Investigating the magnetic and magnetocaloric behaviors of LiSm(PO3)4.

We report a detailed study on the magnetic behaviors and magnetocaloric (MC) effect of a single crystal of lithium samarium tetraphosphate, LiSm(PO3)4. The analyses of temperature-dependent magnetization data have revealed magnetic ordering established with decreasing temperature below T p, where T p is the minimum of a dM/dT vs. T curve and varies as a linear function of the applied field H. The Curie temperature has been extrapolated from T p(H) data, as H → 0, to be about 0.51 K. The establishment of magnetic-ordering causes a substantial change in the heat capacity C p. Above T p, the crystal exhibits paramagnetic behavior. Using the Curie-Weiss (CW) law and Arrott plots, we have found the crystal to have a CW temperature θ CW ≈ -36 K, and short-range magnetic order associated with a coexistence of antiferromagnetic and ferromagnetic interactions ascribed to the couplings of magnetic dipoles and octupoles at the Γ7 and Γ8 states. An assessment of the MC effect has shown increases in value of the absolute magnetic-entropy change (|ΔS m|) and adiabatic-temperature change (ΔT ad) when lowering the temperature to 2 K, and increasing the magnetic-field H magnitude. Around 2 K, the maximum value of |ΔS m| is about 3.6 J kg-1 K-1 for the field H = 50 kOe, and ΔT ad is about 5.8 K for H = 20 kOe, with the relative cooling power (RCP) of ∼82.5 J kg-1. In spite of a low MC effect in comparison to Li(Gd,Tb,Ho)(PO3)4, the absence of magnetic hysteresis reflects that LiSm(PO3)4 is also a candidate for low-temperature MC applications below 25 K.

A comparison of epidural versus general anesthesia for outpatient endoscopic preperitoneal herniorrhaphy.

OBJECTIVES: To study the efficacy of epidural versus general anesthesia on length of stay, patient recovery and anesthetic-related complications in patients undergoing endoscopic preperitoneal herniorrhaphy. METHODS: One hundred sixty-seven consecutive patients undergoing endoscopic preperitoneal herniorrhaphy from July, 1994, to August, 1995, were retrospectively studied. A total of 243 herniorrhaphies were performed. Four patients required conversion of epidural anesthesia to general anesthesia because of inadequate sensory blockade (67/71; 94% success rate). One-hundred-forty-eight patients were available for review. Sixty-seven patients underwent successful epidural anesthesia during the case, while 81 patients were managed with general anesthesia. RESULTS: Thirty patients (37%) receiving general anesthesia required interventions for nausea compared to only six patients (9.0%) in the epidural anesthesia group (p < 0.001). Thirty patients (37%) in the general anesthesia group required intervention because of complaints of pain, compared to 13 (19.4%) in the epidural group (p < 0.05). There were no differences between the two groups for length of stay in OR, PACU, or total hospital times. CONCLUSIONS: The use of epidural anesthesia during the performance of endoscopic preperitoneal herniorrhaphy was associated with a decrease in the incidence of postoperative pain and nausea. The technique was successful in 94% of the cases in which it was used. Epidural anesthesia is recommended as an effective alternative to general anesthesia for the performance of outpatient endoscopic preperitoneal herniorrhaphy.

The efficacy of epidural anesthesia for endoscopic preperitoneal herniorrhaphy: a prospective study.

Laparoscopic herniorrhaphy has been criticized because of the need for general anesthesia. The endoscopic preperitoneal approach allows the use of epidural anesthesia, obviating the potential complications and side effects seen with general anesthesia. The purpose of this study was to determine the efficacy of epidural anesthesia for preperitoneal herniorrhaphy. Fifty-two patients underwent repair of a total of 80 hernias over a 6-month period. Thirty-six patients underwent their repairs with the use of epidural anesthesia with the goal of a T-4 sensory level. A tension-free prosthetic repair was performed in all patients. Seventeen patients had unilateral repairs and nineteen had bilateral repairs under epidural, while seven patients had unilateral repairs and nine patients had bilateral repairs under general anesthesia. There were no significant differences in patient demographics. All herniorrhaphies were electively performed on an outpatient basis by a single surgeon (A.L.S.) in a teaching setting. There were no significant differences for unilateral and bilateral repairs when type of anesthesia was compared. There was only one conversion from epidural to general anesthesia, secondary to poor sensory blockade first noticed during creation of the preperitoneal space (97% success rate). Seven patients receiving epidural anesthesia experienced pneumoperitoneum during the procedure. This did not effect the ability to perform the hernia repair successfully. There were no complications related to the epidural anesthetic. Endoscopic preperitoneal herniorrhaphy can be performed effectively under epidural anesthesia, obviating the need for general anesthesia.

Etidocaine for Caesarean section--effects on mother and baby.

The effectiveness and safety of etidocaine during extradural anaesthesia for Caesarean section were evaluated in 81 patients. Adequate sensory analgesia occurred in 78 patients and muscle relaxation was excellent in all patients. The combined umbilical venous-umbilical arterial/maternal venous ratio was 0.28+/-0.2 following the administration of 1% etidocaine 25 ml with adrenaline and 0.38+/-0.2 following the administration of 1% etidocaine plain 25 ml. Neurobehavioural patterns of the newborn were not affected noticeably. Etidocaine, in appropriate dose and concentration, appears to be an excellent local anaesthetic agent for Caesarean section under extradural anaesthesia.