Search PubMed⌕ Search

Biomedical subjects

R Bellomo

Publications and source records attributed to R Bellomo.

At least 55 records · Page 3Linked to original sources
PubMed2004

A technique for the determination of systolic pressure variation in the systemic and pulmonary arterial circulations.

INTRODUCTION: Systolic pressure variation has previously been used to detect the presence of hypovolemia in mechanically ventilated patients but remains difficult to measure. METHODS: We describe the application of a commercially available physiological data acquisition system, PowerLab (ADI Instruments Castle Hill, NSW, Australia), to acquire and graphically display simultaneous recordings of the airway pressure, as well as systemic and pulmonary arterial pressures. The technique involves the use of standard pressure transducers to record each pressure reading and has been used to obtain measurements in patients undergoing elective cardiac surgery. RESULTS: The technique permits calculation of systolic pressure variation of both the systemic and pulmonary arterial pressure waveforms. In addition it is possible to estimate plateau airway pressure and perform expiratory hold maneuvers to determine its constitutive components delta-up and delta-down. Waveforms can be exported into MS-windows Paint and saved in JPEG or bitmap format. CONCLUSIONS: The technique described will permit future analysis of the factors affecting the systolic pressure variation for the systemic and pulmonary arterial pressure waveforms in the clinical context.

Journal Article↗
PubMed2004

Failure of continuous cardiac output measurement using the PiCCO Device during induced hypothermia: a case report.

Continuous cardiac output measurement using pulse contour analysis is a technique gaining widespread acceptance in intensive care units. We report a case where a pulse contour analysis computer (PiCCO, Pulsion Medical Systems, Munich, Germany) failed to calibrate in a patient who was undergoing induced hypothermia for anoxic brain injury. Despite several attempts to calibrate, using increased cold injectate volumes and exchanging both the PiCCO device and the arterial catheter, we were unable to correct the calibration problem and hence were unable to monitor cardiac output. Subsequent rewarming of the patient allowed calibration of the arterial waveform and continuous cardiac output measurement. We were unable to find any previous reports of this problem using a PiCCO device, although similar problems with thermodilution cardiac output estimation using the pulmonary artery catheter during hypothermic cardiopulmonary bypass have been documented.

Journal Article↗
PubMed2003

Artificial organ treatment for multiple organ failure, acute renal failure, and sepsis: recent new trends.

Sepsis remains the major cause of mortality worldwide, claiming millions of lives each year. The past decade has seen major advances in the understanding of the biological mechanisms involved in this complex process. Unfortunately, no definitive therapy yet exists that can successfully treat sepsis and its complications. At variance with targeting single mediators, therapeutic intervention aimed at the nonselective removal of pro- and anti-inflammatory mediators seems a rational concept and a possible key to successful extracorporeal therapies. A further advantage may lie in the continuous nature of such therapy. With such continuous therapy, sequentially appearing peaks of systemic mediator overflow may be attenuated and persistently high plasma levels reduced. This theoretical framework is proposed as the underlying biological rationale for a series of innovative modalities in sepsis. In this editorial, we will review recent animal and human trials that lend support to this concept. We will also review the importance of treatment dose during continuous renal replacement therapy as a major factor affecting survival in critically ill patients with acute renal failure. Additionally, we will review novel information related to other blood purification techniques using large pore membranes or plasma filtration with adsorbent perfusion. Although these approaches are still in the early stages of clinical testing, they are conceptually promising and might represent an important advance.

Acute Kidney Injury↗
PubMed2003

Defining death in non-heart beating organ donors.

Protocols for retrieving vital organs in consenting patients in cardiovascular arrest (non-heart beating donors, NHBD) rest on the assumptions that irreversible asystole a) identifies the instant of biological death, and b) is clinically assessable at the time when retrieval of vital organs is possible. Unfortunately both assumptions are flawed. We argue that traditional life/death definitions could be actually inadequate to represent the reality of dying under intensive support, and we suggest redefining NHBD protocols on moral, social, and anthropological criteria, admitting that irreversible (however defined) asystole can only equate a clinically determinable point of no return in the process of dying, where organ retrieval can be morally and socially accepted in previously consenting patients.

Attitude to Death↗
PubMed2003

Cryoprecipitate for the correction of coagulopathy associated with liver disease.

In patients with liver disease at risk of pulmonary oedema, cryoprecipitate (small volume) might be a viable alternative to fresh frozen plasma (FFP, large volume) in the correction of coagulopathy. However, the efficacy of cryoprecipitate in these patients has not been tested. We evaluated the role of cryoprecipitate in the correction of the coagulopathy of liver disease. To establish initial evidence of efficacy, six consecutive patients with hepatic failure and coagulopathy received five units of cryoprecipitate. Then, using a crossover design, 11 consecutive patients were randomized to receive either four units of FFP or five units of cryoprecipitate. Pre and post infusion International Normalized Ratio (INR), activated Partial Thromboplastin Time (aPTT), fibrinogen D-dimers, Factors V and IX, and reptilase time were measured. In the first six patients, cryoprecipitate improved the INR, aPTT and fibrinogen concentration (P = 0.03). In the crossover study, FFP administration produced a greater improvement in INR (P = 0.007) and aPTT (P = 0.005) than cryoprecipitate. However, there were no differences in any of the other measured variables. One patient developed acute pulmonary oedema while receiving FFP. Cryoprecipitate improves the coagulopathy of liver disease. Four units of FFP are more efficacious than five units of cryoprecipitate. Cryoprecipitate may have a role in correction of the coagulopathy associated with liver disease where concerns about pulmonary oedema exist.

Adult↗
PubMed2003

Impact of continuous veno-venous hemofiltration on acid-base balance.

BACKGROUND: Continuous veno-venous hemofiltration (CVVH) appears to have a significant and variable impact on acid-base balance. However, the pathogenesis of these acid-base effects remains poorly understood. The aim of this study was to understand the nature of acid-base changes in critically ill patients with acute renal failure during continuous veno-venous hemofiltration by applying quantitative methods of biophysical analysis (Stewart-Figge methodology). METHODS: We studied forty patients with ARF receiving CVVH in the intensive care unit. We retrieved the biochemical data from computerized records and conducted quantitative biophysical analysis. We measured serum Na+, K+, Mg2+, Cl-, HCO3-, phosphate, ionized Ca2+, albumin, lactate and arterial blood gases and calculated the following Stewart-Figge variables: Strong Ion Difference apparent (SIDa), Strong Ion Difference Effective (SIDe) and Strong Ion Gap (SIG). RESULTS: Before treatment, patients had mild acidemia (pH: 7.31) secondary to metabolic acidosis (bicarbonate: 19.8 mmol/L and base excess: -5.9 mEq/L). This acidosis was due to increased unmeasured anions (SIG: 12.3 mEq/L), hyperphosphatemia (1.86 mmol/L) and hyperlactatemia (2.08 mmol/L). It was attenuated by the alkalinizing effect of hypoalbuminemia (22.5 g/L). After commencing CVVH, the acidemia was corrected within 24 hours (pH 7.31 vs 7.41, p<0.0001). This correction was associated with a decreased strong ion gap (SIG) (12.3 vs. 8.8 mEq/L, p<0.0001), phosphate concentration (1.86 vs. 1.49 mmol/L, p<0.0001) and serum chloride concentration (102 vs. 98.5 mmol/L, p<0.0001). After 3 days of CVVH, however, patients developed alkalemia (pH: 7.46) secondary to metabolic alkalosis (bicarbonate: 29.8 mmol/L, base excess: 6.7 mEq/L). This alkalemia appeared secondary to a further decrease in SIG to 6.7 mEq/L (p<0.0001) and a further decrease in serum phosphate to 0.77 mmol/L (p<0.0001) in the setting of persistent hypoalbuminemia (21.0 g/L; p=0.56). CONCLUSIONS: CVVH corrects metabolic acidosis in acute renal failure patients through its effect on unmeasured anions, phosphate and chloride. Such correction coupled with the effect of hypoalbuminemia, results in the development of a metabolic alkalosis after 72 hours of treatment.

Acid-Base Equilibrium↗
PubMed2003

Continuous renal replacement therapy: does technique influence electrolyte and bicarbonate control?

BACKGROUND AND OBJECTIVES: Different techniques of continuous renal replacement therapy (CRRT) might have different effects on electrolyte and acid-base control. The aim of this study was to determine whether continuous veno-venous hemodiafiltration (CVVHDF) or continuous veno-venous hemofiltration (CVVH) achieve better control of serum sodium, potassium and bicarbonate concentrations. DESIGN: Retrospective controlled study. SETTING: Two tertiary intensive care units. PATIENTS: Critically ill patients with acute renal failure (ARF) treated with CVVHDF (n=49) or CVVH (n=50). INTERVENTIONS: Retrieval of daily morning sodium and potassium values and arterial bicarbonate levels from computerized biochemical records before and after the initiation of CRRT for up to 2 weeks of treatment. Statistical comparison of findings. MEASUREMENTS AND RESULTS: Before treatment, abnormal (high or low) values were frequently observed for sodium (65.1% for CVVHDF vs. 80.0% for CVVH; NS), potassium (45.9% vs. 34.0%; NS), and bicarbonate (73.3% vs. 68.0%; NS). After treatment, however, CVVHDF was more likely to achieve serum sodium concentrations within the normal range (74.1% vs. 62.9%; p=0.0026). Both treatments decreased the mean serum potassium concentration over the first 48 h (p=0.0059 and p<0.0001, respectively), but there was no difference in terms of the normalization of serum potassium concentration during the entire treatment period (88.3% vs. 90.5%; NS). Both treatments increased the mean arterial bicarbonate concentration over the first 48 hours (p=0.011 and p<0.0001, respectively). However, CVVH was associated with a lower incidence of metabolic acidosis (13.8% for CVVH vs. 34.5% for CVVHDF; p<0.0001) and a higher incidence of metabolic alkalosis (38.9% vs. 1.1%; p<0.0001) during the entire treatment period. CONCLUSIONS: CRRT strategies based on different techniques have a significantly different impact on sodium and bicarbonate control.

Acute Kidney Injury↗
PubMed2003

The acid-base effects of continuous hemofiltration with lactate or bicarbonate buffered replacement fluids.

OBJECTIVE: To evaluate, quantify and compare the effects of continuous veno-venous hemofiltration (CVVH) with lactate or bicarbonate-buffered replacement fluids on acid-base balance. DESIGN: Randomized double crossover study. SETTING: Intensive Care Unit of Tertiary Medical Center. PARTICIPANTS: Eight patients with severe acute renal failure. INTERVENTIONS: Random allocation to either 2 hours of isovolemic lactate-buffered (treatment A) CVVH or 2 hours of bicarbonate-buffered (treatment B) CVVH with cross over and with same procedure repeated the following day (double cross over). MEASUREMENTS AND RESULTS: Timed collections of arterial blood and ultrafiltrate (UF), measurement of blood and UF gases and lactate concentrations and calculation of buffer-base mass balance. At baseline, both groups of patients had a similar, slight metabolic alkalosis (pH: 7.45 vs. 7.45; BE 3.9 mEq/L for treatment A and 4.0 for treatment B) and a serum bicarbonate of 28.1 mmol/L for treatment A vs. 28.3 mmol/L for treatment B; all NS. This alkalosis was present despite slight hyperlactatemia in both groups (A: 2.4 mmol/L vs. B 2.8 mmol/; NS). Within 60 minutes of treatment, however, treatment A led to a significantly higher lactate concentration (3.9 vs 2.5 mmol/L; p = 0.0011), a significantly lower BE (2.3 vs 4.1 mEq/L; p = 0.0019) and a significantly lower bicarbonate concentration (26.7 vs. 28.3 mmol/L; p = 0.0038) in the presence of an unchanged PaCO2. These differences persisted during the study period. The UF of patients receiving treatment A contained more lactate (10.2 vs 2.9 mmol/L; p < 0.0001) and less bicarbonate (25.6 vs. 30.8 mmol/L; p < 0.0001) than treatment B resulting in a mean buffer-base balance of +20.4 mEq/h compared to -2.6 mEq/h for treatment B; p < 0.0001). CONCLUSIONS: CVVH with lactate-buffered replacement fluids induces iatrogenic hyperlactatemia. Such hyperlactatemia is associated with an acidifying effect despite a positive buffer-base balance.

Acid-Base Equilibrium↗
PubMed2003

Beta2-microglobulin clearance with super high flux hemodialysis: an ex vivo study.

BACKGROUND: Beta2m accumulation induces disease in patients with end-stage renal failure (ESRF). Thus, its removal from patients with ESRF appears desirable. Current dialysis technology, however, has limited effectiveness. AIMS: To measure beta2m clearance with a novel super high flux membrane. DESIGN: Ex vivo experimental study. SETTING: Intensive Care Laboratory of Tertiary institution. SUBJECTS: Six volunteers. MEASUREMENTS AND RESULTS: At a blood flow of 300 ml/min, the clearance of beta2-MG increased from 113.5 +/- 38.5 ml/min with a dialysate flow rate of 200 ml/min to 184.8 +/- 61.1 ml/min with a flow rate of 300 ml/min and 195.0 +/- 60.0 ml/min with a 500 ml/min flow rate. The clearance of albumin was 4.5 ml/min with a dialysate flow rate of 200 ml/min, 5.2 ml/min for a flow rate of 300 ml/min and 5.8 ml/min for a flow rate of 500 ml/min. CONCLUSIONS: High levels of beta2m clearance can be achieved with a super high flux membrane while albumin losses remain limited.

Confidence Intervals↗
PubMed2003

Hemofiltration during cardiopulmonary bypass for high risk adult cardiac surgery.

AIMS: The role of hemofiltration (HF) during cardiopulmonary bypass (CPB) in adult cardiac surgery is controversial. It may be beneficial during prolonged CPB in high-risk surgery. Accordingly, we sought to compare two groups of patients undergoing high-risk cardiac surgery with or without HF. METHODS: One hundred and eighteen patients who underwent complex cardiac surgical procedures during a 12-month period were divided into two groups. Group I (n=61) comprised patients who were treated with hemofiltration during CPB. Group II (n=57) were not filtered. Estimated risk of death, standard demographic, clinical and surgical features were obtained and predetermined outcomes were studied. Statistical comparisons were made. RESULTS: Age, procedure times and mortality rates were similar in both groups. The mean volume of fluid removed in group I was 3.4 L. The preoperative mean Parsonnet score was 24.8 in group I and 22.5 in group II (ns). Postoperative serum hemoglobin, hematocrit, platelet, and albumin levels were all significantly higher in group I patients (p=0.0015) indicating hemoconcentration. Post-operative chest drainage showed a trend toward decreased post-operative bleeding in group I (p=0.065). Postoperative pleural effusions requiring chest tube drainage were significantly less in group I (9.8% vs. 29.8% 6; p = 0.0062). The incidence of lung infection was also decreased from 26.3% to 13.1% (p=0.05). Operative mortality was similar in both groups (11.4% in group 1, 10.5% in group II, ns). CONCLUSION: Hemofiltration during CPB attenuates postoperative anemia, thrombocytopenia and hypoalbuminemia, may reduce post-operative bleeding and appears to decrease post-operative pulmonary complications.

Aged↗
PubMed2003

Caspase-3 and -8 activation and cytokine removal with a novel cellulose triacetate super-permeable membrane in an in vitro sepsis model.

Pro-apoptotic molecules are generated during sepsis which may be responsible for alteration of organ function in sepsis. Removal of systemic apoptotic activity may affect recovery from sepsis. Current high flux membranes might not be sufficiently permeable to eliminate pro-apoptotic factors. We evaluated the elimination of pro-apoptotic factors induced by LPS in human whole blood by a super-permeable cellulose triacetate membrane (SUREFLUX FH 150, Nipro, Osaka, Japan) in comparison to a standard high flux cellulose triacetate membrane (UT 700, Nipro, Osaka, Japan) and a polyethersulfone plasmafilter (Bellco, Mirandola Italy) in an in vitro blood circulation. We spiked human whole blood with lipopolysaccharide from Escherichia coli (Serotype 026-86, 10 mg/ml), incubated it for 3 hours to allow cytokine generation and recirculated it at 300 ml/min for 3 hours. The UF line was first returned to the blood module at 10 min. After this, the UF was drained from 10 to 60 min at a rate of 1000 ml/h. Zero balance was obtained by re-infusion of bicarbonate buffered hemofiltration fluid. Apoptosis was assessed on U937 monocytes (incubated with plasma or ultrafiltrate) by fluorescence microscopy dyes (Hoechst 33342, propidium iodide) and annexin V flow cytometry. Caspase-3 and Caspase-8 activity was assessed on the recirculated blood monocytes by spectrophotometric methods. IL-2, IL-10 and TNFalpha were determined by commercially available ELISAs. Sieving coefficients and clearances were determined for the different cytokines. Caspase-3 and Caspase-8 were activated by LPS and remained either stable or increased during in vitro circulation. Apoptosis activity of U937 cells, when incubated with the ultrafiltrate, increased in parallel with arterial plasma values (for Uf: UT700 = 23.1%; Sureflux FH150 = 42.5%). However, by 60 min the apoptotic activity recorded with the ultrafiltrate was reduced to the levels of arterial plasma (for Uf: UT700 = 19.8%; Sureflux FH150 = 11.2%). Sieving coefficients in the super-permeable membrane were significantly higher for all measured cytokines in comparison to the standard high flux membrane (e.g. TNFalpha 0.72 vs 0.03 p < 0.001) and close to the values observed for the plasmafiltration membrane. Nevertheless protein losses measured by albumin leakage were much lower with the Sureflux filter in comparison to the plasmafilter. In conclusion, pro-apoptotic factors can be eliminated by dialytic membranes with the removal rate maximized by using super high flux dialysers which may represent a compromise between hemofiltration and plasmafiltration membranes.

Apoptosis↗
PubMed2003

Platelet loss across the hemofilter during continuous hemofiltration.

BACKGROUND: Thrombocytopenia is a common finding in patients in the intensive care unit receiving continuous renal replacement therapy (CRRT). It is unknown if the hemofilter itself contributes to the platelet loss. OBJECTIVE: To measure the direct effect of the hemofilter on platelet counts during CRRT. DESIGN: Prospective, observational study. SETTING: Intensive care unit of a University hospital. PATIENTS: Critically ill patients with acute renal failure receiving CRRT. METHODS: Two samples of blood were drawn simultaneously, pre-filter and post-filter, and analyzed for platelet count. A correction factor was applied to the post-filter platelet count to adjust for the hemoconcentrating effect of net ultrafiltration. RESULTS: Forty-eight sets of paired data from 22 patients were studied. There was a small but significant decrease in mean platelet count across the hemofilter. The mean platelet count drop was 2.32 x 10(9)/L (s.e. 1.06, p = 0.0487, 95% CI (0.01, 4.62)). Blood flow was strongly related to degree of platelet loss, with a decreased loss of 0.07 x 10(9)/L for every ml/min increase in blood flow (p = 0.015). There was no overall decrease in concurrently measured red cell counts across the hemofilter. However, there was a machine-specific affect on red cell loss (p < 0.0001). The total calculated daily platelet loss across the filter was 625 x 10(9) cells. CONCLUSION: The hemofilter may contribute to the thrombocytopenia seen during CRRT, by means of either destruction or retention of platelets during passage. This affect appears attenuated by higher blood flows. This information is useful in the assessment of a low platelet count in patients receiving CRRT.

Acute Kidney Injury↗
PubMed2003

Extracorporeal treatments in sepsis: are there new perspectives?

Sepsis continues to provide a major challenge to clinicians. Despite vast advancements achieved in the understanding of its pathways and mechanisms, the incidence of sepsis is increasing and the mortality and morbidity rates remain high, generating a considerable burden to health budgets worldwide. Unfortunately, no definitive therapy yet exists that can successfully treat sepsis and its complications. At variance with targeting single mediators, therapeutic intervention aimed at the non-selective removal of pro- and anti-inflammatory mediators seems a rational concept and a possible key to successful extra-corporeal therapies. A further advantage may lie in the continuous nature of such therapy. With such continuous therapy, sequentially appearing peaks of systemic mediator overflow may be attenuated and persistently high plasma levels reduced. This theoretical framework is proposed as the underlying biological rationale for a series of innovative modalities in sepsis. In this editorial, we will review recent animal and human trials which lend support to this concept. We will also review the importance of treatment dose during continuous renal replacement therapy as a major factor affecting survival in critically ill patients with acute renal failure. We will also review novel information related to other blood purification techniques using largo pore membranes or plasma filtration with adsorbent perfusion. Although these approaches are still in the early stages of clinical testing, they are conceptually promising and might represent an important advance.

Acute Kidney Injury↗
PubMed2002

Super high flux hemofiltration: a new technique for cytokine removal.

OBJECTIVE: To test whether hemofiltration using a hemofilter with large pores (super high flux hemofiltration) achieves effective cytokine removal. DESIGN: : Ex vivo study. SETTING: Laboratory of an intensive care unit in a tertiary hospital. PATIENTS AND PARTICIPANTS: Five healthy volunteers. INTERVENTIONS: Blood was spiked with 1 mg of endotoxin and then circulated through a closed hemofiltration circuit with a large pore polyamide super high flux hemofilter (nominal cut-off point: 100 kDa). Hemofiltration was conducted at 1 l/h or 6 l/h of ultrafiltrate flow. Samples were taken from the arterial, venous and ultrafiltration sampling ports. MEASUREMENTS AND RESULTS: Sieving coefficients (SC) above 0.6 were achieved for interleukin (IL)-1beta, IL-6 and IL-10 and SCs above 0.3 were achieved for IL-8 and TNF-alpha at 1 l/h. SCs of all cytokines (except IL-1) were reduced when the ultrafiltration rate was increased from 1 l/h to 6 l/h ( p<0.01), but cytokine clearances still increased ( p<0.01). The highest SC for albumin was 0.1 at 1 l/h and fell to 0.01 at 6 l/h. No adsorption of cytokines and albumin was observed. CONCLUSION: High volume ultrafiltration using a super high flux filter achieved cytokine clearances comparable to, or greater than, those currently achieved for urea during standard continuous renal replacement therapy.

Albumins↗
PubMed2002

Estimating unmeasured anions in critically ill patients: anion-gap, base-deficit, and strong-ion-gap.

We used 100 routine blood samples from critically ill patients to establish whether correcting the anion-gap and base-deficit for decreased plasma albumin improves agreement with the strong-ion-gap for estimating unmeasured anions and whether the modifications increase the proportion of samples with levels of anion-gap or base-deficit above the reference ranges. We used Bland-Altman analyses to compare the methods of estimating unmeasured ions. Compared with the strong-ion-gap, modification reduced the limits of agreement for both the anion-gap and the base-deficit. The bias for the base-deficit was also reduced but the bias for the anion-gap was increased. The proportion of samples with an anion-gap > 22 meq.l(-1) increased from 4 to 29% (p < 0.001), and the proportion with a base-deficit > 5 meq.l(-1) increased from 8 to 42% (p < 0.001). Consequently, metabolic acidosis from unmeasured ions in critically ill patients maybe more frequent than often recognised.

Acid-Base Equilibrium↗