Search PubMed⌕ Search

Biomedical subjects

R Berguer

Publications and source records attributed to R Berguer.

At least 19 recordsLinked to original sources
PubMed1999

Cervical reconstruction of the supra-aortic trunks: a 16-year experience.

PURPOSE: The purpose of this study was to review 182 consecutive cervical reconstructions of supra-aortic trunks, which were performed over a 16-year period. METHODS: A total of 182 innominate, common carotid, or subclavian arteries were reconstructed with a cervical approach in 173 patients aged 23 days to 83 years. Indications included hemispheric (n = 79), vertebrobasilar (n = 56), upper extremity (24), and internal mammary/cardiac ischemia (n = 5), asymptomatic severe common carotid disease (n = 33), or other (n = 3). Primary atherosclerotic innominate (n = 6), common carotid (n = 84), and subclavian (n = 66) lesions underwent reconstruction. Thirty-one operations were performed for multiple trunk involvement, recurrent disease, arteritis, infection, dissection, coarctation, or aneurysm. There were 122 bypass grafting procedures (98 ipsilateral, 24 contralateral) and 60 arterial transpositions. RESULTS: One death (0.5%) and 7 nonfatal strokes (3.8%) occurred, none in patients who were asymptomatic. Perioperative morbidity included four asymptomatic occlusions (2%), 6 myocardial infarctions (3%), 10 pulmonary complications (5%), and 2 graft infections (1%). Follow-up periods ranged from 1 to 190 months (mean, 53 +/- 5 months). Nineteen patients (10%) were lost to follow-up. Fifty-seven late deaths occurred, most from cardiac causes. Seven reconstructions necessitated late revision. The cumulative primary patency rate at 5 and 10 years was 91% +/- 2% and 82% +/- 5%, respectively. The survival rate at 5 years was 72% +/- 4% and at 10 years was 41% +/- 6%. The stroke-free survival rate was 92% +/- 2% at 5 years and 84% +/- 2% at 10 years. CONCLUSION: Cervical reconstruction of symptomatic and asymptomatic supra-aortic trunk lesions carries acceptable death and stroke rates and provides a long-term patient benefit. This should be the preferred approach for asymptomatic lesions and for patients with significant comorbidity because it carries less morbidity than direct transmediastinal aortic-based reconstruction.

Adolescent↗
PubMed1998

Adrenocortical response and regional T-lymphocyte activation patterns following minimally invasive surgery in a rat model.

BACKGROUND: Laparoscopic surgery is associated with less tissue trauma and postoperative pain as well as a more rapid recovery than open surgery. We hypothesized that these factors may result in less immune impairment following laparoscopic surgery. METHODS: We measured mitogen-induced surface interleukin-2 receptor (IL2R) expression and lymphocyte proliferation in CD4+ and CD8+ T-lymphocytes as well as serum corticosterone levels in rats 24 h following open (OP) and laparoscopic (LAP) fundoplication. RESULTS: Serum corticosterone levels were lower in LAP vs OP rats (p = 0.02). CD4+ IL2R expression was higher in the blood, but not in the spleen, in LAP vs OP animals (p = 0.02). CD8+ IL2R expression was similar in both groups. Mitogen-induced lymphocyte proliferation was no different in the blood but decreased in the spleen in LAP vs OP rats (p = 0.03). CONCLUSIONS: Compared to open surgery, laparoscopic fundoplication in the rat results in lower adrenocortical hormone levels and better-preserved T-helper-cell activation in the blood. Lymphocyte proliferation is suppressed in the spleen 24 h after laparoscopic surgery. Minimally invasive surgery may better preserve cell-mediated immunity in the early postoperative period.

Animals↗
PubMed1998

Surgical technology and the ergonomics of laparoscopic instruments.

Laparoscopic surgery provides patients with less painful surgery and a more rapid recovery, while requiring that surgeons work harder and in a more remote manner from the operating field. Cost-containment pressures on surgeons demand efficient surgery, whereas the increased technological complexity and sometimes poorly adapted equipment have led to increased complaints of surgeon fatigue and discomfort during laparoscopic surgery. There is, therefore, a need to evaluate the ergonomic integration and suitability of the laparoscopic operating room environment to address the issues of efficiency, safety, and comfort for the operating team. This approach is particularly important in the design of laparoscopic surgical instruments. A review of the literature on the biomechanics of laparoscopic surgical instrument use was combined with data from the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) Ergonomics Questionnaire and demonstration station. Laparoscopic instruments suffer from ergonomically inadequate handle designs and inefficient handle to tip force transmission, which lead to surgeon fatigue, discomfort, and hand paresthesias. Improvements in the design of laparoscopic instruments are needed to decrease the work and discomfort of tissue manipulation during video-endoscopic surgery.

Cumulative Trauma Disorders↗
PubMed1998

An ergonomic comparison of in-line vs pistol-grip handle configuration in a laparoscopic grasper.

BACKGROUND: Laparoscopic instruments incorporate both in-line and pistol-grip handle configurations, yet it is unclear which design is most advantageous for surgeons, particularly when operating at angles perpendicular to the surgeon's position. We present a detailed electromyographic (EMG) comparison of these handle configurations under different force and angle conditions. METHODS: Nine general surgeons used a Microsurge grasper with the handle in an in-line (MS-IL) and pistol (MS-PS) configuration, as well as a standard hemostat (HE), to grasp and close two spring-loaded metal plates. The task was performed randomly by each subject with the three instrument configurations at two forces levels (0.7 N, 4.2 N) and at three angles to the surgeons' body (0, 45, and 90 degrees). Surface EMG was measured from the flexor carpi ulnaris (FCU), flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS), extensor carpi ulnaris (ECU), extensor digitorum comunis (EDC), and thenar compartment (TH). The peak root mean squared (RMS) EMG voltage was calculated for each instrument, force, and angle condition. Statistical comparison was carried out by ANOVA. RESULTS: Both laparoscopic handle configurations required significantly higher contractions of all muscle groups compared to the hemostat at the high force level. TH was not affected by laparoscopic handle configuration. MS-IL required higher FCU, ECU, and EDC contractions at 45 degrees compared to MS-PS. However, MS-IL decreased the flexor compartment muscle contractions (FDP, FDS, FCU) at 90 degrees compared to MS-PS. CONCLUSIONS: Laparoscopic grasping requires higher forearm and thumb muscle contractions compared to the use of a hemostat. The in-line handle configuration is no better than the pistol configuration except when grasping at 90 degrees to the surgeon, where rotation of the handle and wrist back toward the surgeon significantly decreases forearm flexor compartment muscle contractions.

Cumulative Trauma Disorders↗
PubMed1998

Carotid resection and replacement with autogenous arterial graft during operation for neck malignancy.

Carotid artery resection as part of the management of advanced head and neck cancers remains controversial. Since 1991, 30 patients have undergone resection of the carotid artery with immediate reconstruction using superficial femoral artery as replacement conduit. There was one stroke/death. Forty-three percent developed neck wound problems but no grafts failed or hemorrhaged. Mean follow-up was 20 months (3-76) and mean life expectancy was 16 months from the time of surgery. Fifty-eight percent were free of local recurrence at the time of death. There was a 35% disease-free survival rate at 2 years. These results compare favorably with alternative therapy including carotid ligation or shaving tumor from the carotid artery. Given the importance of cerebral perfusion and local tumor control we offer superficial femoral artery as a durable conduit for immediate extracranial carotid reconstruction in the often hostile environment associated with cancer resection in the neck.

Adult↗
PubMed1998

A review of 100 consecutive reconstructions of the distal vertebral artery for embolic and hemodynamic disease.

PURPOSE: The aim of our study was to assess the outcome of distal vertebral artery (VA) reconstructions through a retrospective review conducted at a university-affiliated referral center. METHODS: One hundred consecutive distal VA reconstructions had been performed during a period of 14 years (98 patients) and included reversed saphenous vein bypass from the ipsilateral common, internal, or external carotid to the third portion of the VA at the C1-2 level (68 reconstructions) or the C0-1 level (4); transposition of the external carotid or its occipital branch to the VA (23); and transposition of the third portion of the VA onto the internal carotid artery (2). Other methods were used in 3 additional patients. Eighteen patients underwent concomitant carotid operations, and 1 patient underwent a concomitant subclavian transposition. Symptoms were present in 98% of patients and included vertebrobasilar ischemia (89%), vertebrobasilar plus hemispheric ischemia (7%), and hemispheric ischemia (2%). Two asymptomatic patients with bilateral carotid occlusions underwent operations to provide a single artery for cerebral perfusion (2%). Sixty-three lesions were atherosclerotic, 18 were dynamic bony compressions, and 14 were dissection, fibromuscular dysplasia, arteritis, or aneurysm. Five had miscellaneous anatomic indications. RESULTS: Stroke caused the four perioperative deaths that occurred. There was one occurrence of nonfatal hemispheric stroke. Routine postoperative arteriography identified 16 graft abnormalities; 11 patients underwent attempted revision. The introduction of the use of intraoperative angiography in 1990, halfway through the series, lowered the incidence of graft abnormalities from 28% to 4% and the incidence of perioperative death from 6% to 2%. Eighty-seven percent of patients had complete or significant resolution of symptoms. Follow-up ranged from 1 to 168 months (mean, 79 months). Ten patients were lost to follow-up. Twenty late deaths occurred; none were stroke related. Five reconstructions required late revision. The cumulative primary patency at 5 and 10 years was 75% +/- 6 and 70% +/- 7 (mean +/- SE), respectively; cumulative secondary patency was 84% +/- 5 and 80% +/- 6 at 5 and 10 years, respectively. Median survival was 107 months. CONCLUSIONS: Distal VA reconstruction provides excellent long-term patency and stroke protection. Intraoperative angiography is mandatory.

Adult↗
PubMed1998

Transthoracic repair of innominate and common carotid artery disease: immediate and long-term outcome for 100 consecutive surgical reconstructions.

PURPOSE: This is a review of 100 consecutive supraaortic trunk reconstructions (SAT) performed over 16 years. METHODS: There were eight innominate endarterectomies and 92 bypass procedures based on the thoracic aorta (n = 86) or proximal innominate artery (n = 6) in 98 patients 24 to 79 years of age. Indications included cerebrovascular ischemia in 83 and upper extremity ischemia in four. Thirteen patients were asymptomatic. An innominate lesion was bypassed in 78 cases. The left common carotid and left subclavian arteries required reconstruction in 38 and nine patients, respectively. Multiple trunks were reconstructed by direct bypass grafting in 35. Approach was via median sternotomy in 92, partial sternotomy in six, and left thoracotomy in two. Seven patients underwent concomitant cardiac surgery. RESULTS: Eight deaths and eight nonfatal strokes occurred, for a combined stroke/death rate of 16%. The operative mortality rate was 6% for SAT and 29% for SAT/cardiac operations. Perioperative complications included two asymptomatic graft occlusions, three nonfatal myocardial infarctions, seven significant pulmonary complications, three sternal wound infections, and one recurrent laryngeal nerve injury. Follow-up ranged from 1 to 184 months (mean, 51 +/- 4.8 months). Eight patients were lost to follow-up. Twenty-one late deaths occurred. Two SATs required late revision. The cumulative primary patency rates at 5 and 10 years were 94% +/- 3% and 88% +/- 6%, respectively. The stroke-free survival rates at 5 and 10 years were 87% +/- 4% and 81% +/- 7%, respectively. Patients who survived beyond 30 days had a median stroke-free life expectancy of 10 years, 7 months (SE, 6%). CONCLUSIONS: Direct reconstruction of complex symptomatic SAT lesions can be performed with acceptable death/stroke rates and with long-term patient benefit. Asymptomatic lesions in patients who have significant concomitant conditions should be managed with a less-morbid cervical or endovascular approach, even if long-term outcome of the latter is inferior.

Adult↗
PubMed1998

Reflex sympathetic dystrophy of the face: current treatment recommendations.

Reflex sympathetic dystrophy (RSD) of the face is an infrequently reported clinical pain syndrome characterized by dysesthesia, hyperalgia, hyperpathia, and allodynia. Treatment strategies, extrapolated from RSD and causalgia of the extremities, remain variable and poorly defined. Sympathetic blockade is generally the diagnostic and therapeutic treatment of choice; however, the frequency, timing, and duration of injections; need for neurolytic blocks; and role of sympathectomy are not well understood. The objectives of this report are to highlight the clinical behavior of facial RSD and contrast its essential differences from extremity RSD in response to standard treatment regimes. The case studies of two patients with this syndrome, following vascular surgery in the neck, are retrospectively reviewed with existent reported cases. Age, gender, etiology, symptoms, onset, triggers, and examination findings; timing, duration, and method of treatment; and outcome are summarized, forming the database for this study. Findings demonstrate an infrequent association of vasomotor and sudomotor changes with facial RSD, and lack of progression to a dystrophic or an atrophic stage, in contrast to extremity RSD. Furthermore, treatment response to sympathetic blockade is durable and less critically dependent on timing. The authors conclude that facial RSD has a favorable prognosis and should be managed conservatively with nonneurolytic stellate ganglion blocks, even when initiated as a delayed and repetitive injection series.

Aged↗
PubMed1998

Standardized technique of laparoscopic surgery in the rat.

The evolution of advanced laparoscopic techniques requires animal models for instrument development, evaluation of the physiopathological correlation and physician training. Selection of surgical models is primarily based on cost, availability, anatomic and physiologic considerations, and housing and anesthetic methods. The use of large animals is becoming increasingly difficult due to restrictive legislation, public concern, and economic factors. A standardized technique of laparoscopic surgery in the rat has been developed to perform procedures in all abdominal regions including fundoplication, splenectomy, nephrectomy, liver resection, herniorraphy, colotomy, colectomy, and retroperitoneal exploration. The equipment consists of a specially designed small animal operating table, a standard arthroscope and micro-instruments. The rat model gives the opportunity to investigate the physiopathological relations and immune functions of laparoscopic procedures, to develop micro-instruments under realistic conditions of a live organism, and it is an excellent training model especially for pediatric and microsurgery. Besides low costs and easy availability, the rat model requires less logistic and financial efforts.

Animals↗
PubMed1998

The Virtual Instrumentation (VI) Laboratory facilitates customized on-site ergonomic analysis of minimally invasive surgery.

Ergonomic studies are needed to understand and improve the visual and physical interface that minimally invasive surgery methods interpose between the surgeon and the operating field. We used the Virtual Instrumentation (VI) Laboratory of the Biomedical Engineering Program at California State University, Sacramento to develop a portable ergonomic analysis system to compare the physical workloads imposed on the surgeon by tradition open and laparoscopic surgery techniques. We used the system at a national surgery conference to measure electromyogram (EMG) activity from thumb and forearm muscles of volunteer subjects as they performed simulated surgical tasks using open and laparoscopic techniques. We found that EMG activity was significantly greater for the laparoscopic than for the open surgery technique, suggesting that the laparoscopic technique was more physically demanding. The portable ergonomic analysis VI system was quick to set up and convenient to use. We are using the rapid prototyping and modular design capabilities of the VI Lab to develop additional ergonomic analysis VI systems.

Electromyography↗
PubMed1997

A comparison of surgeons' posture during laparoscopic and open surgical procedures.

BACKGROUND: There is increasing recognition of surgeons' physical fatigue in the new ergonomic environment of laparoscopic surgery. The purpose of this study was to determine what the differences are in the movement of the surgeon's axial skeleton between laparoscopic and open operations. METHODS: Surgeons' body positions were recorded on videotape during four laparoscopic (LAP) and six open (OP) operations. The percent of time the head and back were in a normal, bent, or twisted position as well as the number of changes in head and back position were tabulated using a computer program. A separate laboratory study was performed on four surgeons "walking" a 0.5-inch polyethylene tubing forward and backward using laparoscopic and open techniques. The movements of the surgeons' head, trunk, and pelvis were measured using a three-camera kinematic system (Kin). The center of pressure was recorded using a floor-mounted forceplate (Fp). RESULTS: In the operating room surgeons' head and back positions were more often straight in laparoscopic procedures and more often bent in open operations. The number of changes in back position per minute were significantly decreased when the laparoscopic-only part of surgery was analyzed. In the laboratory the subjects' head position was significantly (p = 0.02) more upright and the anteroposterior (AP) and rotational range of motion of the head was significantly reduced during laparoscopy. Subjects' CP was more anterior and there was a significant reduction in the AP range of motion of the CP during laparoscopy. CONCLUSIONS: Our study suggests that surgeons exhibit decreased mobility of the head and back and less anteroposterior weight shifting during laparoscopic manipulations despite a more upright posture. This more restricted posture during laparoscopic surgery may induce fatigue by limiting the natural changes in body posture that occur during open surgery.

Ergonomics↗
PubMed1997

The optimum pneumoperitoneum pressure for laparoscopic surgery in the rat model. A detailed cardiorespiratory study.

BACKGROUND: There is increasing interest in the rat model of laparoscopic surgery. This study evaluates the cardiorespiratory effects of increasing CO2 pneumoperitoneum (PP) in the rat. METHODS: Nine Sprague-Dawley rats were subjected to CO2 PP at pressures of 2, 5, 10, and 15 mmHg or control (no PP) under anesthesia. Catheters were placed in the femoral artery and the jugular vein to measure heart rate (HR), blood pressure (MAP), and arterial pH, PCO2, PO2, and HCO3. A thermistor probe in the aortic arch measured cardiac output (CO) and blood temperature (BT). RESULTS: CO2 PP had no effect on CO, MAP, or BT at any pressure. CO2 PP greater than 5 mmHg caused significant bradycardia and CO2 PP greater than 10 mmHg caused significant respiratory acidosis. CONCLUSIONS: CO2 PP pressures above 10 mmHg in rat should be avoided when performing laparoscopic surgery in the rat model.

Analysis of Variance↗
PubMed1997

Laparoscopic cecal ligation and puncture in the rat. Surgical technique and preliminary results.

BACKGROUND: We describe a technique of laparoscopic cecal ligation and puncture (CLP) in the rat analogous to open CLP which may facilitate the study of minimally invasive surgery (MIS) and peritonitis. METHODS: Forty-four rats were randomized to either laparoscopic or open CLP and their 3-day mortality was recorded. Autopsies were performed for peritoneal fluid cultures, measurement of the length of ligated cecum, and scoring of the degree of cecal necrosis. RESULTS: Laparoscopic CLP required slightly longer operating times compared to open CLP (average 15.6 vs 13.1 min, p = 0.002). Three-day postoperative mortality was 36.4% and 22.7% for open and laparoscopic CLP, respectively (p = NS). There were no differences in the length of ligated cecum or the cecal necrosis score between the open and laparoscopic CLP groups. CONCLUSION: Laparoscopic CLP is feasible and produces a fecal peritonitis with similar characteristics to those of traditional open CLP.

Animals↗
PubMed1997

Use of the virtual instrumentation laboratory for the assessment of human factors in surgery and anesthesia.

There is a growing consensus that human factors issues for anesthesiologists, surgeons, and other operating room personnel require serious attention. We have established a program of collaboration between the University of California Davis Medical Center Departments of Anesthesiology and Surgery and the California State University Sacramento Biomedical Engineering Program to address ergonomic problems in anesthesiology and surgery using a Virtual Instrumentation Laboratory. A 17-workstation Virtual Instrument Laboratory using LabVIEW software on Power Macintosh platforms permits rapid prototyping of medical monitor displays as well as rapid development of data acquisition and processing circuits for physiologic data collection. The Virtual Instrument Lab has been used for three Master's thesis projects and a BME course titled Human Factors in the Design of Medical and Assistive Technology. Course projects have included: 1) The design of novel physiologic data displays for potential use in anesthesia workstations, and 2) The measurement of surface electromyographic signals and heart rate variability to investigate the physical and mental workload of performing laparoscopic surgery. The Virtual Instrument Lab allows BME students to investigate relatively complex human factors issues in anesthesiology and surgery in a short time span.

Anesthesiology↗
PubMed1996

Determination of cardiorespiratory function and the optimum anesthetic regimen during laparoscopic surgery in the rat model.

BACKGROUND: The rat is increasingly being used in laparoscopic research yet the hemodynamic and respiratory effects of CO2 pneumoperitoneum have not been studied in this model. METHODS: Five Lewis rats were anesthetized with inhaled isoflurane (1.4-2.0%) and a 50% O2/50% N2O mixture by mask (ISO). Another five rats were anesthetized with 1 ml/kg intraperitoneal sodium pentobarbital (PB) and given 100% O2 by mask. Catheters were placed in the femoral artery and the right jugular vein and a thermistor probe was placed in the aortic arch. Heart rate (HR), blood pressure (MAP), cardiac index (CI), arterial pH, and PCO2 were measured at baseline and following 10, 20, and 30 min of 2 mmHg CO2 pneumoperitoneum. RESULTS: CO2 pneumoperitoneum had no effect on HR, MAP, CI, pH, or PCO2 in either the ISO or PB anesthetic groups. Comparing the two anesthetic groups, PB demonstrated a significantly higher MAP at all time points, a significantly higher PCO2 at baseline, and 10 min of pneumoperitoneum, a significantly lower pH at baseline, 10, and 30 minutes of pneumoperitoneum, and a significantly longer induction time (31 vs. 6 min). There was no difference in HR or CI between the two anesthetics. CONCLUSION: Low-pressure CO2 pneumoperitoneum up to 30 min in the spontaneously breathing rat does not significantly affect HR, MAP, CI, pH, or PCO2. Inhalational isoflurance/N2O anesthesia produces less hypertension and respiratory acidosis than intraperitoneal pentobarbital during pneumoperitoneum in the rat.

Anesthesia, Inhalation↗
PubMed1996

A comparison of operating room crowding between open and laparoscopic operations.

BACKGROUND: The clutter of equipment and lines in today's operating room (O.R.) is increasing. Endoscopic surgical procedures are particularly afflicted by this problem because they require additional equipment. Increasing O.R. crowding may present unnecessary hazards to traffic and adversely affect the performance of the surgical team. The purpose of this study is to provide a quantitative summary of the furniture, equipment, cables, and tubes present during open and laparoscopic operations. METHODS: We prospectively studied an unselected series of general surgical open (OP, n = 10) and laparoscopic (LAP, n = 10) operations performed at a major university teaching hospital. We recorded the location of all furniture and equipment as well as the source, course, and destination of all cables and tubes in the O.R. Cables and tubes touching the surgeon or the assistant were particularly noted. Results are expressed as median values for each group. RESULTS: The percent of O.R. space occupied increased from OP = 36% to LAP = 41% (p < 0.002). The median number of cables and tubes present increased from OP = 27 to LAP = 34 (p < 0.0002), with the number of these lines touching a member of the surgical team increasing from OP = 2 to LAP = 6 (p < 0.0003). CONCLUSIONS: We conclude that there is a significant trend toward increasing O.R. crowding during laparoscopic surgery. Innovative designs will be needed to reduce clutter in the O.R. of the future.

Crowding↗
PubMed1996

Successfully establishing laparoscopic surgery programs in developing countries. Clinical results and lessons learned.

BACKGROUND: Laparoscopic surgery has not been widely established in developing countries due to the lack of access to training and lack of money. We describe our experience using on-site training programs to efficiently teach and propagate laparoscopic surgery in Leon, Nicaragua; La Paz, Bolivia; and Santa Cruz, Bolivia. METHODS: A group of well-trained and motivated local surgeons was identified in each country as the initial target for teaching. Participants were taught basic and advanced laparoscopic surgery during on-site didactics, animal laboratories, and proctoring sessions. Follow-up courses were held until the target group of surgeons was capable of independently teaching and supervising laparoscopic surgery among other surgeons in each country. RESULTS: Multiple technical and logistic difficulties were encountered. In Leon, Nicaragua, and La Paz, Bolivia, a total of eight surgeons were fully trained and proctored in laparoscopic cholecystectomy. In La Paz and Santa Cruz, Bolivia, a total of seven surgeons were instructed in advanced laparoscopic procedures. To date, over 180 patients have undergone laparoscopic cholecystectomy or advanced procedures with a morbidity similar to that reported in literature series in the United States. CONCLUSIONS: Our experience demonstrates that in spite of numerous limitations, basic and laparoscopic surgery can be efficiently and safely taught in developing countries. Many lessons were learned in how to safely and efficiently use laparoscopic equipment and instruments within strict financial constraints.

Clinical Competence↗