A variable time step self-consistent mean field DSMC model for three-dimensional environments.

A self-consistent mean field direct simulation Monte Carlo (SCMFD) algorithm was recently proposed for simulating collision environments for a range of one-dimensional model systems. This work extends the one-dimensional SCMFD approach to three dimensions and introduces a variable time step (3D-vt-SCMFD), enabling the modeling of a considerably wider range of different collision environments. We demonstrate the performance of the augmented method by modeling a varied set of test systems: ideal gas mixtures, Poiseuille flow of argon, and expansion of gas into high vacuum. For the gas mixtures, the 3D-vt-SCMFD method reproduces the properties (mean free path, mean free time, collision frequency, and temperature) in excellent agreement with theoretical predictions. From the Poiseuille flow simulations, we extract flow profiles that agree with the solution to the Navier-Stokes equations in the high-density limit and resemble free molecular flow at low densities, as expected. The measured viscosity from 3D-vt-SCMF is ∼15% lower than the theoretical prediction from Chapman-Enskog theory. The expansion of gas into vacuum is examined in the effusive regime and at the hydrodynamic limit. In both cases, 3D-vt-SCMDF simulations produce gas beam density, velocity, and temperature profiles in excellent agreement with analytical models. In summary, our tests show that 3D-vt-SCMFD is robust and computationally efficient, while also illustrating the diversity of systems the SCMFD model can be successfully applied to.

Effects of pre-emptive pregabalin and multimodal anesthesia on postoperative opioid requirements in patients undergoing robot-assisted laparoscopic prostatectomy.

BACKGROUND: Previous findings indicate that pre-emptive pregabalin as part of multimodal anesthesia reduces opioid requirements compared to conventional anesthesia in patients undergoing robot-assisted laparoscopic prostatectomy (RALP). However, recent studies show contradictory evidence suggesting that pregabalin does not reduce postoperative pain or opioid consumption after surgeries. We conducted a register-based analysis on RALP patients treated over a 5-year period to evaluate postoperative opioid consumption between two multimodal anesthesia protocols. METHODS: We retrospectively evaluated patients undergoing RALP between years 2015 and 2019. Patients with American Society of Anesthesiologists status 1-3, age between 30 and 80 years and treated with standard multimodal anesthesia were included in the study. Pregabalin (PG) group received 150 mg of oral pregabalin as premedication before anesthesia induction, while the control (CTRL) group was treated conventionally. Postoperative opioid requirements were calculated as intravenous morphine equivalent doses for both groups. The impact of pregabalin on postoperative nausea and vomiting (PONV), and length of stay (LOS) was evaluated. RESULTS: We included 245 patients in the PG group and 103 in the CTRL group. Median (IQR) opioid consumption over 24 postoperative hours was 15 (8-24) and 17 (8-25) mg in PG and CTRL groups (p = 0.44). We found no difference in postoperative opioid requirement between the two groups in post anesthesia care unit, or within 12 h postoperatively (p = 0.16; p = 0.09). The length of post anesthesia care unit stay was same in each group and there was no difference in PONV Similarly, median postoperative LOS was 31 h in both groups. CONCLUSION: Patients undergoing RALP and receiving multimodal analgesia do not need significant amount of opioids postoperatively and can be discharged soon after the procedure. Pre-emptive administration of oral pregabalin does not reduce postoperative opioid consumption, PONV or LOS in these patients.

Neuronal plasticity and neurotrophic factors in drug responses.

Neurotrophic factors, particularly brain-derived neurotrophic factor (BDNF) and other members of the neurotrophin family, are central mediators of the activity-dependent plasticity through which environmental experiences, such as sensory information are translated into the structure and function of neuronal networks. Synthesis, release and action of BDNF is regulated by neuronal activity and BDNF in turn leads to trophic effects such as formation, stabilization and potentiation of synapses through its high-affinity TrkB receptors. Several clinically available drugs activate neurotrophin signaling and neuronal plasticity. In particular, antidepressant drugs rapidly activate TrkB signaling and gradually increase BDNF expression, and the behavioral effects of antidepressants are mediated by and dependent on BDNF signaling through TrkB at least in rodents. These findings indicate that antidepressants, widely used drugs, effectively act as TrkB activators. They further imply that neuronal plasticity is a central mechanism in the action of antidepressant drugs. Indeed, it was recently discovered that antidepressants reactivate a state of plasticity in the adult cerebral cortex that closely resembles the enhanced plasticity normally observed during postnatal critical periods. This state of induced plasticity, known as iPlasticity, allows environmental stimuli to beneficially reorganize networks abnormally wired during early life. iPlasticity has been observed in cortical as well as subcortical networks and is induced by several pharmacological and non-pharmacological treatments. iPlasticity is a new pharmacological principle where drug treatment and rehabilitation cooperate; the drug acts permissively to enhance plasticity and rehabilitation provides activity to guide the appropriate wiring of the plastic network. Optimization of iPlastic drug treatment with novel means of rehabilitation may help improve the efficacy of available drug treatments and expand the use of currently existing drugs into new indications.

Uvulopalatopharyngoplasty with an ultrasound scalpel or laser: is there a difference?

Uvulopalatopharyngoplasty (UPPP) is used for treatment of the obstructive sleep apnoea syndrome, mainly in the lower range of the apnoea-hypopnea index or partial upper airway obstruction. Significant severe pain after UPPP is associated in the area having surgery and therefore less pain causing methods should be investigated. In this study, we compared laser-assisted and ultrasound scalpel-performed UPPP. Sleep apnoea patients (n = 40) recruited to the study were divided into two groups. UPPP was performed with either laser-assisted or an ultrasound scalpel. Perioperative bleeding, operating room time and duration of operation together with histological injury of soft palate were analysed. A postoperative follow-up questionnaire included a self analysis of pain, dietary intake and pain drug consumption. In the same follow-up form, filled in by patients themselves, possible side effects and adequacy of pain medication together with any postoperative haemorrhage events were recorded during 10-day study period after UPPP. The ultrasound scalpel group had significantly fewer haemorrhagic events (P = 0.037) during postoperative follow-up time after UPPP when compared to laser-assisted group. The pain values of all 40 patients were significantly higher in the morning than in the afternoon (P < 0.001) or evening (P < 0.001). Pain increased up to the fifth postoperative day (visual analogue scale, VAS = 46). The significant relief of pain to the mild level (VAS < 30 mm) occurred at ninth and tenth postoperative day. The ultrasound scalpel used as a surgical method in UPPP did not offer significant comprehensive benefits in this study compared to laser-assisted UPPP. Exclusively, postoperative haemorrhage events were minor, paralleling findings of previous studies where ultrasound scalpel had been used for tonsillectomy. We conclude that the ultrasound scalpel is comparable to laser-assisted UPPP.

Increase in the use of rebreathing gas flow systems and in the utilization of low fresh gas flows in Finnish anaesthetic practice from 1995 to 2002.

BACKGROUND: The use of rebreathing systems together with low fresh gas flows saves anaesthetic gases, reduces the costs of anaesthesia, causes less environmental and ergonomic adverse effects, i.e. less air contamination in the operating room, and has favourable physiological effects. We assessed whether the use of non-rebreathing vs. rebreathing gas flow systems and high vs. lower fresh gas flows has changed during recent years. METHODS: The use of rebreathing and non-rebreathing systems and the utilization of fresh gas flows were evaluated by sending a questionnaire to the heads of anaesthesia departments at all public health care hospitals in Finland in 1996 and 2003. The data was gathered from the previous years 1995 and 2002, respectively. RESULTS: The use of rebreathing systems increased from 62% to 83% of all instances of general anaesthesia (P < 0.001). In rebreathing gas flow systems, there was a significant shift from high fresh gas flows (3 l min(-1) and more) towards lower fresh gas flows (between 1 to 2 l min(-1) and even below 1 l min(-1)) (P < 0.001). CONCLUSIONS: The benefits of low fresh gas flows have now been achieved in most instances of rebreathing system anaesthesia, which was not the case in 1995.

Difficult airway in a patient with Marshall-Smith syndrome.

Marshall-Smith syndrome is a rare clinical disorder characterized by accelerated bone maturation, dysmorphic facial features, airway abnormalities and death in early infancy because of respiratory complications. Although patients with Marshall-Smith syndrome have several features with potential anaesthetic problems, previous reports about anaesthetic management of these patients do not exist. We present a case, in which severe hypoxia developed rapidly after routine anaesthesia induction in an eight-month-old male infant with this syndrome. After several unsuccessful attempts the airway was finally secured by blind oral intubation. After 2 weeks, laryngeal anatomy was examined with fibreoptic laryngoscopy which revealed significant laryngomalacia. Laryngoscopy was performed without problems with ketamine anaesthesia and spontaneous breathing. The possibility of a compromised airway should always be borne in mind when anaesthetizing patients with Marshall-Smith syndrome. Anaesthesia maintaining spontaneous breathing is safest for children with this syndrome. If tracheal intubation or muscle relaxation is required, precautions are needed to maintain a patent airway. Muscle relaxants should possibly be avoided before intubation.

Neurolytic thoracic paravertebral block in cancer pain. A clinical report.

BACKGROUND: Paravertebral block has successfully been used in the treatment of acute and chronic pain. The duration of paravertebral block could theoretically be prolonged by using neurolytic agents. METHODS: We retrospectively analyzed the results of neurolytic paravertebral blocks performed in 7 patients suffering from intense cancer-related thoracic pain. Thirty-seven spinal nerve roots were blocked during 20 visits. Nerve roots were identified by eliciting paresthesia radiating to the painful area. Each root was blocked separately. After test block using 0.5% bupivacaine, the paravertebral blocks were performed with 1-4 ml of 7% phenol in aqua. RESULTS: No technical failures or complications were recorded in the patient files. Pain relief lasted over 2 months after 4 visits (20%), from 1 week to 1 month after 5 visits (25%), and less than 1 week after a single visit (5%). After 9 visits (45%), the results were poor with no significant pain relief. CONCLUSION: Neurolytic paravertebral block with phenol doses used in our patients appears to have only limited use. Some patients with pain restricted to a small number of thoracic segments may benefit from its use. Because of complication risks, this technique should be limited to intractable pain in cancer patients with poor prognosis.

Effect of Lactobacillus rhamnosus strain GG (ATCC 53103) on the growth of Streptococcus sobrinus in vitro.

Lactobacillus GG, a recently characterized L. rhamnosus GG strain (ATCC 53103), has been shown to exert inhibitory activity against a variety of bacterial species, including streptococci. We isolated and studied the effect of the inhibitory substance of Lactobacillus GG on some oral streptococci. The inhibitory activity of the isolated substance was weak, but some growth inhibition was observed in Streptococcus sobrinus pretreated with the substance in comparison with untreated controls. Zones of growth inhibition on agar plates were apparent only at pH values below 5, indicating that the inhibitory activity was restricted to a low pH range. Growth curve experiments showed a statistically significant inhibition between series with and without the isolated substance (P < 0.05). The ultrastructure of S. sobrinus was not affected when treated with the inhibitory substance. The Lactobacillus GG itself did not ferment sucrose. The results offer interesting perspectives for future research focusing on the protective function of normal flora and in the attempt to replace harmful bacterial species in oral microflora with less harmful ones.

The effect of intermaxillary fixation on leukocyte zinc, serum trace elements and nutritional status of patients undergoing maxillofacial surgery.

Mononuclear cell (MNC), polymorphonuclear cell (PMNC) and serum zinc levels were studied in 17 oral surgical patients with intermaxillary fixation. Serum copper, iron, selenium and bromide concentrations were also measured together with common indices of nutritional status. Nine patients received nutritional counselling. Eight patients had, in addition, oral supplementation with a commercial formula. No changes in intracellular or serum zinc levels were seen during the study period. A statistically significant decrease was seen in mean body weight with subsequent changes in anthropometry. Maximal mean weight loss was 6.0 +/- 3.8% in control group and 3.8 +/- 2.7% in supplemental group. The impaired oral intake due to intermaxillary fixation does not interfere significantly with zinc status as estimated by MNC, PMNC or serum zinc levels. The reduction in body weight and anthropometric indices in the relatively short fixation period may be clinically significant in some patients. Supplementation with a commercial formula helps to maintain the nutritional status of these patients.

Articaine and lidocaine for maxillary infiltration anesthesia.

This study was undertaken to compare the anesthetic properties of articaine hydrochloride with 1:200,000 epinephrine (Ultracain DS) and lidocaine with 1:80,000 epinephrine (Xylocain-Adrenalin) for maxillary infiltration anesthesia. Twenty healthy dental student volunteers were included in this double-blind study. Each subject received 0.6 mL of each test solution at different times. Infiltration anesthesia was performed on the upper lateral incisor. The onset and duration of anesthesia were monitored using an electric pulp tester. No statistically significant differences were seen in the onset and duration of anesthesia between the articaine and lidocaine solutions.

Thoracic paravertebral block in chronic postoperative pain.

BACKGROUND AND OBJECTIVES: Chronic postoperative pain in thoracic dermatomes is common. The most frequently used methods of pain relief in this area are posterior multidermatomal intercostal nerve or thoracic epidural blocks. Compared with these methods, thoracic paravertebral block may have some advantages. Usually only one injection is needed, and the use of larger volumes of local anesthetic (up to 25 ml) results in widespread unilateral analgesia including sympathetic block without the potential risk of hypotension and motor block associated with epidural block. METHODS: We retrospectively analyzed 281 thoracic paravertebral blocks performed for chronic postoperative pain (post-thoracotomy and postmastectomy) from 1986 to 1990 in our pain clinic. RESULTS: In post-thoracotomy group, patients were without pain for at least a month after 58% of the blocks; in 30%, the effect lasted for at least two months; in 8%, more than four months and, in 3%, more than five months. In 88% of patients with postmastectomy pain, the achieved pain relief with thoracic paravertebral block was less than a month. No severe complications occurred. CONCLUSIONS: Thoracic paravertebral block proved to be a reliable and safe technique for unilateral pain relief in chronic post-thoracotomy pain.

Successful pain management by Finnish oral surgeons. A clinical follow-up study.

The current practice of postoperative pain management among Finnish oral surgeons was evaluated in a two-phase study. In the first phase, a questionnaire was sent to specialist members of the Finnish Society of Oral and Maxillofacial Surgeons that concerned the routine use of analgesic drugs after surgical removal of third molar teeth. In the second phase, the clinical adequacy of pain medication was assessed in 84 patients who had the same procedure. Patients estimated the intensity of pain with a 100 mm visual analogue scale at five time points during the day of surgery and on three postoperative days. Anti-inflammatory analgesics were widely used either alone or in combination with centrally acting analgesic drugs. Tolfenamic acid, diclofenac, and ketoprofen were the most commonly used analgesic drugs. The analgesic effect of the currently used drug combinations proved to be sufficient except in a few patients during the first night after surgery.

Serum trace element concentrations and iron metabolism in allogeneic bone marrow transplant recipients.

Serum trace element concentrations, parameters of iron metabolism and serum protein concentrations were investigated in thirteen adult recipients of bone-marrow transplants receiving total parenteral nutrition. Six of the patients died during the four weeks follow-up. Serum zinc concentrations were initially low but increased during the treatment. They also tended to be lower in dying patients than in survivors. Concentrations of serum copper and selenium remained unaltered. Serum iron started to increase during the preconditioning and remained raised for three weeks. No significant changes occurred in serum transferrin levels. Transferrin saturation increased during the preconditioning and started to return to normal after day +14. Serum ferritin was greatly raised from the start and increased further during the procedure. Routine trace element substitution seemed to be sufficient during total parenteral nutrition with the possible exception of zinc. A return to normal transferrin saturation after day +14 may be an early favourable sign that the graft is taking and hematopoietic recovery commencing.

Comparison of propofol infusion and isoflurane for maintenance of anesthesia for dentistry in mentally retarded patients.

A continuous infusion of propofol following an induction dose of 2 mg/kg was compared with thiopental/isoflurane for the induction and maintenance of anesthesia in 20 mentally retarded outpatients undergoing routine dental procedures. The infusion rate of propofol and the concentration of isoflurane were adjusted to maintain the heart rate and blood pressure within +/- 25% of the baseline values. Postoperative wakefulness was assessed using a 100-mm visual analogue scale at the time of extubation and at 5, 10, 15, 30, 60, 90, and 120 min after extubation. Both agents provided adequate anesthesia for the treatment, and no major adverse reactions occurred. Recovery was more complete during the first hour after extubation in the propofol group, and these patients were discharged earlier.

The effect of postoperative radiotherapy on leukocyte zinc, serum trace elements and nutritional status of breast cancer patients.

Mononuclear (MNC) and polymorphonuclear cell (PMNC) zinc content was determined together with serum zinc, copper, selenium and iron concentrations in 24 operable breast cancer patients during and after postoperative radiotherapy. Anthropometric and biochemical indices of nutritional status were measured as background data. The measurements were carried out in the years 1987-1988. Nine patients used unconventional multivitamin or trace element preparations. A steady but statistically insignificant decrease in PMNC zinc was seen during treatment. No changes occurred in MNC zinc. Serum copper levels increased in five patients possibly due to tamoxifen treatment, but no other alterations occurred in serum trace element levels. Appetite was well maintained and nutritional status remained unaltered. Postoperative radiotherapy for breast carcinoma had thus no effect on either trace element or nutritional status. Patient-initiated alternative treatments did not significantly affect their trace element levels. This was probably due to small supplementation doses or irregular use of the preparations.

Serum carnitine levels in bone marrow transplant recipients.

This study investigated plasma carnitine levels in patients undergoing allogenic bone marrow transplantation. The patients received fat-based TPN (50% fat, 50% CHO; calorie: nitrogen ratio 125:1) for an average of 33 +/- 7.5 days. TPN was started before transplantation and stopped when patients were able to eat. Caloric needs were estimated using the Harris-Benedict equation; 150% of the estimated BEE was given for the first two weeks after transplantation. The amount of TPN was gradually decreased as patients resumed their oral intake. All patients had low-normal serum carnitine levels before transplantation. There was no significant change in total or free serum carnitine levels during the course of TPN. However, in patients who had symptoms of graft vs. host reaction (GVH), the highest carnitine values during GVH (total 72.3 +/- 6.5 and free 61.2 +/- 12.4 mumol/l) were significantly higher (p < 0.001) than the baseline values (total 27.1 +/- 9.3 and free 24.9 +/- 9.6 mumol/l) or the highest non GVH values after transplantation (total 32.0 +/- 10.7 and free 29.0 +/- 10.7 mumol/l, respectively). The serum triglyceride, total cholesterol, and HDL cholesterol remained within normal range. In conclusion, bone marrow transplant patients receiving fat-based TPN have normal circulating levels of carnitine. GVH reaction caused an increase in the carnitine levels, which was probably due to increased tissue catabolism.

Serum iron, zinc, copper, selenium, and bromide concentrations after coronary bypass operation.

The effect of surgical trauma on serum trace elements was studied in 10 patients undergoing coronary bypass surgery. After the initial decrease due to the hemodilution during operation serum iron, zinc, copper and selenium remained depressed for the immediate postoperative period. Zinc was still at significantly lower level 2 months after the operation. Low serum iron values were also observed. Changes in trace element concentrations were parallel with changes in the concentrations of their transport and binding proteins in the serum. The multielemental technique also measured nonessential bromide, which returned to initial levels in 7 days. Effects of trauma on metabolism, acute phase reaction with redistribution of zinc and copper and losses via increased urinary excretion explain the above changes. Development of a subclinical deficiency of zinc and possibly iron is suggested by the persistence of low serum levels during recovery after operation.

The significance of arthroscopy and examination under anaesthesia in the diagnosis of fresh injury haemarthrosis of the knee joint.

Arthroscopy and examination under anaesthesia were performed for 328 consecutive knee injuries with haemarthrosis. These examinations were grouped according to a modified classification (Jackson and Abe, 1972) into very useful (117/328, 36 per cent), useful (98/328, 30 per cent) and useless (113/328, 34 per cent) categories. The probability of arthroscopy being useful was estimated mathematically. The factors which made this procedure useful were knee pain on exertion before the injury (P = 0.0561), the mechanism of the injury (P less than 0.0001) and the clinical stability of the patella (P = 0.0007). On arrival in the emergency department it was first decided whether the leg should be mobilized, immobilized in a plaster cast, operated on or, if a definitive diagnosis could not be reached, arthroscopy was deemed necessary. This resulted in the treatment following arthroscopy, and examination under anaesthesia, being altered from conservative to operative (P less than 0.0001). Results suggest that arthroscopy and examination under anaesthesia should always be considered to help in the diagnosis of acute injury haemarthrosis of the knee especially after a valgus or varus strain.

The effect of taurocholate on canine bile flow, biliary excretion and concentration of ioglycamide.

The bile acid taurocholate increases the biliary excretion of organic anions, such as sulfobromophthalein (BSP), bilirubin and iopanoic acid. In the present study has been investigated the effect of taurocholate on 1. Canine biliary excretion and concentration of the i.v. contrast medium ioglycamide and 2. Canine bile flow. The experimental model consisted of cholecystectomized, anaesthetized dogs with a fistula, through which the common bile duct could be catheterized and drained. One hour after cannulation, i.v. infusion of ioglycamide at a rate of 4 mumol/min./kg. was started. Two hours after the infusion start a control group received i.v. infusion of saline, while in another a 1.5% sodium taurocholate infusion was started with stepwise increases with 30 min. intervals from 0.4 to 0.8, 1.6 and 3.2 mumol/min./kg. Compared with control, all rates of taurocholate infusion increased bile flow and decreased biliary ioglycamide concentration. Although the bile flow with increasing taurocholate infusion rates was enhanced, the biliary ioglycamide excretion did not increase. The results indicate that ioglycamide and taurocholate are excreted into bile by separate excretion mechanisms. As taurocholate increases the biliary excretion of some other organic anions, it supports the hypothesis that organic anions are excreted into bile by more than two excretion mechanisms, taurocholate affecting only some of them.