A possible mechanism of motor blockade of high volume pericapsular nerve group (PENG) block: A cadaveric study

The clinical effects of high-volume spinal anaesthesia with bupivacaine 0.125% were studied in 30 patients presenting for postpartum sterilisation. Group A, B and C patients received 6, 8 and 10 ml of bupivacaine 0.125% respectively. Onset, duration and regression of sensory block and motor blockade, haemodynamic parameters and postoperative complications were studied. A sensory level of T10 was reliably obtained in Group B and C but not in Group A. Similarly motor blockade was unreliable in Group A compared with Group B (P < 0.05) and Group C (P < 0.05). Two segment regression times were similar in all three groups. L1 regression times were 4 7.9, 94.3 and 99.0 minutes in Groups A, B and C respectively. The corresponding times for complete recovery of motor power were 120, 212.3 and 182.7 minutes respectively (P < 0.01 when Group A compared to B and C). A significant incidence of high spinal anaesthesia occurred when 10 ml bupivacaine 0.125% was administered (P < 0.05 when compared with Group A). No patient experienced respiratory discomfort in spite of sensory levels of up to T1. Hypotension responded readily to intravenous fluids and small doses of ephedrine (three patients). Only one patient (Group A) developed a postdural puncture headache. In this study, high-volume spinal anaesthesia with bupivacaine 0.125% was found to be satisfactory for postpartum tubal ligation. The optimal volume of bupivacaine 0.125% was 8 ml.

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Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071326 ◽

1973 ◽

Vol 31 ◽

pp. 176-177

Author(s):

D. E. Fornwalt ◽

A. R. Geary ◽

B. H. Kear

Keyword(s):

Electron Microscope ◽

Grain Boundaries ◽

Volume Fraction ◽

Rupture Life ◽

Stress Rupture ◽

High Volume ◽

Precipitate Morphology ◽

Stress Rupture Life ◽

Nickel Base ◽

Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

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A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011742x ◽

1985 ◽

Vol 43 ◽

pp. 70-71

Author(s):

M.G. Burke ◽

M.K. Miller

Keyword(s):

Low Temperature ◽

Microstructural Characterization ◽

Superlattice Reflection ◽

High Volume ◽

Atom Probe ◽

Dark Field ◽

Miscibility Gap ◽

Second Phase ◽

Two Phase ◽

Probe Field

Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

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