PATIENTS AND METHODS: Four patients with type II and eleven with type III hiatal hernias were treated. Twelve of them manifested symptoms of reflux preoperatively. The operative technique consisted of resection of the sac, closure of the crura and gastric fundoplication, anchored to the diaphragm. RESULTS: All but two patients were completed laparoscopically. Mean operative time was 320 (+/-49 SD) minutes, and mean hospital stay was 3 (+/-1.2 SD) days. Early postoperative complications were subcutaneous emphysema (two patients) and atrial fibrillation (one patient). At one year all patients were asymptomatic without dysphagia, reflux, or recurrence of the hernia. CONCLUSION: The addition of fundoplication to paraesophageal hernia repair restores competency of the sphincter in patients with reflux associated to the hernia and prevents postoperative gastroesophageal reflux that results from the extensive dissection required. In addition, it provides an ideal means of fixing the stomach in the subdiaphragmatic position, decreasing the long term-risk of recurrence.

Adult↗
PubMed1995

Thoracoscopic Heller's myotomy. Treatment of achalasia by the videoendoscopic approach.

In summary, the authors believe that minimally invasive surgery has added a new dimension to the treatment of achalasia. Thoracoscopic myotomy is feasible, safe, and effective in relieving dysphagia in the great majority of individuals affected with this disease without the many problems associated with dilatation; thus, the authors offer it to patients with achalasia as the initial and preferred form of treatment. Whether an antireflux procedure should be routinely added and whether a laparoscopic rather than a thoracoscopic approach is preferred, remains unanswered questions at this time.

Cardia↗
PubMed1984

Laparotomy for intra-abdominal sepsis in patients in an intensive care unit.

Patients in an intensive care unit who have intra-abdominal (IA) infections producing clinical deterioration in their conditions require urgent intervention. However, detection is often difficult. To define preoperative criteria for, and improve the specificity of, laparotomy, we reviewed 100 explorations in 71 patients with suspected IA sepsis. Eighty-one explorations demonstrated an infected or ischemic process; 19 were negative. Preoperative features associated with a positive laparotomy were as follows: (1) objective evidence by physical examination, ultrasonography, or computed tomography suggesting an IA focus (89%); (2) septic shock (80%); and (3) positive blood cultures (95%). Absence of these features significantly lowered the accuracy of exploration. Septic shock or bacteremia had a 90% mortality regardless of findings at exploration. The best accuracy (89%) and survival (51%) rates were achieved with "directed" exploration before septic shock or bacteremia. Early use of sensitive detection techniques that permit directed laparotomy before septic deterioration should improve survival.

Abscess↗
PubMedDate not supplied

Force-feedback grasper helps restore sense of touch in minimally invasive surgery.

The age of minimally invasive surgery has brought forth astounding changes in the health care field. Less pain and quicker patient recovery have been demonstrated with several types of operations that were once performed by an open technique. With these changes have come reports of complications. The decreased sense of touch is just one of several limitations inherent to current techniques of minimally invasive surgery that limit detection of subtle or unapparent lesions on palpation, such as common duct stones and liver lesions. The purpose of this study is to demonstrate the ability of a force-feedback-equipped grasper to restore some of the sense of touch that is lost in minimally invasive surgery. To demonstrate this ability, we created six silicone phantoms of identical dimensions but graded compliance, and asked 10 subjects to place them in increasing/decreasing order of compliance. They used three tools (their dominant gloved hand, a standard laparoscopic Babcock grasper, and our force-feedback device fitted with the identical Babcock grasper) to rate the compliance of the samples in a blinded fashion. These conditions thus approximated the conditions of open surgery, minimally invasive surgery, and minimally invasive surgery fitted with a force-sensing device, in terms of palpating tissues. Five surgeons skilled in minimally invasive surgery and five nonsurgeons participated in the study. The results indicate that the force-feedback device is significantly (P <0.05) better than a standard Babcock grasper at rating tissue compliance, but was not as successful as a gloved hand (mean of squared errors = 1.06, 3. 15, and 0.25, respectively). There was no significant difference between surgeons and nonsurgeons in rating compliance. We conclude that this force-feedback instrument is able to partially restore the sense of touch in minimally invasive surgery. This restored ability may thus potentially result in more efficient operations with improved diagnostic capabilities and fewer complications during minimally invasive surgery.

Biocompatible Materials↗