Phosphates recovery from iron phosphates sludge.

Recovery of phosphates from ferrous and/or ferric residues as a result of chemical precipitation was investigated. The product of biological reduction of sulphates--sulphides and free hydrogen sulphide--can react with iron ions forming ferrous sulphide which are less soluble then ferrous phosphates, releasing phosphates into solution. Laboratory scale experiments have confirmed the possibility of phosphates recovery. It was found that strict anaerobic conditions are required and that the process is COD/S ratio dependent.

Patterns of practice in emergency department management of chest pain of suspected cardiac origin: clinical utility of single stat creatine kinase (CK).

The patterns of practice and the clinical utility of a single stat creatine kinase (CK) level in the emergency department management of chest pain of suspected cardiac origin were examined by a prospective observational study using a two-part questionnaire, completed by physicians before and after availability of CK results. The results showed that of the 776 patients in the study, 135 were admitted to hospital with acute myocardial infarction (AMI), 285 were admitted for reasons other than AMI, 343 were discharged, and 13 died or were transferred to another hospital. Although initial and final diagnoses in the emergency department did not differ in 597 patients (77%), initial decisions to admit or discharge were made in only 244 (31%) patients without waiting for CK results, and in 401 (52%) cases, decisions on patient disposition were deferred. Of 218 patients who had elevated CK levels, 193 (89%) were admitted, 121 for AMI. Only five (< 1%) patients who would otherwise have been discharged were admitted because of elevated CK levels. Of the 343 discharges, 245 (71%) occurred after the physicians knew the CK results. It is concluded that emergency department physicians routinely make changes in their diagnostic and management decisions based on current information and as it becomes updated. This study also suggests that there appears to be a heavy reliance on a single CK assay, although the relative importance of this diagnostic test compared to other factors is not known. Further studies are necessary.

The effect of acute hypocapnia on middle cerebral artery transcranial Doppler velocity during orthotopic liver transplantation: changes at reperfusion.

This study examines the effects of acute hypocapnia, instituted prior to reperfusion of the graft liver, on the middle cerebral artery (MCA) Doppler blood flow velocity response to reperfusion during orthotopic liver transplantation in humans. Seventeen patients with chronic liver disease underwent continuous, noninvasive Doppler imaging of the MCA. Hyperventilation to an end-tidal Pco2 of 25 +/- 1 mm Hg was associated with a decrease in mean MCA flow velocity (FVm) from 51.6 +/- 5.7 to 37.0 +/- 3.3 cm/s (P < 0.05). After reperfusion, the Paco2 increased from 32 +/- 1 to 40 +/- 1 mm Hg (P < 0.05), mean arterial pressure (MAP) decreased from 76 +/- 3 to 60 +/- 2 mm Hg, and the FVm increased from 37.0 +/- 3.3 to 54.0 +/- 4.7 cm/s (P < 0.05). FVm increased postreperfusion despite prior hyperventilation, decreased MAP, and abrupt increases in central venous and pulmonary artery pressure, but FVm did not exceed the prereperfusion level. In 10 of the 17 patients, the baseline FVm versus Paco2 response slopes and Paco2 measured postreperfusion were used to predict the FVm response to Paco2 after reperfusion. The slopes were similar to those reported for anesthetized patients without liver disease. Predicted FVm exceeded measured FVm in 9 of the 10 patients. We conclude that mild hyperventilation prior to reperfusion of the graft liver prevents FVm increases above prereperfusion baseline level.

Intraoperative transesophageal echocardiography in orthotopic liver transplantation in a patient with hypertrophic cardiomyopathy.

With improvements in the surgical technique for orthotopic liver transplantation, patients with significant underlying systemic disease are considered candidates for transplantation, thus increasing the complexity of the medical management of these patients and necessitating additional monitoring in order to minimize the anesthetic risk. We describe the anesthetic management of orthotopic liver transplantation for a patient with severe hypertrophic cardiomyopathy and mitral insufficiency. In this case, transesophageal echocardiography proved useful in the management of the postreperfusion period of the surgical procedure.

Gastric intramural pH as indicator of early allograft viability in orthotopic liver transplantation.

The determination of the viability of OLT grafts has relied upon metabolic tests of the liver, which take several hours to evaluate and therefore are only conclusive in most patients well into the postoperative period. Earlier diagnosis of graft failure or nonfunction would allow intraoperative reassessment of surgical technique and, in the case of graft failure, earlier planning for retransplantation. Since gastrointestinal mucosal ischemia is one of the earliest manifestations of impaired core tissue in the critically ill, a tonometric nasogastric tube (Tonomitor) was used in our patients to measure intramucosal gastric pH (pHi) during the preanhepatic (stage I), anhepatic (stage II), and neohepatic (stage III) phases of OLT in 35 patients as an indicator of graft liver function and viability. Based on the results of the pHi measurement 30 min after reperfusion during stage III, patients were divided into 2 groups using a pHi of 7.30 as the dividing point. Patients with a pHi equal or higher than 7.30 were assigned to group 1 (n = 24) and patients with a pHi lower than 7.30 were assigned to group 2 (n = 11). The pHi in group 1 patients averaged 7.37 +/- 0.5 30 min after reperfusion and throughout surgery. The pHi in group 2 patients was lower than that of the group 1 patients 30 min after reperfusion, 7.23 +/- 0.04 (P < 0.001). The pHi in 10 group 2 patients returned to normal within 3 hr after reperfusion and the pHi values for these patients were not significantly different from those of group 1 at 3 hr after reperfusion. The pHi in 1 group 2 patient remained lower than 7.30 and never returned to normal; this patient underwent retransplantation the following day. Utilizing the tonometric nasogastric tube to sample intramucosal pH allowed early detection of graft function and intermittent trending of pHi in patients with questionable graft function during the operative period. It also provided a means of assessing graft function independent of enzymatic criteria, which provide little information in the early phase of transplantation.

Middle cerebral artery transcranial Doppler velocity monitoring during orthotopic liver transplantation: changes at reperfusion--a report of six cases.

STUDY OBJECTIVE: To determine the effect of reperfusion of the grafted liver on transcranial Doppler blood flow velocity in the middle cerebral artery in humans during orthotopic liver transplantation. DESIGN: Clinical study. SETTING: University hospital. PATIENTS: 6 patients scheduled for orthotopic liver transplantation. INTERVENTIONS: Middle cerebral artery blood flow velocity (MCAVm) was monitored continuously using a transcranial Doppler (TCD) probe. The TCD measurements were noninvasive. MEASUREMENTS AND MAIN RESULTS: The EME TC2000S TCD probe (Nicolet, Inc., Memphis, TN) was secured to the head using a strap providing continuous measurement of MCAVm. All other data were recorded by a patient monitoring system and a respiratory gas analyzer. Averaged MCAVm increased significantly in 5 of 6 patients (p < 0.001) when pre-reperfusion and post-reperfusion values were compared. Maximum post-reperfusion values for MCAVm, pulsatility index (PI), and systolic Doppler velocity (Vs) were greater than the corresponding immediate pre-reperfusion values (p < 0.05, p < 0.05, and p < 0.001, respectively). The increases in MCAVm cannot be explained on the basis of hypercarbia alone and were observed in the presence of systemic arterial hypotension and abrupt increases in central venous pressure, particularly at the time of graft reperfusion. CONCLUSIONS: MCAVm increased with reperfusion of the grafted liver. These data suggest that multiple factors--including hypercarbia, lactic acidosis, or multiple vasoactive substances released by the grafted liver--may contribute to the observed increases in MCAVm, Vs, and PI.

Spectral evidence for 2,2,3-trichloro-oxirane formation during microsomal trichloroethylene oxidation.

During aerobic incubation of trichloroethylene with rabbit liver microsomes and NADPH a difference absorption peak appears at 451-452 nm. Trichloroethylene does not form a ligand absorption spectrum with hepatic microsomes reduced by dithionite, or in anaerobic incubates in the presence of NADPH. Addition of trichloroethylene epoxide (2,2,3-trichloro-oxirane) to reduced suspensions of rabbit liver microsomes produces high difference absorption at 452 nm, the optical Ks being approximately 2 mM. Of all possible metabolites of trichloroethylene only trichloroethanol forms absorption in the vicinity of 480 nm, and the broad absorption band reveals relatively low absorption near 450 nm. Dichloroacetyl chloride is the main thermal rearrangement product of trichloroethylene epoxide, and also produces 452 nm absorption in reduced microsomes. However, the difference absorption is 5 times smaller than the absorption produced by the intermediate formed during incubation of trichloroethylene in metabolising liver microsomes. These observations include strong evidence for epoxide formation during microsomal oxidation of trichloroethylene. 14C-labelled trichloroethylene binds irreversibly to hepatic macromolecules in vivo and in vitro. Possible rearrangement pathways of 2,2,3-trichloro-oxirane and reactive intermediates are presented.

Irreversible binding of 3-14C-antipyrine to hepatic protein in vivo and in metabolizing liver microsomes.

After i.p. injection of 3-14C-antipyrine (10 micronmole = 1.9 mg with 10 micronCi per 10 g of body weight) to mice radioactivity was irreversibly bound to liver proteins. The irreversible binding reached maximal values of 0.15 nmole/mg protein in liver microsomes after 30-60 min. During 60 min incubation with liver microsomes of mice and rabbits (phenobarbital pretreated) and a NAKPH-regenerating system 3-14C-antipyrine was irreversibly bound to microsomal protein at a rate of 1.5 nmole/mg protein (mouse) and 3 nmole/mg protein (rabbit). In identical incubates with rabbit liver microsomes the 4-hydroxylation of antipyrine was 24 nmole/mg protein in 60 min and formaldehyde production from antipyrine 3 nmole/mg protein in 60 min. In incubates with rabbit liver microsomes the binding rate was 80-90% inhibited by 1mM metyrapone, SKF 525-A and trichloropropene epoxide respectively; 4-hydroxylation was 70-80% inhibited by the same substances. In the presence of 1mM GSH, cysteine or ethylene diamine binding was 30-40% inhibited, whereas 4-hydroxylation showed no inhibition.