Continuous renal replacement therapy in patients following traumatic injury.

In critically injured patients, the incidence of acute renal failure has been reported to occur in as many as 31% of patients. The use of CRRT modalities for patients following traumatic injuries is becoming more common, albeit slowly, and this therapy may impact upon long-term recovery of renal function and mortality. Historical studies investigating the early use of intermittent dialysis reported significant improvement in survival in patients who were dialyzed earlier and more vigorously than in control subjects. Early trauma patients also showed improved survival following war injuries when dialyzed prophylactically. Although there is a growing acceptance in favor of earlier renal replacement therapy, the published consensus and the practice in many centers has been to dialyze/filter relatively ill rather than relatively healthy patients. The R Adams Cowley Shock Trauma Center (STC) in Baltimore, Maryland, USA, admits over 8,000 trauma patients each year. Within the STC, a program of continuous renal replacement therapy was established in the early 1980's. We review both historical and current literature on the use of renal replacement therapies after traumatic injury, and suggest some future areas of investigation and indications for these modalities.

Outcome in post-traumatic acute renal failure when continuous renal replacement therapy is applied early vs. late.

OBJECTIVE: To determine whether the timing of initiation of continuous renal replacement therapy (CRRT) affects outcome in patients with post-traumatic acute renal failure (ARF). DESIGN: The medical records of patients treated with CRRT for post-traumatic ARF were retrospectively reviewed. Chi-square testing was used to test frequencies between groups, and Student's t -test was used to compare means. SETTING: A Level I trauma center. PATIENTS: 100 Adult trauma patients treated with CRRT for ARF from 1989 to 1997. Patients were characterized as "early" or "late" starters, based upon whether the blood urea nitrogen (BUN) was less than or greater than 60 mg/dl, prior to CRRT initiation. RESULTS: The mean BUN of the early and late starters was 42.6 and 94.5 mg/dl, respectively (p < 0.0001). CRRT was initiated earlier in the hospital course of early starters compared to late starters (hospital day 10.5 vs 19.4, p < 0.0001). Creatinine clearance prior to CRRT did not differ statistically between the two groups. No significant difference was found between early and late starters with respect to Injury Severity Score, admission Glasgow Coma Scale, presence of shock at admission, age, gender distribution, or trauma type. Admission laboratory values including BUN, serum creatinine, lactate, and bilirubin as well as fluid and blood requirements in the first 24 h were statistically the same for the two groups, suggesting a similar risk of developing renal failure. Survival rate was significantly increased among early starters compared to late starters (39.0 vs 20. 0 %, respectively, p = 0.041). CONCLUSIONS: This retrospective review indicates that an earlier initiation of CRRT, based on pre-CRRT BUN, may improve the rate of survival of trauma patients who develop ARF.

Low blood flow extracorporeal carbon dioxide removal (ECCO2R): a review of the concept and a case report.

Despite advances in respiratory and critical care medicine, the mortality from ARDS remains unchanged. Recent research suggests current ventilatory therapy may produce additional lung injury, retarding the recovery process of the lung. Alternative supportive therapies, such as ECMO and ECCO2R, ultimately may result in less ventilator induced lung injury. Due to the invasiveness of ECMO/ECCO2R, these modalities are initiated reluctantly and commonly not until patients suffer from terminal or near-terminal respiratory failure. Low flow ECCO2R may offer advantages of less invasiveness and be suitable for early institution before ARDS becomes irreversible. We describe a patient with ARDS and severe macroscopic barotrauma supported with low flow ECCO2R resulting in significant CO2 clearance, reduction of peak, mean airway pressures and minute ventilation.

Glucose dynamics during continuous hemodiafiltration and total parenteral nutrition.

OBJECTIVE: To determine glucose balance during dextrose-free continuous hemodiafiltration with or without dextrose-containing ultrafiltrate replacement fluid and full nutritional support. DESIGN: Prospective, nonrandomized, observational study. SETTING: A 24-bed multiple trauma critical care unit in a level-I trauma center. PATIENTS: Seventeen multiple trauma patients with multiple organ dysfunction syndrome requiring hemodialysis for acute renal failure. INTERVENTIONS: Continuous hemodiafiltration effluent volume and glucose concentration were measured. Study days were classified according to whether dextrose was used in the ultrafiltrate replacement therapy. Use of dextrose in replacement therapy was determined clinically. Parenteral nutrition was not altered for potential glucose absorption from continuous hemodiafiltration. Ultrafiltrate replacement consisted of 5% dextrose in saline on 21 study days (D5YES) and dextrose-free solutions on 54 study days (D5NO). RESULTS: The D5YES group received 316 +/- 145 g glucose/day from the ultrafiltrate replacement fluid, in addition to glucose in total parenteral nutrition (total glucose intake = 942 +/- 229 g/day in D5YES, 682 +/- 154 g/day in D5NO) (p < 0.05). Glucose loss in continuous hemodiafiltration effluent was 82 +/- 61 g/day in D5YES and 57 +/- 22 g/day in D5NO (P < 0.05), for a net glucose uptake of 8.1 +/- 2.1 mg/kg per min in D5YES and 5.4 +/- 1.5 mg/kg per min in D5NO (p < 0.05). Glucose loss was predictable when dialysate and ultrafiltrate replacement fluids were dextrose-free (R2 = 0.77), but less so when dextrose was used as ultrafiltrate replacement (R2 = 0.47). CONCLUSION: Dextrose-free dialysate promotes glucose loss during continuous hemodiafiltration, but the loss is small and predictable. Use of a dextrose-containing ultrafiltrate replacement fluid results in a significant increase in glucose intake without a commensurate increase in glucose loss, and makes glucose loss in effluent less predictable.

Nutritional effect of continuous hemodiafiltration.

Continuous arterial-venous and veno-venous hemodiafiltration are reliable methods of renal replacement therapy and are particularly suited to critically ill patients in acute renal failure. Fluid and uremic toxin removal from continuous hemodiafiltration is sufficient to allow unrestricted nutrition support. However, the hemodiafilter cannot discriminate between uremic toxins and nutrients. Therefore, the potential exists for significant nutrient loss during continuous hemodiafiltration. Amino acid loss during continuous hemodiafiltration is approximately 10-15 g/day, although in individual cases > or = 30 g/day can be lost. Neither lipids nor intact proteins are lost to any appreciable degree during continuous hemodiafiltration. Small amounts of glucose are lost if dextrose-free dialysate is used for dialysis. If dextrose-containing dialysate is used, significant amounts of glucose can be absorbed (35-45% of the infused glucose). Fluid replacement with dextrose-containing electrolyte solutions can also lead to significant infusion of glucose. Vitamin and mineral losses during continuous hemodiafiltration are not known; neither are the vitamin requirements for patients receiving continuous hemodiafiltration. Effects of continuous hemodiafiltration on vitamin and mineral loss and status remain an important research question.

Full protein alimentation and nitrogen equilibrium in a renal failure patient treated with continuous hemodiafiltration: a case report of 67 days of continuous hemodiafiltration.

Standard care for patients with renal failure while in an intensive care unit involves traditional hemodialysis or peritoneal dialysis and protein restriction. We present a case of a patient with renal failure supported with continuous arteriovenous hemofiltration with dialysis (CAVH-D) who was given full protein alimentation. Total daily urea clearance was measured from the CAVH-D output. Protein load was 196 +/- 34 g/day while receiving total parenteral nutrition and 164 +/- 30 g/day while receiving enteral alimentation. Serum blood urea nitrogen was controlled between 40 and 75 mg/dL, except during septic episodes. Nitrogen balance was estimated based upon known alimentation protein load and measurable and estimated nitrogenous losses. The patient was potentially in nitrogen equilibrium during most of the dialysis period. The cumulative nitrogen balance was positive by 5.2 g after 67 days of dialysis. Volume of alimentation was 3.49 +/- 0.7 liters/day. With CAVH-D, the renal failure patient can receive full alimentation without volume or protein load limitations. Furthermore, nitrogen balances can be estimated easily while the patient is on CAVH-D.

Amino acid loss and plasma concentration during continuous hemodiafiltration.

Amino acid loss, plasma concentration, and the relationship between amino acid intake and balance during continuous hemodiafiltration (CHD) were investigated in a prospective, nonrandomized study of trauma patients exhibiting the systemic inflammatory response with acute renal failure. Data were compared with those from a group of similar patients who had maintained renal function (control). Both groups received similar amounts of nonprotein calories (3015 +/- 753 nonprotein calories per day in the control group vs 3077 +/- 1018 nonprotein calories per day in the CHD group) and amino acids (2.24 +/- 0.36 g/kg per day in the control group vs 2.19 +/- 0.48 g/kg per day in the CHD group) via the parenteral route. Amino acid solutions were either 19% or 45% branched-chain amino acid enriched. Studies were performed every 12 hours for a maximum of 6 days. Amino acid loss was 2.5 +/- 2.3 g/12 h in the control group vs 6.6 +/- 2.4 g/12 h in the CHD group (p < .0001). Increasing the dialysate rate from 15 to 30 mL/min increased amino acid loss from 5.7 +/- 1.7 to 7.9 +/- 2.6 g/12 h (p < .0001). Amino acid loss was unrelated to amino acid intake but was directly related to plasma amino acid concentration, CHD effluent volume, and the efficiency of filtration as measured by the ratio of filtered urea nitrogen to blood urea nitrogen (R2 = .69). A linear relationship was found between amino acid intake and balance (R2 = .991). The patterns of plasma amino acid concentrations were consistent with metabolic changes wrought by a combination of sepsis and multiple organ dysfunction and type of amino acid intake but seemed unaffected by increased amino acid loss in CHD effluent. Amino acid losses were 2 to 3 times greater from CHD than from normal kidney. However, CHD amino acid losses may not be clinically significant unless amino acid intake is restricted to levels used typically in traditional hemodialysis.

Utility of the routine chest X-ray after "over-wire" venous catheter changes.

The Seldinger technique is commonly used to change central venous access catheters in the Intensive Care Unit. These catheters are routinely being changed to prevent septic complications. Some of these changes are performed by an "over-wire" technique. To assess the utility of postprocedural chest X-rays on critically ill patients after an over-wire catheter change, we followed 68 patients after they had 80 catheter changes. This study assesses catheter position by use of a postprocedural X-ray. During the study, we found no misplaced catheters and minimum symptomatology in 80 patients. The trauma/critical care fellows performing the procedures rated them as easy in 97.5 percent of the changes. The conclusion of the study is that, if the catheter change is technically easy and the patient has no symptoms, a postprocedural X-ray is not necessary.

Life-threatening acute systemic lupus erythematosus: survival after multiple extracorporeal modalities: a place for the multipotential extracorporeal service.

Diffuse alveolar hemorrhage secondary to systemic lupus erythematosus (SLE) may cause life-threatening respiratory failure and may be associated with multiple organ failure. Extensive support may be necessary to sustain life while systemic therapy becomes effective. We report here a patient with profound respiratory failure secondary to SLE associated with multiorgan failure, who was supported with veno-arterial extracorporeal lung assist (ECLA), veno-venous ECLA, and multiple continuous renal replacement therapies during plasmapheresis. The full spectrum of extracorporeal life support and treatment modalities was performed seamlessly by a single service within the critical care department.

Veno-venous extracorporeal lung assist with concurrent distal aortic perfusion: repair of ruptured aorta in a patient with dense ARDS.

Extracorporeal lung assist (ECLA) allowed surgical repair of a ruptured descending thoracic aorta to be performed in a patient with profound respiratory failure. Dense acute respiratory distress syndrome (ARDS) developed during his 15-day hospitalization at a regional trauma center. After transfer to a Level I facility, an additional injury was diagnosed: traumatic rupture of the aorta, contained within a pseudoaneurysm. ECLA by the veno-venous route was required immediately preoperatively and distal aortic perfusion was performed during the aortic repair. Despite deflation of the left lung, the patient was oxygenated and ventilated adequately during surgery. Cross-clamp time was 48 minutes. The patient was weaned from ECLA by the fifth postoperative day. To our knowledge, this is the first report of concurrent veno-venous pulmonary support with distal aortic perfusion.

An in vitro physiologic model for cardiopulmonary simulation: a system for ECMO training.

Extracorporeal life support (ELS) systems may be run by certified perfusionists, specially trained nurses or respiratory therapy staff. Guidelines for the training, certification and retraining of ELS operators have been established by the Extracorporeal Life Support Organization. Recommendations include "... a well defined program for staff training, certification, and retraining". Some clinicians have suggested that ELS operators be certified and recertified in an animal laboratory. But such practice involves veterinary expenses, animal use issues and considerable clean-up and disposal. We describe an alternative method of training, using an in vitro physiologic model designed to simulate various pathophysiologic states. In addition, the in vitro physiologic model may be used to evaluate membrane lung characteristics. This model's ease of construction, maintenance and use for training compared with live animal techniques are discussed. Research capabilities may be more flexible than with the use of the live animal technique. The in vitro physiologic model can be a useful and convenient asset to an extracorporeal membrane oxygenation/extracorporeal carbon dioxide removal (ECMO/ECCO2R) program.

Continuous arteriovenous hemofiltration with dialysis (CAVH-D): an alternative to hemodialysis in the mass casualty situation.

Renal failure is a common sequela of mass casualty, particularly when crush injury is involved. Traditional management of renal failure with hemodialysis equipment may be difficult or inaccessible due to lack of electricity and water supply or damage to existing equipment. Furthermore, a sudden new population of renal failure patients may overwhelm an existing dialysis program. The rapid mobilization of traditional hemodialysis equipment may be delayed due to limited supply, manufacturing delays, or inventory shortages. For these reasons, we propose the use of continuous arteriovenous hemofiltration with dialysis (CAVH-D) as an alternative renal support modality for the mass casualty situation.

Effects of foveal stimulation on peripheral visual processing and laterality in deaf and hearing subjects.

This research examines visual field differences in the detection and identification of a peripheral stimulus for deaf and hearing subjects, as a function of concurrent foveal stimulation. Deaf and hearing subjects were presented with peripheral target stimuli (simple geometric shapes) presented tachistoscopically to the left or right visual fields under four conditions of foveal stimulation: (a) no stimulus; (b) simple geometric shapes; (c) pictorial shapes (outline drawings); and (d) orthographic letters. Dependent measures were detection response latency and peripheral shape recognition (errors). With error data, hearing subjects showed a right field advantage under foveal conditions of no stimulus and simple shape stimulus, but a left field advantage with pictorial and letter foveal stimuli. Deaf subjects showed the opposite effect, with a left field advantage under foveal conditions of no stimulus and simple shape stimulus, but a right field advantage with pictorial and letter foveal stimuli. Latency data revealed the same pattern of results for hearing subjects, but no significant visual field differences for deaf subjects. Results are interpreted in terms of differences in hemispheric visual processing used by deaf and hearing subjects, as affected by varying conditions of foveal load.

Flush resuscitation for group A streptococcus toxic shock: a possible role for continuous renal replacement therapy and plasmapheresis.

Group A streptococcus has emerged as a major cause of aggressive life-threatening deep-seated infections. In addition, toxic shock syndrome caused by Group A streptococcus was recognized in 1983. Group A streptococcus produces several potent exotoxins which explain the pathophysiology of these invasive infections. Other virulence factors such as M protein, which can impede phagocytosis, are associated with some Group A streptococcus. M protein and streptococcal pyrogenic exotoxins may act as super antigens. Host factors may influence the severity of infection. Blood purification techniques such as continuous renal replacement therapy and plasmapheresis can remove streptococcal exotoxins as well as inflammatory mediators. Replacement with fresh-frozen plasma corrects coagulopathy and may provide some antibody protection. Four patients with Group A streptococcus-toxic shock syndrome treated with continuous renal replacement therapy, plasmapheresis, or both showed dramatic, rapid improvement in cardiovascular dynamics and respiratory parameters. Two patients died. The mainstay of treatment for Group A streptococcus-toxic shock syndrome remains early diagnosis, aggressive surgical control of the infection, and appropriate antibiotics (i.e., penicillin and clindamycin). Flush resuscitation may rescue some patients from profound toxic shock. The mechanisms of action need to be delineated.

Impact of critical care physician staffing on patients with septic shock in a university hospital medical intensive care unit.

To evaluate the effects of reorganizing physician resources in a medical intensive care unit (MICU), we studied the impact of these changes in patients with septic shock. Patients were compared during two consecutive 12-month periods: (1) an interval in which faculty without critical care medicine (CCM) training supervised the MICU (before CCM, n = 100) and (2) following staffing with physicians formally trained in CCM (after CCM, n = 112). Acute Physiology and Chronic Health Evaluation scores were utilized to compare severity of illness and were similar for each group (29 +/- 11 before CCM vs 28 +/- 10 after CCM). However, mortality was significantly lower during the post-CCM interval (74% vs 57%, respectively). There was no significant difference in the frequency of use of mechanical ventilation (83% vs 87%), although pulmonary artery catheters (48% vs 64%) and arterial catheters (24% vs 73%) were employed more frequently after CCM. The number of subspecialty consultations and MICU and hospital length of stay were similar for both intervals. We conclude that the implementation of dedicated staffing by CCM physicians in a university hospital MICU was associated with a favorable impact on patients with septic shock.

Outcome following prolonged intensive care unit stay in multiple trauma patients.

OBJECTIVE: To describe the hospital course and outcomes of trauma patients requiring ICU stays greater than 30 days and the charges they incur. DESIGN: A retrospective case series analysis of data collected from patient charts and trauma registry. SETTING: A Level I regional trauma center that is part of a statewide trauma system. PATIENTS: Over a 3-yr period, 87 patients (3% of all trauma ICU admissions) had prolonged stays (greater than 30 days) in the ICU; they constitute the study group. Blunt trauma was responsible for 90% of injuries, and the mean Injury Severity Score was 34 +/- 16 SD. RESULTS: Mechanical ventilation was required for 78.5% of the time spent in the ICU. The mean time spent on mechanical ventilators was 47 +/- 23 days; in the ICU, 60 +/- 27 days; and in the hospital, 72 +/- 29 days. Infectious complications occurred in 90% and organ dysfunction was seen in 76% of patients. The overall mortality rate was 17.2% (31% for patients greater than 65 yr). Patients less than 40 yr had lower mortality rates despite a significantly higher Injury Severity Score and lower Glasgow Coma Scale score compared with those greater than 65 yr. More patients greater than 65 yr were discharged to chronic care facilities than those younger (23% vs. 5%). The number of patients followed at 3 and 12 months after discharge was 74% and 54%, respectively, with only two deaths. The mean hospital and professional charges to the patients were $101,000 +/- 61,000 and $35,000 +/- 13,000, respectively. CONCLUSION: Length of ICU stay was most closely associated with the need for mechanical ventilation. The presence of premorbid illness, age greater than 65 yr, and organ dysfunction was associated with increased mortality. Although trauma patients requiring prolonged ICU stays utilize many resources, the ultimate outcome may be fairly good.

Efficacy of continuous arteriovenous hemofiltration with dialysis in patients with renal failure.

OBJECTIVE: To document the efficacy of continuous arteriovenous hemofiltration with dialysis following renal failure, without protein restriction, and to explore the magnitude and clinical applications of total daily urea clearance. DESIGN: A noncomparative, descriptive account of a case series. Data were collected prospectively and analyzed retrospectively. SETTING: A tertiary care facility in a statewide emergency medical services system. PATIENTS: Twenty-eight patients with renal failure were supported by continuous arteriovenous hemofiltration with dialysis in a critical care unit during a 14-month period (21 patients with multitrauma; three patients with soft tissue infections; and four patients with multisystem organ failure who had been transferred from other hospitals). Renal failure was most commonly due to multisystem organ failure or associated with adult respiratory distress syndrome. RESULTS: Continuous arteriovenous hemofiltration with dialysis days totaled 308 (mean 10.9). All patients received full protein alimentation (mean protein load 131 g/day). The blood urea nitrogen concentration was controlled, generally to 40 to 75 mg/dL (14.3 to 26.7 mmol/L) within 3 to 5 days. Total daily urea clearance ranged from 15 to 21 g/day. Five (18%) of the 28 patients survived. CONCLUSION: Continuous arteriovenous hemofiltration with dialysis appears to be effective for the control of blood urea nitrogen and clearance of urea. This modality also permits full protein alimentation. Total daily urea clearance can be calculated easily and may have important clinical uses and implications.

Extracorporeal support in an adult with severe carbon monoxide poisoning and shock following smoke inhalation: a case report.

The objective of this study was to discuss the case of a patient with severe smoke inhalation-related respiratory failure treated with extracorporeal support. The study was set in a 12-bed multi-trauma intensive care unit at a level one trauma center and hyperbaric medicine center. The patient under investigation had carbon monoxide poisoning, and developed acute respiratory distress syndrome and cardiovascular collapse following smoke inhalation. Rapid initiation of extracorporeal support, extreme inverse-ratio ventilation and intermittent prone positioning therapy were carried out. Admission and serial carboxyhemoglobin levels, blood gases, and computerized tomography of the chest were obtained. The patient developed severe hypoxia and progressed to cardiovascular collapse resistant to resuscitation and vasoactive infusions. Veno-venous extracorporeal support was initiated. Cardiovascular parameters of blood pressure, cardiac output, and oxygen delivery were maximized; oxygenation and ventilation were supported via the extracorporeal circuit. Airway pressure release ventilation and intermittent prone positioning therapy were instituted. Following 7 days of extracorporeal support, the patient was decannulated and subsequently discharged to a transitional care facility,neurologically intact. Smoke inhalation and carbon monoxide poisoning may lead to life-threatening hypoxemia associated with resultant cardiovascular instability. When oxygenation and ventilation cannot be achieved via maximal ventilatory management, extracorporeal support may prevent death if initiated rapidly.

Urea removal during continuous hemodiafiltration.

OBJECTIVE: To compare urea nitrogen removal by continuous hemodiafiltration vs. functional native kidneys in critically ill, septic patients receiving > 2 g of amino acids/kg body weight per day. DESIGN: Prospective, comparative, unblinded study. SETTING: Trauma critical care units of a Level I adult trauma hospital. PATIENTS: Fifteen septic patients with multiple organ failure including renal failure who were receiving continuous hemodiafiltration; 11 septic patients with multiple organ failure without renal failure (control group). Ages of patients ranged from 18 to 60 yrs. INTERVENTIONS: Collection of effluent (dialysate + ultrafiltrate) from hemodiafilters. Collection of urine from control patients. MEASUREMENTS: Urea nitrogen and creatinine concentrations in blood, urine, and the hemodiafiltration effluent, measured every 24 hrs for 6 days. Effluent and urine volumes were measured. MAIN RESULTS: Hemodiafilters were operational for 21.8 +/- 3.0 hrs/day. Mean urea nitrogen removal in the renal failure group was 28 +/- 10 g/day. Blood urea nitrogen was stable over the 6-day study period. In control subjects, urea nitrogen removal was 27 +/- 9 g/day, which was not significantly different from the continuous hemodiafiltration group. Blood urea nitrogen concentrations in control patients increased over the 6-day study period (p < .05). Urea nitrogen removal correlated moderately well with amino acid intake in the control group (r2 = .30), but not in the continuous hemodiafiltration group (r2 = .0004). In patients receiving continuous hemodiafiltration, effluent volume was most significantly correlated with urea nitrogen removal (r2 = .69). CONCLUSIONS: The technique of continuous hemodiafiltration can remove substantial amounts of urea nitrogen, similar to that of normal native kidneys. In addition, at amino acid intake rates of > 2 g/kg body weight/day, urea nitrogen removal during continuous hemodiafiltration remains a function of effluent volume, so there is no need to restrict amino acid intake in acute renal failure patients supported with continuous hemodiafiltration.