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Biomedical subjects

R Mårvik

Publications and source records attributed to R Mårvik.

At least 19 recordsLinked to original sources
PubMed2006

Hemodynamic and tissue blood flow responses to long-term pneumoperitoneum and hypercapnia in the pig.

BACKGROUND: Increased peritoneal blood flow may influence the ability of cancer cells to adhere to and survive on the peritoneal surface during and after laparoscopic cancer surgery. Carbon dioxide (CO2) pneumoperitoneum is associated with a marked blood flow increase in the peritoneum. However, it is not clear whether the vasodilatory effect in the peritoneum is related to a local or systemic effect of CO2. METHODS: In this study, 21 pigs were exposed to pneumoperitoneum produced with either CO2 (n = 7) or helium (He) (n = 7) insufflation at 10 mmHg for 4 h, or to two consecutive levels of hypercapnia (7 and 11 kPa) (n = 7) produced by the addition of CO2 to the inhalational gas mixture. Tissue blood flow measurements were performed using the colored microsphere technique. RESULTS: Blood flow in peritoneal tissue increased during CO2, but not He, pneumoperitoneum, whereas it did not change at any level of hypercapnia alone. There was no change in blood flow in most organs at the partial pressure of CO2 (PaCO2) level of 7 kPa. However, at a PaCO2 of 11 kPa, blood flow was increased in the central nervous system, myocardium, and some gastrointestinal organs. The blood flow decreased markedly in all striated muscular tissues during both levels of hypercapnia. CONCLUSION: The effect of CO2 on peritoneal blood flow during laparoscopic surgery is a local effect, and not attributable to central hemodynamic effects of CO2 pneumoperitoneum or high systemic levels of CO2.

Animals↗
PubMed2006

Ergonomic design criteria for a novel laparoscopic tool handle with tactile feedback.

Laparoscopic surgery has many ergonomic disadvantages often not considered in the design of instruments. The poorly designed surgical tools produce inconveniences in both functional and cognitive aspects; including tactile sensation and visual-motor space coordination. The aim of this article is to find out how laparoscopic handle design can be improved by combining classical ergonomic guidelines with tactile feedback related to handle design. The article briefly discusses how the human hand and hand-held tools are used to perform tasks. An ergonomic handle for laparoscopic grasping, with a built-in tactile sensation display, is presented. Our review of laparoscopic instruments reveals important aspects for handle design. It is concluded that there is a need for greater awareness of ergonomic guidelines for users' sensory requirements when designing and manufacturing laparoscopic instruments.

Equipment Design↗
PubMed2005

Postoperative morbidity and recurrence after local excision of rectal adenomas and rectal cancer by transanal endoscopic microsurgery.

OBJECTIVE: Tumours in the middle and upper part of the rectum are not easy accessible to local excision. Transanal endoscopic microsurgery (TEM) has been recommended for excision of sessile adenomas in the middle and upper part of the rectum, and for small cancers in patients not fit for major surgery. The purpose of this study was to evaluate postoperative morbidity and local recurrence after TEM. MATERIAL AND METHODS: Seventy-nine patients were treated by TEM in the period 1994-2001. The median age was 74 years. The indications for TEM were rectal adenoma in 72 patients and rectal cancer in 7 patients. The tumours were located within 18 cm from the dentate line, median 10 cm. There were performed 69 transmural and 10 mucosal excisions. Mean follow up was 24 months (range 1-95 months). Twenty (25%) patients died during the follow up period, two because of metastases and 18 of other causes. RESULTS: Seven patients had complications. Two (2.5%) patients had peroperative perforation in the intra-abdominal part of the rectum treated by laparotomy. Five (6%) patients had postoperative cardiopulmonal or surgical complications. Eight patients with benign pre-operative histopathological examination had cancer. The local recurrence rate (13%) was similar for adenomas and for carcinomas. CONCLUSION: TEM is a safe technique well tolerated also by high-risk patients, and should be the preferred method in patients with benign tumours in the middle and upper part of the rectum, and in selected cases of early rectal cancer. Benign pre-operative histology does not preclude malignancy and some patients may need further treatment for unexpected malignancy.

Adenoma↗
PubMed2005

Image-guided laparoscopic surgery. Review and current status.

The main drawback with laparoscopic surgery is that the surgeon is unable to palpate vessels, tumours and organs during surgery. Further-more, the laparoscope only provides a surface view of organs. There is a need for more advanced visualizations techniques that can enhance the display presented to the surgeon so that important information below the surface of the organs is included when planning the procedure as well as for guidance and control during treatment. In this paper, we present a review of the literature and the state of art within image-guided laparoscopic surgery. We describe our own experience using a prototype navigation system for advanced visualizations and guidance during laparoscopic procedures in the retroperitoneum. Furthermore, we show sample images from the Future Operating Room for laparoscopic surgery in Trondheim, where this technology is being further developed and tested in clinical studies. Our system is based on three-dimensional navigation technology, i.e. preoperatively acquired magnetic resonance or computed tomography data used in combination with tracked instruments, allowing the surgeon to interactively control the display of images prior to and during surgery with normal use of the instruments. In summary, we believe that abdominal image navigation using tracked instruments and advanced visualizations has a large potential for improving future laparoscopic surgery, especially in cases where vessels and anatomical relations beyond surfaces is difficult to identify using only a laparoscope. The technology helps the surgeon to better understand the anatomy and locate blood vessels. Accordingly, we believe that this new technology could increase safety and make it easier for the surgeon to perform successful laparoscopic surgery.

Diagnostic Imaging↗
PubMed2004

Laparoscopic navigation pointer for three-dimensional image-guided surgery.

BACKGROUND: The main drawback with the laparoscopic approach is that the surgeon is unable to palpate vessels, tumors, and organs during surgery. Furthermore, the laparoscope provides only surface view of organs. There is a need for more advanced visualizations that can enhance the view to include information below the surface of the organs for planning of the procedure and for control and guidance during treatment. METHODS: We propose three-dimensional (3D) navigation technology based on preoperatively acquired magnetic resonance or computed tomography data used in combination with a laparoscopic navigation pointer (LNP). The LNP has an attached position tracker that allows the surgeon to control the display of images interactively before and during surgery. This study evaluated the patient registration accuracy, the feasibility of image-based navigation and, qualitatively, the navigation precision in the retroperitoneum during laparoscopic surgery. RESULTS: This technology was used during the treatment of six patients (involving adrenalectomies and a neuroma protruding into the pelvis). An average patient registration accuracy of 6.90 mm was achieved. The precision during navigation in the retroperitoneum was, in some cases, better than the patient registration accuracy suggested. The technology helped the surgeons to understand better the anatomy and to locate blood vessels. CONCLUSIONS: In the reported cases, the LNP was a useful tool for image guidance in laparoscopic surgery, both for planning the surgical approach in detail and for guidance. The authors believe that adominal 3D image guidance using an LNP has a large potential for improving laparoscopic surgery, especially when vessels and anatomic relations may be difficult to identify using only a laparoscope. Accordingly, they believe this new technology could increase safety and make it easier for the surgeon to perform successful laparoscopic surgery.

Adenoma↗
PubMed2003

Effect of carbon dioxide pneumoperitoneum on tissue blood flow in the peritoneum, rectus abdominis, and diaphragm muscles.

BACKGROUND: Changes in local blood flow may play a role in the pathogenesis of port-site metastasis. This study aimed to investigate the effect of pneumoperitoneum induced by carbon dioxide (CO2) on the blood flow in the peritoneum and abdominal wall muscle layers, which are target structures for this phenomenon. METHODS: The study was performed on domestic farm swine of both genders weighing 20 to 25 kg. Intraabdominal pressures (IAP) of 0, 5, and 10 mmHg were produced by either CO2 ( n = 9) or helium (He) ( n = 6) insufflations. The colored microsphere technique was used to measure blood flow distributions in the parietal peritoneum, rectus abdominis, and diaphragm muscles. RESULTS: Insufflation of CO2 was associated with a threefold increase in blood flow of the parietal peritoneum at both 5 and 10 mmHg IAP ( p < 0.001 for both pressure levels). In contrast, insufflation of He caused a significant decrease in blood flow in the parietal peritoneum at both 5 and 10 mmHg ( p < 0.05). In the rectus abdominis and diaphragm muscles, blood flow remained unchanged after insufflation of CO2 at both 5 and 10 mmHg IAP. However, after insufflation of He, there was a substantial decrease in blood flow both in the rectus abdominis and diaphragm muscles at both 5 mmHg ( p < 0.01 and p < 0.05, respectively) and 10 mmHg ( p < 0.001 and p < 0.01, respectively). CONCLUSIONS: Despite high intraabdominal pressure, tissues surrounding the abdominal cavity, particularly the peritoneum, respond to insufflation of CO2 with increased blood flow, which may favor the growth of tumor cells.

Animals↗
PubMed2003

3D ultrasound-based navigation for radiofrequency thermal ablation in the treatment of liver malignancies.

BACKGROUND: The aim of the study was to compare three methods for ultrasound-based guidance of a radiofrequency probe into liver tumors in a model setup. METHODS: The liver model tumors were placed inside excised calf livers, and the radiofrequency probe was guided into the center using either a new 3D navigation method or two conventional 2D methods-freehand scanning and a method based on a biopsy guide. We performed 54 experiments, measuring the physical distance (all methods) and image distance (3D method only) from the tip of the probe to the center of the tumors. RESULTS: Based on the physical measurements alone, the biopsy-based guiding performed better than both the 2D freehand and the 3D navigation method. However, the 3D image measurements showed that the tip of the probe was better positioned in the center of the model tumors for the 3D navigation method as compared to the physical measurement results for the 2D methods. CONCLUSION: Although it was easier to position the radiofrequency probe accurately using the 3D image display technique, movement of the model tumor during 3D navigation is a challenge.

Animals↗
PubMed2003

Medical image quality as a socio-technical phenomenon.

OBJECTIVES: The study aims to interpret image quality in laparoscopic surgery not only as a technical parameter but also as the result of the situation of use. METHODS: Observational studies of laparoscopy in use, semi-structured and informal interviews with laparoscopists. RESULTS: When medical images are digitized to exploit novel technical possibilities, image quality becomes a paramount issue. Image quality is often discussed exclusively in technical terms, but the socio-technical study of image quality in surgical telemedicine presented in this paper showed that it is definitely more than a purely technical parameter. CONCLUSIONS: While the resulting quality of the image was significantly shaped by the persons involved, the concept of "quality" itself was also relative and changing with the situation of use. A given technology does not determine image quality. Rather than focusing only on the technical quality, the attention of designers and decision makers should also be directed to the socio-technical network surrounding the image and its use.

Diagnostic Imaging↗
PubMed2002

Laparoscopic antiperistaltic versus isoperistaltic gastrojejunostomy for palliation of gastric outlet obstruction in advanced cancer.

The purpose of the study was to compare the impact of the peristaltic orientation of laparoscopic gastrojejunal anastomoses (LGJ) in patients with malignant gastric outlet obstruction (GOO) on postoperative delayed-return gastric emptying (DRGE) rates. GOO was defined as complete holdup of contrast at barium meal and/or failure of gastroscope to pass beyond stricture. DRGE was defined as inability to eat regular diet by day 10. Thirty-four patients undergoing antiperistaltic LGJ were compared with 21 patients undergoing isoperistaltic LGJ at two institutions during the same period. Thirty-day mortality was 5.4%, and median survival was 6.2 months. Thirty-day morbidity was 20%, and conversion rate was 3.6%. DRGE rates were increased after isoperistaltic LGJ (0 vs. 3; P < 0.05), but patient groups were not well matched for type of primary cancer (P < 0.05). All patients with DRGE resumed food intake 12 to 16 days after surgery. There were 21 admissions before death, with a reoperation rate of 11.5% and a recurrent GOO rate of 3.8%. Although no conclusions could be drawn about whether the peristaltic orientation of the anastomosis had a bearing on DRGE rates, LGJ resulted in an overall 6% rate of DRGE.

Aged↗
PubMed2001

Effect of increased intraabdominal pressure on cardiac output and tissue blood flow assessed by color-labeled microspheres in the pig.

BACKGROUND: Studies of the hemodynamic effects associated with the pneumoperitoneum have had controversial results. We set out to investigate the effect of increased intraabdominal pressure (IAP) on cardiac output and tissue blood flow in various intraabdominal and extraabdominal organs using the color-labeled microsphere (CLM) technique. METHODS: IAP was induced by CO2 insufflation in anesthetized pigs; 0, 5, and 10 mmHg was used in the low-pressure group and 0, 15, and 24 mmHg in the high-pressure group. Tissue blood flow (ml.min-1.g-1) and cardiac output (CO) (ml/min) were determined by the CLM technique. RESULTS: CO decreased at IAP > or = 15 mmHg. Arterial PaCO2 and hydrogen ion concentration increased in response to all levels of IAP. Arterial PaO2, oxygen saturation, and bicarbonate ion concentration remained unchanged. Low IAP did not influence tissue blood flows in most of the organs. However, in the spleen, pancreas, esophagus, and gastric mucosal specimens, tissue blood flow was significantly decreased at 24 mmHg. CONCLUSION: The level of IAP used in current practice (10-12 mmHg) appears to be safe with regard to hemodynamic variables and tissues blood flow; however, higher levels may induce a decrease in cardiac output and tissue blood flow.

Animals↗
PubMed2000

Initial experience with stereoscopic visualization of three-dimensional ultrasound data in surgery.

Initial in vivo and in vitro experiments were performed to evaluate the feasibility of stereoscopically displaying three-dimensional (3D) ultrasound data from neurosurgery, laparoscopic surgery, and vascular surgery. Stereoscopic visualization was illustrated by four video sequences, which can be downloaded from http://www.us.unimed. sintef.no/. These sequences show a brain tumor, hepatic arteries in relation to the gallbladder, a model that mimics a neuroendoscope in a cyst, and a "flight" into model of an artery with an intima flap. The experiments indicate that stereoscopic display of ultrasound data is feasible when there is sufficient contrast between the objects of interest and the surrounding tissue. True 3D vision improves perception, thus enhancing the ability to understand complex anatomic structures such as irregular lesions and tortuous vessels.

Filtration↗
PubMed2000

Oxyntic lesions may be provoked in the rat both by the process of acid secretion and also by gastric acidity.

BACKGROUND: Gastric ischaemia appears to be a common pathogenetic factor for stress ulcers. These ulcers occur predominantly in the oxyntic mucosa, suggesting that the acid secretory process or its stimulation is involved in the pathogenesis. METHODS: We examined separately the role of the acid secretory process and gastric luminal acidity in the pathogenesis of gastric lesions using the isolated vascularly perfused acid-secreting rat stomach. RESULTS: Pentagastrin-stimulated acid secretion induced submucosal bleeding in the oxyntic mucosa whether accompanied by perfusion of the gastric lumen with saline or a phosphate buffer at pH 7.0. On the other hand, acidity, whether endogenous or introduced by luminal perfusion, induced erosions in both the oxyntic and antral mucosa. CONCLUSION: It is concluded that the acid secretory process itself contributes to the particular vulnerability of the oxyntic mucosa to ischaemia. Histamine released upon stimulation of gastric acid secretion or shortage of energy due to the requirements for acid secretion may both contribute to this vulnerability. Furthermore, these findings suggest that inhibition of gastric acid secretion should be superior to antacids in preventing stress ulcers.

1-Methyl-3-isobutylxanthine↗
PubMed2000

A comparative experimental study evaluating the performance of surgical robots aesop and endosista.

The aim of this study was to experimentally assess and compare the accuracy of the surgical robots Aesop and Endosista as camera holders for use in laparoscopic surgery. The performance of these two robotic systems was examined for linear (upwards, downwards, diagonal), complex, and "in and out" movements using laparoscopic training boxes. Standard distances and tests were used for each system, and the time required to achieve each task was measured. The majority of the linear movements of the verbal and preprogrammed modes of Aesop were quicker than those of Endosista. Diagonal movements were significantly faster with the preprogrammed-mode Aesop. Complex or three-dimensional movements were also significantly faster with both modes of Aesop than with Endosista. Under the experimental conditions, Aesop, particularly in the preprogrammed mode, is quicker and more accurate than Endosista.

Evaluation Studies as Topic↗
PubMed1999

Open vs laparoscopic repair of perforated peptic ulcer.

BACKGROUND: Most studies have found that the only advantage to the laparoscopic treatment of perforated peptic ulcer is a reduced need for postoperative analgesia. Therefore, we set out to assess the short-term outcome of open (OR) versus laparoscopic (LR) repair of perforated peptic ulcer. METHODS: A total of 62 consecutive OR patients were compared with a concurrent cohort of 17 diagnosis-matched LR controls treated at the same hospital between 1991 and 1996. RESULTS: The OR and LR patients were comparable for age, weight, American Society of Anesthesiologists (ASA) grade, Acute Physiology and Chronic Health Evaluation (APACHE II) score, Boey score, ulcer site, Mannheim Peritonitis Index (MPI), delay of surgery, Helicobacter pylori infection, nonsteroidal antiinflammatory drug (NSAID) intake, and previous abdominal surgery. More LR than OR patients were operated on by staff surgeons (chi2 = 46.9, 1 d.f., p << 0.01). Mortality (OR: 12, LR: two), morbidity (OR: eight, LR: two), estimated blood loss (OR: 120 ml, LR: 95 ml), solid food intake resumption (OR: 5 days, LR 4 days), NSAID consumption (OR: 2,225 mg, LR: 1,815 mg), delayed gastric emptying (OR: two, OR: one), and hospital stay (OR: 9 days, LR: 7 days) were not significantly different for the two groups. Four LR patients (23. 5%) were converted to OR due to failure to progress (n = 3) or posterior perforation (n = 1). Operating time was shorter in OR patients (65 min versus 92 min, p << 0.01). LR patients had reduced opioid consumption (256 mg versus 134 mg, p << 0.01). One LR and 16 OR patients were lost to follow-up. Median follow-up was 14 months (range, 2-55) and 18 months (range, 1-62) in OR and LR patients, respectively. There were more LR than OR patients with Visick score I (p = 0.002) and more OR than LR patients with Visick score II (p = 0.0001). Scores III and IV did not differ significantly. CONCLUSION: The laparoscopic repair of perforated peptic ulcer does not yield any additional benefits over the open repair.

Adult↗
PubMed1999

Selective endoscopic retrograde cholangiography prior to laparoscopic cholecystectomy for gallstones.

BACKGROUND: To assess the outcome of endoscopic retrograde cholangiography (ERC) before laparoscopic cholecystectomy (LC) for symptomatic gallbladder and suspected duct stones. METHODS: During 3 years, one or more of four criteria led to ERC: jaundice, choledocus >8 mm, cholestasis, and severe biliary pancreatitis. Endoscopic extraction (ESE) of ductal stones was attempted before LC. RESULTS: In all, 990 patients were prospectively included. There were no exclusions. There were no deaths. A multivariate logistic regression analysis identified jaundice (P = 0.001), pancreatitis (P = 0.001), and cholestasis (P = 0.001) as statistically significant predictors of ductal stones. Choledocus >8 mm was not a significant predictor (P = 0.12). A total of 155 (16%) patients underwent ERC for suspected stones: 21 of 155 (13%) patients had no stones; and 6 of 134 (4%) patients had stone impaction cleared at open surgery. ERC clearance rate was 95% (128 of 134). LC was performed in 149 of 155 patients after a median interval of 3 days (range 1 to 7). Morbidity rates were 3% (4 of 134), 2% (3 of 149), and nil (0 of 6) after ESE, LC, or open surgery, respectively. Median hospital stay was 11 days. A total of 835 patients underwent LC with a 1.5% complication rate. Laparoscopic fluoro-cholangiography showed < or =3 mm-sized stones in 10 of 835 (1.2%) patients. No stones were reported at a median follow-up of 4 months including 990 patients. CONCLUSIONS: Ninety-five percent of patients with ductal stones can be successfully and safely managed by ERC prior to LC.

Adolescent↗
PubMed1998

Carbachol stimulation of gastric acid secretion and its effects on the parietal cell.

1. The acid secretagogue effect of gastrin is mainly mediated by the release of enterochromaffin-like (ECL) cell histamine, but the mechanism of muscarinic stimulation of acid secretion remains unclear. The results of studying aminopyrine uptake in isolated parietal cells, and histamine release in isolated ECL cells suggest that muscarinic agents may act both directly on the parietal cell and indirectly via histamine release from ECL cells. 2. We examined parietal and ECL cell responses to the muscarinic agent carbamylcholine (carbachol) in conscious rats and in rat isolated vascularly perfused stomachs. 3. Intravenous carbachol stimulated acid secretion in conscious gastric fistula rats and increased H+K+ ATPase mRNA abundance, indicating activation of parietal cells. In these experiments there was no increase in portal venous histamine, or in oxyntic mucosal histidine decarboxylase (HDC) enzyme activity and HDC mRNA abundance. 4. In rat isolated stomachs stimulated with carbachol in the dose range 10 nM(-1) mM only the 1 microM concentration increased venous histamine significantly. 5. We concluded that the muscarinic agent carbachol stimulates acid secretion and H+K+ ATPase mRNA in vivo by a direct effect on the parietal cell, that does not depend on the release of ECL cell histamine.

Animals↗
PubMed1998

Open versus laparoscopic gastrojejunostomy for palliation in advanced pancreatic cancer.

To assess short-term outcome of open (OGJ) versus laparoscopic (LGJ) gastrojejunostomy in palliation of gastric outlet obstruction (GOO) caused by advanced pancreatic cancer, 22 OGJ patients were compared with 9 diagnosis-matched LGJ controls operated on at the same hospital between 1991 and 1996. Patients undergoing OGJ and LGJ were comparable for age, gender, weight, American Society of Anesthesiologists grading, and previous extensive abdominal surgery, but not for gastroenterostomy performed as a prophylactic procedure (9 vs. 0, respectively). Mortality (5 vs. 1, p = 1.5), overall morbidity (9 vs. 3, p = 0.42), operating time (113.6 +/- 24.5 minutes vs. 125 +/- 15.2 minutes, p < 0.5), time to oral solid food intake (7.2 +/- 0.9 days vs. 5.3 +/- 1.3 days, p < 0.5), nonsteroidal anti-inflammatory drug consumption (7,563.6 +/- 3,381.3 mg vs. 2,044 +/- 673 mg, p < 0.5), opioid consumption (688.5 +/- 258.6 mg vs. 2,910.5 +/- 2,659.9 mg, p < 0.5), delayed-return gastric emptying (5 vs. 1, p = 0.12), postoperative hospital stay (14.6 +/- 1.9 days vs. 10.1 +/- 1.8 days, p < 0.5), survival (5.7 +/- 0.8 months vs. 4.6 +/- 0.6 months, p < 0.5), and further hospital stay before death (9.8 +/- 3.3 days vs. 11.6 +/- 3.4 days, p > 0.5) were not significantly different in 22 OGJ and 9 LGJ patients, respectively. Estimated blood loss was significantly lower in LGJ patients (270.2 +/- 45.8 ml vs. 66 +/- 15.7 ml, p < 0.01). When 13 of 22 patients undergoing OGJ for treatment were compared with 9 LGJ patients, only estimated blood loss (p < 0.01) and hospital stay (p < 0.05) were significantly reduced in LGJ patients. Recurrent GOO before death occurred in one patient (1 of 22, 4.5%) 9 months after OGJ. LGJ for palliative treatment of GOO in advanced pancreatic cancer offered (in spite of the learning curve) reduced estimated blood loss and hospital stay when compared with OGJ.

Aged↗