Septic complications of corticosteroid administration after central nervous system trauma

The hypothalamic-pituitary-adrenal axis in critical illness

Hypothalamic-pituitary-adrenal (HPA) axis function is crucial to maintain and restore homeostasis. The HPA axis does not function in isolation. Rather, the HPA axis modulates and reacts to signals from endocrine, neural, and immune systems. Cortisol is the major glucocorticoid secreted by the human adrenal cortex. Its actions are largely mediated by the glucocorticoid receptor. The potent anti-inflammatory actions of glucocorticoids led to their use in critically ill patients. Metaanalyses of these early studies (before 1985) concluded that large glucocorticoid doses had no effect and were potentially detrimental. More recently, the pendulum has swung in the opposite direction based on the concept that critically ill patients may have relative adrenal insufficiency and/or acquired glucocorticoid resistance. However, inconsistent diagnostic criteria, heterogeneity of subjects, variable nutritional status, and pre-existing conditions preclude formulating definitive conclusions regarding glucocorticoid use among critically patients. Diagnosing adrenal insufficiency in the critically ill patient remains challenging. To resolve the issue, our challenge is to develop physiologically relevant tools to assess glucocorticoid action and GR function at the cellular level.

Factors predicting postoperative infectious complications and early induction of inflammatory mediators in ulcerative colitis patients

BACKGROUND

Positive outcomes after restorative proctocolectomy are compromised by a number of specific septic complications. However, there is no useful perioperative marker predicting postoperative infectious complications (PICs) in steroid overdosed patients with ulcerative colitis (UC).

METHODS

To determine factors associated with PICs and their relation to circulating levels of pro- and anti-inflammatory cytokines and neutrophil elastase (NE), we obtained perioperative blood samples from 60 UC patients.

RESULTS

Postoperative infectious complications were identified in 47% of cases. Patients who developed PICs had significantly longer disease duration, had been administered a greater total preoperative dosage of prednisolone, and had a higher body mass index. Logistic regression analysis showed that the total preoperative dosage of prednisolone was independently associated with the development of PICs. These patients showed suppressed systemic inflammation and pro- and anti-inflammatory cytokine induction. An early increase in the NE level was found to be predictive of PICs in the high-dose group, whereas there was no significant difference in neutrophil counts between the high- and low-dose groups.

CONCLUSIONS

Circulating NE levels in the early postoperative period might be a useful predictor of PICs in immune-controlled UC patients who received high doses of steroids.

Adrenal Insufficiency in the Critically Ill Trauma Population

Acute adrenal insufficiency has been demonstrated in a number of patients with shock. This study was designed to evaluate the rate of occult adrenal insufficiency in the critically ill trauma population and to determine the impact of hypoproteinemia on the use of random cortisol levels as a marker for adrenal insufficiency. Forty-four patients were prospectively enrolled on admission to the trauma intensive care unit, with three excluded, for a total n of 41. Random total serum cortisol and albumin levels were drawn on hospital Days 1, 4, 8, and 14. Occult adrenal insufficiency was defined as a cortisol less than 25 mcg/dL in the setting of an albumin greater than 2.5 g/dL. The prevalence of cortisol less than 25 mcg/dL ranged from 51 to 81 per cent during the study period, and peaked on Days 4 and 8. Albumin 2.5 g/dL or less ranged from 37 to 60 per cent, and this prevalence also peaked on Days 4 and 8. The patients with a low albumin had a high prevalence of low cortisol, ranging from 67 to 100 per cent. The prevalence of adrenal insufficiency, with low cortisol and normal albumin, ranged from 41 to 82 per cent during the study period. None of our patients with occult adrenal insufficiency were treated with steroids, which was a decision made by the treating physicians. Among the patients with occult adrenal insufficiency, survival was 100 per cent. Occult adrenal insufficiency is common in critically ill trauma patients, and is a dynamic entity that can be acquired and even resolved during critical illness. Random cortisol of 25 mcg/dL may actually not be an adequate marker of occult adrenal insufficiency. Low albumin predicts a low cortisol. Hemodynamically stable occult adrenal insufficiency should not be treated with steroid replacement in the critically ill trauma patient, as survival in our series was 100 per cent without replacement.

Establishing the dose of the oral NK1 antagonist aprepitant for the prevention of chemotherapy-induced nausea and vomiting

BACKGROUND

The neurokinin-1 antagonist aprepitant (EMEND; Merck Research Laboratories, West Point, PA) has been shown to reduce chemotherapy-induced nausea and vomiting when it is given with a 5-hydroxytryptamine-3 receptor antagonist and dexamethasone. The current study sought to define the most appropriate dose regimen of oral aprepitant.

METHODS

This multicenter, randomized, double-blind, placebo-controlled study was conducted in patients with cancer who were receiving initial cisplatin (> or = 70 mg/m(2)) and standard antiemetic therapy (intravenous ondansetron plus oral dexamethasone). Patients were randomized to receive standard therapy plus either aprepitant 375 mg on Day 1 and 250 mg on Days 2-5, aprepitant 125 mg on Day 1 and 80 mg on Days 2-5, or placebo. Due to an apparent interaction with dexamethasone suggested by pharmacokinetic data obtained while the study was ongoing, the aprepitant 375/250 mg dose was discontinued and replaced with aprepitant 40 mg on Day 1 and 25 mg on Days 2-5, and a new randomization schedule was generated. Patients recorded nausea and emesis in a diary. The primary endpoint was complete response (no emesis and no rescue therapy), which was analyzed using an intent-to-treat approach with data obtained after the dose adjustment. Treatment comparisons were made using logistic regression models. Tolerability was assessed by reported adverse events and physical and laboratory assessments, and included all available data.

RESULTS

The percentages of patients who achieved a complete response in the overall study period were 71.0% for the aprepitant 125/80-mg group (n = 131 patients), 58.8% for the aprepitant 40/25-mg group (n = 119 patients), and 43.7% for the standard therapy group (n = 126 patients; P < 0.05 for either aprepitant regimen vs. standard therapy). Rates for Day 1 were 83.2% for the aprepitant 125/80-mg group, 75.6% for aprepitant 40/25-mg group, and 71.4% for the standard therapy group (P < 0.05 for aprepitant 125/80 mg vs. standard therapy), and rates on Days 2-5 were 72.7% for the aprepitant 125/80-mg group, 63.9% for the aprepitant 40/25-mg group, and 45.2% for the standard therapy group (P < 0.01 for either aprepitant group vs. standard therapy). The efficacy of the aprepitant 375/250-mg regimen was similar to that of the aprepitant 125/80-mg regimen. The overall incidence of adverse events was generally similar across treatment groups: 85% in the aprepitant 375/250-mg group (n = 34 patients), 76% in the aprepitant 125/80-mg group (n = 214 patients), 71% in the aprepitant 40/25-mg group (n = 120 patients), and 72% in the standard therapy group (n = 212 patients), with the exception of a higher incidence of infection in the aprepitant 125/80-mg group (13%) compared with the standard therapy group (4%).

CONCLUSIONS

When it was added to a standard regimen of intravenous ondansetron and oral dexamethasone in the current study, aprepitant reduced chemotherapy-induced nausea and vomiting and was generally well tolerated, although increases in infection were noted that were assumed to be due to elevated dexamethasone levels as a result of the pharmacokinetic interaction. The aprepitant 125/80-mg regimen had the most favorable benefit:risk profile.

Risks and benefits of preoperative high dose methylprednisolone in surgical patients: a systematic review

BACKGROUND

A single preoperative high dose of methylprednisolone (15 to 30 mg/kg) has been advocated in surgery, because it may inhibit the surgical stress response and thereby improve postoperative outcome and convalescence. However, these potential clinical benefits must be weighed against possible adverse effects.

OBJECTIVE

To conduct a risk-benefit analysis using a meta-analysis, to compare complication rates and clinical advantages associated with the use of high dose methylprednisolone in surgical patients.

METHODS

Randomised controlled trials of high dose methylprednisolone in elective and trauma surgery were systematically searched for in various literature databases. Outcome data on adverse effects, postoperative pain and hospital stay were extracted and statistically pooled in fixed-effects meta-analyses.

RESULTS

We located 51 studies in elective cardiac and noncardiac surgery, as well as traumatology. Pooled data failed to show any significant increase in complication rates. In patients treated with corticosteroids, nonsignificantly more gastrointestinal bleeding and wound complications were observed; the 95% confidence interval boundaries of the numbers-needed-to-harm were 59 and 38, respectively. The only significant finding was a reduction of pulmonary complications (risk difference -3.5%; 95% confidence interval -1.0 to -6.1), mainly in trauma patients.

CONCLUSION

For patients undergoing surgical procedures, a perioperative single-shot administration of high dose methylprednisolone is not associated with a significant increase in the incidence of adverse effects. In patients with multiple fractures, limited evidence suggests promising benefits of glucocorticoids on pulmonary complications.

Experience with prolonged induced hypothermia in severe head injury

BACKGROUND: Recent prospective controlled trials of induced moderate hypothermia (32-34 degrees C) for relatively short periods (24-48 h) in patients with severe head injury have suggested improvement in intracranial pressure control and outcome. It is possible that increased benefit might be achieved if hypothermia was maintained for more periods longer than 48 h, but there is little in the literature on the effects of prolonged moderate hypothermia in adults with severe head injury. We used moderate induced hypothermia (30-33 degrees C) in 43 patients with severe head injury for prolonged periods (mean 8 days, range 2-19 days). RESULTS: Although nosocomial pneumonia (defined in this study as both new chest radiograph changes and culture of a respiratory pathogen from tracheal aspirate) was quite common (45%), death from sepsis was rare (5%). Other findings included hypokalaemia on induction of hypothermia and a decreasing total white cell and platelet count over 10 days. There were no major cardiac arrhythmias. There was a satisfactory neurological outcome in 20 out of 43 patients (47%). CONCLUSION: Moderate hypothermia may be induced for more prolonged periods, and is a relatively safe and feasible therapeutic option in the treatment of selected patients with severe traumatic brain injury. Thus, further prospective controlled trials using induced hypothermia for longer periods than 48 h are warranted.

Consequences of high-dose steroid therapy for acute spinal cord injury

OBJECTIVE

High-dose Solu-Medrol (Upjohn, Kalamazoo, Mich) therapy has become standard care in the management of acute spinal cord injury (ASCI). This study attempts to define the adverse effects that Solu-Medrol therapy has on these patients.

DESIGN

Retrospective review with historical control.

MATERIALS AND METHODS

From May 1990 to April 1994, all patients with ASCI admitted within 8 hours of injury received high-dose Solu-Medrol per the National Acute Spinal Injury Study (NASCIS-2) protocol. Their demographic and outcome parameters were compared with those of a group admitted from March 1986 to December 1993 with an associated ASCI who received no steroid therapy.

MEASUREMENTS AND MAIN RESULTS

Steroid therapy was associated with a 2.6-fold increase in the incidence of pneumonia and an increase in ventilated and intensive care days. However, it was associated with a decrease in duration of rehabilitation and had no significant impact on other outcome parameters, including mortality.

CONCLUSIONS

Although the NASCIS-2 protocol may promote early infectious complications, it has no adverse impact on long-term outcome in patients with ASCIs.

Functional outcome after incomplete spinal cord injuries due to blunt injury

During a 3-year period, 19 patients with incomplete spinal cord injuries caused by blunt trauma were admitted to a single rural referral centre. The mean age was 50 years. Injury mechanisms included falls in eight, road traffic accidents in five, diving mishaps in two, and miscellaneous in four. The level of spinal cord injury was cervical in 11, thoracic in five, and thoracolumbar in three. Initial management included a standard high-dose methylprednisolone protocol for 24 h after injury in eight patients treated since May, 1990. Neurosurgical procedures were performed in 11 patients. There were three deaths, all in patients over 75 years of age with pulmonary complications. Of 16 survivors, 10 demonstrated significant functional neurological improvement by the time of hospital discharge, and 11 by late follow up. Complete recovery occurred in five of the survivors. Complications occurred in 11 patients, including pulmonary (nine), infectious (six), and gastrointestinal (three), but could not be associated specifically with the high-dose steroid protocol. In conclusion, incomplete spinal cord injuries after blunt injury were relatively uncommon in this setting. No significant increase in complications was observed after institution of the high-dose methylprednisolone protocol in May, 1990. However, pulmonary, gastrointestinal, and infectious complications were common. Of the 16 survivors, 11 demonstrated significant functional improvement. Mortality appeared to be related to advanced age and to pulmonary complications.

Clinicopathologic effects of a 21-aminosteroid compound (U74389G) and high-dose methylprednisolone on spinal cord function after simulated spinal cord trauma

A model simulating acute-compressive spinal cord trauma at the second lumbar spinal cord segment (100 g, 300 seconds) was used to evaluate the efficacy of a vehicle control, methylprednisolone sodium succinate (MPSS), and a 21-aminosteroid compound (U74389G). Dogs were allocated into one of five treatment groups (A to E) using ultrasonographic determination of spinal cord diameters to ensure even distribution of spinal cord diameters among the treatment groups. Initial dosages of the vehicle control (A), methylprednisolone (30 mg/kg of body weight) (B), or U74389G (30 mg/kg, 3 mg/kg, or 10 mg/kg of body weight) (C, D, or E, respectively) were administered intravenously 30 minutes after trauma. Dosages were reduced by one-half for 2 and 6 hour treatments. Then every 4 hours for 42 hours, dosages were reduced one-third and one-sixth from the original dose of methylprednisolone and U74389G, respectively. Neurological examinations were performed daily for 21 days. Histopathological examination of the traumatized spinal cord showed malacic and degenerative lesions. Although significant differences in some portions of the neurological and histopathologic examinations were observed, clinical efficacy for MPSS and U74389G could not be established in this model.

Antibiotic prophylaxis in dermatologic surgery

Antibiotic prophylaxis is generally administered either to prevent wound infection or to hinder the development of endocarditis. Although the use of antibiotics in certain circumstances to prevent wound infection can be straightforward, there are other circumstances in which the decision to use antibiotics is much less clear. Endocarditis prophylaxis has traditionally been based on the American Heart Association's guidelines, which do not cover dermatologic surgery. This article discusses the rationale and controversies surrounding the use of antibiotic prophylaxis for prevention of both wound infection and endocarditis, reviews the few studies that pertain to dermatology, and provides recommendations for antibiotic prophylaxis on a case-by-case basis for those who perform dermatologic surgery.

Peri-operative changes of cellular and humoral components of immunity with brain tumour surgery

Nosocomial infections, which are not uncommon in neurosurgical intensive care medicine, may possibly be favoured by an impairment of immunological competence of the patient. In a prospective observational trial, we investigated several parameters of cellular and humoral immunity in 32 patients before and after resection of an intracranial tumour. We quantified the effects of operative procedure, dexamethasone pretreatment, and tumour type. Dexamethasone alone causes an increase of neutrophilic granulocyte count and monocytes, whereas IgG and eosinophilic granulocytes decrease as well as lymphocytes. CD4+ T lymphocytes (T helper cells) and CD8+ T lymphocytes (T cytotoxic/suppressor cells) were more severely affected than B lymphocytes. Dexamethasone and operation in combination act synergistically on T lymphocytes and IgG, while no synergism is obvious in other clinical test parameters. The skin sensitivity reaction was depressed accordingly. With intracerebral tumours (gliomas WHO grades II to IV), levels of T helper cells and eosinophilic granulocytes were lower, and levels of IgM and neutrophilic granulocytes were higher than with benign extracerebral neoplasms. Postoperative nosocomial infections of the lower respiratory tract occurred almost exclusively in patients subject to severe depression of T helper cells.

The two-edged sword of large-dose steroids for spinal cord trauma

OBJECTIVE

In 1990, large-dose steroid administration was advocated in spine-injured patients to lessen neurologic deficits. The authors undertook both prospective and retrospective studies to evaluate the response of such profound pharmacologic intervention.

SUMMARY BACKGROUND DATA

Of all sources of nonfatal injury, spinal cord trauma remains the most devastating in both cost and impact on the quality of the patient's life. One study found that routine large-dose steroid administration after injury lessened the extent of neurologic injury. After uncommonly prompt and broad lay press publicity, this practice was widely accepted. Biased by knowledge of the known immunosuppressive effects of steroids, the authors suspected that pneumonia was both more frequent and severe in steroid-treated patients.

METHODS

Thirty-two patients with cervical or upper thoracic spinal injuries (C3-6, 20 patients; C6-7, 6 patients; and T1-6, 6 patients) were studied at an urban level I trauma center from January 1987 to February 1993. Complete spinal cord injury was present in 22 of 32 patients; 14 patients received steroids postinjury. There was no difference in mean age, cord level, age-adjusted injury severity score, or the percent of injury severity score caused by the spinal injury.

RESULTS

The length of hospital stay was longer in steroid-treated patients (S) than in nonsteroid (NS) patients, that is, 44.4 days versus 27.7 days, respectively (p = 0.065). Seventy-nine per cent of S patients had pneumonia compared with 50% of NS patients (p = 0.614). There was no statistical difference in the episodes of pneumonia per patient between the two groups (p > 0.05). Prospectively, the authors evaluated sequentially several parameters known to be important in human immune responses to bacterial challenges in nine S and five NS patients. In S patients, both the per cent and density of monocyte class II antigen expression and T-helper/suppressor cell ratios were lower than in NS patients. However, S patients did have an initially higher, earlier boost in some host defense parameters that rapidly declined, and their subsequent response was both blunted and delayed. These differences became even clearer when stratified according to cord level and incomplete versus complete cord status. Not surprisingly, infected patients, whether S or NS, had lower levels of monocyte antigen expression, CR3, and helper/suppressor ratios.

CONCLUSIONS

These data do not permit a judgment to be made whether neurologic status was improved by S administration. It is known that vital immune responses were adversely affected, that pneumonia was somewhat more prevalent, and that hospitalization was prolonged and costs therefore increased by an average of $51,504 per admission. Further clinical studies will be needed to determine to what extent these observations offset the putative benefits of large-dose steroids in the treatment of spinal trauma.

Current concepts in cerebral protection

In the past, physicians viewed ischemic injury as an irreversible event. Modern science has shown that this view is incorrect and that ischemic neuronal damage is an ongoing, active process that might be amenable to various therapies. Figure 2 illustrates some of the possible sites where these therapies might be active. Pending evidence of their effectiveness, cerebral protection can best be achieved by maintaining adequate CPP and CBF during periods when patients are at risk for cerebral ischemia, restoring perfusion after ischemia occurs, and optimizing the metabolic milieu of the ischemic penumbra.

Significant trends in the treatment of hepatic trauma. Experience with 411 injuries

Several significant advances in the treatment of hepatic injuries have evolved over the past decade. These trends have been incorporated into the overall treatment strategy of hepatic injuries and are reflected in experiences with 411 consecutive patients. Two hundred fifty-eight patients (63%) with minor injuries (grades I to II) were treated by simple suture or hemostatic agents with a mortality rate of 6%. One hundred twenty-eight patients (31%) sustained complex hepatic injuries (grades III to V). One hundred seven patients (83.5%) with grades III or IV injury underwent portal triad occlusion and finger fracture of hepatic parenchyma alone. Seventy-three surviving patients (73%) required portal triad occlusion, with ischemia times varying from 10 to 75 minutes (mean, 30 minutes). The mortality rate in this group was 6.5% (seven patients) and was accompanied by a morbidity rate of 15%. Fourteen patients (11%) with grade V injury (retrohepatic cava or hepatic veins) were managed by prolonged protal triad occlusion (mean cross-clamp time, 46 minutes) and extensive finger fracture to the site of injury. In four of these patients an atrial caval shunt was additionally used. Two of these patients survived, whereas six of the 10 patients managed without a shunt survived, for an overall mortality rate of 43%. Over the past 4 years, six patients (4.7%) with ongoing coagulopathies were managed by packing and planned re-exploration, with four patients (67%) surviving and one (25%) developing an intra-abdominal abscess. One additional patient (0.8%) was managed by resectional debridement alone and survived. During the past 5 years, 25 hemodynamically stable and alert adult patients (6%) sustaining blunt trauma were evaluated by computed tomography scan and found to have grade I to III injuries. All were managed nonoperatively with uniform success. The combination of portal triad occlusion (up to 75 minutes), finger fracture technique, and the use of a viable omental pack is a safe, reliable, and effective method of managing complex hepatic injuries (grade III to IV). Juxtahepatic venous injuries continue to carry a prohibitive mortality rate, but nonshunting approaches seem to result in the lowest cumulative mortality rate. Packing and planned reexploration has a definitive life-saving role when used adjunctively in the presence of a coagulopathy. Nonoperative management of select hemodynamically stable adult patients, identified by serial computed tomography scans after sustaining blunt trauma is highly successful (95-97%).

Severe cardiovascular adverse effects in association with acute, high-dose corticosteroid administration

Severe cardiovascular adverse reactions including death have been associated with high-dose intravenous corticosteroid therapy. Some of the patients appeared to have acute hypersensitivity reactions to the corticosteroid, with rashes and bronchospasm; other problems included arrhythmias and myocardial infarctions. Most of the patients had underlying renal disease and/or were undergoing renal transplantation. All of the patients having the cardiovascular reactions associated with the corticosteroid received individual doses of at least 250 mg of methylprednisolone or its equivalent. The doses were usually administered over a 30-minute period or less. A cause-effect relationship between high-dose corticosteroid therapy and severe cardiovascular reactions has not been scientifically proved by a controlled trial, but caution is advised when high-dose corticosteroid therapy is administered.

Hepatic trauma revisited

As stated in the introduction to this monograph, much has changed in the management of major hepatic injuries during the past 5 to 10 years. The major changes are summarized as follows: 1. Computed tomographic scanning is now the mainstay of diagnosis for hepatic injuries after blunt trauma and allows for nonoperative therapy in many patients with lacerations, intrahepatic hematomas, or subcapsular hematomas; 2. Realization that the time limit for application of the Pringle maneuver can be extended. 3. Recognition that fibrin glue appears to be a useful topical agent in preliminary clinical studies; 4. Use of hepatotomy with selective vascular ligation instead of mattress sutures for deep lacerations or to control hemorrhage from tracts of penetrating wounds; 5. Use of resectional débridement of devitalized tissue and selective vascular ligation instead of formal anatomical resection; 6. Use of an "omental pack" as a filler of deep cracks or hepatotomy sites instead of closure with mattress sutures; 7. Use of perihepatic packing in selected patients instead of resection when a coagulopathy or major subcapsular hematoma is present; 8. Discontinued use of perihepatic drains for minor or moderate hepatic injuries as long as discrete methods of selective vascular and biliary ligation have been used.

Prognostic factors for lower respiratory tract infections after brain-tumor surgery

Nosocomial infection of the lower respiratory tract is a frequent and serious complication after major operations. A 32% incidence of lower respiratory tract infections was found after brain-tumor surgery in 289 patients, with a 21% incidence of pneumonia. In 186 of these patients (Group A), five factors were identified which were associated with an increased risk of postoperative lower respiratory tract infection. These were: age, tumor type, cardiac insufficiency, preoperative disturbances of consciousness, and preoperative corticosteroid treatment. Based on these factors, a risk score was developed which correlated well with the incidence of infection in this group of patients. In a second group of patients (Group B), the derived risk score was applied and was found to possess a high degree of validity. As long as patients were intubated postoperatively, their freedom from infection decreased exponentially, with a half-life of 3.5 days.

A retrospective survey of treatment and mortality in aspiration pneumonia

A retrospective survey was conducted of all patients with severe aspiration pneumonitis requiring artificial ventilation in our Intensive Care Unit from 1982-1986 inclusive. Of 38 patients, 8 (21%) died. Five of these deaths were due to severe primary intracranial pathology, and occurred after complete or almost complete resolution of the pneumonitis. One death (2.5%) due to myocardial infarction was possibly related to aspiration, and 2 deaths (5%) were definitely related to aspiration. The 7.5% mortality related to aspiration is considerably lower than in previous clinical studies of severe aspiration pneumonia. There was only one death due to aspiration in patients under the age of 70. The mean arterial to alveolar oxygen tension ratio was 0.221, and the mean predicted mortality by apache II was 43%. Patients were managed with rapid intravascular volume restoration using crystalloid fluids, early ventilation, no steroids, and no immediate antibiotics. We conclude that with such management it is possible to achieve a low hospital mortality in severe aspiration pneumonia, particularly in young patients.

Dexamethasone therapy and endogenous cortisol production in severe pediatric head injury

A prospective randomised study was performed on 25 children aged 1.4 to 15.8 years with severe head injury (Glasgow Coma Scale less than or equal to 7) to determine the clinical effectiveness and the impact on endogenous cortisol production of high-dose steroid therapy. Thirteen patients (group 1) received dexamethasone 1 mg/kg/day during the first 3 days and 12 (group 2) not. All patients were treated with a standardized regimen. Urinary free cortisol was measured by radioimmunoassay, and the clinical data were recorded at hourly intervals. Outcome was assessed 6 months later using the Glasgow Outcome Scale. We found a higher frequency of bacterial pneumonias in the dexamethasone-treated patients (7/13 versus 2/12). Group 1 showed a suppression of endogenous cortisol production from day 1 to day 6. In group 2, mean free cortisol was up to 5-fold higher than under basal conditions. The results in group 2 showed that the endogenous steroid production reacts adequately to the stress of severe head injury. It probably is sufficient to elicit maximum glucocorticoid effects. There was no other statistically significant difference in the clinical and laboratory data between the two groups. We conclude that dexamethasone in high doses suppresses endogenous cortisol production up to 6 days and may increase the risk of bacterial infection without affecting the outcome or the clinical and laboratory data.

Hormonal responses to surgical stress

Surgical stress is associated with activation of both the HPA axis and the sympathetic nervous system. Emergence from anesthesia appears to be a far more potent stimulus for both of these axes than the surgery itself. Intraoperative HPA activation can be moderate in degree and the mild cortisol elevation observed is compatible with an uneventful perioperative course. This observation was confirmed in adrenalectomized nonhuman primates where a physiologic replacement dose of cortisol was both necessary and sufficient to tolerate surgical stress. Taken together these human and nonhuman primate data suggest that the role of glucocorticoids during surgery is primarily permissive. Catecholamines appear to act in synergy with glucocorticoids during surgical stress.

Stress and the pituitary-adrenal axis

The hypothalamo-pituitary-adrenal axis is controlled by complex regulatory mechanisms. Numerous factors such as CRF, vasopressin, oxytocin, angiotensin II and conceivably other hormones--all controlled by various substances acting on central locations--stimulate the release of the stress hormone ACTH. On the other hand, glucocorticoids inhibit the secretion of ACTH by acting at the hypothalamic and/or pituitary level. The release of ACTH is therefore the final outcome of the interactions between the hypothalamus, the adrenal gland and possibly other organs. The multimolecular nature of the factors responsible for the control of the pituitary-adrenal axis is an attractive hypothesis because of the great variety of stress stimuli. The various factors could have specific roles in various stress situations. They provide a highly sensitive mechanism regulating very finely the stress hormone in response to a whole variety of endogenous and exogenous stimuli. Depending on the type of stress, they may therefore singly or in combination affect the amount and duration of ACTH and steroid secretion. The released glucocorticoids may then produce their numerous effects on inflammatory and immunological processes, carbohydrate metabolism, shock and water balance. It has been postulated that these effects may be important in order to prevent host responses from over-reacting to stress and threatening homeostasis. However, proof of the necessity of the glucocorticoid hypersecretion in response to stress remains elusive.

Adaptation during surgical stress. A reevaluation of the role of glucocorticoids

Pharmacologic doses of glucocorticoids are administered to patients with adrenal insufficiency during operative procedures to prevent hemodynamic instability, cardiovascular collapse, and death. Since these supraphysiologic doses might not be necessary and might have adverse effects, we examined the effects of different doses of glucocorticoids on hemodynamic adaptation during surgical stress in adrenalectomized primates. Sham-adrenalectomized placebo-treated animals served as controls. Adrenalectomized monkeys were maintained for 4 mo on physiologic glucocorticoid and mineralocorticoid replacement. The adrenalectomized monkeys were then stratified into three groups receiving, respectively, subphysiological (one-tenth the normal cortisol production rate), physiological, or supraphysiological (10 times the normal cortisol production rate) cortisol (hydrocortisone) treatment. 4 d later a cholecystectomy was performed. The intraoperative hemodynamic and metabolic parameters, perioperative survival rates, and postoperative wound healing were compared. The subphysiologically treated group was hemodynamically unstable before, during, and after surgery and had a significantly higher mortality rate than control. In this group, arterial blood pressure was low, and the cardiac index, systemic vascular resistance index, and left ventricular stroke work index were all reduced, suggesting decreased cardiac contractility and blood vessel tone. In contrast, the physiologically replaced group was indistinguishable from either supraphysiologically treated animals or sham-operated controls. All groups had similar metabolic profiles and normal wound healing. These findings suggest that the permissive actions of physiologic glucocorticoid replacement are both necessary and sufficient for primates to tolerate surgical stress. Supraphysiological glucocorticoid treatment has no apparent advantage during this form of stress in the primate.