EXTERNAL DOSE RATE MONITORING IN FINLAND: HISTORY, EXPERIENCES AND A GLIMPSE AT THE FUTURE.

Finland has a long history in monitoring external radiation. Regular monitoring began in the early 1960s when the first networks measuring exposure rates were established. Today the nation-wide network is fully automatic and consists of about 260 stations with Geiger-Muller (GM) tubes. Some 25 stations also have a LaBr3 spectrometer. In this article the authors describe the history, experiences and major development stages of the Finnish dose rate monitoring arrangements and also have a brief look at the possible future.

Does blood transfusion affect intermediate survival after coronary artery bypass surgery?

BACKGROUND: The aim of this study was to investigate the impact of transfusion of blood products on intermediate outcome after coronary artery bypass surgery. PATIENTS: Complete data on perioperative blood transfusion in patients undergoing coronary artery bypass surgery were available from 2001 patients who were operated at our institution. RESULTS: Transfusion of any blood product (relative risk = 1.678, 95% confidence interval = 1.087-2.590) was an independent predictor of all-cause mortality. The additive effect of each blood product on all-cause mortality (relative risk = 1.401, 95% confidence interval = 1.203-1.630) and cardiac mortality (relative risk = 1.553, 95% confidence interval = 1.273-1.895) was evident when the sum of each blood product was included in the regression models. However, when single blood products were included in the regression model, transfusion of fresh frozen plasma/Octaplas® was the only blood product associated with increased risk of all-cause mortality (relative risk = 1.692, 95% confidence interval = 1.222-2.344) and cardiac mortality (relative risk = 2.125, 95% confidence interval = 1.414-3.194). The effect of blood product transfusion was particularly evident during the first three postoperative months. Since follow-up was truncated at 3 months, transfusion of any blood product was a significant predictor of all-cause mortality (relative risk = 2.998, 95% confidence interval = 1.053-0.537). Analysis of patients who survived or had at least 3 months of potential follow-up showed that transfusion of any blood product was not associated with a significantly increased risk of intermediate all-cause mortality (relative risk = 1.430, 95% confidence interval = 0.880-2.323). CONCLUSIONS: Transfusion of any blood product is associated with a significant risk of all-cause and cardiac mortality after coronary artery bypass surgery. Such a risk seems to be limited to the early postoperative period and diminishes later on. Among blood products, perioperative use of fresh frozen plasma or Octaplas seems to be the main determinant of mortality.

Immediate and 5-year outcome after coronary artery bypass surgery in very high risk patients (additive EuroSCORE ≥ 10).

AIM: We have evaluated the outcome after coronary artery bypass surgery in very high risk patients (additive EuroSCORE ≥ 10). The impact of beating heart coronary artery bypass surgery (BHCAB) on their outcome has been evaluated. METHODS: Retrospective study including 160 consecutive patients with additive EuroSCORE ≥ 10. RESULTS: . The overall survival rates at 30-day, 1-year, 3-year and 5-year were 83.8%, 76.0%, 72.4% and 66.8%, respectively. Baseline cardiac index (O.R. 0.20, 95%C.I. 0.08-0.53), preoperative inotropic support (O.R. 4.55, 95%C.I. 1.41-14.73) and preoperative resuscitation (O.R. 3.937, 95%C.I. 1.02-15.26) were independent predictors of 30-day mortality. Baseline cardiac index (R.R. 0.48, 95%C.I. 0.28-0.85), left ventricular ejection fraction (P=0.032), preoperative use of intraaortic balloon pump (R.R. 3.22, 95% C.I. 1.50-6.93), preoperative tracheal intubation (R.R. 3.44, 95%C.I. 1.37-8.68) and creatinine (R.R. 1.004, 95%C.I. 1.00-1.01) were independent predictors of late death. OPCAB/BHCAB was associated with somewhat lower 30-day mortality rate (16.2% vs. 18.0%, P=0.73), stroke (2.0% vs. 4.9%, P=0.37), red blood cells transfusion (3.4 vs. 5.4 units, P=0.004) and combined adverse outcome (43.4% vs. 50.8%, P=0.42). OPCAB/BHCAB surgeons compared with surgeons with a prevalent conventional approach achieved slightly better the 30-day mortality rate (16.7% vs. 27.9%, P=0.15) and stroke rate (2.8% vs. 4.7%, P=0.60) and 5-year survival rate (65.3% vs. 57.4%, P=0.35). CONCLUSION: Despite their poor immediate postoperative outcome, 5-year survival of these high risk patients is satisfactory and supports efforts in the treatment of this very high risk population. A more confident approach toward OPCAB/BHCAB is also suggested in these patients.

Deep pericardial sling versus lateral pericardial sutures in off-pump coronary artery bypass surgery.

AIM: The aim of this study was to evaluate the safety and efficacy of deep pericardial sling (DPS) versus lateral pericardial sutures (LPSs) for heart stabilization and adequate coronary artery exposure during off-pump coronary artery bypass surgery (OPCAB). METHODS: One surgeon employed in 101 consecutive patients a series of four to six 2-0 polyglactin sutures placed laterally between the left phrenic nerve and the left pulmonary veins (LPS). Two other surgeons used in 104 consecutive patients a single 0-0 braided silk suture with moistened gauze placed in the oblique sinus of the posterior pericardium, between the inferior vena cava and the right lower pulmonary vein (DPS). RESULTS: One conversion to beating heart surgery with cardiopulmonary bypass support occurred in each study group. No patient in the LPS group was converted to DPS technique. The use of LPSs allowed a number of distal anastomoses somewhat higher than the DPS technique (4.1+/-1.1 vs. 3.7+/-1.1, P=0.02). Postoperative results were similar in both study groups. A lower incidence of postoperative low-cardiac output syndrome and of prolonged need of inotropes has been observed in the LPS group, but the difference failed to reach statistical significance. One patient in the LPS group had postoperative left phrenic nerve palsy. One patient in the DPS group suffered of intraoperative bleeding secondary to rupture of the inferior vena cava likely related to placement of DPS, which was successfully repaired. CONCLUSION: LPS technique is as effective as DPS technique and allows complete revascularization with a postoperative outcome similar to the latter technique.

Risk of retinal microembolism after off-pump and on-pump coronary artery bypass surgery.

AIM: In order to investigate the neuroprotective efficacy of off-pump coronary artery bypass surgery (OPCAB) over conventional on-pump coronary artery bypass surgery (CCAB), we have performed a prospective randomized study evaluating retinal circulation changes after OPCAB and CCAB. METHODS: Twenty patients were randomized to OPCAB or CCAB. Retinal fluorescein angiography and 60 degrees black-and-white as well as color fundus photographs of both eyes of each patient were taken 1 to 24 h before and 5 to 6 days after the operation. RESULTS: Patients undergoing OPCAB had more severely stenosed carotid arteries (P=0.075), higher incidence of slightly diseased ascending aorta (P=0.087) and higher Northern New England Cardiovascular Study Group stroke risk score (P=0.075). Neither stroke nor transient ischemic attack occurred postoperatively in these patients. Inferotemporal retinal arterial embolization and microinfarction was detected in one patient after CCAB, but in none of the OPCAB group. CONCLUSION: The risk of retinal embolism can be minimized by the use of OPCAB and, most likely, by adequate epiaortic ultrasound scanning of the ascending aorta and avoiding clamping in case of severely diseased aorta.

Off-pump versus on-pump coronary artery bypass surgery in high-risk patients (EuroSCORE >/= 6).

OBJECTIVE: The aim of this study was to review the results of off-pump (OPCAB) versus conventional on-pump coronary artery bypass surgery (CCAB) in high-risk patients. METHODS: In a cohort of patients with an additive EuroSCORE >/= 6, 67 underwent OPCAB and 112 underwent CCAB. RESULTS: Thirty-day postoperative death and stroke rates were 7.5 % and 6.0 % for the OPCAB group, and 5.4 % ( P = 0.75) and 8.0 % ( P = 0.77) for the CCAB group, respectively. No significant differences were observed for other major outcome endpoints other than cardiac troponin I (OPCAB: 117 +/- 428 ng/ml vs. CCAB: 58 +/- 99 ng/ml, P = 0.028), a result which was probably due to preoperative massive myocardial infarction in two very high-risk patients who underwent OPCAB. A similar outcome was also observed among propensity score-matched pairs. Congestive heart failure ( P = 0.006, OR: 6.366, 95 % CI: 1.682 - 24.093) and baseline cardiac index ( P = 0.018, OR: 0.171, 95 % CI: 0.040 - 0.735) were independent predictors of 30-day postoperative mortality. CONCLUSIONS: OPCAB can be safely performed in high-risk patients with results as satisfactory as those achieved with CCAB.

Adhesion as an interplay between particle size and surface roughness.

Surface roughness plays an important role in the adhesion of small particles. In this paper we have investigated adhesion as a geometrical effect taking into account both the particle size and the size of the surface features. Adhesion is studied using blunt model particles on surfaces up to 10 nm root-mean-square (RMS) roughness. Measurements with particles both smaller and larger than surface features are presented. Results indicate different behavior in these areas. Adhesion of particles smaller than or similar in size to the asperities depend mainly on the size and shape of the asperities and only weakly on the size of the particle. For large particles also the particle size has a significant effect on the adhesion. A new model, which takes the relative size of particles and asperities into account, is also derived and compared to the experimental data. The proposed model predicts adhesion well over a wide range of particle/asperity length scales.

Radiation monitoring strategy: factors to be considered.

In a nuclear or radiological emergency radiation measurements provide indispensable data needed in the management of the situation at hand. In order to assess the possible consequences correctly and to carry out proper countermeasures on time, the authorities must have a pre-prepared monitoring strategy at their disposal. There are, however, many different factors that affect a strategy. Thus, drawing up a comprehensive yet realistic emergency monitoring strategy is far from being an easy task. Some of the key factors related to strategies are reviewed and a simple way of producing a strategy plan is presented.

Sedimentation dynamics of spherical particles in confined geometries.

We study the steady-state dynamics of sedimenting non-Brownian particles in confined geometries with full hydrodynamic interactions at small but finite Reynolds numbers. We employ extensive computer simulations using a method where a continuum liquid phase is coupled through Stokesian friction to a discrete particle phase. In particular, we consider a sedimentation box which is otherwise periodic except that it is confined by two parallel walls parallel to gravity with a spacing Lx. By systematically varying Lx we explore the change in dynamics from a quasi-two-dimensional (2D) case to a three-dimensional case. We find that in such confined geometries there is a depletion of particle number density at the walls for small volume fractions, while for large volume fractions there is an excess number of particles at the walls. For the average sedimentation velocity, we find that the Richardson-Zaki law is well obeyed but the decrease of the velocity for dilute systems is slower for smaller values of Lx. We study the anisotropy of the velocity fluctuations and find that in the direction of gravity there is excellent agreement with the predicted scaling with respect to Lx. We also find that the behavior of the corresponding diffusion coefficients as a function of Lx is qualitatively different in the direction parallel to gravity and perpendicular to it. In the quasi-2D limit where particles block each other, the velocity fluctuations behave differently from the other confined systems.

Influence of hydrodynamics on many-particle diffusion in 2D colloidal suspensions.

We study many-particle diffusion in 2D colloidal suspensions with full hydrodynamic interactions through a novel mesoscopic simulation technique. We focus on the behaviour of the effective scaled tracer and collective-diffusion coefficients DT(rho)/D0 and DC(rho)/D0 respectively, where D0 is the single-particle diffusion coefficient, as a function of the density of the colloids rho. At low Schmidt numbers Sc - 1, we find that hydrodynamics has essentially no effect on the behaviour of DT (rho)/D0. At larger Sc, DT (rho)/D0 seems to be enhanced at all densities, although the differences compared to the case without hydrodynamics are rather minor. The collective-diffusion coefficient, on the other hand, is much more strongly coupled to hydrodynamical conservation laws and is distinctly different from the purely dissipative case without hydrodynamic interactions.

Collective effects in settling of spheroids under steady-state sedimentation.

We study the settling dynamics of non-Brownian prolate spheroids under steady-state sedimentation. We consider the case of moderate particle Reynolds numbers properly taking into account the hydrodynamic effects. For small volume fractions, we find an orientational transition of the spheroids, characterized by enhanced density fluctuations. Around the transition, the average settling velocity has a maximum which may even exceed the terminal velocity of a single spheroid, in accordance with experiments.

Scaling of random spreading in small world networks.

In this study we have carried out computer simulations of random walks on Watts-Strogatz-type small world networks and measured the mean number of visited sites and the return probabilities. These quantities were found to obey scaling behavior with intuitively reasoned exponents as long as the probability p of having a long range bond was sufficiently low.

Diffusion of hard disks and rodlike molecules on surfaces.

We study the submonolayer diffusion of hard disks and rodlike molecules on smooth surfaces through numerical simulations and theoretical arguments. We concentrate on the behavior of the various diffusion coefficients as a function of the two-dimensional (2D) number density rho in the case where there are no explicit surface-particle interactions. For the hard disk case, we find that while the tracer diffusion coefficient D(T)(rho) decreases monotonically up to the freezing transition, the collective diffusion coefficient D(C)(rho) is wholly determined by the inverse compressibility which increases rapidly on approaching freezing. We also study memory effects associated with tracer diffusion, and present theoretical estimates of D(T)(rho) from the mode-mode coupling approximation. In the case of rigid rods with short-range repulsion and no orientational ordering, we find behavior very similar to the case of disks with the same repulsive interaction. Both D(T)(rho) and the angular diffusion coefficient D(R)(rho) decrease with rho. Also in this case D(C)(rho) is determined by inverse compressibility and increases rapidly close to freezing. This is in contrast to the case of flexible chainlike molecules in the lattice-gas limit, where D(C)(rho) first increases and then decreases as a function of the density due to the interplay between compressibility and mobility.

Microbiological quality and shelf-life of vacuum-packaged 'gravad' rainbow trout stored at 3 and 8 degrees C.

Microbiological and sensory changes of vacuum-packaged 'gravad' rainbow trout slices were studied during storage at 3 and 8 degrees C. At the time of spoilage, after 27 and 20 days of storage at 3 and 8 degrees C, respectively, both mesophilic viable counts (MVC) and psychrotrophic viable counts (PVC) reached 10(6)-10(7) cfu/g at 3 degrees C and 10(7)-10(5) cfu/g at 8 degrees C. H2S-producing bacteria constituted a high proportion of the PVCs and lactic acid bacteria (LAB) counts were lower than the other determined bacterial counts. Sensory scores decreased with increasing MVC and PVC. The judges considered samples unfit for human consumption at MVC and PVC levels exceeding 10(6) and 10(7) cfu/g for samples stored at 3 and 8 degrees C, respectively. At respective levels of 10(7) and 10(8) cfu/g, most of the samples were deemed unfit. The main reasons for sensory rejection at both storage temperatures were the lack of the typical product odour or an ammonia off-odour and colour change to dark violet. The shelf-lives of the rainbow trout slices based on microbiological and sensory analyses were 20 days and 18 days at 3 and 8 degrees C, respectively.

Neuromuscular functioning of athletes and non-athletes in the drop jump.

In many sports vertical jumping is important. This study compared neuromuscular functioning of the lower extremity muscles together with some kinetic and kinematic parameters before and during ground contact in drop jumps from two heights [0.4 m (DJ40) and 0.8 m (DJ80)] in 7 highly trained triple-jumpers and 11 physically active controls. The triple-jumpers jumped 32% higher in DJ40 and 34% higher in DJ80, had shorter braking and total contact times, and greater average and peak vertical ground reaction forces than the controls. In both drop jumps in the electromyogram pre-activity of the vastus lateralis and gastrocnemius muscles started earlier in the jumpers than in the controls. For the control group the increase in dropping height was associated with a decrease in the propulsion force, and resulted in more extended knee and ankle angles at touch down and more flexed angles at the deepest position than for the jumpers. All angular displacements for DJ80 were larger than for DJ40 in the control group. The triple jumpers and control subjects differed with respect to their neuromuscular functioning in the drop jump exercise and they responded in a different way to the increase in dropping height.

Computed tomographic evaluation of retrosternal adhesions after pericardial substitution.

BACKGROUND: Reoperative median sternotomy can result in cardiac injury and serious bleeding, with the rate ranging from 2% to 6%. Closure of the native pericardium can maintain a preventing plane of cleavage. In patients in whom primary pericardial closure is not possible, several substitutes have been tried with variable results. We conducted a prospective study to evaluate the clinical feasibility of polytetrafluoroethylene and polyglycolic acid patches as pericardial substitutes, using computed tomography for imaging the postoperative state of the retrosternal space. METHODS: The basic population comprised 540 patients who were scheduled for coronary artery bypass grafting, and 52 of them who met the research criteria were chosen for computed tomographic evaluation after 5 years after the primary operation. RESULTS: As a substitute, polytetrafluoroethylene seemed to be less adhesive to the posterior surface of the sternum. Total adhesion scores were also statistically significant (p < 0.001) to the advantage of polytetrafluoroethylene over polyglycolic acid as a pericardial substitute. CONCLUSIONS: Polytetrafluoroethylene membrane seems to be capable of minimizing retrosternal adhesion formation and thus it may protect the heart during subsequent reoperative sternotomy.

Pericardial closure with polytetrafluoroethylene surgical membrane or biodegradable polyglycolic acid mesh after coronary artery bypass surgery--a baseline report.

BACKGROUND AND AIMS: Complete and tight closure of the native pericardium may kink or even occlude bypass grafts after coronary artery bypass grafting (CABG) and therefore the feasibility of tight closure has been debated. The growing number of reoperations has raised the question how to reduce the risk of damage of the right ventricle and patent grafts. We are performing a prospective randomized trial aiming to evaluate the feasibility of polytetrafluoroethylene (PTFE) surgical membrane and biodegradable polygycolic acid (PGA) mesh as pericardial substitutes for closure purposes in patients undergoing primary isolated CABG surgery. MATERIAL AND METHODS: The series comprises 540 patients who underwent a primary isolated CABG procedure at the Oulu University Hospital from October 1989 to May 1994. RESULTS AND CONCLUSIONS: The baseline results suggest that the PTFE and PGA materials seem to be similar despite the subtle early expression of tamponade related to the PTFE membrane after postoperative bleeding.

Options for the management of poststernotomy mediastinitis.

The management of 27 consecutive deep sternotomy wound infections is reviewed. In 22 cases the initial treatment was debridement, sternal refixation and dilute antibiotic irrigation via multiple irrigation-suction catheters. In the nine cases (41%) in which these measures failed, more extensive sternal and costal cartilage debridement and closure with a muscle flap were performed. Five cases were initially managed with major reconstructive surgery. For reconstruction, a bilateral pectoralis major myocutaneous flap was used alone in eight cases, while in six the flap was insufficient to obliterate the whole poststernectomy space, and was supplemented with rectus abdominis muscle. Early mediastinitis can be effectively treated with thorough wound debridement and mediastinal irrigation, but if there is a two-week delay from the initial sternotomy to manifestation of infection, radical debridement with muscle flap closure should be seriously considered.