Oxygen consumption and delivery relationship in brain-dead organ donors

The oxygen delivery (DO2) and consumption (VO2) relationship in brain- dead organ donors is unknown. Therefore, in a prospective study, we determined the DO2/VO2 relationship in 21 consecutive brain-dead patients. Patients were allocated to one of two groups, according to plasma lactate concentration: normal (group NL, n = 11) or high (> 2.5 mmol litre-1) (group HL, n = 10). VO2 was measured independently, using indirect calorimetry, under control conditions, during low DO2 challenge with PEEP administration, and high DO2 challenge with inflation of medical antishock trousers and volume expansion or blood transfusion, as required. Under control conditions, there were no significant differences between groups NL and HL in haemodynamic or oxygenation variables, both groups having a low VO2 (mean 114 (SD 21) ml min-1 m-2). In group HL there was a different DO2/VO2 relationship pattern, with a dependent VO2 only. The mean slope of the DO2/VO2 relationship was significantly higher in group HL than in group NL (0.12 (0.09) vs 0.04 (0.07), P < 0.05). We conclude that brain death was associated with a low VO2, and patients in group HL exhibited DO2/VO2 dependency which was not observed in patients in group NL.      

Oxygen consumption following trauma: a reappraisal in severely injured patients requiring mechanical ventilation

Oxygen consumption (VO2) immediately following major injury in man has been said to be reduced. The evidence for this is poor. We have therefore measured VO2 soon after major injury in 16 patients. VO2 was reduced in only two patients, within the normal range in four and increased in ten. VO2 was maintained by increased oxygen extraction in six patients leading to low levels of mixed venous oxygen saturation. There is no evidence for an 'ebb phase' response in man.     

Oxygen delivery and consumption during hypothermia and rewarming in the dog

Changes in oxygen consumption (VO2) and oxygen delivery (DO2) were compared in three groups of paralyzed, sedated dogs: 1) a group (n = 5) cooled to 29 degrees C and immediately rewarmed to 37 degrees C; 2) a group (n = 5) cooled to and maintained at 29 degrees C for 24 h, and then rewarmed; and 3) a group (n = 5) maintained at 37 degrees C for 24 h. During the cooling phase, in both the acute and prolonged hypothermia animals, VO2 and DO2 decreased significantly from control values (P less than 0.05). The decrease in DO2 occurred as a result of a similar decrease in cardiac index (CI; P less than 0.05) that was associated with a significant increase in systemic vascular resistance index (SVRI; P less than 0.05). Arteriovenous oxygen content difference (C(a-v)O2), O2 extraction ratio, mixed venous oxygen tension (PVO2), pH, and base deficit (BD) were not different from control values even during prolonged hypothermia. Normothermic control dogs also demonstrated a significant decrease in CI (P less than 0.05) at 24 h. Surface rewarming increased VO2 back to control values in the acute hypothermia group and to values above control (P less than 0.05) in the prolonged hypothermia group. DO2 remained below control in both groups, resulting in a significant increase in O2 extraction (P less than 0.05) and a decrease in PVO2 (P less than 0.05) in the prolonged hypothermia animals. Following rewarming administration of sodium nitroprusside returned DO2, CI, and SVRI to control values but did not increase VO2. All animals survived the study without need for inotropic support.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dreams in head-injured patients

It is commonly believed that patients following severe head injury tend to dream less than before the injury. In order to evaluate this assumption 51 married head injury patients were interviewed about the frequency and content of their dreams before and after injury. Dreams with threatening content and dreams with manifest sexual content were especially analysed. The results indicate that the overall incidence of dreams in the late post-traumatic phase was similar to the pre-injury era. Threatening dreams were almost significantly more frequent after injury, and the reported incidence of dream with sexual manifest content decreased significantly post-injury. It is suggested that the dynamic mechanism for this phenomenon in head-injured patients is different from that found in the post-traumatic neurosis syndrome.     

Thromboprophylaxis in multiple trauma and head injury patients

Venous thromboembolic disease (VTD) is a frequent condition with serious clinical consequences and elevated mortality related to underdiagnosis or undertreatment, especially in patients with multiple trauma. The incidence of VTD in these patients ranges from 5% to 58% and thromboprophylaxis is considered essential for proper management. Traditionally, pelvic and lower extremity fractures, head injury, and prolonged immobilization have been cited as risk factors for VTD; however, how these factors combine with others to predict high risk is still unclear. The best way to approach VTD prophylaxis in multiple trauma patients is currently unclear. Both mechanical and pharmacologic means are available. The main clinical practice guidelines recommend thromboprophylaxis with low-molecular weight heparin, which can be started 48 hours after trauma, unless patients are still bleeding, in which case mechanical compression is recommended in spite of the limited effectiveness of that measure. Compression is maintained until the risk of hemorrhage has diminished. There is insufficient evidence to support routine use of ultrasound imaging or venography. In patients with head injury who are at risk for intracranial bleeding, the use of low-molecular weight heparin should be delayed until risk disappears but mechanical prophylaxis (compression) can be considered according to clinical status.     

Pelvic fractures in pregnant multiple trauma patients

OBJECTIVE: To study the outcome of pelvic fractures and fetuses in pregnant patients involved in blunt multiple trauma. DESIGN: Retrospective follow-up study. SETTING: Level I trauma center. PATIENTS: Pregnant multiple trauma patients with pelvic fractures between 1974 and 1998. INTERVENTIONS: Conservative and operative treatment of pelvic fractures adapted to the clinical status of the mother. MAIN OUTCOME MEASURES: Clinical, functional, and social outcomes were evaluated. RESULTS: Out of 4,196 patients with blunt multiple trauma treated between 1974 and June 1998, seven demonstrated the combination of blunt multiple trauma, pregnancy, and pelvic fractures. These patients had a mean Injury Severity Score of 29.9 points. Five mothers and three fetuses survived their injuries. All dead fetuses died on the scene. One surviving fetus was found to have hydrocephalus unrelated to the injury; the remaining fetuses had an uneventful delivery and were healthy. In two of the three patients whose fetuses survived, the treatment of the pelvic fracture was modified for the sake of fetal well-being. In all of these patients, acceptable outcome was achieved. CONCLUSION: Modification of the treatment of the pelvic fracture in pregnant women with multiple trauma may be necessary to minimize the risk of fetal injury. In our experience with these rare cases, this modified treatment did not severely alter the clinical outcome of the mother's pelvic fracture.     

Missed injuries in patients with multiple trauma

BACKGROUND: Understanding the etiology of missed injuries is essential in minimizing its occurrence. A retrospective review was conducted to identify the incidence, contributing factors, and clinical outcomes of missed injuries. METHODS: All trauma patients assessed by St Michael's Hospital trauma service from April 1, 1995, to July 31, 1997, were included in the study. Demographic and medical data were compared and statistically analyzed in two patient groups to identify factors associated with missed injuries. RESULTS: Forty six of 567 patients (8.1%) had missed injuries. Patients with missed injuries had higher mean Injury Severity Scores and longer stays in the hospital and intensive care unit compared with patients without missed injuries (p < 0.05). Patients with missed injuries were more likely to have lower Glasgow Coma Scale scores and to have required pharmacologic paralysis (p < 0.05). Of the factors contributing to missed injuries, 56.3% were potentially avoidable and 43.8% were unavoidable. Seven patients with missed injuries had clinically significant outcomes, including one patient death. Of the seven clinically significant missed injuries, five were attributable to potentially avoidable factors. CONCLUSION: Patients with missed injuries tend to be more severely injured with initial neurologic compromise. The majority of missed injuries are potentially avoidable with repeat clinical assessments and a high index of suspicion.     

Pharmacokinetics and pharmacodynamics of enoxaparin in multiple trauma patients

BACKGROUND: Enoxaparin is the only low molecular-weight heparin (LMWH) with documented efficacy for the prevention of venous thromboemobolism (VTE) following trauma, and it is currently considered the treatment of choice. Recent reports have suggested that the pharmacokinetics (PK) and pharmacodynamics of LMWH products may be altered in critically ill patients. METHODS: Two cohorts of critically ill multiple trauma patients were enrolled in this study: A (nonedematous) and B (edematous, defined as the presence of peripheral edema and an increase in body weight of > or =10 kg). All patients received at least four doses of enoxaparin 30 mg subcutaneously every 12 hours before the study dose. Blood samples were collected before and 0.5, 1, 2, 3, 4, 6, 8, and 12 hours following a morning dose. Plasma anti-Xa and antithrombin (AT) activities were determined using chromogenic assays. A compartmental PK analysis model was defined for the data. PK parameters for the two cohorts were compared using a Mann-Whitney Rank Sum test. RESULTS: The area under the curve (AUC)0-12 hour, maximal plasma anti-activated Factor Xa (anti-Xa) activity (Amax), and AT activity were significantly lower in the edematous trauma patients (p < 0.05). The AUC0-12 hour for plasma anti-Xa activity was highly variable in both study cohorts. Seven of the 10 edematous patients had barely quantifiable anti-Xa results. Activity levels were too low to reliably estimate the PK parameters for most patients in cohort B. CONCLUSION: The standard dose of enoxaparin recommended for the prevention of VTE following multiple trauma provides unreliable and highly variable anti-Xa activity in critically ill trauma patients, and is strongly affected by the presence of significant peripheral edema.     

Epidemiology, mortality and morbidity in multiple trauma patients

Three hundred, twenty-nine multiple trauma patients with skeletal injuries admitted to Hennepin County Medical Center, Minneapolis were analyzed for mortality and morbidity based on injury severity score (ISS) and timing of fracture stabilization. Fifty-three deaths (16%) occurred with 38% dying during the first six hours. Survival prospects with injury severity score over 40 were bleak. Age, sex, mechanism of injury, and time of occurrence of injury was also tabulated. Two hundred, twenty-nine patients with 474 long bone fractures were analyzed based on timing of fracture stabilization: immediate stabilization within 24 hours; delayed primary stabilization over 24 hours to one week; secondary osteosynthesis more than one week; non-operative treatment. Respiratory distress syndromes occurred in 6%, 2.4%, 9%, and 12%; mortality rate of 3%, 0%, 6.4%, and 26% for treatment groups A, B, C, and D respectively. However, it must be noted that treatment group B with lower ARDS and mortality rate had no type III open fractures and lower injury severity score.     

Cerebral vasomotor reactivity in head-injured patients

The avoidance of the development of secondary brain damage following head injury is a key point in treating severe brain injury. Recently cerebral perfusionpressure (CPP)-based management, in which volume expansion and vasopressor therapies are often employed to reduce the risk of such secondary brain damage, has improved the long-term neurological outcome as compared with traditional intracranial pressure-based management. However, it is indicated that CPP-based management may possibly induce severe vasogenic edema and intracerebral bleeding, if the patients suffer from disturbances in vascular response ability including vasospasm caused by head injury. Therefore, it is important to know the condition of the vascular response ability, before applying CPP-based management. Recently, there have been many excellent papers about cerebrovascular reactivity, including vasospasm following head injury. The purpose of this review is to evaluate the most advanced diagnostic methods at the bedside as a monitor for checking the disturbance of the cerebral vascular response ability, including vasospasm following head injury, in order to get a much better outcome by CPP-based management for head injury patients.