Quantitative evaluation of surgical task performance by remote-access endoscopic telemanipulation.

BACKGROUND: The performance limitations inherent in minimally invasive surgery may be overcome by using an interface that provides intuitive orientation for video display and tool manipulation. A prototype remote-access endoscopic telemanipulator was designed to fulfill these requirements and used for a surgical anastomosis task. METHODS: A remote-access telemanipulator system, employing remote center-of-motion geometry, was used to complete distant in vitro tubular anastomoses. The performance of four surgeons using this system was compared with that achieved in completing the same anastomosis task in an open environment using open surgical techniques and in a minimally invasive environment using standard laparoscopic methods. RESULTS: The average performance times for completion of the anastomosis task was 1448 +/- 130 s using the telemanipulator system compared with 2108 +/- 291 s with laparoscopic instruments and 296 +/- 25 s with conventional techniques. Leakage rates from the tubular anastomoses were 5.2 +/- 1.4 ml/s in the telemanipulator group, 6.9 +/- 2.0 ml/s in the laparoscopic group, and 3.2 +/- 0.9 ml/s in the conventional methods group. All experimental subjects were able to complete the assigned task in each experimental condition successfully without complications. CONCLUSIONS: Our results in this pilot study suggest that remote-access endoscopic telemanipulation can execute complex three-dimensional manipulations, and that the intuitive orientation of the surgeon's workstation may contribute to easier task completion.

Microvascular anastomoses performed in rats using a microsurgical telemanipulator.

OBJECTIVE: To determine the feasibility of performing microsurgical procedures with a remote telemanipulator using a rat femoral artery anastomosis model. MATERIALS AND METHODS: A remote telemanipulator system was developed that enabled precision movements to be performed at up to 30x magnification. Ten 1-mm femoral artery anastomoses were performed in rats using the telemanipulator, and results were compared to those from a control group in which the procedure was performed with conventional microsurgical techniques. Study endpoints included anastomosis completion time, short-term patency, and procedural complications. Statistical analysis was performed using Student's t-test. RESULTS: All anastomoses performed by remote telemanipulation and by conventional microsurgery were completed successfully. Anastomosis completion times were 100.0 +/- 18.6 minutes in the telemanipulator group and 38.8 +/- 5.0 minutes using conventional techniques (p < 0.001). Patency in both groups at 5 minutes and at one hour was 100%. No intraoperative complications were encountered. Postmortem ex vivo examination of the excised arterial segment revealed no technical defects in either group. CONCLUSIONS: Complex procedures requiring a high degree of precision and dexterity can be performed using an electromechanical interface specifically designed for micromanipulation. Performance limitations are similar to those previously reported for remote surgical teleoperation, and most likely reflect incompletely characterized restrictions on multi-sensory information.

Remote operative urology using a surgical telemanipulator system: preliminary observations.

OBJECTIVES: A prototype surgical telemanipulator system was evaluated to determine the feasibility of remotely performing operative urology. METHODS: Surgeons operated remotely on anesthetized swine (n = 4), using a four degree-of-freedom teleoperator system. A stereoscopic video display of the remote surgical field guided tissue manipulation, which was performed using standard instrument tips attached to robotic arms. Nephrectomies, cystotomy closures, and ureteral anastomoses were performed by surgeons linked only by electronic cables to the remote operative field (5 m away). Flexible fiberoptic endoscopy was performed remotely, as well, using a simulated ureter in an ex vivo testing apparatus. The endoscope was positioned and manipulated remotely, and was maneuvered through a 25-cm-long tube. RESULTS: All procedures were completed successfully, demonstrating the capability to remotely incise, dissect, suture, and ligate tissues. Operative times were prolonged; however, the surgical telemanipulator was precise and accurate. Surgeons guided a flexible fiberoptic endoscope by remote observation and manipulation through 5-mm-diameter simulated ureters. There were no operative complications. CONCLUSIONS: Telesurgical manipulation is feasible in a controlled, experimental environment. All critical tasks performed by surgeons can be completed remotely, although performance must be improved substantially before telemanipulators enter the clinical armamentarium. Major hurdles remain in identifying clinical needs, improving performance and safety, and developing telecommunications capabilities that will enable telesurgical systems to achieve regulatory approval and acceptance.

Use of an intuitive telemanipulator system for remote trauma surgery: an experimental study.

BACKGROUND: Death from battlefield trauma occurs rapidly. Potentially salvageable casualties generally exsanguinate from truncal hemorrhage before operative intervention is possible. An intuitive telemanipulator system that would allow distant surgeons to remotely treat injured patients could improve the outcome from severe injuries. STUDY DESIGN: We evaluated a prototype, four-degree-of-freedom, telesurgery system that provides a surgeon with a stereoscopic video display of a remote operative field. Using dexterous robotic manipulators, surgical instruments at the remote site can be precisely controlled, enabling operative procedures to be performed remotely. Surgeons (n = 3) used the telesurgery system to perform organ excision, hemorrhage control, suturing, and knot tying on anesthetized swine. The ability to complete tasks, times required, technical quality, and subjective impressions were recorded. RESULTS: Surgeons using the telesurgery system were able to close gastrotomies remotely, although times required were 2.7 times as long as those performed by conventional techniques (451 +/- 83 versus 1,235 +/- 165 seconds, p < 0.002). Cholecystectomies, hemorrhage control from liver lacerations, and enterotomy closures were successfully completed in all attempts. Force feedback and stereoscopic video display were important for achieving intuitive performance with the telesurgery system, although tasks were completed adequately in the absence of these sensory cues. CONCLUSIONS: We demonstrated the feasibility of performing standard surgical procedures remotely, with the operating surgeon linked to the distant field only by electronic cabling. Complex manipulations were possible, although the times required were much longer. The capabilities of the system used would not support resuscitative surgery. Telesurgery is unlikely to play a role in early trauma management, but may be a unique research tool for acquiring basic knowledge of operative surgery.

Vascular applications of telepresence surgery: initial feasibility studies in swine.

PURPOSE: Telepresence surgery is a novel technology that will allow procedures to be performed on a patient at locations that are physically remote from the operating surgeon. This new method provides the sensory illusion that the surgeon's hands are in direct contact with the patient. We studied the feasibility of the use of telepresence surgery to perform basic operations in vascular surgery, including tissue dissection, vessel manipulation, and suturing. METHODS: A prototype telepresence surgery system with bimanual force-reflective manipulators, interchangeable surgical instruments, and stereoscopic video input was used. Arteriotomies created ex vivo in segments of bovine aortae or in vivo in femoral arteries of anesthetized swine were closed with telepresence surgery or by conventional techniques. Time required, technical quality (patency, integrity of suture line), and subjective difficulty were compared for the two methods. RESULTS: All attempted procedures were successfully completed with telepresence surgery. Arteriotomy closures were completed in 192+/-24 sec with conventional techniques and 483+/-118 sec with telepresence surgery, but the precision attained with telepresence surgery was equal to that of conventional techniques. Telepresence surgery was described as intuitive and natural by the surgeons who used the system. CONCLUSIONS: Blood-vessel manipulation and suturing with telepresence surgery are feasible. Further instrument development (to increase degrees of freedom) is required to achieve operating times comparable to conventional open surgery, but the system has great potential to extend the expertise of vascular surgeons to locations where specialty care is currently unavailable.

Complex task performance in Cyberspace. Surgical procedures in a telepresence environment.

To assess the capabilities of our fully functional, prototype telepresence surgery system, experienced surgeons performed complete operative procedures on live, anesthetized pigs. Cholecystectomy, the prototypical procedure for evaluating the integration of surgical skills, was successfully performed in six animals. There were no aborted attempts or complications. Other procedures completed included gastrotomy and enterotomy closures, anastomosis of the small intestine, and nephrectomy. No specific training was required for using the telepresence surgery system, and the "feel" of the system was described as intuitive. Operative times were longer than required in conventional, open surgery, most likely the result of the four degrees of freedom available in the manipulators of the current-generation system. Force feedback and high-resolution, stereoscopic video input facilitated performance. Surgeons operating through a first-generation telepresence system can achieve technical results equivalent to those obtained in conventional surgery.

Assessment of popliteal arterial occlusive disease with 2D time-of-flight MRA.

OBJECTIVE: The purpose of this study was to evaluate both morphology and blood flow in peripheral arteries with occlusive lesions using MR angiography (MRA) and velocity-encoded cine MRI. MATERIALS AND METHODS: Two-dimensional time-of-flight MRA and velocity-encoded cine MRI were performed in nine patients with peripheral arterial occlusive disease. Findings on MR angiograms were verified by conventional angiography. RESULTS: All the stenotic lesions in the popliteal arteries were depicted by MRA. The degree of the stenoses in the artery was overestimated by MRA. Major collateral circulations were demonstrated. Velocity-encoded cine MRI provided flow velocity information on the arteries above and below the stenoses. The flow velocity waveform was monophasic above and below the stenosis. The peak systolic velocity in the artery below the stenosis was reduced compared with that above the stenosis (p < 0.05). CONCLUSION: The combination of MRA and velocity-encoded cine MRI has clinical potential for the evaluation of peripheral arterial occlusive disease.

Efficacy of a fibrin hemostatic bandage in controlling hemorrhage from experimental arterial injuries.

OBJECTIVE: To determine if a pressure dressing containing fibrinogen and thrombin could provide more effective control of arterial hemorrhage than a pressure dressing alone in an animal model of arterial injury. DESIGN: Randomized acute (nonsurvival) experiment in swine. SETTING: Federal biomedical research institute. ANIMALS: Six anesthetized Yorkshire swine. INTERVENTIONS: Uncontrolled arterial hemorrhage was induced in anesthetized swine by creating femoral artery lacerations. Hemorrhage was controlled by a gauze bandage containing fibrinogen and thrombin, applied with 1 minute of 3.5-kg pressure. The dressings were left in place for 1 hour after the pressure was removed. The contralateral limbs received identical treatment with plain gauze dressings. MAIN OUTCOME MEASURES: Total blood loss, mean arterial pressure, and mortality were measured after 1 hour. RESULTS: After 1 hour, blood loss in the fibrin bandage group was 123 +/- 48 mL, compared with 734 +/- 134 mL in the control group (P = .0022). In the group treated with the fibrin bandages, there was no significant decrease in the mean arterial pressure after arterial laceration. In contrast, there was a decrease of 30 mm Hg in the group treated with gauze dressings alone. There was no animal mortality during the study period. CONCLUSIONS: Bandages containing fibrinogen and thrombin significantly reduced the amount of blood loss and allowed mean arterial pressures to be maintained in animals with uncontrolled hemorrhage from femoral artery lacerations. A hemostatic bandage may be an important adjuvant for controlling severe extremity hemorrhage in the prehospital setting.

Assessment of carotid artery stenosis by ultrasonography, conventional angiography, and magnetic resonance angiography: correlation with ex vivo measurement of plaque stenosis.

PURPOSE: Several studies have investigated the correlation between Doppler ultrasonography (DUS), angiography (CA), and magnetic resonance angiography (MRA) in the evaluation of stenosis of the carotid bifurcation. However, these studies suffer from the lack of a true control-the lesion itself-and therefore conclusions about the diagnostic accuracy of each method remain relative. To determine the absolute accuracy of these modalities, we have prospectively studied lesion size with DUS, MRA, and CA in 28 patients undergoing 31 elective carotid endarterectomies and compared the percent of carotid stenosis determined by each technique to the carotid atheroma resected en bloc. METHODS: All patients were evaluated by each modality within 1 month before the thromboendarterectomy. With DUS, stenosis size was determined by standard flow criteria. For angiography and MRA, stenosis was defined as residual lumenal diameter/estimated normal arterial diameter (European Carotid Surgery Trial criteria). At surgery the carotid atheroma was removed en bloc in all patients. Patients in whom the lesion could not be removed successfully without damage were excluded from the study. Stenosis of the atheroma was determined ex vivo with high-resolution (0.03 mm3) magnetic resonance and confirmed by acrylic injection of the specimen under pressure and measurement of the atheroma wall and lumen. RESULTS: The measurements of the ex vivo stenosis by high-resolution magnetic resonance imaging correlated closely with the size of stenosis determined by the acrylic specimen casts (r = 0.92). By ex vivo measurement, the lesions were placed in the following size categories: 40% to 59% stenosis (n = 2), 60% to 79% stenosis (n = 6), 80% to 89% stenosis (n = 7), and 90% to 99% stenosis (n = 16). CONCLUSIONS: In general, the correlation of measurements of ex vivo stenosis with all modalities was good in these severely diseased arteries, although it was better for DUS (r = 0.80; p < 0.001) and MRA (r = 0.76; p < 0.001) than for CA (r = 0.56; p < 0.05).

Trauma and military applications of blood substitutes.

PURPOSE: To review potential clinical uses of erythrocyte substitutes in treating military battlefield casualties, with specific emphasis on combat injury rates and wounding patterns, resuscitation doctrine and logistic requirements. METHODS: Review of published medical literature and of unclassified documents from the U.S. Armed Forces Blood Program. RESULTS: Hemorrhage is the leading cause of death on the battlefield. Early intervention, with definitive treatment, could save up to 30% of soldiers who are killed in action or who die of wounds. Hemorrhage control and rapid volume expansion in appropriate casualties are the main priorities in pre-hospital resuscitation of battlefield casualties. The role for oxygen-carrying fluids in the initial management of military injuries is undefined; however, erythrocyte substitutes could reduce the logistic requirements for blood in field hospitals. In recent wars, outdating of stored blood resulted in 60-95% of units being discarded: 60% of 1.3 million units in Vietnam and 95% of 120,000 units in the Persian Gulf War. CONCLUSIONS: Safety, long storage life, light unit weight, and tolerance to environmental extremes are all characteristics that are necessary for erythrocyte substitutes to extend or replace the use of stored blood in treating battlefield casualties.

Limb salvage and wound coverage in patients with large ischemic ulcers: a multidisciplinary approach with revascularization and free tissue transfer.

PURPOSE: Large ischemic wounds, particularly with exposed bone or tendons, may not heal even after successful revascularization. We have taken an aggressive approach for limb salvage that uses autogenous vein grafting and simultaneous microvascular free tissue transfer. METHODS: In the past year, seven patients (average age 67 years; range 56 to 79) with ischemic disease and distal ulceration underwent revascularization for limb salvage and free tissue transfer. Each had a nonhealing wound (average size 80 cm2), present for 8.6 months (range 2 to 24 months). Simultaneous vein bypass and free tissue transfer was performed in four (57%) of the seven patients. RESULTS: All flaps were initially viable; however, one was lost on day 4 because of hypotension and congestive heart failure. One patient with a successful flap died at 1 month of pneumonia. Minor wound complications were seen in four (57%) of seven patients. Five of the seven patients had the wounds heal completely and are ambulatory at an average follow up of 10 months. CONCLUSIONS: Our aggressive approach was successful in preserving limb length and function in 71% of our patients. We perform simultaneous procedures whenever possible to minimize operative and hospitalization times. We believe that this combined approach optimizes the treatment of ischemic limbs with large ulcers.

New technology in U.S. Army health care: the role of laparoscopic cholecystectomy.

In the near future, laparoscopic cholecystectomy could become one of the most frequently performed surgical procedures in U.S. military hospitals. To determine the best way to implement this new technology in the U.S. Army Health Services Command (HSC), we have assessed the safety, efficacy, and health consequences of laparoscopic cholecystectomy. Approximately 2,800 open cholecystectomies are performed annually in HSC hospitals, 11% of them on active duty personnel. If cholecystectomies were performed using laparoscopic surgical techniques on active duty patients who meet currently accepted indications, 3,360 personnel duty days lost to convalescence and 7,048 days of limited duty (time on physical profiles) would be recouped. Applying the procedure to other beneficiaries (dependents and retired service members) would result in a potential annual savings of 11,000 hospital bed days. If implemented using stringent criteria for training and certification, these savings could be achieved with no increase in patient morbidity or mortality and with significant improvement in patient outcome.

Duplex ultrasonography in the diagnosis of celiac and mesenteric artery occlusive disease.

Duplex ultrasound criteria for the diagnosis of celiac and superior mesenteric artery (SMA) occlusive disease have not been well defined. We performed a blinded retrospective comparison of mesenteric duplex data with arteriography in 24 consecutive patients who underwent both studies. Arteriography revealed that eight superior mesenteric arteries were normal; five were minimally stenotic; eight had stenoses greater than or equal to 50%, and three were occluded. Nine celiac arteries were normal or minimally stenotic; 12 had stenoses greater than or equal to 50%, and three were occluded. Duplex scans were obtained after an overnight fast. In normal superior mesenteric arteries, peak systolic velocity (PSV) was 134 +/- 18 cm/sec and end-diastolic velocity (EDV) was 24 +/- 4 cm/sec. Superior mesenteric artery PSV in patients with minimal or no stenosis (171 +/- 22 cm/sec) was less than PSV in patients with severe (greater than 50%) stenosis (299 +/- 40 cm/sec, p = 0.006), and less than PSV in patients with patent superior mesenteric arteries who underwent revascularization (366 +/- 86 cm/sec, p = 0.017). Similarly, EDV was elevated in superior mesenteric arteries with severe stenosis (78 +/- 11 cm/sec, p = 0.001) and in patients who underwent revascularization (111 +/- 19 cm/sec, p less than 0.001) compared to those with less than 50% stenosis (30 +/- 6 cm/sec, p = 0.001). An EDV greater than 45 cm/sec was the best indicator of severe stenosis (sensitivity, 1.0; specificity, 0.92). Peak systolic velocity greater than 300 cm/sec was less sensitive (0.63), but highly specific (1.0) for severe superior mesenteric artery stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Data-based resource planning for battlefield trauma management.

Optimal medical care of the wounded soldier can be provided only if clinicians have appropriate supplies present in adequate quantities. At the same time, the battlefield environment requires maximum efficiency in resource utilization. Logistical support for field surgical units can be allocated more efficiently without compromising the quality of care by using a database derived from trauma patient management. The records of patients treated for gunshot wounds at an urban level I trauma center were reviewed and the use of medications at each stage of treatment was quantified. From this information, a database was compiled that could be used to predict medical resource requirements for combat scenarios. Such a database could be used to assist in planning logistical support, resulting in better tailoring of deployable medical unit resources to meet the actual needs of injured soldiers.

Army trauma research: tapping the potential.

Trauma management is the primary mission of military surgeons. Since the Vietnam War, however, military surgeons have relinquished leadership in clinical trauma care to the civilian sector, particularly to urban university surgeons. In this paper we explore whether the Army's contribution to trauma research has also diminished. Using standard bibliometric analysis of publication counts, we have shown that few recent publications related to trauma have originated from U.S. Army Medical Centers, compared with adjacent civilian universities. In 1988, 16 papers originating from the eight Army Medical Centers had key words related to trauma. In contrast, eight universities adjacent to the Army's medical centers published 139 articles on trauma. Problems including lack of clinical exposure to trauma patients, lack of funding, and inadequate emphasis on staff research training have contributed to this decline. We review these factors and describe solutions that could reverse this trend.