Rohrer's constant, K2, as a factor of determining inspiratory resistance of common adult endotracheal tubes.

The aim of the study was to calculate the in vitro inspiratory resistance (R(ETT)) of adult endotracheal tubes (ETT), via the end-inspiratory occlusion method, and to apply this method in vivo in order to estimate R(ETT) value in real time. By plotting R(ETT) over inspiratory flow (V) and calculating Rohrer's coefficients of linear and nonlinear resistance, K1 and K2 respectively, we determined the resistive behaviour of each ETT. Peak and plateau pressures were recorded at both proximal and distal sites of the ETT after applying a three-second occlusion under constant flow. Distal pressure was obtained via an intraluminal catheter R(ETT) was calculated as (P(peak) - P(plateau))/(V), at both sites. R(ETT) value resulted from the difference R(proximal) - R(distal). Graph R(ETT) over (V) was plotted and Rohrer's constants were calculated by the method of least squares. For ETTs with inner diameter 9.0, 8.5, 8.0, 7.5, 7.0 and 6.5 mm, K2 was 2.42, 3.05, 4.65, 6.01, 9.17 and 12.80 cmH2O/l/s, respectively. The intraluminal catheter increased R(ETT) No.7.0 by an average of 49%. Finally, ten patients with partially obstructed ETTs were tested and K2 in vivo constants found to be higher than their corresponding in vitro values (P value 0.00012). Therefore, knowing the performing size of an ETT may help the clinicians identify ETT obstruction and deal with weaning problems.

Procalcitonin as an early indicator of outcome in sepsis: a prospective observational study.

This study explores the role of procalcitonin (PCT) in predicting the outcome of sepsis. In a prospective multicentre observational investigation, blood was sampled within 24 h of onset of sepsis in 1156 hospitalised patients; 234 were in the intensive care unit (ICU) at the point of presentation of sepsis while 922 were not. PCT was estimated in serum by the ultrasensitive Kryptor assay in a double-blinded fashion. Among patients outside the ICU, mortality was 8% in those with PCT ≤0.12 ng/mL but 19.9% in those with PCT >0.12 ng/mL [P<0.0001, odds ratio (OR) for death: 2.606; 95% confidence interval (CI): 1.553-4.371]. Among patients whose sepsis presented in ICU, mortality was 25.6% in those with PCT ≤0.85 ng/mL but 45.3% in those with PCT >0.85 ng/mL (P=0.002; OR for death: 2.404; 95% CI: 1.385-4.171). It is concluded that PCT cut-off concentrations can contribute to predicting the outcome of sepsis and might be of particular value in identifying patients who would benefit from ICU admission.

Serum of patients with septic shock stimulates the expression of Trem-1 on U937 monocytes.

OBJECTIVES: To describe the concentrations of sTREM-1 in patients with sepsis and to explore the effects of their serum on the expression of TREM-1 on U937 monocytes. METHODS: Blood was sampled at regular time intervals in 56 patients with sepsis. Concentrations of tumour necrosis factor-alpha (TNFalpha), interleukin-1beta (IL-1alpha), IL-6, IL-8, IL-10 and IL-12p70 and sTREM-1 were measured. U937 monocytes were incubated in the presence of serum at sepsis onset. RESULTS: Median sTREM-1 concentration on day 1 for patients with septic shock was 915 pg/ml and 228.5 pg/ml for those without shock (p = 0.002). TNFalpha, IL-1alpha, IL-6, IL-8 and IL-10 did not differ between them. A positive correlation was found between changes of sTREM-1 and SOFA scores from day 1 to 7. Sera of patients with septic shock evoked a significant increase of the expression of TREM-1. The concentrations of TNFalpha and IL-8 in supernatants increased only after stimulating with sera of patients without shock, but not after stimulating with sera of patients with shock. CONCLUSIONS: Levels of sTREM-1 correlated with sepsis severity. sTREM-1 is considerably higher in patients with shock compared to patients without shock. The serum of shocked patients could stimulate the expression of TREM-1 on U937 monocytes.

Wavelet analysis of head acceleration response under dirac excitation for early oedema detection.

The present work deals with the application of an innovative in-house developed wavelet-based methodology for the analysis of the acceleration responses of a human head complex model as a simulated diffused oedema progresses. The human head complex has been modeled as a structure consisting of three confocal prolate spheroids, whereas the three defined regions by the system of spheroids, from the outside to the inside, represent the scull, the region of cerebrospinal fluid, and the brain tissue. A Dirac-like pulse has been used to excite the human head complex model and the acceleration response of the system has been calculated and analyzed via the wavelet-based methodology. For the purpose of the present analysis, a wave propagation commercial finite element code, LS-DYNA 3D, has been used. The progressive diffused oedema was modeled via consecutive increases in brain volume accompanied by a decrease in brain density. It was shown that even a small increase in brain volume (at the level of 0.5%) can be identified by the effect it has on the vibration characteristics of the human head complex. More precisely, it was found that for some of the wavelet decomposition levels, the energy content changes monotonically as the brain volume increases, thus providing a useful index of monitoring an oncoming brain oedema before any brain damage appears due to uncontrolled intracranial hypertension. For the purpose of the present work and for the levels of brain volume increase considered in the present analysis, no pressure increase was assumed into the cranial vault and, associatively, no brain compliance variation.

Immunomodulatory effect of three-day continuous administration of clarithromycin for experimental sepsis due to multidrug-resistant Pseudomonas aeruginosa.

Based on former animal studies showing the effect of clarithromycin in experimental sepsis by multidrug-resistant Pseudomonas aeruginosa following administration of single doses, the significance of its administration for three consecutive days was evaluated. Acute pyelonephritis was induced in 20 rabbits after inoculation of the test isolate in the renal pelvis. Therapy was administered upon signs of sepsis in group B; A served as control. Survival was recorded; monocytes were isolated for determination of ex vivo TNFalpha secretion. Quantitative cultures of organs were performed after death. Mean survival of groups A and B was 2.65 and 7.95 days respectively. At 24 hours, serum malondialdehyde of group B, which is an index of the oxidant status in serum, was lower than A. Ex vivo release of TNFalpha by the isolated monocytes of group B was lower than A at 3.5 and 48 hours. Tissue bacterial load was similar in two groups after animal death. It is concluded that clarithromycin possessed considerable immunomodulatory effects restraining release of TNFalpha from blood monocytes.

Stimulation of monocytes is a pathway involved in systemic inflammatory response following haemorrhagic shock resuscitation: the effect of hypoxaemic resuscitation.

The present study was designed to investigate whether serum of animals subjected to hypoxaemic resuscitation from haemorrhagic shock may be a weak stimulant for monocytes or not. Twenty rabbits were subjected to haemorrhagic shock after blood exsanguination; resuscitation was performed by infusion of the shed blood in eight rabbits under normoxaemic conditions (NormoxRes) and in 12 under hypoxaemic conditions (HypoxRes); seven rabbits were subjected to sham operation. Malondialdehyde (MDA) and tumour necrosis factor (TNF)-alpha were estimated in serum at serial time intervals; the serum was applied for stimulation of U937 monocytes with or without the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580. Expression of triggering receptor expressed on myeloid cells-1 (TREM-1) on U937 was also assessed by flow cytometric analysis. Death supervened in four animals of the NormoxRes (50%) and in one animal of the HypoxRes group (8.33%, P: 0.032). Serum levels of TNF-alpha and MDA were higher in NormoxRes compared to HypoxRes animals. Expression of TREM-1 on U937 monocytes was similar after stimulation with serum sampled from both groups. Concentrations of interleukin (IL)-1beta, IL-6 and IL-8 of monocyte supernatants were higher after stimulation with serum of NormoxRes than HypoxRes rabbits. Production of cytokines after stimulation with serum was decreased significantly after addition of SB203580. It is concluded that stimulation of monocytes may contribute to the generation of the systemic inflammatory response during reperfusion after ischaemia. Lower stimulation of the p38 MAPK-mediated production of IL-1beta, IL-6 and IL-8 by monocytes may be implicated as an explanation for the benefits shown for the host when resuscitation is performed under hypoxaemic conditions.

Early apoptosis of blood monocytes is a determinant of survival in experimental sepsis by multi-drug-resistant Pseudomonas aeruginosa.

Apoptosis of blood monocytes was studied in experimental sepsis by multi-drug-resistant Pseudomonas aeruginosa. Thirty-six rabbits were used, divided into the following groups: A (n = 6), sham; B (n = 6), administered anaesthetics; and C (n = 24), acute pyelonephritis induced after inoculation of the test isolate in the renal pelvis. Blood was sampled at standard time intervals for estimation of tumour necrosis factor (TNF)-alpha and isolation of monocytes. Half the monocytes were incubated and the other half was lysed for estimation of the cytoplasmic activity of caspase-3 by a kinetic chromogenic assay. No animal in groups A and B died; those in group C were divided into two subgroups, CI (n = 8) with present activity of caspase-3 of blood monocytes at 3.5 h and CII (n = 16) with absent activity. Their median survival was 2.0 and 3.5 days, respectively (P = 0.0089). Ex vivo secretion of TNF-alpha from monocytes was higher by monocytes of subgroup CII than subgroup CI at 3.5 h (P = 0.039) and of group A than CII at 48 h (P = 0.010). Median change of caspase-3 activity between 3.5 and 24 h of sampling was 56.1 and -5.8 pmol/min per 10(4) cells for subgroups CI and CII (P = 0.040), respectively. Respective changes between 3.5 and 48 h were 28 981.0 and 0 pmol/min per 10(4) cells (P = 0.036). Early induction of apoptosis in blood monocytes is of prime importance for the survival of the septic host and might be connected to changes of monocyte potential for the secretion of TNF-alpha.

A new method for the early diagnosis of brain edema/brain swelling. An experimental study in rabbits.

The aim of the present work is to develop a non-destructive, non-invasive technique for the early diagnosis of an oncoming brain edema based on the variation of vibration characteristics of the head system (i.e. eigenfrequency spectrum and modal damping). Besides the theoretical model that supports the basic principle, the proposed technique has been verified experimentally in animal tests. The advantage of such an approach is that the relative information is available well in advance an increase of intracranial pressure is detected. The uncontrolled intracranial hypertension is associated with increased mortality or vegetative state in head trauma. Traumatic lesions located on temporal lobe render particularly impeding the transtendorial herniation. From the medical point of view, intracranial pressure (ICP) monitoring represents an effective way for early consideration of neurological decompensation in various neurosurgical conditions particularly in the head-injured setting. However, the use of ICP monitoring is not an effective way of brain edema detection, since ICP increase very often causes irreversible problems to the patient's brain. Therefore, the determination of an earlier, less invasive and more sensitive indicator of the oncoming intracranial hypertension and of the impeding neurological deterioration is of profound importance. The present work aims at experimental verification of both eigenfrequency shifting and modal damping increase of the spectral response of the head system of rabbits, wherever a mass increase in the content of cranial shell appears. The conducted analysis concludes that the eigenfrequency spectrum and its modal damping characteristics are sufficiently sensitive parameters in order to characterize mass increase in the cranial shell. Therefore the combination of both the above parameters could be used with confidence for the early diagnosis of brain edema.

Sarcomas of the head and neck. Results from the treatment of 25 patients.

AIMS: Head and neck sarcomas comprise a heterogenous and biologically diverse group of rare neoplasms. In an effort to clarify some of the obscure clinical behavior of head and neck sarcomas, we present our experience and review the relevant literature. METHODS: Retrospective analysis of patients with histologically proven head and neck sarcomas treated in a tertiary Hospital Department between 1992 and 2002. RESULTS: During this period, 25 patients with head and neck sarcomas were registered. Follow-up ranged from 8 to 144 months. Twenty-three patients were treated with surgery as the primary modality; 14 were treated by surgery alone. Clear margins were obtained in all of them and local control was achieved in 12/13. The 2- and 5-year survival rates for the entire group were 80 and 40%, respectively. Mean overall survival time of our patients was 62 months (median 52 months). CONCLUSIONS: Surgical treatment remains the cornerstone of therapeutic management of head and neck sarcomas.

The frequency and distribution of mast cells in pleomorphic adenomas of salivary glands.

AIM: To investigate whether the frequency and distribution of mast cells (MCs) in pleomorphic adenomas (PAs) of major and minor salivary glands justifies the suggestion that there exists an association between MCs and mucoid stromal changes in PAs. METHODS: The material consisted of 22 cases of pleomorphic adenoma (eight arising in major and 14 in minor salivary glands) and a control group represented by five cases of monomorphic adenoma (MA). Representative 3-microm thick, paraffin-embedded sections were stained with H&E and Azur A. Computer-aided image analysis was performed in order to evaluate the relative surface area occupied by epithelial and connective tissue components, as well as the absolute number of MCs. RESULTS: According to our findings, PAs from minor salivary glands contain significantly greater numbers of mast cells compared with tumours from major glands. Additionally, the distribution of MCs within the stromal connective tissue appeared not to be random. CONCLUSION: It is possible that differences in the pattern of connective tissue might influence the actual concentration of MCs and that these differences are responsible for the observed variations between major and minor gland PAs.

Hypoxaemic reperfusion ameliorates the histopathological changes in the pig brain after a severe global cerebral ischaemic insult.

BACKGROUND AND PURPOSE: We have recently shown that hypoxaemic reperfusion, after an ischaemic brain insult, improves neurological outcome and decreases lipid peroxidation. In the present study, we investigated the effect of hypoxaemic reperfusion on brain histopathological changes. METHODS: Sixteen pigs subjected to a 10-min global cerebral ischaemia were either hypoxaemically (PaO2 = 35 mmHg, hypoxaemic reperfusion (HR) group, n = 8) or hyperoxaemically (PaO2 > 300 mmHg, control (C) group, n = 8) reperfused. The brains were removed 24 h after reperfusion and six neuropathological abnormalities were evaluated blindly and scored semi-quantitatively (0: normal to 3: severe injury) on eight representative regions of the brain. The overall cumulative score of the abnormalities and their regional prevalence, as well as the neurological outcome, were compared between the two groups. RESULTS: The neuronal degeneration, assessed in terms of cumulative score (P = 0.002) and regional prevalence (P = 0.025 to P = 0.041), was lower in the HR group than in the C group. Spongy degeneration attained statistically significant difference only in cerebellum (P = 0.002) and inflammation only in hippocampus (P = 0.046) but the difference in the cumulative score of these abnormalities was not statistically significant. The difference of the three neurological assessments over time was statistically significant between the two groups, i.e. after resuscitation (P = 0.001), at 8 h (P = 0.006) and at 24 h (P = 0.001) after reperfusion. CONCLUSIONS: Hypoxaemic reperfusion during resuscitation from a severe global ischaemic cerebral insult is associated with statistically significantly fewer histopathological changes of the brain than in controls. This is associated with a superior neurological outcome.

The effect of hypoxemic reperfusion on cerebral protection after a severe global ischemic brain insult.

BACKGROUND AND PURPOSE: Reactive oxygen species contribute to membrane lipid peroxidation and neuronal death and have been implicated in anoxic encephalopathy. We tested whether hypoxemic reperfusion (HR) after global cerebral ischemia would improve neurological recovery. METHODS: Two groups of pigs (n = 11 in each group) were subjected to a model of a 10-min global cerebral and systemic ischemia to compare the effect of hypoxemic reperfusion (group HR) with the classical hyperoxemic control (group C). A third group not subjected to ischemia served as control to the control group (n = 6, group CC), but received hyperoxygenation at the respective period of reperfusion. The outcome was evaluated by means of neurological assessment and the extent of lipid peroxidation measuring the plasma malonaldehyde (MDA) together with hydroxyalkenals (HALK). RESULTS: Animals of group HR exhibited a significantly superior neurological outcome compared with those of group C at all three consecutive assessments after reperfusion (post-resuscitation P = 0.006, at 8 h P = 0.003, and at 24 h P = 0.007). The levels of MDA and HALK are lower in the HR group than in group C (P = 0.029). Additionally, in the CC group these molecules increased significantly early at hyperoxygenation (P = 0.02). A faster lactate metabolism in the HR group was observed during reperfusion, though non-significant. CONCLUSIONS: Hypoxemic reperfusion during resuscitation from a severe global ischemic cerebral insult improves the neurological outcome compared with classic hyperoxemic reperfusion. This is additionally confirmed by the decreased production of the molecules of lipid peroxidation. In the absence of preceding ischemia, these molecules may increase by simple over-oxygenation.

Prevention of infection in multiple trauma patients by high-dose intravenous immunoglobulins.

OBJECTIVE: To investigate the activity of intravenous immunoglobulin (IVIG) as a prophylactic agent against infection in trauma victims. DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: A 20-bed university intensive care unit. PATIENTS: Thirty-nine trauma patients with injury severity scores (ISSs) of 16-50. INTERVENTIONS: Penicillin was given at the time of admission and continued at least until day 4. Twenty-one patients received IVIG and 18 patients received human albumin at 1 g/kg in four divided doses (days 1, 2, 3, and 6). The two groups had similarities in age, gender, Acute Physiology and Chronic Health Evaluation II score, risk of death, and Glasgow Coma Scale score, but differing ISSs (p = .02), at the time of admission. Blood was collected on days 1, 4, and 7. MEASUREMENTS AND MAIN RESULTS: Clinical variables related to infection were recorded. The complement components C3c, C4 and CH50, IgG, and the fractions of IgG were measured. The serum bactericidal activity (SBA) was assessed at 37 degrees C (98.6 degrees F) and 40 degrees C (104.0 degrees F) at the time of admission and during the course of IVIG administration. Controlling for ISS, IVIG-treated patients had fewer pneumonias (p = .003) and total non-catheter-related infections (p = .04). Catheter-related infections (p = .76), length of stay in the intensive care unit, antibiotic days, and infection-related mortality did not differ between the two groups. A significantly increased trend in IgG and its subclasses was shown on days 4 and 7 in the IVIG group but not in the control group (p<.000001). No important differences were noted in complement fractions. The SBA of the groups was similar on day 1, but significantly higher on days 4 and 7 (p<.000001) in the IVIG group, remaining so controlling for complement and ISS. SBA was higher at 40 degrees C (104.0 degrees F) compared with 37 degrees C (98.6 degrees F) (p<.0001) under all three conditions. In both groups, low SBA (on days 1, 4, and 7) was associated with increased risk of pneumonia (p<.01) and non-catheter-related infections (p = .06 for day 1; p<.01 for days 4 and 7). CONCLUSIONS: Trauma patients receiving high doses of IVIG exhibit a reduction of septic complications and an improvement of SBA. Early SBA measurement may represent an index of susceptibility to infection.

Brain eigenfrequency shifting as a sensitive index of cerebral compliance in an experimental model of epidural hematoma in the rabbit: preliminary study.

OBJECTIVE: To verify brain eigenfrequency shifting after the occurrence of a lesion producing mass effect into the cranial vault. DESIGN: Experimental animal study. SETTING: Laboratory of experimental surgery affiliated with a university critical care department. SUBJECTS: Six adult male New Zealand white rabbits. INTERVENTIONS: A Camino ICP monitor was placed in the parenchyma, and a 5-Fr balloon-tipped catheter and accelerometer were placed into the epidural space. MEASUREMENTS: Before and after the introduction of successive 0.1-mL increments of autologous blood into the balloon, intracranial pressure (ICP) was recorded along with the accelerometer signal obtained during free vibration of the skull triggered by a calibrated hammer. Fast Fourier transformation of the digitized signal provided the eigenfrequency spectrum. The eigenfrequency showing the sharpest decrease after the initial 0.1-mL volume addition was considered as the best frequency, and its variation in response to subsequent 0.1-mL increments represents the brain eigenfrequency shifting. MAIN RESULTS: Brain eigenfrequency shifting to lower values occurs for small blood volume increments (up to 0.2 mL). When volume addition becomes >0.3 mL, brain eigenfrequency shifting to higher values is exhibited. The decrease in best frequency after the initial introduction of 0.1 mL is statistically significant (p = .003), in a range of volume in which no significant intracranial pressure difference appears. The respective variation of ICP is explained using a quadratic curve. For volumes of 0 to 0.1 mL, the change in ICP is not statistically significant (p = .08). CONCLUSIONS: Changes of the brain's physical characteristics by mass addition in the cranial vault can be expressed by brain eigenfrequency shifting. The method seems advantageous because it reliably detects mass additions at low levels where no ICP change occurs. Additionally, it provides serial measurements, and it is less invasive than the currently used methods for intracranial compliance.

The regional production of cytokines and lactate in sepsis-related multiple organ failure.

In order to explore whether an organ-specific pattern in cytokine and lactate concentrations exists in patients with multiple organ failure (MOF), we measured the cytokines interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha), and lactate in blood taken from the hepatic vein, pulmonary capillaries, and peripheral veins of 10 patients with MOF with hepatic involvement (MOF-HI), eight patients with MOF and adult respiratory distress syndrome (MOF-ARDS), and five head-injured patients (controls). Ten additional patients participated in a study of arteriovenous pulmonary concentration gradients of these substances. For statistical analysis, nonparametric tests and analysis of variance (ANOVA) were used. The regional concentrations of these substances exhibited a different pattern in the two MOF groups. In the MOF-HI group, mean +/- SD cytokines IL-1beta and IL-6 (pg/ml) were respectively 216 +/- 100 and 461 +/- 343 in the hepatic sinusoidal blood; 149 +/- 52 and 293 +/- 204 in pulmonary capillary blood; and 148 +/- 105 and 234 +/- 162 in peripheral venous blood. In the MOF-ARDS group the corresponding levels were 180 +/- 103 and 235 +/- 124; 235 +/- 94 and 280 +/- 108; and 130 +/- 77 and 194 +/- 127. The TNF-alpha levels also exhibited the same pattern. The mean +/- SD corresponding levels (mmol/L) for lactate in the MOF-HI group were 3.1 +/- 1.8, 1.5 +/- 0.3, and 1.2 +/- 0.6, and in the MOF-ARDS group were 1.1 +/- 0.9, 1.8 +/- 1.1, and 1.0 +/- 0.2, respectively. The differences in the levels of all substances between the liver and lungs in the two MOF groups were statistically significant (p < 0.003). In the study of transpulmonary gradients it was shown that the levels of cytokine and lactate were lower in arterial blood than in mixed venous blood in MOF-HI patients, whereas the opposite was true in MOF-ARDS patients. In this study, we found that in MOF, cytokines and lactate are secreted from the most severely affected organs.