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.

Hyperlactatemia, increased osmolar gap, and renal dysfunction during continuous lorazepam infusion.

OBJECTIVE: To review effects of the vehicle of lorazepam, propylene glycol, in regard to lactate, osmolarity, and renal dysfunction. DESIGN: Case report. SETTING: Intensive care unit of a Level I trauma center. Patient A 36-yr-old Hispanic man who developed severe respiratory failure and required high-dose lorazepam for sedation. The patient was ventilated with low tidal volumes in a lung-protective fashion, with resultant "permissive hypercapnia." Lactates and osmolalities rose on initiation and fell, as expected, on discontinuation of the lorazepam infusion. However, there was no renal compensation for the hypercapnia except while the patient was not receiving lorazepam. MEASUREMENTS AND MAIN RESULT: Serial osmolalities, lactates, serum bicarbonate, PaCO2, and pH were measured during lorazepam infusion. Rise and fall of serum lactate and osmolality closely correlated with lorazepam. Serum bicarbonate rose significantly while the patient was not receiving lorazepam in response to hypercarbia and failed to rise while the patient was receiving lorazepam. CONCLUSION: The vehicle of lorazepam, propylene glycol, can cause hyperlactatemia and elevated osmolar gaps. However, propylene glycol may also interfere with renal tubular function and may blunt renal compensation for respiratory acidosis.

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.

Interhospital transport of the extremely ill patient: the mobile intensive care unit.

BACKGROUND: Critically ill patients may require specialized care that is offered only at tertiary referral centers. As regionalization and specialization of critical care become more common, transportation of critically ill patients must be refined. Transportation of critically ill patients within a hospital, much less outside the hospital, is often deemed unsafe because of medical instability. We report, here, our results from 2 yrs' experience of transporting extremely ill patients with respiratory failure via a ground critical care transport service. METHODS: A mobile intensive care unit was equipped and staffed to nearly recreate the intensive care environment. Staffing included a physician, nurse, respiratory therapist, and driver--all with extensive critical care experience. The mobile intensive care unit was equipped with a full pharmacy, advanced ventilatory equipment, and capability for full invasive hemodynamic monitoring. Data were analyzed by retrospective review. The predicted mortality rate, based on Pao2/Fio2 ratios, was compared with the actual mortality rate. RESULTS: During a 2-yr period, 39 critically ill patients were transported. Thirty-six of the 39 were candidates for extracorporeal lung assist, with a mean positive end-expiratory pressure requirement of 15.9, a mean Fio2 requirement of .93, and a mean Pao2/Fio2 ratio of 59.8. Pulmonary arterial catheters and peripheral arterial catheters were in place in 66.6% and 72% of patients, respectively. Vasoactive medications were being infused in 56%, and 74% were receiving medical paralytics. One patient died during movement from the bed to the transport gurney. Other than one episode of transient hypotension, there were no complications or untoward outcomes related to transport. Unique therapeutic interventions were performed at the receiving facility on 34 of 39 patients. The predicted mortality rate, based on indicators of lung dysfunction, was 68% to 100%; the actual subsequent hospital mortality rate was 43%. CONCLUSIONS: When a mobile intensive care unit is properly staffed and equipped and patient stabilization is performed before transfer, severely ill patients with respiratory failure can be transferred safely. For patients with respiratory failure, there may be a survival advantage in transfer to regional centers of expertise.

End-points of resuscitation how much is enough?

Fluid resuscitation after traumatic hemorrhage has historically been instituted as soon after injury as possible. Patients suffering from hemorrhagic shock may receive several liters of crystalloid, in addition to colloid solutions, in an attempt to normalize blood pressure, heart rate, urine output, and mental status, which are the traditional end-points of resuscitation. Current theory and recent investigations have questioned this dogma. Resuscitation goals may be different between when the patient is actively hemorrhaging, and once bleeding has been controlled. Newer markers of tissue and organ system perfusion may allow a more precise determination of adequate resuscitation.

Physician utilization of a portable computed tomography scanner in the intensive care unit.

OBJECTIVE: To determine the utilization of a portable computed tomography (CT) scanner for critically ill adult patients in an intensive care unit (ICU). DESIGN: Survey study and retrospective review. SUBJECTS: Critical care attending staff and fellows and neurosurgery residents. SETTING: A university hospital and Level I trauma center with a multitrauma ICU, a neurotrauma ICU, and a neurosurgical ICU. INTERVENTIONS: We surveyed all physicians who ordered portable CT scans from December 1996 through June 1998. Ordering physicians included critical care attending staff and fellows (anesthesiology, surgery, internal medicine) and neurosurgery residents. Physicians who no longer worked at the institution were contacted by mail or fax. Radiology records were reviewed to determine the actual number and type of scans performed. MEASUREMENTS AND MAIN RESULTS: The survey response was 100%. Most physicians reported ordering portable head CT scans (97%), followed by chest CT (88%), abdominal CT (78%), and pelvic CT (34%) scans. Analysis of the actual number of scans performed correlated with these reports (511 head, 115 chest, 88 abdomen, and 87 pelvis). The indication for portable CT scans (as opposed to a "fixed" or "stationary" scans) cited most often was patient severity of illness (77%). Patients on extracorporeal support (93%), those with cardiovascular instability (70%), followed by those with respiratory instability (57%) and neurologic instability (40%) were deemed too ill to transport. If the portable CT scanner was unavailable, however, most physicians (67%) ordered a fixed helical CT scan and the patient was transported to the radiology suite, regardless of medical condition. CONCLUSIONS: Access to a portable CT scanner impacts the physician ordering patterns for ICU patients. We found that 100% of surveyed physicians used the portable CT scanner for critically ill patients when the patient was unstable. If the diagnostic study was deemed medically necessary, and the portable scanner was unavailable, most surveyed physicians ordered a "fixed" helical scan and the patient was transported by an experienced transport team for the study. The portable CT offered an alternative and potentially safer means of obtaining diagnostic studies.

Acute respiratory distress syndrome: estimated incidence and mortality rate in a 5 million-person population base.

BACKGROUND: Various estimates of the incidence and mortality rate of the acute (adult) respiratory distress syndrome (ARDS) have been published. The studies that led to those estimates were based on relatively small patient populations and employed variable diagnostic identifiers of ARDS. The purpose of this study was to estimate the incidence of ARDS and its mortality rate from a large database to which refined diagnostic criteria were applied. We conducted a retrospective review of all hospital discharges over a 4-year period, using screening criteria designed to select patients with ARDS. Discharges from all acute care hospitals in the state of Maryland were reviewed using a computer database from the Health Services Cost Review Commission (HSCRC). Patients >/= 12 years of age were included. Screening criteria consisted of ICD-9 codes 518.5 and 518.82 cross-referenced with procedural codes for ventilatory support (96.70, 96.71 and 96.72). Data were normalized to the number of cases per 100,000 people. RESULTS: During the 4-year study period there were 2,501,147 hospitalizations. Applying the ICD-9 ARDS criteria yielded lower and upper limits of 159-205, 439-568, 531-694 and 529-720 cases of ARDS for 1992, 1993, 1994 and 1995, respectively. Normalizing for a population of 5 million yields yearly lower and upper limit rates of 3.2-4.2, 8.8-11.4, 10.6-13.8 and 10.5-14.2 cases of ARDS per 100,000 people. Mortality upper and lower limit rates based upon the same duration, admissions and population were 38-49%, 39-52%, 36-47%, and 36-49%, respectively. CONCLUSIONS: The incidence of ARDS in Maryland is in the range of 10-14 cases per 100,000 people. The ARDS mortality rate is 36% to 52%, similar to that calculated in previous studies.