Fluid resuscitation in acute medicine: what is the current situation?

The administration of intravenous fluids for resuscitation is the most common intervention in acute medicine. There is increasing evidence that the type of fluid may directly affect patient-centred outcomes. There is a lack of evidence that colloids confer clinical benefit over crystalloids and they may be associated with harm. Hydroxyethyl starch preparations are associated with increased mortality and use of renal replacement therapy in critically ill patients, particularly those with sepsis; albumin is associated with increased mortality in patients with severe traumatic brain injury. Crystalloids, such as saline or balanced salt solutions, are increasingly recommended as first-line resuscitation fluids for the majority of patients with hypovolaemia. There is emerging evidence that saline may be associated with adverse outcomes due to the development of hyperchloraemic metabolic acidosis, although the safety of balanced salt solutions has not been established. Fluid requirements vary over the course of critical illness. The excessive use of fluids during the resuscitative period is associated with increased cumulative fluid balance and adverse outcomes in critically ill patients. The selection of fluid depends on the clinical context in which it is administered and requires careful consideration of the dose and potential for toxicity. There is an urgent need to conduct further high-quality randomized controlled trials of currently available fluid therapy in patients with critical illness.

Vitamin D status and supplementation in adult patients receiving extracorporeal membrane oxygenation.

The prevalence of vitamin D deficiency in critical illness is known to be high and associated with adverse clinical outcomes. Patients receiving extracorporeal membrane oxygenation (ECMO) may be at increased risk of vitamin D deficiency due to high severity of acute illness. Challenges with drug dosing in ECMO patients are recognised due to increased volume of distribution and drug absorption to circuit components. To describe the prevalence of vitamin D deficiency in ECMO patients and the effect of intramuscular dosing of cholecalciferol on levels of vitamin D metabolites, and to compare these data with intensive care unit (ICU) patients not receiving ECMO, two prospective studies were performed sequentially: an observational study of 100 consecutive ICU patients and an interventional study assessing effects of intramuscular cholecalciferol in 50 ICU patients. The subgroup of patients who required ECMO support in each of these studies was analysed and compared to patients who did not receive ECMO. Twenty-four ECMO patients, 12 from the observational study and 12 from the interventional study (who received intramuscular cholecalciferol) were studied-21/24 (88%) ECMO patients were vitamin D deficient at baseline compared to 65/126 (52%) of non-ECMO patients (P=0.006). Of the 12 ECMO patients who received cholecalciferol, six patients (50%) achieved correction of deficiency compared to 36/38 (95%) non-ECMO patients (P=0.001). The prevalence of vitamin D deficiency is higher in ECMO patients compared to other critically ill adults. Correction of deficiency with single dose cholecalciferol is not reliable; higher or repeated doses should be considered to correct deficiency.

Rat hepatoproliferin revealed the status of a complete hepatomitogen in human hepatoma cells.

Hepatoproliferin (HPF), a liver regeneration factor isolated from rat hepatocytes, was assessed for its mitogenic status in the human hepatoma cell line PLC/PRF-5. HPF was able to enhance hepatoma cell growth on its own without the aid of the established complete mitogens EGF and TGF-alpha or the hepato-priming factor TNF-alpha. HPF therefore acted as a complete hepatomitogen and had no co-mitogenic properties since it did not augment proliferation when combined with EGF or TGF-alpha but showed only an additive effect in the presence of TGF-alpha. Rat HPF was phylogenetically unrestricted, because it was found active in human cells. When each of the established growth factors (GFs) was used alone, the hepatoma cells responded with the same kind of response profile, namely a bi-phasic bell-shaped dose-dependent response due to stimulation at low levels and inhibition at higher levels. However, hepatocyte growth factor (HGF) was an exception since it did not induce a growth response in hepatoma cells. On the contrary HPF, on its own, showed a progressive enhanced linear dose response at the levels used for the GFs (ie 1.0-15 ng/5 x 10(5) cells). The comparative potency (CP) (dpm x 10(3)/microg DNA/ng GF) of HPF (CP = 13) was in the same range as for the complete hepatomitogens EGF (CP = 12) and TGF-alpha (CP = 14), revealing that HPF has indeed the status of a complete mitogen.

Chronic granulocytic leukemia in a patient with a renal allograft.

A man received a cadaver renal allograft for end-stage renal failure. After 35 months of immunosuppressive therapy with azathioprine and prednisone, he developed septicemia and a high leukocyte count. In spite of successful treatment of the infection, the leukocyte count continued to rise and a diagnosis of Philadelphia chromosome positive chronic granulocytic leukemia was made. An increased incidence of malignant disease, especially lymphoreticular malignancy, is well described in immunosuppressed patients with allografts. However, the association of chronic granulocytic leukemia and immunosuppressive therapy previously has not been reported. An additional etiological factor in this patient may have been the extensive diagnostic radiological investigations undertaken in childhood. The recent addition of allopurinol to the immunosuppressive therapy has normalized the platelet and leukocyte counts, probably by potentiating mercaptopurine.

Prolongation of liver allograft survival by donor-specific soluble transplantation antigens and antigen-antibody complexes.

Soluble transplantation antigens were prepared from chacma baboon spleen cell membranes by a modified 3 M KCl technique. The extracts were soluble according to usually accepted criteria. Molecular weight was 37,700 daltons. Antigenicity was confirmed by inhibition of cytotoxicity of alloantibody. The antigens stimulated sensitized lymphocytes in culture but failed to stimulate unsensitized lymphocytes. Antigen-antibody complexes were assembled in vitro in the regions of equivalence and marked antigen excess. Administration of a single dose of soluble donor antigen at the time of orthotopic liver allotransplantation prolonged graft survival significantly. Concomitant administration of a polyspecific alloantibody, previously shown to prolong baboon liver allograft survival, abrogated the graft prolongation produced by the antigen or antibody given alone. When the administration of the soluble antigen was preceded by a dose of cyclophosphamide (20 mg/kg), graft prolongation was slightly curtailed. Antecedent administration of azathioprine and prednisolone for 3 days seemed to render the antigen immunogenic in that liver allograft rejection was accelerated. Antigen-antibody complexes at equivalence prolonged liver allograft survival beyond that seen with antigen alone, but complexes in marked antigen excess were immunogenic, inasmuch as graft survival was not prolonged and the histological features were those of accelerated rejection.

Suppressor mechanisms in neonatally acquired tolerance to a Gross virus-induced lymphoma in rats.

Tolerance to a highly immunogenic Gross virus-induced tumour in Wistar/Furth rats (C58NT)D was produced by neonatal infection of the rats with the virus. These rats failed to reject the tumours when challenged 8 weeks after virus inoculation and to mount the appropriate cell-mediated immune response to the tumour. The mechanisms involved were studied in vivo by adoptive transfers into sub-lethally irradiated rats of tumour cells mixed with spleen cells and/or sera from normal, tolerant, or tumour immune rats, and in vitro by a 51Cr release assay involving similar mixtures. The results indicate the presence of a suppression mechanism which is sensitive to irradiation and abolished by trypsinisation. Weak blocking factors can also be detected in serum. An interpretation in terms of the release of virion proteins from infected cells is proposed, although participation of suppressor lymphocytes has not been excluded.

Active enhancement in the primate by bone marrow I. Ia-like determinants on nucleated bone marrow cells.

This study investigates the possibility that the active enhancing properties of bone marrow (BM) cells may be related to Ia-like determinants on their surface membranes. Less chromium was released on a cell per cell basis from nucleated baboon BM cells used as targets in complement-dependent cytotoxicity than from labelled lymph node lymphocytes. On the other hand, BM cells stimulated allogeneic lymphocytes in culture more vigorously than lymph node lymphocytes. BM cells with lymphocyte-activating properties could be enriched by fractionation on a discontinous bovine serum albumin gradietnt. BM cells responded poorly to allogeneic cell stimulation in mixed culture. Platelet absorption studies of an alloantiserum supported the conclusion that nucleated BM cells, and particularly BM fractions collected from the less dense interfaces of a bovine serum albumin gradient, express relatively more lymphocyte-activating or Ia-like determinants than "serologically defined" determinants.

Nonspecific mixed lymphocyte culture inhibitory antibodies in sera of tolerant transplanted baboons conditioned with total lymphoid irradiation.

Pretransplant conditioning of baboons with total lymphoid irradiation allows long-term renal allograft acceptance in one third of the recipients. Brief additional immunosuppression was given to some animals, but always for less than 14 days after transplant. This enabled us to study mechanisms of graft tolerance in the absence of long-term, nonspecific drug immunosuppression. While 3 patterns of unresponsiveness were noted, this study concentrated on serum-mediated suppression. Eleven of 16 (69%) baboons destined to become tolerant to their grafts developed a nonspecific MLC inhibitory factor in their sera. In most animals it appeared within 3-5 weeks after transplantation and persisted over the period of study (91-793 days after Tx). The suppressor factor was absent in sera from 38 control animals and 8/9 rejectors. It was shown to be a low affinity IgG antibody that inhibited MLC by binding to stimulator cells, an effect that could be overcome by addition of rIL-2 to cultures. NK cell lysis, cell-mediated lympholysis, and polyclonal mitogenesis were unaffected. Antibody binding to purified baboon T cells could not be demonstrated, though binding to EBV-transformed B cells was readily shown. Our study shows that total lymphoid irradiation permits the generation of blocking antibodies directed against APCs as one mechanism of maintaining T cell unresponsiveness. These observations are consistent with the masking of ligands involved in antigen presentation or costimulation leading to a sustained state of autoenhancement.

Transplantation tolerance in primates following total lymphoid irradiation and allogeneic bone marrow injection. II. Renal allografts.

A modified regimen of fractionated total lymphoid irradiation and allogeneic bone marrow (BM) injection in chacma baboons produced transplantation tolerance for allografted kidneys from the BM donors, and substantial chimerism without evidence of graft-versus-host disease. Increasing the dose of nucleated BM cells injected 4-fold over that used in liver transplantation resulted consistently in normal graft function in the early weeks after transplantation. Bone marrow injection and challenge with renal allografts could be delayed for at least 3 weeks after completion of irradiation. If it can be shown that this period can be extended even further, the protocols will be relevant to the circumstances of clinical cadaveric renal transplantation.

Transplantation tolerance in primates after total lymphoid irradiation and allogeneic bone marrow injection. III. Lymphocyte responsiveness and suppressor cell activity.

After total lymphoid irradiation (TLI), allogeneic bone marrow (BM) injection, and organ transplantation in baboons, there is a prolonged period of reduced lymphocyte proliferative responsiveness to polyclonal mitogens and allogeneic lymphocytes. The effect observed is greater with the use of fractionated TLI than after single doses of irradiation. Suppressor cell activity can be demonstrated in vitro in most animals by inhibition of mixed lymphocyte reactivity (MLR) by mitomycin-treated recipient lymphocytes harvested after TLI, with or without allogeneic BM injection, and organ transplantation. Preliminary data suggest the presence of both donor-specific and nondonor-specific suppression, although other interpretations are possible, and suppressor phenomena may not be responsible for the transplantation tolerance observed.

Detergent solubilisation of baboon histocompatibility antigens and their use in prolonging liver allograft survival.

Histocompatibility antigens have been solubilised from baboon spleen cell membranes by brief exposure to sodium deoxycholate (DOC). Preparations contained a high molecular weight species (DOCH-Ag) excluded by Sephadex G-200, and a low molecular weight species (DOCL-Ag) which eluted in the included fraction (molecular weight 46,000). The low molecular weight antigen was stable and was not sedimented by high speed centrifugation even after dialysis against a low molar salt solution. It elicited a delayed-type hypersensitivity response in sensitised baboons but not in normal animals. DOCL-Ag cultured in vitro with sensitised allogeneic lymphocytes produced a 1.3- to 24.9-fold stimulation, whereas when cultured with normal lymphocytes the maximum stimulation index was 2. Intravenous administration of donor DOCL-Ag (2 mg/kg) at the time of transplantation and without additional immunosuppression significantly prolonged the mean survival time of baboon liver allografts. The same treatment with donor DOCH-Ag did not prolong graft survival.

Immunological compatibility between the chacma baboon and man.

Predictions of an increasing shortage of donor organs for the future has led to a resurgence of interest in xenotransplantation. We have methodically assessed the immunological compatibility of humans against the chacma baboon with a view to narrowing the gap of concordance by careful immunological screening. The necessity of major blood group compatibility in xenotransplantation is now established. While no group O universal donor exists in the baboon, groups A (45%), B (15%), and AB (40%) are well represented. Baboon histocompatibility antigens could not be precisely defined using human antisera. This does not necessarily imply lack of homology between the species, as we have shown specific crossreactivity of numerous antihuman monoclonal antibodies with baboon leukocytes. Normal humans do not exhibit preformed agglutinins to erythrocytes of the chacma baboon (Papio ursinus orientalis)) but cytotoxic antibodies are occasionally found. Sera from allosensitized patients may contain crossreacting hemagglutinins, leukoagglutinins and complement-dependent cytotoxic antibodies. Binding of human immunoglobulin-G and -M to baboon targets was demonstrated by flow cytometry. Negative crossmatch combinations for antibodies of the IgG subclass were easily found, but IgM antibodies from allosensitized patients were polyspecific in their action. In vitro assessment of lymphocyte mediated cytotoxicity showed that preformed cellular immunity between the species was rare. The response of human lymphocytes to xenoantigen stimulation in mixed lymphocyte cultures showed a normal distribution, permitting the selection of low-responding combinations. Screening for viruses, especially HTLV-1 and Coxsackie-BL34, is important. These findings demonstrate a closer degree of concordance than has previously been suspected.

Renal allograft survival in the baboon using a pretreatment protocol with cyclosporine.

Cyclosporine extends kidney allograft survival in the chacma baboon, and this study explores various administration protocols to generate optimal serum concentrations of the drug, assessed by radioimmunoassay and by inhibition of lymphocyte transformation by phytohemagglutinin and allogeneic lymphocytes in culture. Serum levels commensurate with concentrations that have been shown to be immunosuppressive in humans (150-400 ng/ml) are reached after 14 days of pretreatment with 10 mg cyclosporine/kg, and after 7 days with 20 and 30 mg cyclosporine/kg. The 10-mg dose prolongs median graft survival from 11 to 21 days, which is the same as that obtained with 20 mg/kg administered after transplantation. Further increases in the pretreatment dose to 20 or 30 mg/kg result in survivals of 27 and 31 days, respectively. All the animals died from rejection during therapy and the T-cell-binding avidity, and absorptive or degradative processes may necessitate doses far in excess of those currently used in transplantation.

Tolerance in baboon kidney transplantation with total lymphoid irradiation (TLI) and anti-CD3/CD4-idarubicin conjugates.

BACKGROUND: We previously reported the induction of transplantation tolerance by a modified wide field method of pretransplant total lymphoid irradiation (TLI), cumulative dose 800 cGy, given as 80 or 100 cGy fractions twice/week, in approximately one-third of chacma baboons receiving liver or kidney allografts (1-4) and in vervet monkeys receiving baboon kidney xenografts (5). In this study, the effects of the administration of brief courses of anti-CD3 or CD4-Idarubicin conjugates on the frequency and predictability of tolerance induction by TLI were examined. METHODS: TLI was administered pretransplant in doses of 800, 600, or 400 cGy. The conjugates were administered either after transplantation in doses of 0.25 mg/kg body weight, 3 times/week for 2 weeks, or as a single dose of 1.0 mg/kg body weight 24 hr before transplantation. RESULTS: Operational tolerance, defined as normal graft function >1 year after transplantation, was obtained in one-half of six baboons receiving the single dose of 1 mg/kg of Idarubicin conjugate pretransplant after 800 cGy of TLI and also in one of four baboons treated with 400 cGy of TLI and a single dose of anti-CD3 conjugate before transplantation. By contrast, administration of the conjugated antibodies 3 times/week for 2 weeks after transplantation prevented tolerance induction in all animals, providing further evidence for the involvement of active mechanisms, capable of inhibition by immunosuppressive agents, in tolerance induction with TLI, and of relevance to our reported clinical experience with TLI (6). CONCLUSIONS: These promising findings invite further studies with a larger number of animals and additional brief regimens of irradiation and antibody dosages and specificities.

Definition and characterization of chicken Gal alpha(1,3)Gal antibodies.

BACKGROUND: The Gal alpha(1,3)Gal epitope is of interest as, in pig-to-primate xenotransplantation, it is the major target of naturally occurring human IgM and IgG antibodies, leading to hyperacute rejection. Human and Old World monkeys make anti-Gal alpha(1,3)Gal antibodies as they lack a functional gene and do not express Gal alpha(1,3)Gal. Interestingly, the cultured fibroblasts of some other species, such as chickens, have been reported also not to express Gal alpha(1,3)Gal--if this is true for other tissues, and chickens do not express Gal alpha(1,3)Gal antigen, then they would have anti-Gal antibodies--which could have diagnostic and therapeutic value, particularly as chicken antibodies do not fix mammalian complement. METHODS: Standard serological methods were used to characterize the antibodies. Several baboons received pig kidney xenografts that had been perfused with hyperimmune chicken anti-Gal antibodies. RESULTS AND CONCLUSIONS: We now demonstrate that chickens do not express Gal alpha(1,3)Gal on their red cells, leukocytes, or tissues, and that their serum contains large amounts of anti-Gal alpha(1,3)Gal antibodies. In addition, chickens could be immunized to produce high-titer, high-avidity antibodies (9.5x10(9) M(-1))--an avidity considerably greater than that of the Gal alpha(1,3)Gal binding lectin IB4 (2.9x10(8) M(-1)) or Gal antibodies in human serum (2.2x10(5) M(-1)). Chicken antibodies, obtained from both normal and immunized chickens, could block the in vitro cytolysis of pig endothelial cells or lymphocytes by human or baboon antibodies. However, such antibodies tested in vivo in pig-to-baboon xenotransplantation failed to block hyperacute rejection and, indeed, may have accelerated this.

A prospective comparison of a percutaneous tracheostomy technique with standard surgical tracheostomy.

A prospective non-randomized study was undertaken to compare, in intensive care patients, the safety and utility of a percutaneous tracheostomy technique performed at the bedside with a surgical tracheostomy technique performed in the operating room. During a 21 month period, 153 percutaneous tracheostomies were performed. Complications occurred in 6 patients (3.9%). Secondary wound haemorrhage occurred in 4 patients and primary wound haemorrhage occurred in 2 patients. During the same period, 74 surgical tracheostomies were performed. Complications occurred in 14 patients (18.9%) which included tracheal obstruction, haemorrhage, pneumothorax, wound infection, wound breakdown and one death. In comparison to surgical tracheostomies, percutaneous tracheostomies were rapidly and easily performed at the bedside and were associated with significantly fewer complications.

The P50 is reduced in critically ill patients.

A prospective study was designed to measure the P50 in 20 critically ill patients, and compare it with the P50 measured in 20 normal individuals. Arterial blood gases, lactate, haemoglobin (Hb) and phosphate (PO4) levels were also measured and compared with the P50 in the critically ill patients. The mean P50 of the critically ill patients was 24.5 mmHg (SD +/- 2.9) and was significantly lower than the mean P50 of 26.2 (SD +/- 2.2) in the normal individuals (p less than 0.05). In the critically ill patients, strong correlations were observed between the P50 and the arterial pH and base excess (BE) levels, with coefficients of 0.79 and 0.69 respectively whereas correlations between the P50 and arterial oxygen tension (PO2), carbon dioxide tension (PCO2), lactate, Hb and PO4 levels were poor, with correlations of 0.001, 0.008, 0.07, 0.13 respectively. It is concluded that the P50 is commonly reduced in critically ill patients, and has a strong correlation with arterial pH and BE.

Epinephrine, norepinephrine and dopamine infusions decrease propofol concentrations during continuous propofol infusion in an ovine model.

OBJECTIVE: To determine the effects of exogenous ramped infusions of epinephrine, norepinephrine and dopamine on arterial and effluent brain blood concentrations of propofol under steady state intravenous anesthesia. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SUBJECTS: Five adult female merino sheep. INTERVENTIONS: Induction (5 mg/kg) and continuous infusion of propofol (15 mg/min) with controlled mechanical ventilation to maintain PaCO2 40 mmHg. After 1 h of continuous anesthesia, each animal randomly received ramped infusions of epinephrine, norepinephrine (10, 20, 40 microg/min) and dopamine (10, 20, 40 microg x kg x min) in 3 x 5 min intervals followed by a 30-min washout period. MEASUREMENTS: Arterial and sagittal sinus whole blood for determination of propofol concentrations using high-pressure liquid chromatography. Cardiac output using a thermodilution method. Level of consciousness using an observational scale. MAIN RESULTS: All three drugs significantly and transiently increased cardiac output in a dose-dependent fashion to a maximum of 146-169% of baseline. Baseline arterial and sagittal sinus propofol concentrations were not statistically different prior to catecholamine infusions. All three drugs significantly reduced mean arterial propofol concentrations (95 % CI, p < 0.05): epinephrine to 41.8% of baseline (11.4-72), norepinephrine to 63 % (27-99) and dopamine to 52.9 % (18.5-87.3). There were parallel reductions of concentrations in sagittal sinus blood leaving the brain. The lowest blood concentrations were associated with emergence from anesthesia. Arterial concentrations were inversely related to the simultaneously determined cardiac output (r2 = 0.74, p < 0.0001). Comparison of the data with the predictions of a previously developed recirculatory model of propofol disposition in sheep showed the data were consistent with a mechanism based on increased first pass dilution and clearance of propofol secondary to the increased cardiac output. CONCLUSIONS: Catecholamines produced circulatory changes that reversed propofol anesthesia. These observations have potential clinical implications for the use of propofol in hyperdynamic circulatory conditions, either induced by exogenous catecholamine infusions or pathological states.

Surgical biliary drainage in primary sclerosing cholangitis. The role of the Hepp-Couinaud approach.

OBJECTIVE: To assess the value of bilioenteric bypass, particularly by the Hepp-Couinaud technique, in patients with primary sclerosing cholangitis and dominant strictures in the extrahepatic biliary tract. DESIGN: Prospective study and analysis of a personal series. SETTING: Academic hospital. PATIENTS: Twenty-four of 69 patients with primary sclerosing cholangitis were selected for operative intervention. In all patients both intrahepatic and extrahepatic ducts had multiple strictures. In 22 patients the major proximal extrahepatic site of stricturing was at the confluence of the right, left, and common hepatic ducts. All patients were jaundiced at some stage before operation and 19 had persistent jaundice. Five patients were cirrhotic at presentation. INTERVENTIONS: Twenty Hepp procedures were performed in 19 patients, involving a side-to-side anastomosis 2.5 to 3.5 cm wide between a Roux-en-Y loop and the right and left hepatic ducts at their confluence. No transanastomotic stents were used. MAIN OUTCOME MEASURES: Survival and relief of jaundice. RESULTS: Follow-up ranged from 20 months to 11 years; median, 6.5 years. At the time of this report, three of the five cirrhotic patients had died, and the two surviving patients had progressive liver disease. In the 16 noncirrhotic patients who underwent bypass, actuarial survival was 100% up to 8 years. Four of these patients were mildly icteric but stable 2.3 and 7 years after bypass. Eleven patients remained free of jaundice for 2.3 to 9 years after bypass. One patient died of hepatic failure 8.5 years after bypass. CONCLUSIONS: In noncirrhotic patients with primary sclerosing cholangitis and dominant extrahepatic biliary strictures, bilioenteric bypass with the Hepp technique and without transanastomotic stenting relieves jaundice durably, safely, and effectively and is associated with freedom from recurrent bouts of cholangitis. This may attenuate or halt the development of secondary biliary cirrhosis. Patients with cirrhosis derive minimal benefit from biliary bypass and should undergo liver transplantation.

Diagnosis and management of lymphoceles after renal transplantation.

Eight lymphoceles were encountered in 232 renal transplant procedures. The patients presented with either a palpable pelvic mass, ipsilateral leg pain and edema, or deteriorating renal function. Two patients were asymptomatic. The diagnosis is readily established by a combination of intravenous urography, ultrasound, and aspiration although ultrasound is the most useful method for the diagnosis and follow-up of these lesions. A functioning arteriovenous shunt in the leg on the side of the transplant may predispose to lymphocele formation. Most lymphoceles may be managed conservatively initially. However, if surgery is required, open drainage and packing would appear to be the most reliable procedure.