A new photogrammetric method to measure fetal breathing movements.
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OBJECTIVE: In most recent studies, fetal respiratory movements have been measured with real-time and Doppler echography. We describe an alternative approach using photogrammetry that provides more objective measurements. METHODS: Respiratory movements were studied in 28 women with uncomplicated pregnancies of 30-38 weeks' gestation. Fetal echographic images were recorded on videotape and digitized to obtain coordinates of the reference point (midpoint on the anterior abdominal wall of the fetus between the xiphoid process and the insertion of the umbilical vessels) and generate graphic representations of fetal movements in the anterior abdomen. RESULTS: The mean duration of a complete respiratory cycle was 1.194 s, the mean distance representing the extent of movement was 2.92 mm, the mean inspiratory velocity was 5.52 mm/s and the mean expiratory velocity was 5.06 mm/s. CONCLUSIONS: Photogrammetric analysis of images obtained with real-time echography provided accurate measurements of fetal breathing movements. (+info)
Mechanical contribution of expiratory muscles to pressure generation during spinal cord stimulation.
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Lower thoracic spinal cord stimulation (SCS) results in the generation of large positive airway pressures (Paw) and may be a useful method of restoring cough in patients with spinal cord injury. The purpose of the present study was to assess the mechanical contribution of individual respiratory muscles to pressure generation during SCS. In anesthetized dogs, SCS was applied at different spinal cord levels by using a 15-lead multicontact electrode before and after sequential ablation of the external and internal obliques, transversus abdominis (TA), rectus abdominis, and internal intercostal muscles. Paw was monitored after tracheal occlusion. SCS at the T(9) spinal cord level resulted in maximal changes in Paw (60 +/- 3 cmH(2)O). Section of the oblique muscles resulted in a fall in Paw to 29 +/- 2 cmH(2)O. After subsequent section of the rectus abdominis and TA, Paw fell to 25 +/- 2 and 12 +/- 1 cmH(2)O respectively. There was a small remaining Paw (4 +/- 1 cmH(2)O) after section of the internal intercostal nerves. Stimulation with a two-electrode lead system (T(9) + T(13)) resulted in significantly greater pressure generation compared with a single-electrode lead due to increased contributions from the obliques and transversus muscles. In a separate group of animals, Paw generation was monitored after section of the abdominal muscles and again after section of the external intercostal and levator costae muscles. These studies demonstrated that inspiratory intercostal muscle stimulation resulted in only a small opposing inspiratory action (+info)
Lumbar spine stability can be augmented with an abdominal belt and/or increased intra-abdominal pressure.
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The increased intra-abdominal pressure (IAP) commonly observed when the spine is loaded during physical activities is hypothesized to increase lumbar spine stability. The mechanical stability of the lumbar spine is an important consideration in low back injury prevention and rehabilitation strategies. This study examined the effects of raised IAP and an abdominal belt on lumbar spine stability. Two hypotheses were tested: (1) An increase in IAP leads to increased lumbar spine stability, (2) Wearing an abdominal belt increases spine stability. Ten volunteers were placed in a semi-seated position in a jig that restricted hip motion leaving the upper torso free to move in any direction. The determination of lumbar spine stability was accomplished by measuring the instantaneous trunk stiffness in response to a sudden load release. The quick release method was applied in isometric trunk flexion, extension, and lateral bending. Activity of 12 major trunk muscles was monitored with electromyography and the IAP was measured with an intra-gastric pressure transducer. A two-factor repeated measures design was used (P < 0.05), in which the spine stability was evaluated under combinations of the following two factors: belt or no belt and three levels of IAP (0, 40, and 80% of maximum). The belt and raised IAP increased trunk stiffness in all directions, but the results in extension lacked statistical significance. In flexion, trunk stiffness increased by 21% and 42% due to 40% and 80% IAP levels respectively; in lateral bending, trunk stiffness increased by 16% and 30%. The belt added between 9% and 57% to the trunk stiffness depending on the IAP level and the direction of exertion. In all three directions, the EMG activity of all 12 trunk muscles increased significantly due to the elevated IAP. The belt had no effect on the activity of any of the muscles with the exception of the thoracic erector spinae in extension and the lumbar erector spinae in flexion, whose activities decreased. The results indicate that both wearing an abdominal belt and raised IAP can each independently, or in combination, increase lumbar spine stability. However, the benefits of the belt must be interpreted with caution in the context of the decreased activation of a few trunk extensor muscles. (+info)
Six-fold suture:wound length ratio for abdominal closure.
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Midline laparotomy incision is generally closed as a continuous single layer with monofilament suture. To achieve safe abdominal closure, it is advised to have a suture:wound length (SL:WL) ratio of more than 4:1. The importance of a high SL:WL ratio led us to standardise a safe abdominal closure technique. We calculated the subsequent SL:WL ratio and support our finding with a mathematical model. Between March 1996 and February 1997, 100 consecutive patients undergoing elective or emergency laparotomy through a midline incision were entered into this prospective study. The wounds were closed with a single layer continuous suture to approximate the abdominal muscles. Suture and wound lengths were recorded. Patients were followed for one year. Five patients developed incisional hernia at 12 months postoperatively. There was no burst abdomen. The mean SL:WL ratio: was 6.2:1. A mathematical model confirms that a SL:WL ratio of 6:1 should be achieved with this suture technique. We recommend an optimal SL:WL ratio: greater than or equivalent to 6:1 to achieve safe closure of midline laparotomy incision. (+info)
Transient increases in diameter and [Ca(2+)](i) are not obligatory for myogenic constriction.
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Studies were performed to determine the significance of temporal variation in vascular smooth muscle Ca(2+) signaling during acute arteriolar myogenic constriction and, in particular, the importance of the stretch-induced intracellular Ca(2+) concentration ([Ca(2+)](i)) transient in attaining a steady-state mechanical response. Rat cremaster arterioles (diameter approximately 100 microm) were dissected from surrounding tissues, and vessel segments were pressurized in the absence of intraluminal flow. For [Ca(2+)](i) measurements, vessels were loaded with fura 2 and fluorescence emitted by excitation at 340 and 380 nm was measured using video-based image analysis. Ca(2+) and diameter responses were examined after increases in intravascular pressure were applied as an acute step increase or a ramp function. Additional studies examined the effect of longitudinal vessel stretch on [Ca(2+)](i) and arteriolar diameter. Step increase in intraluminal pressure (from 50 to 120 mmHg) caused biphasic change in [Ca(2+)](i) and diameter. [Ca(2+)](i) transiently increased to 114.0 +/- 2.0% of basal levels and subsequently declined to 106.7 +/- 4.4% at steady state. Diameter initially distended to 125.4 +/- 2.1% of basal levels before constricting to 71.1 +/- 1.2%. In contrast, when the same pressure increase was applied as a ramp function (over 5 min) transient vessel distension and transient increase in [Ca(2+)](i) were prevented, yet at steady state vessels constricted to 71.3 +/- 2.5%. Longitudinal stretch resulted in a large [Ca(2+)](i) transient (158 +/- 19% of basal) that returned to baseline despite maintenance of the stretch stimulus. The data demonstrate that the initial vessel distension (reflecting myocyte stretch) and associated global [Ca(2+)](i) transient are not obligatory for myogenic contraction. Thus, although arteriolar smooth muscle cells are responsive to acute stretch, the resulting changes in myogenic tone may be more closely related to other mechanical variables such as wall tension. (+info)
Protein kinase C modulates insulin action in human skeletal muscle.
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There is good evidence from cell lines and rodents that elevated protein kinase C (PKC) overexpression/activity causes insulin resistance. Therefore, the present study determined the effects of PKC activation/inhibition on insulin-mediated glucose transport in incubated human skeletal muscle and primary adipocytes to discern a potential role for PKC in insulin action. Rectus abdominus muscle strips or adipocytes from obese, insulin-resistant, and insulin-sensitive patients were incubated in vitro under basal and insulin (100 nM)-stimulated conditions in the presence of GF 109203X (GF), a PKC inhibitor, or 12-deoxyphorbol 13-phenylacetate 20-acetate (dPPA), a PKC activator. PKC inhibition had no effect on basal glucose transport. GF increased (P < 0.05) insulin-stimulated 2-deoxyglucose (2-DOG) transport approximately twofold above basal. GF plus insulin also increased (P < 0.05) insulin receptor tyrosine phosphorylation 48% and phosphatidylinositol 3-kinase (PI 3-kinase) activity approximately 50% (P < 0.05) vs. insulin treatment alone. Similar results for GF on glucose uptake were observed in human primary adipocytes. Further support for the hypothesis that elevated PKC activity is related to insulin resistance comes from the finding that PKC activation by dPPA was associated with a 40% decrease (P < 0.05) in insulin-stimulated 2-DOG transport. Incubation of insulin-sensitive muscles with GF also resulted in enhanced insulin action ( approximately 3-fold above basal). These data demonstrate that certain PKC inhibitors augment insulin-mediated glucose uptake and suggest that PKC may modulate insulin action in human skeletal muscle. (+info)
The search for an ideal method of abdominal fascial closure: a meta-analysis.
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BACKGROUND AND OBJECTIVE: The ideal suture for abdominal fascial closure has yet to be determined. Surgical practice continues to rely largely on tradition rather than high-quality level I evidence. The authors conducted a systematic review and meta-analysis of randomized controlled trials to determine which suture material and technique reduces the odds of incisional hernia. METHODS: MEDLINE and Cochrane Library databases were searched for articles in English published from 1966 to 1998 using the keywords "suture", "abdomen/surgery", and "randomized controlled trials". Randomized controlled trials, trials of adult patients, and trials with a Jadad Quality Score of more than 3, comparing suture materials, technique, or both, were included. Two independent reviewers critically appraised study quality and extracted data. The reviewers were masked to the study site, authors, journal, and date to minimize bias. The primary outcome was postoperative incisional hernia. Secondary outcomes included wound dehiscence, infection, wound pain, and suture sinus formation. RESULTS: The occurrence of incisional hernia was significantly lower when nonabsorbable sutures were used. Suture technique favored nonabsorbable continuous closure. Suture sinuses and wound pain were significantly lower when absorbable sutures were used. There were no differences in the incidence of wound dehiscence or wound infection with respect to suture material or method of closure. Subgroup analyses of individual sutures showed no significant difference in incisional hernia rates between polydioxanone and polypropylene. Polyglactin showed an increased wound failure rate. CONCLUSIONS: Abdominal fascial closure with a continuous nonabsorbable suture had a significantly lower rate of incisional hernia. The ideal suture is nonabsorbable, and the ideal technique is continuous. (+info)
Polypropylene mesh substitute for the fascial defect after using for the dural repair--technical note.
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Use of the anterior sheath of the rectus abdominis muscle (anterior sheath) as a dural substitute and patching of the large defect of the anterior sheath with polypropylene mesh are described. Five patients were treated using the anterior sheath and the mesh. No postoperative complications such as cerebrospinal fluid leakage, infection, or abdominal wall hernia occurred. The mesh is useful as a patch for the sheath defect. (+info)