Annealing studies combined with low temperature emission Mössbauer spectroscopy of short-lived parent isotopes: Determination of local Debye-Waller factors.

An extension of the online implantation chamber used for emission Mössbauer Spectroscopy (eMS) at ISOLDE/CERN that allows for quick removal of samples for offline low temperature studies is briefly described. We demonstrate how online eMS data obtained during implantation at temperatures between 300 K and 650 K of short-lived parent isotopes combined with rapid cooling and offline eMS measurements during the decay of the parent isotope can give detailed information on the binding properties of the Mössbauer probe in the lattice. This approach has been applied to study the properties of Sn impurities in ZnO following implantation of 119In (T½ = 2.4 min). Sn in the 4+ and 2+ charge states is observed. Above T > 600 K, Sn2+ is observed and is ascribed to Sn on regular Zn sites, while Sn2+ detected at T < 600 K is due to Sn in local amorphous regions. A new annealing stage is reported at T ≈ 550 K, characterized by changes in the Sn4+ emission profile, and is attributed to the annihilation of close Frenkel pairs.

Effect of different limb lengths on quality of life, eating patterns and gastrointestinal symptoms after Roux-en-Y gastric bypass in superobese patients: randomized study.

BACKGROUND: Distal Roux-en-Y gastrojejunal bypass (DRYGJB) gives better weight reduction than standard Roux-en-Y gastric bypass (RYGB) but at the risk of increased malnutrition side-effects. This study compared the effects of RYGB and DRYGJB on gastrointestinal symptoms, eating patterns and health-related quality of life (QoL). METHODS: This was a single-blind RCT from a university-affiliated obesity centre. Patients with a BMI of 50 kg/m2 or above were invited to participate. Treatment arms were standard gastric bypass with an alimentary limb of 150 cm and a biliopancreatic limb of 60 cm, with a variable common channel length, or DRYGJB with biliopancreatic limb of 200 cm, common channel limb of 150 cm and variable alimentary limb length. Baseline and follow-up data to 5 years on quality of life, obesity-related problems and gastrointestinal symptoms were collected using prospectively created and validated questionnaires. RESULTS: Some 140 patients were included. Those with a DRYGJB had better weight loss at 5 years (mean(s.d.) 68·3(21·8) kg versus 55·7(19·8) kg for standard RYGB; P = 0·011). Eating patterns improved, with no difference between the groups. Gastrointestinal symptoms (diarrhoea, indigestion) worsened significantly in both groups, but only patients with DRYGJB had significantly worse diarrhoea at the end of the study than at baseline (P = 0·006). Both groups had improved perceived generic QoL over baseline, and obesity-related problems were markedly reduced. CONCLUSION: Standard RYGB and both improved generic and disease-specific QoL and eating behavioural pattern. Diarrhoea was increased more following DRYGJB than after RYGB. Registration number: NCT01514799 (https://clinicaltrials.gov).

ANTECEDENTES: El bypass gastroyeyunal distal (distal gastrojejunal bypass, DRYGB) proporciona una mejor pérdida de peso que el RYGB estándar, pero con el riesgo de aumentar los efectos secundarios de malnutrición. El presente estudio comparó los efectos de RYGB y DRYGJB en los síntomas gastrointestinales, patrón alimentario y calidad de vida relacionada con la salud. MÉTODOS: Estudio aleatorizado simple-ciego y controlado efectuado en un centro de obesidad con afiliación universitaria. Se invitó a participar a pacientes con un IMC de ≥ 50 kg/m2 . Las ramas del tratamiento fueron el bypass gástrico estándar con asa alimentaria (alimentary lim, AL) de 150 cm y asa biliopancreática (biliopancreatic, BP) de 60 cm, con asa común (common cannel, CC) de longitud variable, o DRYGJB con asa BP de 200 cm, asa CC de 150 cm y AL variable. Se recogieron datos basales y de seguimiento a los 5 años respecto a la calidad de vida, problemas relacionados con la obesidad y síntomas gastrointestinales utilizando cuestionarios prospectivos creados y validados. RESULTADOS: Se incluyeron un total de 140 pacientes. Los pacientes con DRYGJB tuvieron una mayor pérdida de peso a los 5 años (media (DE) 68,3 kg (21,9) versus 55,7 (19,8); P = 0,011)). Los patrones alimentarios mejoraron sin diferencia entre grupos. Los síntomas gastrointestinales (diarrea, indigestión) empeoraron significativamente en ambos grupos, pero solo los pacientes con DRYGJB presentaron diarrea al final del estudio significativamente peor en comparación con la situación basal (P = 0,006). Ambos grupos presentaron una mejor percepción de la QoL genérica en comparación con el estado basal, y los problemas relacionados con la obesidad se redujeron considerablemente. CONCLUSIÓN: El bypass gástrico estándar (RYGB) y el bypass gastroyeyunal distal (DRYGJB) mejoraron la QoL, tanto genérica como la específica de la enfermedad, así como el patrón de comportamiento alimentario. El DRYGJB aumentó la diarrea más que el RYGJB.

Local increase of the Curie temperature in Mn/Fe implanted Y3Fe5O12 (YIG).

The change in the Curie temperature of single crystalline garnet Y3Fe5O12 (YIG) sample due to lattice damage induced by ion implantation has been investigated in 57Fe emission Mössbauer Spectroscopy (eMS) following implantation of 57Mn (T½ = 1.5 min). The Mössbauer spectra analysis reveal high spin Fe3+ ions substituted on both the octahedral and the tetrahedral sites. Measurements in the temperature range 298 K-798 K show that average values of the magnetic hyperfine field are decreased by the implantation-induced damage on the local lattice structure of the YIG. The Curie temperature, however, is determined to be 651 ± 5 K, considerably higher than the value of bulk YIG (559 K). This is most likely due to lattice damage-induced changes on the spin configurations of YIG through a FeA-O-FeD distortion scheme.

Statistical modelling of sea lice count data from salmon farms in the Faroe Islands.

Fiskaaling regularly counts the number of sea lice in the attached development stages (chalimus, mobiles and adult) for the salmon farms in the Faroe Islands. A statistical model of the data is developed. In the model, the sea-lice infection is represented by the chalimus (or mobile) lice developing into adult lice and is used to simulate past and current levels of adult lice-including treatments-as well as to predict the adult sea lice level 1-2 months into the future. Time series of the chalimus and adult lice show cross-correlations that shift in time and grow in size with temperature. This implies in situ the temperature-dependent development times of about 56 down to 42 days and the inverted development times (growth rates) of 0.018 up to 0.024 lice/day at 8-10°C. The temperature dependence DT=α1T+α2α3=17,840T+7.439-2.128is approximated byD1T=105.2-6.578T≈49 days at the mean temperature 8.5°C-similar to DchaT=100.6-6.507T≈45 days from EWOS data. The observed development times at four sites for a year (2010-11) were 49, 50, 51 and 52 days, respectively. Finally, we estimate the sea lice production from fish farms to discuss approaches to control the sea lice epidemics-preferably by natural means. This study is useful for understanding sea lice levels and treatments, and for in situ analysis of the sea-lice development times and growth rates.

Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films.

The underlying mechanism driving the structural amorphous-to-crystalline transition in Group VI chalcogenides is still a matter of debate even in the simplest GeTe system. We exploit the extreme sensitivity of 57Fe emission Mössbauer spectroscopy, following dilute implantation of 57Mn (T½ = 1.5 min) at ISOLDE/CERN, to study the electronic charge distribution in the immediate vicinity of the 57Fe probe substituting Ge (FeGe), and to interrogate the local environment of FeGe over the amorphous-crystalline phase transition in GeTe thin films. Our results show that the local structure of as-sputtered amorphous GeTe is a combination of tetrahedral and defect-octahedral sites. The main effect of the crystallization is the conversion from tetrahedral to defect-free octahedral sites. We discover that only the tetrahedral fraction in amorphous GeTe participates to the change of the FeGe-Te chemical bonds, with a net electronic charge density transfer of ~ 1.6 e/a0 between FeGe and neighboring Te atoms. This charge transfer accounts for a lowering of the covalent character during crystallization. The results are corroborated by theoretical calculations within the framework of density functional theory. The observed atomic-scale chemical-structural changes are directly connected to the macroscopic phase transition and resistivity switch of GeTe thin films.

Charge states and lattice sites of dilute implanted Sn in ZnO.

The common charge states of Sn are 2+ and 4+. While charge neutrality considerations favour 2+ to be the natural charge state of Sn in ZnO, there are several reports suggesting the 4+ state instead. In order to investigate the charge states, lattice sites, and the effect of the ion implantation process of dilute Sn atoms in ZnO, we have performed 119Sn emission Mössbauer spectroscopy on ZnO single crystal samples following ion implantation of radioactive 119In (T ½ = 2.4 min) at temperatures between 96 K and 762 K. Complementary perturbed angular correlation measurements on 111mCd implanted ZnO were also conducted. Our results show that the 2+ state is the natural charge state for Sn in defect free ZnO and that the 4+ charge state is stabilized by acceptor defects created in the implantation process.

Corticosteroids or Not for Postoperative Nausea: A Double-Blinded Randomized Study.

BACKGROUND: Postoperative nausea and vomiting (PONV) is common after general anaesthesia, and corticosteroids are used in many protocols for enhanced recovery after surgery (ERAS). However, surgical techniques are developing, and ERAS protocols need to be reevaluated from time to time. PATIENTS AND METHOD: In this study, we compared the effects of oral vs. parenteral corticosteroid administration on postoperative nausea. Elective Roux-y-gastric bypass (RYGB) patients were randomly assigned to either 8 mg betamethasone orally (n = 50) or parentally (n = 25) or as controls (n = 25), in a double-blind design. PONV risk factors were noted. All patients had the same anaesthetic technique. Data were collected at baseline, on arrival to the recovery room (RR) and at five more time points during the first 24 h. Nausea and tiredness were patient assessed using visual analogue scales; rescue drug consumption was recorded. RESULTS: Operation time was 30-40 min. Neither demographics nor risk factors for nausea differed between groups. Neither peak values for nor total amount of nausea differed between groups. The number of supplemental injections was the same for all groups. COMMENTS: In a setting of modern laparoscopic RYGB, the value of betamethasone in preventing PONV seems to be limited. ERAS protocols may need re-evaluation.

The diet of whiting Merlangius merlangus in the western Baltic Sea.

The diet of whiting Merlangius merlangus in the western Baltic Sea was investigated and compared to the diet in the southern North Sea. Clupeids were important prey in both areas, but especially in the western Baltic Sea where they constituted up to 90% of the diet of larger individuals. Gobies, brown shrimps and polychaetes were the main prey of juveniles in the western Baltic Sea, while a wider range of species were consumed in the North Sea. The shift to piscivory occurred at smaller sizes in the western Baltic Sea and the fish prey consumed was proportionately larger than in the southern North Sea. Estimates of prey abundance and food intake of M. merlangus are required to evaluate its predatory significance in the western Baltic Sea, but its diet suggests that it could be just as significant a fish predator here as in the southern North Sea.

Intraabdominal Pressure and Postoperative Discomfort in Laparoscopic Roux-en-Y Gastric Bypass (RYGB) Surgery: a Randomized Study.

BACKGROUND: High intraabdominal pressure (IAP) during laparoscopic surgery has been associated with postoperative discomfort. Effects on nausea and access have not been subjected to randomized studies. In cholecystectomy, lower IAP may cause less pain, but nausea and surgical access in RYGB surgery have not been investigated. We studied the influence of two IAP levels on surgical access, operation time, postoperative pain, and nausea. METHODS: Fifty consecutive female gastric bypass patients were randomized to intraabdominal pressure of 12 (IAP12) or 18 (IAP18) mm Hg. Surgeons and personnel were blinded to randomization; study groups were well matched for age and BMI. Operative time was noted in minutes. Visual analogue scales were used for assessing access and for patients assessing pain (abdomen-shoulder) and nausea (supine-standing) at six time points during the first 16 postoperative hours. Rescue medication was recorded. RESULTS: In 3/25 patients in the IAP12 group, the code was broken due to access problems vs. 0/25 in the IAP18 group (p = 0.1398). Operative time did not differ. Access was significantly better for IAP18 (92.2 ± 2.3 vs. 69.3 ± 4.2; p = 0.0001). Postoperative shoulder pain was maximal after 6 h but throughout less than in the abdomen (p < 0.0001); there were no differences in pain between IAP18 and IAP12 (p = 0.7408). Postoperative nausea was significantly greater standing than supine but without differences between groups. CONCLUSION: Higher IAP gives better surgical access in laparoscopic Roux-en-Y gastric bypass with no negative effect on pain or nausea.

Preoperative Nutrition and Postoperative Discomfort in an ERAS Setting: A Randomized Study in Gastric Bypass Surgery.

BACKGROUND: Many patients experience postoperative nausea and vomiting (PONV). Preoperative treatment with carbohydrate solutions seems to improve the course after different types of surgery. This study was undertaken to investigate the potential value of different models for preoperative hydration/nutrition, in addition to our ERAS (enhanced recovery after surgery) protocol. METHODS: Ninety non-diabetic women planned for elective laparoscopic gastric bypass and aged 18-65 years were included. All were on preoperative low-calorie diet (LCD). They were randomized into three arms, either a carbohydrate-rich drink, a protein-enriched drink, or tap water and instructed to drink 800 and 200 mL 16 and 2 h, respectively, prior to operation. Risk factors for PONV were recorded preoperatively. All patients were operated before lunch and received 1500-2000 mL of Ringer-Acetate solution during the 24-30-h postoperative hospital time. Four variables (nausea, pain, tiredness, and headache) were registered on 100-mm visual analog scales six times over 22 h. The need for additional medication was registered. RESULTS: Out of 90 patients, 73 complete datasets were obtained. Nausea peaked at 7 p.m. but with no statistically significant differences between groups for any of the variables. Pain peaked the first 2 h postoperatively, remained longer, and had not returned to baseline values at 6 a.m. the morning after surgery but with no difference between groups. CONCLUSIONS: Inside our ERAS protocol, additional preoperative carbohydrate- or protein-enriched fluid treatment did not further reduce immediate patient discomfort in laparoscopic gastric bypass surgery.

Water with food intake does not influence caloric intake after gastric bypass (GBP): a cross-over trial.

BACKGROUND: Bariatric patients seeking information meet very different recommendations on postoperative diet and eating behaviour. A reason for variability may be lack of hard evidence. A national survey on current dietary advice was conducted to serve as background for the present study on how drinking during a meal influenced caloric consumption. METHODS: A standardised questionnaire was sent to all units in the Scandinavian Obesity surgery registry (SOReg) in order to obtain information regarding current diet advice after gastric bypass. Twenty-eight patients, 14 in each group, were studied either 2 months or 1 year after a standard gastric bypass (GBP). A standardised lunch was served on two separate days with or without water in randomised order. Meal and water weights were measured before and after. Hunger/satiety scores were obtained using visual analogue scales. RESULTS: Response rate for surgeons was low, for dieticians 75 %. No clear consensus for liquid intake during meals was found; few surgeons advised patients whether or not to drink with meals. All patients ate to full satiety. Two months post-GBP, 7/14 patients consumed more solid food when allowed drinking water; the increase in caloric consumption was not significant. One year post-GBP, 5/14 patients consumed more solid food when allowed drinking water, the difference not reaching statistical significance. CONCLUSION: Our study does not indicate that patients should refrain from drinking during meals the first year after a GBP, at least not from a caloric intake point of view.

Management of suspected anastomotic leak after bariatric laparoscopic Roux-en-y gastric bypass.

BACKGROUND: Anastomotic leak is one of the most serious complications following bariatric laparoscopic Roux-en-Y gastric bypass (LRYGB), and associated with high morbidity rates and prolonged hospital stay. Timely management is of utmost importance for the clinical outcome. This study evaluated the approach to suspected leakage in a high-volume bariatric surgery unit. METHODS: All consecutive patients who underwent LRYGB performed by the same team of surgeons were registered prospectively in a clinical database from September 2005 to June 2012. Suspected leaks were identified based on either clinical suspicion and/or associated laboratory values, or by a complication severity grade of at least II using the Clavien-Dindo score. RESULTS: A total of 6030 patients underwent LRYGB during the study period. The leakage rate was 1·1 per cent (64 patients). Forty-five leaks (70 per cent) were treated surgically and 19 (30 per cent) conservatively. Eight (13 per cent) of 64 patients needed intensive care and the mortality rate was 3 per cent (2 of 64). Early leaks (developing in 5 days or fewer after LRYGB) were treated by suture of the defect in 20 of 22 patients and/or operative drainage in 13. Late leaks (after 5 days) were managed with operative drainage in 19 of 23 patients and insertion of a gastrostomy tube in 15. Patients who underwent surgical treatment early after the symptoms of leakage developed had a shorter hospital stay than those who had symptoms for more than 24 h before reoperation (12·5 versus 24·4 days respectively; P < 0·001). CONCLUSION: Clinical suspicion of an anastomotic leak should prompt an aggressive surgical approach without undue delay. Early operative treatment was associated with shorter hospital stay. Delays in treatment, including patient delay, after symptom development were associated with adverse outcomes.

Fe charge state adjustment in ZnO upon ion implantation.

The influence of the ion implantation process on the charge state of dilute (57)Fe impurities implanted as radioactive (57)Mn in ZnO is investigated by (57)Fe emission Mössbauer spectroscopy. One sample is additionally implanted with stable (23)Na impurities. Both Fe(2+) and Fe(3+) charge states are observed, and the Fe(3+)/Fe(2+) ratio is found to increase with the fluence of both (57)Mn/(57)Fe and (23)Na ions, demonstrating that the build-up of Fe(3+) is not related to the chemical nature of the implanted ions. The results are interpreted in terms of radiation damage induced changes of the Fermi level, and illustrate that the Fe(3+)/Fe(2+) ratio can be adjusted by ion implantation. The spin-lattice relaxation time for Fe(3+) in ZnO is found to be independent of the implantation fluence, and is evidently an intrinsic property of the system.

High-volume bariatric surgery in a single center: safety, quality, cost-efficacy and teaching aspects in 2,000 consecutive cases.

BACKGROUND: Obesity surgery is the most effective treatment for morbid obesity and the fastest growing area in surgery. Laparoscopic Roux-en-Y gastric bypass (LRYGB) is the gold standard procedure in many countries. Optimization of the treatment process is important in order to keep the morbidity rate down and cost of treatment as low as possible. METHODS: In September 2005, we established a bariatric surgery program. Until December 2010, 2,000 patients underwent LRYGB. Clinical pathways were established, with focus on safety, fast-track methodology and training of surgeons. Time recordings from all parts of the treatment, as well as clinical outcome, were prospectively registered. RESULTS: Time consumption for the total procedure in the operating theater was reduced from 102 to 54 min (P < 0.001). With only 11 min turnover between patients, the total time for one patient has been reduced to 65 min, enabling us to perform six operations in a single operating theater during ordinary daytime. Early complication rate was 2.8%, and mean hospital stay was 2.3 days. We were able to double the patients treated in 2010 compared to 2007 with only 10% increase in staff. Three surgeons were trained during the period into fully qualified senior bariatric surgeons. CONCLUSIONS: Multimodal evidence-based care within the fast-track methodology and routine time recordings was successful in order to increase the production volumes and reduce costs, without compromising the safety or quality for the patients. This kind of approach may be transferred to other types of standardized surgery.

Fast-track surgery for bariatric laparoscopic gastric bypass with focus on anaesthesia and peri-operative care. Experience with 500 cases.

BACKGROUND: Bariatric surgery for morbid obesity implies challenges in anaesthesiological handling. We report our experience from 500 consecutive patients during 3 years. METHODS: The patients were due for laparoscopic Roux-en-Y gastric bypass and enteral bypass. Sleep was induced after pre-oxygenation with target control infusions (TCI) of remifentanil and propofol; vecuronium was supplied for facilitating endotracheal intubation. The propofol infusion was stopped and desflurane 3-6% was given for BIS-titrated anaesthetic maintenance together with remifentanil TCI. Antiemetic prophylaxis was supplied with intravenous (IV) droperidol, ondansetron and dexamethasone; post-operative pain prophylaxis was IV paracetamol, parecoxib and bupivacaine infiltration. The patients were extubated in the operating room and kept in the post-operative care unit for 3-4 h, being tested for a 20 m walk before discharge to the ward. RESULTS: The procedure was uncomplicated peri-operatively in all 500 cases and in 497 patients (99.4%) post-operatively. Three patients had one complication, which resolved without sequelae: oesophageal rupture from gastric tubing, reoperation for anastomosis leakage and pneumonia. The mean duration of surgery was 57 min (range 37-91). The mean time from the start of anaesthesia until the start of surgery and time from the end of surgery until the end of anaesthesia were both significantly reduced throughout the study period, from 23 to 7.8 and 5.8 to 1.9 min, respectively (P<0.001). The mean total hospital stay was reduced from 3 days at start to 2 days in the end of the series (P<0.05). CONCLUSION: Safe bariatric short-stay surgery is feasible with a dedicated anaesthesiological concept in an expert surgical team.

Life-history constraints on the success of the many small eggs reproductive strategy.

The reproductive strategy of most fishes is to produce a large number of tiny eggs, leading to a huge difference between egg size and asymptotic body size. The viability of this strategy is examined by calculating the life-time reproductive success R(0) as a function of the asymptotic body size. A simple criterion for the optimality of producing small eggs is found, depending on the rate of predation relative to the specific rate of consumption. Secondly it is shown that the success of the reproductive strategy is increasing with asymptotic body size. Finally the existence of both upper and lower limits on the allowed asymptotic sizes is demonstrated. A metabolic upper limit to asymptotic body size for all higher animals is derived.

Cholecystectomy improves long-term success after endoscopic treatment of CBD stones.

BACKGROUND/AIMS: The aim was to study prospectively primary endoscopic treatment of CBD stones and further the long-term need for renewed gallstone disease interventions, defined as short- and long-term outcome. METHODOLOGY: Seven years prospective follow-up of 101 consecutive patients with CBD stones who underwent endoscopic treatment with the intent of primarily achieving duct clearance. RESULTS: Many patients underwent several endoscopy sessions before stone clearance was completed in 83%. Eleven patients were treated surgically, 2 patients received a permanent stent, and the remaining 3 became stone free with other means. Complications occurred in 47 patients. During follow-up, 31 patients were readmitted for gallstone disease and 15 of these had recurrent CBD stones. Ten percent (8/78) of patients with the gallbladder in situ had acute cholecystitis during follow-up and late cholecystectomy was carried out in 22%. Risk factors for new gallstone disease were an in situ gallbladder containing stones and previous episodes of CBD stones. CONCLUSIONS: A goal of complete CBD stone clearance with ERC and ES proved to be relatively resource consuming. Subsequent cholecystectomy after duct clearance for CBD should be advised when the gallbladder lodges gallstones, especially in younger patients. Recurrent CBD stones were not influenced by cholecystectomy.

Acute pancreatitis in Bergen, Norway. A study on incidence, etiology and severity.

BACKGROUND: Studies on the incidence and etiology of acute pancreatitis show large regional differences. This study was performed to establish incidence, etiology and severity of acute pancreatitis in the population of Bergen, Norway. METHODS: A study of all patients with acute pancreatitis admitted to Haukeland University Hospital over a 10-year period was performed. Information was obtained about the number of patients with acute pancreatitis admitted to the Deaconess Hospital in Bergen. RESULTS: A total of 978 admissions of acute pancreatitis were recorded in these two hospitals giving an incidence of 30.6 per 100,000. Haukeland University Hospital had 757 admissions of acute pancreatitis in 487 patients. Pancreatitis was severe in 20% (96/487) of patients, more often in males (25%) than in females (14%). Mortality due to acute pancreatitis was 3% (16/487). Gallstones were found to be an etiological factor in 48.5% and alcohol consumption in 19% of patients. The risk of recurrent pancreatitis was 47% in alcohol induced and 17% in gallstone induced pancreatitis. The last five years of the study period, endoscopic sphincterotomy of patients with gallstone pancreatitis, resulted in drop in relapse rate from 33% to 1.6%. CONCLUSION: The incidence of acute pancreatitis was found to be 30.6 per 100,000 with 48.5% associated with gallstones and 17% alcohol induced. Incidence of first attack was 20/100,000. Pancreatitis was classified as severe in 20% of cases with a mortality of 3%.

Vacancy defects as compensating centers in Mg-doped GaN.

We apply positron annihilation spectroscopy to identify V(N)-Mg(Ga) complexes as native defects in Mg-doped GaN. These defects dissociate in postgrowth annealings at 500-800 degrees C. We conclude that V(N)-Mg(Ga) complexes contribute to the electrical compensation of Mg as well as the activation of p-type conductivity in the annealing. The observation of V(N)-Mg(Ga) complexes confirms that vacancy defects in either the N or Ga sublattice are abundant in GaN at any position of the Fermi level during growth, as predicted previously by theoretical calculations.

Comparison of different methods for measuring intra-abdominal pressure.

OBJECTIVE: Intra-abdominal pressure (IAP) can be measured in different ways but is usually measured indirectly via the urinary bladder. The aim of the study was to: 1) compare urinary bladder pressure, femoral vein pressure, and inferior caval vein pressure with IAP at different levels of IAP; and 2) try to find an optimal amount of fluid to be instilled into the urinary bladder before measurement of the bladder pressure, and to compare changes in blood flow in the femoral vein with that in the caval vein at different pressure levels. DESIGN: Experimental study. SETTING: Animal research laboratory. SUBJECTS: Eight domestic swine of both sexes, weighing 30.6+/-2.9 kg (mean+/-SD). INTERVENTIONS: Catheters connected to pressure transducers were placed into the urinary bladder, the inferior caval vein, the femoral vein, and the superior caval vein. Transit time flow probes were placed around the inferior caval vein and the femoral vein. After a stabilizing period, the abdominal pressure was increased stepwise by instillation of Ringer's solution into the abdomen and then decreased. Thereafter, we instilled fluid into the bladder at an IAP of 8 mmHg and at 20 mmHg and measured the amount of fluid needed to elevate the intra-vesical pressure by 2 mmHg. RESULTS: The pressures recorded in the urinary bladder, the inferior caval vein, and the femoral vein reflected the pressure in the abdominal cavity very well. The fluid volume needed to increase the bladder pressure by 2 mmHg was significantly lower at 20 mmHg IAP than at 8 mmHg. Blood flow in the femoral vein and the inferior caval vein showed a similar pattern and decreased when the intra-abdominal pressure increased. CONCLUSIONS: In our porcine model, and increasing the IAP by means of instillation of Ringer's solution, a reliable estimation of the IAP was obtained by measuring the pressure in the urinary bladder, the femoral vein or the inferior caval vein. The IAP estimated indirectly as the urinary bladder pressure is affected by the amount of fluid in the bladder, which should not exceed 10-15 ml. The decrease in femoral vein blood flow reflects the changes in inferior caval vein flow during increased IAP.