Variations in the response of interleukins in neurosurgical intensive care patients monitored using intracerebral microdialysis

OBJECT: The aim of this study was to make a preliminary evaluation of whether microdialysis monitoring of cytokines and other proteins in severely diseased neurosurgical patients has the potential of adding significant information to optimize care, thus broadening the understanding of the function of these molecules in brain injury. METHODS: Paired intracerebral microdialysis catheters with high-cutoff membranes were inserted in 14 comatose patients who had been treated in a neurosurgical intensive care unit following subarachnoidal hemorrhage or traumatic brain injury. Samples were collected every 6 hours (for up to 7 days) and were analyzed at bedside for routine metabolites and later in the laboratory for interleukin (IL)-l and IL-6; in two patients, vascular endothelial growth factor and cathepsin-D were also checked. Aggregated microprobe data gave rough estimations of profound focal cytokine responses related to morphological tissue injury and to anaerobic metabolism that were not evident from the concomitantly collected cerebrospinal fluid data. Data regarding tissue with no macroscopic evidence of injury demonstrated that IL release not only is elicited in severely compromised tissue but also may be a general phenomenon in brains subjected to stress. Macroscopic tissue injury was strongly linked to IL-6 but not IL- lb activation. Furthermore, IL release seems to be stimulated by local ischemia. The basal tissue concentration level of IL-lb was estimated in the range of 10 to 150 pg/ml; for IL-6, the corresponding figure was 1000 to 20,000 pg/ml. CONCLUSIONS: Data in the present study indicate that catheters with high-cutoff membranes have the potential of expanding microdialysis to the study of protein chemistry as a routine bedside method in neurointensive care.     

Neurochemical monitoring using intracerebral microdialysis during systemic haemorrhage

Summary Background. Intracerebral microdialysis is a sensitive tool to analyse tissue biochemistry, but the value of this technique to monitor cerebral metabolism during systemic haemorrhage is unknown. The present study was designed to assess changes of intracerebral microdialysis parameters both during systemic haemorrhage and after initiation of therapy. Methods. Following approval of the Animal Investigational Committee, 18 healthy pigs underwent a penetrating liver trauma. Following haemodynamic decompensation, all animals received a hypertonic-hyperoncotic solution and either norepinephrine or arginine vasopressin, and bleeding was subsequently controlled. Extracellular cerebral concentrations of glucose (Glu), lactate (La), glycerol (Gly), and the lactate/pyruvate ratio (La/Py ratio) were assessed by microdialysis. Cerebral venous protein S-100B was determined. Haemodynamic data, blood gases, S-100B, and microdialysis variables were determined at baseline, at haemodynamic decompensation, and repeated after drug administration. Results. Microdialysis measurements showed an increase of La, Gly, and La/Py ratio at BL Th compared to BL (mean ± SEM; La 2.4 ± 0.2 vs. 1.4 ± 0.2 mmol · l⁻¹, p < 0.01; Gly 37 ± 7 vs. 27 ± 6 μmol · l⁻¹, n.s.; La/Py ratio 50 ± 8 vs. 30 ± 4, p < 0.01), followed by a further increase during the therapy phase (La 3.4 ± 0.3 mmol · l⁻¹; Gly 69 ± 10 μmol · l⁻¹; La/Py ratio 58 ± 8; p < 0.001, respectively). Cerebral venous protein S-100B increased at decompensation and after therapy, but decreased close to baseline values after 90 min of therapy. Conclusions. In this model of systemic haemorrhage, changes of cerebral energy metabolism detected by intracerebral microdialysis indicated anaerobic glycolysis and degradation of cellular membranes throughout the study period.     

A method for monitoring intracerebral temperature in neurosurgical patients

Current interest in brain temperature and selective brain cooling makes a method allowing for continuous monitoring of intracerebral temperature in humans desirable. The authors describe a safe, simple, and reliable technique using a thermocouple of copper and constantan in combination with intraventricular monitoring of intracranial pressure for measurement of brain temperature in neurosurgical patients.     

Secondary insults during intrahospital transport of neurosurgical intensive care patients

Secondary insults occuring after injury have been prospectively assessed in seven head-injured patients who required intrahospital transfer to a computerized tomography unit for re-evaluation of their brain injury. During transportation the intracranial pressure, blood pressure, and arterial blood gases were monitored. A significant increase in intracranial pressure was observed during transport (p<0.01). The conclusion is that patients should be ventilated and have appropriate sedation and analgesia. This could provide some protection against secondary insults.     

Hyperthermia in the neurosurgical intensive care unit

OBJECTIVE: In patients with traumatic or ischemic brain injury, hyperthermia is thought to worsen the neurological injury. We studied fever in the neurosurgical intensive care unit (ICU) population using a definition common to surgical practice (rectal temperature >38.5 degrees C). We sought to determine fever incidence, fever duration, and peak temperature and to quantify the use of antipyretic therapy. We also attempted to determine the patient subgroups that are at highest risk for development of fever. METHODS: In a retrospective chart review of a 6-month period, all febrile episodes that occurred in a consecutive series of neurosurgical ICU patients in a university hospital setting were studied. A febrile episode was defined as a rectal temperature of at least 38.5 degrees C; an episode lasted until the temperature fell below this threshold. RESULTS: The 428 patients studied had 946 febrile episodes. Fever occurred in 47% of patients, with a mean of 4.7 febrile episodes in each febrile patient. Fevers occurred in more than 50% of patients who were admitted to the ICU for subarachnoid hemorrhage, a central nervous system infection, seizure control, or hemorrhagic stroke, but they occurred in only 27% of patients admitted for spinal disorders. Fevers occurred in 15% of the patients who stayed in the ICU less than 24 hours, but in 93% of those who remained longer than 14 days. Despite the use of antipyretic therapy for 86% of the febrile episodes, 57% lasted longer than 4 hours and 5% lasted longer than 12 hours. CONCLUSION: Fever is common in critically ill neurosurgical patients, especially those with a prolonged length of stay in the ICU or a cranial disease. If hyperthermia worsens the functional outcome after a primary ischemic or traumatic injury, as has been suggested by several studies of stroke patients, treatment of fever is a clinical issue that requires better management.     

Prospective survey on neurosurgical intensive care for patients with severe head injury

ＴＤｅｐａｒｔｍｅｎｔｏｆＮｅｕｒｏｓｕｒｇｅｒｙ ,ＧｅｎｅｒａｌＨｏｓｐｉｔａｌｏｆＴｉａｎｊｉｎＭｅｄｉｃａｌＵｎｉｖｅｒｓｉｔｙ ,Ｔｉａｎｊｉｎ 30 0 0 5 2 ,Ｃｈｉｎａ (ＹａｎｇＸＪ ,ＹａｎｇＳＹ ,ＷａｎｇＭＬａｎｄＧａｏＹＺ)ｈｅｍａｒｋｅｄｉｍｐｒｏｖｅｍｅｎｔｏｆｃｕｒａｔｉｖｅｏｕｔｃｏｍｅｆｏｒｓｅｖｅｒｅｈｅａｄｉｎｊｕｒｙｉｓａｓｃｒｉｂｅｄｔｏｕｎｄｅｒｓｔａｎｄｉｎｇｏｆｉｔｓｐａｔｈｏｐｈｙｓｉｏｌｏｇｙａｎｄａｄｏｐｔｉｎｇａｎｉｎｔｅｎｓｉｖｅａｐｐｒｏａｃｈｆｏｒｐ…     

神经外科重症患者有创与无创血压监测比较研究

目的分析神经外科重症患者有创血压测量(IBPM)与无创血压测量(NIBPM)值的差异性和相关性。方法选择神经外科术后重症患者61例,行IBPM和NIBPM配对监测,分别行3 977例次血压测量,并行配对t检验和直线相关与回归分析。结果在3 977例次血压测量中,经桡动脉IBPM 1 828例次,经足背动脉IBPM 2 149例次。桡动脉组和足背动脉组IBPM收缩压、平均动脉压显著高于NIBPM值(均P0.01);舒张压显著低于NIBMP值(均P0.01)。IBPM与NIBPM收缩压、舒张压和平均动脉压呈正相关(均P0.01)。结论IBPM与NIBPM存在相关性与差异性。神经外科重症患者进行IBPM同时间断辅以NIBPM,有助于确认和排除部分误差。     

神经外科ICU过渡护理标准化流程的制定及实施

目的提高神经外科ICU患者转出效率及安全性。方法将神经外科ICU患者1 176例按时间段分为对照组580例、观察组596例;患者由神经外科ICU转出至普通病房过渡护理期间,对照组采用常规交接方式,观察组制订和实施标准化流程实施交接。结果观察组转运期间患者病情变化、物品遗漏发生率及交接时间显著少/短于对照组(均P0.01),患者/家属满意度显著高于对照组(P0.01)。结论制定并实施标准化流程,有利于提高神经外科ICU患者转出工作效率和保障患者安全。     

Organ donation rates in a neurosurgical intensive care unit

OBJECT: The number of patients waiting for organ transplantation continues to grow, while organs are donated by very few of the thousands of potential donors who die every year. The authors' neurosurgical intensive care unit (NICU) has worked closely with coordinators from the local organ procurement organization (OPO) for many years. In this study, the authors analyze donation rates in the NICU and discuss factors that may be important in maximizing these rates. METHODS: All referrals from the NICU to the OPO from 1996 to 1999 were analyzed. Of the 180 referrals, 98 patients were found to be medically suitable as potential donors. Another 15 patients died of hemodynamic collapse shortly after admission to the NICU. If one assumes that all 15 patients would have been suitable donors, the unsuccessful resuscitation rate becomes 15 (13.3%) of 113. Of the 98 eligible donors, consent was obtained and organs or tissue were recovered in 72, yielding a successful organ procurement rate of 73.5%. CONCLUSIONS: Close working relationships among physicians, nurses, and OPO coordinators can result in higher donation rates than have been reported previously. Aggressive resuscitation and stabilization of all patients, early identification of potential organ donors, prompt declaration of brain death, and attempts by the OPO coordinator to build rapport with families are all important factors that may increase donation rates. Because most organ donors have sustained catastrophic intracranial events, neurosurgeons are uniquely positioned to influence organ donation policies at their hospitals and thus to salvage some benefit from tragic cases of overwhelming brain injury.     

Potential use of quantitative bedside CBF monitoring (Xe-CT) for decision making in neurosurgical intensive care

During a 3-year period, mobile xenon-computerized tomography (Xe-CT) for bedside quantitative assessment of cerebral blood flow was used as an integrated tool for decision making during the care of complicated patients in our neurosurgical intensive care units (NSICU), in an attempt to make a preliminary evaluation regarding the usefulness of this method in routine work in the neurosurgical intensive care. With approximately 200 studies involving 75 patients, we identified six different categories where the use of bedside Xe-CT significantly influenced (or, with more experience, could have influenced) the decision making, or facilitated the handling of patients. These categories included identification of problems not apparent from other types of monitoring, avoidance of adverse effects from treatment, titration of standard treatments, evaluation of the vascular resistance reserve, assessment of adequate perfusion pressure and better utilization of resources from access to the bedside cerebral blood flow (CBF) technology. We conclude that quantitative bedside measurements of CBF could be an important addition to the diagnostic and monitoring arsenal of NSICU-tools.     

Pharmacokinetic monitoring of nephrotoxic antibiotics in surgical intensive care patients

An assessment of the dosage regimens prescribed for potentially nephrotoxic antibiotics (amikacin, gentamicin, tobramycin, and vancomycin) was undertaken on surgical intensive care unit patients. In 166 patients, 224 series of blood antibiotic level determinations were obtained. Using individualized pharmacokinetic determinations, the regimens were revised as necessary to provide optimal blood levels. Because of variable volumes of distribution and elimination rates, dosing according to standard clinical guidelines produced significantly lower peaks than did pharmacokinetically determined regimens for gentamicin (p less than 0.005), tobramycin (p less than 0.0001), and vancomycin (p less than 0.05). Importantly, fewer patients achieved therapeutic levels with the original regimens than with the revised regimens for gentamicin (9% vs. 91%, p less than 0.0005), tobramycin (27% vs. 92%, p less than 0.0001), and vancomycin (30% vs. 69%, p less than 0.0001). Individualized pharmacokinetic analysis of potentially nephrotoxic antibiotics in critically ill patients is essential if therapeutic, non-toxic levels are to be maintained.     

Long-term monitoring of renal function in poly-traumatized intensive care patients

INTRODUCTION: For the long-term monitoring of kidney function, polytraumatized patients were examined and routine as well as specialized parameters were compared. MATERIALS AND METHODS: 30 patients of the Surgical Intensive Care Unit (ICU) were examined daily over the entire period they stayed in the ICU. The patients were retrospectively classified as either survivors or deceased patients. Group 1 consisted of 20 patients who resided in the ICU for 11-15 (Median 14) days before they could be transferred to a normal hospital unit. Group 2 consisted of 10 patients who had passed away after 13-18 (Median 16) days in the ICU. In addition to the routine parameters diuresis, serum creatinine and serum urea, specialized parameters for kidney function including the excretion rates of alpha1-microglobulin (alpha1-MG), N-Acetyl-beta-D-glucosaminidase (NAG), angiotensinase A (ATA) and immunoglobulin G (IgG) were determined. RESULTS: Similar biometric data were shown by all patients at admission into the ICU, but differences did exist regarding the Revised Trauma Score, Injury Severity Score and the APACHE-II-Score. In the period between the 5th and 8th day of intensive treatment almost all patients showed pathological excretion rates of tubular and glomerular parameters whereby no increased frequency of unusual events could be determined at these time-points. CONCLUSION: During treatment in the ICU, all examined patients showed at times pathological excretion rates of specialized kidney function parameters. Such transient damage was only apparent in a few of the patients when the standard parameters serum creatinine and serum urea were employed. In 90% of the surviving patients the kidney parameters had normalized until the time they were transferred, indicating that such parameters reflected the general state of health of these patients.     

“Medical decision making” for repeated computed tomography in neurosurgical intensive care patients

Multiple CT investigations in critical ill neurosurgical patients are useful for monitoring the course of the illness and for the early detection of complications. CT's, however, are expensive and require transportation of the patient, which is often inconvenient and, in some cases, dangerous. The decision to perform CT scanning should be based on the quantitative knowledge of potential benefits and harms (as well as costs) of the procedure. In a prospective trial, in which 59 such decisions were considered, we found it to be absolutely necessary to order a CT-investigation whenever neurological deterioration occurs. Even in patients not showing changes of neurological symptoms, about 30% of CT findings gave reason for therapeutic intervention. Thus, in critical ill neurosurgical patients, especially in those under sedative medication and artificial ventilation, neurological findings alone are insufficient as sole criteria for the decision to order a CT scan. To optimize this decision, more sensitive indicators of deterioration are needed.     

Cerebral microdialysis combined with single-neuron and electroencephalographic recording in neurosurgical patients. Technical note.

Monitoring physiological changes in the brain parenchyma has important applications in the care of neurosurgical patients. A technique is described for measuring extracellular neurochemicals by cerebral microdialysis with simultaneous recording of electroencephalographic (EEG) and single-unit (neuron) activity in selected targets in the human brain. Forty-two patients with medically intractable epilepsy underwent stereotactically guided implantation of a total of 423 intracranial depth electrodes to delineate potentially resectable seizure foci. The electrodes had platinum alloy contacts for EEG recordings and four to nine 40-microm microwires for recording single-unit neuron activity. Eighty-six electrodes also included microdialysis probes introduced via the electrode lumens. During monitoring on the neurosurgical ward, electrophysiological recording and cerebral microdialysis sampling were performed during seizures, cognitive tasks, and sleep-waking cycles. The technique described here could be used in developing novel approaches for evaluation and treatment in a variety of neurological conditions such as head injury, subarachnoid hemorrhage, epilepsy, and movement disorders.