In vivo oscillations of the soleus muscle can be quantified using b-mode ultrasound imaging during walking and running in humans.

Impact forces, due to the foot contacting the ground during locomotion, can be considered input signals to the body that must be dissipated to prevent impact-related injuries. One proposed mechanism employed by the body to damp the impact is through vibrations of the skeletal muscles. However, there is yet to be direct in vivo measures of muscle oscillations during locomotion. This study investigated the use of 2D ultrasound imaging to quantify transverse muscle oscillations (deep-superficial displacement of the muscle boundary relative to the skin) in response to impact forces elicited by walking and running at a range of speeds. Increases in vertical impact forces with faster walking and running was consistent with changes in both magnitude and frequency in the measured oscillations of the soleus muscle; one of the main human ankle plantar flexors. Muscle oscillations contained more higher frequency components at fast running (50% signal power in frequencies below ~ 14 Hz) compared with slow walking (50% signal power contained in frequencies below ~ 5 Hz). This study provides a platform for ultrasound imaging to examine muscle oscillation responses to impact forces induced by changes in external interfaces such as shoe material, locomotion type and ground surface properties.

Ultrasound-derived changes in thickness of human ankle plantar flexor muscles during walking and running are not homogeneous along the muscle mid-belly region.

Skeletal muscle thickness is a valuable indicator of several aspects of a muscle's functional capabilities. We used computational analysis of ultrasound images, recorded from 10 humans walking and running at a range of speeds (0.7-5.0 m s-1), to quantify interactions in thickness change between three ankle plantar flexor muscles (soleus, medial and lateral gastrocnemius) and quantify thickness changes at multiple muscle sites within each image. Statistical analysis of thickness change as a function of stride cycle (1d statistical parametric mapping) revealed significant differences between soleus and both gastrocnemii across the whole stride cycle as they bulged within the shared anatomical space. Within each muscle, changes in thickness differed between measurement sites but not locomotor condition. For some of the stride, thickness measures taken from the distal-mid image region represented the mean muscle thickness, which may therefore be a reliable region for these measures. Assumptions that muscle thickness is constant during a task, often made in musculoskeletal models, do not hold for the muscles and locomotor conditions studied here and researchers should not assume that a single thickness measure, from one point of the stride cycle or a static image, represents muscle thickness during dynamic movements.

Differences in in vivo muscle fascicle and tendinous tissue behavior between the ankle plantarflexors during running.

The primary human ankle plantarflexors, soleus (SO), medial gastrocnemius (MG), and lateral gastrocnemius (LG) are typically regarded as synergists and play a critical role in running. However, due to differences in muscle-tendon architecture and joint articulation, the muscle fascicles and tendinous tissue of the plantarflexors may exhibit differences in their behavior and interactions during running. We combined in vivo dynamic ultrasound measurements with inverse dynamics analyses to identify and explain differences in muscle fascicle, muscle-tendon unit, and tendinous tissue behavior of the primary ankle plantarflexors across a range of steady-state running speeds. Consistent with their role as a force generator, the muscle fascicles of the uniarticular SO shortened less rapidly than the fascicles of the MG during early stance. Furthermore, the MG and LG exhibited delays in tendon recoil during the stance phase, reflecting their ability to transfer power and work between the knee and ankle via tendon stretch and storage of elastic strain energy. Our findings add to the growing body of evidence surrounding the distinct mechanistic functions of uni- and biarticular muscles during dynamic movements.

Correlations between the experimental and numerical investigations on the mechanical properties of erythrocyte by laser stretching.

The deformation and mechanical properties of the erythrocytes are studied experimentally and numerically. For the experimental part, an osmotic swollen spherical erythrocyte was attached with a pair of silica beads, and then stretched at two opposite ends by a laser trap. The purpose of this experiment is to find the empirical correlation between the stretching force and the cell deformation in terms of the transverse strain, which is a measure of the change of radius in a spherical cell along its equator. Experimental results show the cell shape become more oblate, elliptic as the stretching force increases. On the numerical front, a physical model from the original work by Pamplona and Calladine for the lipsomes was extended to simulate the deformation of the cell membrane. Numerical analyses were performed to solve the nondimensionalized governing equations with proper boundary conditions imposed to simulate the experimental conditions. The simulated results indicate that at high tensile stiffness, the cell can deform into a spindle shape with negative curvature close to the ends of stretch. Finally, the experimental data and the simulated results were correlated through optimization by minimizing their discrepancy at various values of the shear stiffness. The optimal value of shear stiffness was found in the range of 2.35 approximately 4.29 10(-6) N.m(-1), which is comparable with those values reported in the literature.

Twelve years' local experience in ambulatory anaesthesia.

OBJECTIVES: To determine the incidence of adverse events after ambulatory anaesthesia (postoperative nausea and vomiting, postoperative pain, difficulty in movement), and to evaluate the level of satisfaction of patients with our service. DESIGN: Retrospective study with questionnaire survey. SETTING: Tertiary referral centre, Hong Kong. PARTICIPANTS: All patients whose duly completed questionnaires were available. MAIN OUTCOME MEASURES: Incidence of adverse events and level of patient satisfaction. RESULTS: A total of 9197 patients underwent surgery under general anaesthesia or neuraxial blockade by anaesthetists in ambulatory settings from October 1993 to December 2005: questionnaires filled out by 8231 of these patients were analysed, whereas 549 questionnaires were lost, and 417 patients could not be contacted. The response rate was 90%; 59% of the respondents were males, 50% were younger than 15 years and 5% older than 60 years. Fifty-one percent of surgery with anaesthetists' involvement was performed under general anaesthesia and 48.9% under general anaesthesia and regional blocks and 0.1% under neuraxial blockade. There were 3.3% of patients experienced postoperative nausea and vomiting, 60.2% experienced episodes of pain between the time of discharge and the time of interview, and 46% required analgesics. Nonetheless, 80% resumed normal activities within 5 hours after anaesthesia and 97.5% resumed normal diet the following morning. Over 99% rated our service as good or excellent. CONCLUSION: Although ambulatory anaesthesia was associated with minor adverse events, patients could resume normal diet and daily activities quickly and were satisfied with the service.

Emergency aortic stent grafting for traumatic rupture of the thoracic aorta.

OBJECTIVE: To investigate the role of aortic stent grafting in emergency treatment of traumatic rupture of the descending thoracic aorta in patients with multiple injuries. DESIGN: Retrospective study. SETTING: Cardiothoracic surgery facility of a tertiary referral hospital, Hong Kong. PATIENTS: Between September 2001 and September 2002, four patients who had sustained a blunt injury to the chest after high-speed deceleration injury were recruited. Three patients were treated with stent grafting because concomitant head injury and multiple other injuries precluded the use of open thoracic surgery. One patient had no head injury and was offered stent grafting as a less invasive treatment. INTERVENTION: The pseudoaneurysm was covered with an aortic stent graft under fluoroscopic and angiographic guidance. MAIN OUTCOME MEASURES: Technical success of treatment, complications, and treatment outcome. RESULTS: Three patients recovered and were discharged from hospital. The computed tomography scan at 3 months to 6 months after surgery showed resolution of the pseudoaneurysm. The final patient was still in the hospital. Follow-up computed tomography 2 weeks later showed exclusion of the pseudoaneurysm. There was one external iliac artery thrombosis on the side of femoral arteriotomy, which was recanalised with thrombectomy. There was another unintentional partial coverage of the left subclavian artery, which was asymptomatic. No other major complication was present and there was no paraplegia after the stent grafting. CONCLUSION: Aortic stent graft is useful for emergency treatment of descending thoracic aortic injury. In the short term, it causes less morbidity and mortality than does open surgery, and can be life-saving when there is no surgical alternative. The long-term effect is still unknown.

Rare pulmonary complications after transarterial chemoembolisation for hepatocellular carcinoma: two case reports.

We report two rare cases of acute pulmonary complication after transarterial chemoembolisation for inoperable hepatocellular carcinoma. Both cases involved a large tumour and hepatic vein invasion. The first patient, a 27-year-old man, died of pulmonary tumour embolism 4 days after transarterial chemoembolisation. Acute dyspnoea developed in the second patient, a 63-year-old man, following the procedure due to pulmonary oil embolisation and chemical pneumonitis. The chest condition of this patient improved, but he subsequently died of liver failure 3 weeks later. Our cases illustrate the point that if locoregional treatment is offered as a palliative treatment, patients with hepatic vein invasion should be warned of the possible complications of massive tumour embolism, pulmonary oil embolisation, and subsequent death.

A blinded clinical trial comparing conventional cleansing enema, Pico-salax and Golytely for barium enema bowel preparation.

UNLABELLED: An evaluator-blinded randomized clinical trial was undertaken to assess the effectiveness and patient acceptance of three bowel cleansing regimens: conventional cleansing enema, Pico-salax and Golytely. PATIENTS AND METHODS: One hundred and fifty patients, referred for barium enema examination, were allocated to one of the three regimens. Both the radiographers and the radiologists did not know the method of preparation. Radiographers were requested to enter the patients' data, the number of bowel openings, the patients' comments of the preparation and side effects. Films were reviewed independently by two experienced radiologists for the degree of bowel cleanliness and quality of barium coating. RESULTS: The mean (standard deviation) of bowel opening frequency for the cleansing enema, Pico-Salax and Golytely were 3.6(4.4), 8.3(4.8) and 7.1(4.2), respectively, with less bowel opening in the cleansing enema. There was less nausea associated with the cleansing enema (P = 0.006), more vomiting with Golytely (P = 0.008), less abdominal fullness with Pico-salax (P = 0.0006), less anorectal irritation with Golytely (P = 0.025), and no difference in the abdominal pain amongst three groups. There was no statistically significant difference in the number of bowel openings between the groups. Patients found that Pico-salax tasted better than Golytely (P = 0.0094) and Golytely was less accepted in the amount of fluid intake (P = 0.0018 and P < 0.0002 comparing Golytely with the cleansing enema and Pico-salax). Chi-squared testing showed no statistically significant difference in bowel cleanliness and quality of barium coating among the three preparations. CONCLUSIONS: There was no difference in the effectiveness of the three regimens. Pico-salax seems the most acceptable because it has the fewest side effects.