Fracture strength of ceramic brackets during arch wire torsion.

This study evaluated the fracture strengths of eight new vintage ceramic brackets with application of torsional forces. Palatal root torque was applied at the distal side of right maxillary central incisor brackets with 0.022-inch slots by means of a 0.0215 x 0.027-inch rounded edge stainless steel arch wire. A specially designed apparatus that attached to an Instron machine was used to test the ceramic brackets. The amount of torque, degrees of torsion at failure, and fracture locations were measured. The monocrystalline bracket did not break when the torquing test was applied; the portion of the wire outside the slot of the bracket twisted on itself. The mean torquing forces at failure ranged from 5755.2 gm-mm to 9316.5 gm-mm and could be separated into three statistically different groups. The mean torsional rotation at fracture ranged from 32.7 degrees to 68.1 degrees for the polycrystalline brackets. The results suggested that all the brackets studied were sufficiently strong to withstand the commonly accepted magnitudes of arch wire torquing forces. The present investigation showed higher angulation values for all the brackets than those reported by Holt who used the same apparatus with older style brackets.

[Biological changes in intra-uterine resections under glycine irrigation]. / Perturbations biologiques au cours des résections intra-utérines sous irrigation de glycocolle.

This study was carried out to assess the relations between plasma glycine concentrations and the biochemical changes occurring during intra-uterine resections (IUR) under glycine irrigation. Sixty patients with benign uterine conditions were included. They were all ranked ASA 1 or 2. The biological parameters were assessed before surgery (T0), at the end of surgery (T1) and 60 min afterwards (T2). They included the blood count and blood concentrations of sodium, potassium, chloride, proteins, bicarbonates, glucose, urea nitrogen, creatinine and glycine. Plasma osmolarity was calculated. The irrigation of the uterine cavity resulted in an increase of glycine concentrations (28% of cases), and a decrease of sodium (22% of cases), proteins and haematocrit (32% of cases). Mean osmolarity remained unchanged. Blood glycine concentrations were directly correlated with the volume of irrigating solution, as well as with the duration of surgery. Protidaemia was inversely related to the blood glycine concentration. Multiparous patients had lower glycine concentrations than nulliparous patients. This was probably due to the uterine cavity being less compliant in the latter. On the other hand, there was no correlation with the uterine pathological condition. In this series, five cases of uterine perforation occurred with very large biological variations, especially a decrease in haematocrit and osmolarity. In these cases a clinical and biological water intoxication syndrome may occur as a result of large volumes of irrigating fluid passing into the peritoneal cavity.

Septic shock: a goal-directed therapy using volume loading, dobutamine and/or norepinephrine.

In patients with septic shock and acute respiratory failure, norepinephrine (NE) alone or in combination with dobutamine was used. The aim of therapy was to obtain or maintain Cl greater than or equal to 4.5 l.min-1.m-2, SVR greater than or equal to 700-800 dyn.s.cm-5 and oxygen delivery (Do2) greater than or equal to 550 ml.min-1.m-2. Twenty-three patients (58 +/- 3 years) were studied. Initially patients were given intravenous fluid resuscitation to obtain optimal cardiac filling pressures. Eleven patients were considered to be in hyperdynamic septic shock (cardiac index (CI) greater than 4.5 l.min-1.m-2, SVR less than or equal to 600 dyn.s.cm-5 and oliguria) and were given NE as a single agent (0.9 +/- 0.2 micrograms kg-1.min-1). The other 12 patients had Cl less than 3.5 l.min-1.m-2 and were given a combination of dobutamine (12 +/- 0.09 micrograms.kg-1.min-1) and NE (1.1 +/- 0.2 micrograms.kg-1.min-1). The latter drug was added since systemic vascular resistance (SVR) was less than 600 and oliguria persisted while on dobutamine. In all patients, during NE infusion SVR was greater than 700 dyn.s.cm-5, Cl greater than or equal to 4.5 l.min-1.m-2 and Do2 greater than 550 ml.min-1.m-2. Urine flow was significantly increased during NE infusion, and only four patients remained oliguric. Anion gap and oxygen consumption were not modified. A complete resolution of septic shock was seen in 16 out of 23 patients (70%). Hospital mortality was 56%.

Renal effects of norepinephrine used to treat septic shock patients.

Twenty-four patients with septic shock (cardiac index [CI] greater than or equal to 4 L.min-1.m-2, systemic vascular resistance index [SVRI] less than or equal to 350 dyne.sec.cm-5.m-2, systolic BP less than or equal to 90 mm Hg, oliguria less than 30 ml/h) were treated with norepinephrine (NE) infused either alone or in combination with dopamine and/or dobutamine. In all patients, NE resulted in either an increase in BP, no change, or an increase in CI and restored SVRI to the normal range. In 20 patients, normalization of systemic hemodynamics was followed by re-establishment of urine flow, decrease in serum creatinine, and increase in creatinine clearance. None of these 20 patients received low dose dopamine or furosemide. Four patients remained oliguric. Two of these four patients died and two developed acute renal failure. These findings suggest that NE infusion does not worsen renal ischemia related to hemodynamic disturbances in septic shock patients, and may have beneficial effects on renal function.

[Aortic paraprosthetic infection. Diagnostic and therapeutic difficulties. Apropos of a case]. / Infection paraprothétique aortique. Difficultés diagnostiques et thérapeutiques. A propos d'un cas.

Despite advances in vascular surgical techniques and antimicrobial therapy, aortic graft infection remains a difficult clinical problem to manage. We report a case of secondary paraprosthetic fistula. All complementary investigations were negative and the fistula was diagnosed by laparotomy. In situ replacement of the infected graft was decided despite signs of infection. The postoperative course was complicated by septic shock, successfully treated by organism-specific antibiotic therapy. In conclusion, complementary investigations should not delay laparotomy in patients with a aortic prosthesis presenting with unexplained infection. They must be considered to be suffering from a graft infection until proven otherwise. Conditions in situ replacement of the graft appears to be possible under these.

Lower oesophageal reflux during priming with vecuronium.

We have studied the effects of vecuronium given in divided doses (priming principle) on the frequency of acid reflux into the oesophagus. Two groups of 16 patients were studied. After induction with thiopentone 6 mg kg-1 and fentanyl 3 micrograms kg-1, patients in one group were given vecuronium 0.01 mg kg-1 as a priming dose, followed by an intubation dose of 0.1 mg kg-1 4 min later. Patients in the other group were given no priming dose. Lower oesophageal pH was monitored continuously and acid reflux was defined as a decrease in pH to less than 4.0. One patient in each group had acid reflux during the time course of the induction. This study suggests that vecuronium 0.01 mg kg-1 given as a priming dose does not increase the risk of acid reflux into the oesophagus.

[Use of norepinephrine in the treatment of septic shock]. / Utilisation de la noradrénaline dans le traitement du choc septique.

The effects of noradrenaline were studied in 16 patients, with either a hyperkinetic septic shock syndrome or a septic shock resistant to dobutamine treatment. The study aimed to restore normal tissue perfusion pressure, assessed by a return to normal of urine output or blood pressure. An optimal left ventricular filling pressure, estimated by the pulmonary capillary wedge pressure, was obtained for each patient using a Swan-Ganz catheter. The administration of 10.6 +/- 0.5 micrograms.kg-1.min-1 dobutamine (starting dose: 6 micrograms.kg-1.min-1) was started when the cardiac index (CI) was less than 3.3 l.min-1.m-2 after vascular filling with plasma expanders. Patients became eligible for noradrenaline treatment when they fulfilled the following conditions: arterial systolic pressure (Pasys) less than or equal to 90 mmHg; systemic vascular resistances less than or equal to 600 dyn.s.cm-5; CI greater than 3.5 l.min-1.m-2; persistent oliguria (less than 30 ml.h-1). This drug was given at a constant rate with a starting dose of 0.5 micrograms.kg-1.min-1, increased every 10 min by 0.3 to 0.6 micrograms.kg-1.min-1 according to the effects on Pasys and hourly urine output. Eight patients received noradrenaline alone; the efficient dose was 0.9 +/- 0.2 micrograms.kg-1.min-1, and it was used for a mean 5.1 +/- 1 days. CI increased in those patients who were given both noradrenaline and dobutamine. Thirteen out of the 16 patients had a dramatic increase in urine output; only three patients remained oliguric. There were no effects on serum creatinine concentration, anion gap, intrapulmonary shunt and oxygen consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

[Protein C deficiency and cerebral venous thrombosis in pregnancy]. / Déficit en protéine C et thrombose veineuse cérébrale au cours de la grossesse.

A fatal case of cerebral venous thrombosis associated with protein C deficiency is reported. It occurred at six months of gestation in a 25 year old patient during her first pregnancy. She had generalized seizures. Computed axial tomography displayed cerebral haemorrhagic infarction, and the carotid angiograms signs of superior longitudinal sinus thrombosis. Before the patient's death on the seventh day after admission, protein C deficiency was discovered. The occurrence of thrombosis of the superior longitudinal sinus during pregnancy, as well as that of protein C deficiency in atypical cases of thromboembolic disease, are discussed.