Limitations of volumetric indices obtained by trans-thoracic thermodilution

Transthoracic thermodilution (TTT) measures cardiac output without the need for right heart catheterization. In addition, two volumetric hemodynamic indices have been derived from the mathematical analysis of the TTT curve: the global end diastolic volume (a quantitative measure of cardiac preload) and the extravascular lung water volume (a quantitative measure of pulmonary edema). Despite the undeniable appeal of these two novel parameters, uncertainty exists regarding both the validity of their mathematical derivation and their physiological significance. This concise review attempts to discuss such concerns.

Daily monitoring of biomarkers of sepsis in complicated long-term ICU-patients: can it support treatment decisions?

BACKGROUND

Diagnosis/grading of infection and the systemic response to infection may be difficult on admission to the intensive care unit, but it is even more complicated for severely ill patients with long intensive care stays. The ACCP-SCCM criteria are difficult to apply for such patients, and objective, validated biomarkers would be of great use in this setting.

METHODS

Long-term (>6 days) critically ill patients in the general ICU of University Hospital were prospectively enrolled in the study. All patients were assessed daily by the attending physician using the ACCP-SCCM classification. C-reactive protein (CRP, mg/dL), procalcitonin (PCT, ng/mL), and interleukin-6 (IL-6, pg/mL) of daily stored sera were measured after each patient's discharge. After discharge, an independent, overall clinical evaluation and an a posteriori ACCP-SCCM classification were chosen as the reference standard for all comparisons. The assessor was aware of the patient's clinical course but was blinded to levels of biomarkers.

RESULTS

We studied clinical variables and biomarkers of 26 patients over a total of 592 patient days. The day-by-day ACCP-SCCM classification of the attending physician overestimated the severity of the inflammatory response to infection. The diagnostic discriminative ability of severe-sepsis/septic-shock for PCT was high (ROC area 0.952 [0.931-0.973]) and had a best threshold value of 1.58 (83.7% sensitivity, 94.6 % specificity). IL-6 had better discriminative ability than CRP, but both were worse than PCT.

CONCLUSION

PCT > 0.43 ng/mL could add to the clinical propensity for sepsis vs. SIRS not related to infection. Values higher than 1.58 ng/mL may support the bedside clinical diagnosis of severe-sepsis. PCT between 0.5 and 1.0 suggest tight daily monitoring of clinical conditions and re-evaluation of PCT.

Classification of a traumatic brain injury: the Glasgow Coma scale is not enough

BACKGROUND

Classifying the severity of a traumatic brain injury (TBI) solely by means of the Glasgow Coma scale (GCS) is under scrutiny, because it overlooks other important clinical signs. Clinicians treating patients with acute TBI are well placed to suggest which variables, in addition to the GCS, should concur in a new classification of TBI.

METHODS

In Italy, acute TBI patients are treated by anaesthetists, and so we asked them, in a questionnaire survey, to rate the weight they give to the GCS and to other clinical variables in their approach to TBI. Because sedation may underestimate GCS scores, we also inquired whether anaesthetists select sedatives that allow drug-free GCS scores. The questionnaire was distributed to 1334 anaesthetists attending courses on neurotrauma; the response rate was 63%.

RESULTS

Two thirds of the respondents believe that the definition of severe TBI should include, in addition to GCS scores, pupil reactivity to light and computer tomogram (CT) findings, the variables that guide Italian anaesthetists in TBI management. Most respondents (68.2%) administer sedation which allows prompt neurological evaluation and reliable GCS scoring. A minority of respondents (9.3%) withhold or antagonize sedation, delay tracheal intubation or allow patient-ventilator asynchrony.

CONCLUSIONS

Italian anaesthetists would welcome a definition of TBI severity that includes CT findings and pupil reactivity in addition to the GCS.

A European survey of noninvasive ventilation practices

Although noninvasive ventilation (NIV) is becoming very popular, little is known about its pattern of clinical and technical utilisation in different environments. We conducted a web-based survey in Europe to identify the perceived pattern of NIV utilisation and the reason for choosing a specific ventilator and interface type in four common clinical scenarios: acute hypercapnic respiratory failure (AHRF), cardiogenic pulmonary oedema (CPE), de novo hypoxic respiratory failure and weaning/post-extubation failure (W/PE). A response was obtained from 272 (51.3%) out of 530 selected European physicians involved in NIV practice. The NIV utilisation rate was higher for pulmonologists than intensivists/anesthesiologists (p<0.05). The most common indication for all the physicians was AHRF (48%). Physicians were more likely to use NIV dedicated ventilator in AHRF and CPE and an intensive care unit (ICU) ventilator with NIV module in de novo hypoxic respiratory failure and W/PE, mainly because of the possibility of using the double circuit and inspiratory oxygen fraction control. Overall, the oro-nasal mask was the most frequently used interface, irrespective of clinical scenarios. The use of NIV in Europe is generally relatively high, especially among pulmonologists and in AHRF. Dedicated NIV ventilators and ICU ventilators with NIV modules are preferably in AHRF and in de novo hypoxic respiratory failure, respectively, together with oro-nasal masks.

Improved n-3 fatty acid status does not modulate insulin resistance in fa/fa Zucker rats

The objective was to examine the effect of polyunsaturated fatty acid type (plant vs fish oil-derived n-3, compared to n-6 fatty acids in the presence of constant proportions of saturated, monounsaturated and polyunsaturated fatty acids) on obesity, insulin resistance and tissue fatty acid composition in genetically obese rats. Six-week-old fa/fa and lean Zucker rats were fed with a 10% (w/w) mixed fat diet containing predominantly flax-seed, menhaden or safflower oils for 9 weeks. There was no effect of dietary lipid on obesity, oral glucose tolerance (except t=60min insulin), pancreatic function or molecular markers related to insulin, glucose and lipid metabolism, despite increased n-3 fatty acids in muscle and adipose tissue. The menhaden oil diet reduced fasting serum free fatty acids in both fa/fa and lean rats. These data suggest that n-3 composition does not alter obesity and insulin resistance in the fa/fa Zucker rat model when dietary lipid classes are balanced.

High mobility group box-1 expression correlates with poor outcome in lung injury patients

Chest trauma is frequently followed by pulmonary contusion and sepsis. High mobility group box-1 (HMGB-1) is a late mediator of severe sepsis that has been associated with mortality under experimental conditions. We studied HMGB-1 mRNA expression in patients with lung injury and its relationship with the severity of trauma and survival. A total of 24 consecutive patients with chest trauma referring to the Intensive Care Unit of Messina University Hospital, were enrolled. Lung trauma was established on the basis of chest X-ray and computed tomography. Injury Severity Score (ISS), Revised Trauma Score (RTS) and Glasgow Coma Scale (GCS) were also assessed. Accordingly to these results 6 patients were considered as controls because of no penetrating trauma and low ISS. Blood and broncho-alveolar lavage fluid (BALF) from chest trauma patients were withdrawn at admission and 24h after the beginning of the standard therapeutic protocol. HMGB-1 mRNA increased significantly in blood (r=0.84) and BALF (r=0.87) from patients with trauma and pulmonary contusion and positively correlated with the severity of trauma (based on ISS and RTS) and the final outcome. HMGB-1 protein levels were also elevated in BALF macrophages from severe trauma patients compared to control subjects, furthermore TNF-alpha and its receptor TNFR-1 mRNA levels were also markedly increased in patients with a poor outcome respect to other subjects. Our study suggests that HMGB-1 may be an early indicator of poor clinical outcome in patients with chest trauma.

Hyperemia beneath evacuated acute subdural hematoma is frequent and prolonged in patients with an unfavorable outcome: a xe-computed tomographic study

OBJECTIVE

To verify the values and the time course of regional cerebral blood flow (rCBF) in the cortex located beneath an evacuated acute subdural hematoma (SDH) and their relationship with neurological outcome.

METHODS

rCBF levels were measured in multiple regions of interest, by means of a Xe-computed tomographic technique, in the cortex underlying an evacuated SDH and contralaterally in 20 patients with moderate or severe traumatic brain injury and an evacuated acute SDH. Twenty-three patients with moderate or severe traumatic brain injury and an evacuated extradural hematoma or diffuse injury served as the control group. Outcome was evaluated by means of the Glasgow Outcome Scale at 12 months.

RESULTS

Values for the maximum (rCBFmax) and the mean of all rCBF levels in the cortex beneath the evacuated SDH were more frequently consistent with hyperemia. The side-to-side differences in the mean of all rCBF and rCBFmax levels between lesioned and nonlesioned hemispheres were greater in patients with evacuated SDH than in controls (P = 0.0013 and P = 0.0018, respectively). The side-to-side difference in the maximum rCBF value was higher in SDH patients with unfavorable outcomes than in controls at 24 to 96 hours and at 4 to 7 days and higher than in patients with favorable outcomes at 4 to 7 days. The widest side-to-side difference in rCBFmax value was more elevated in patients with an evacuated SDH with unfavorable outcome than in patients with a favorable outcome (P = 0.047), whereas no differences were found in controls. The SDH thickness and the associated midline shift were greater in patients with unfavorable outcomes than in those with favorable outcomes.

CONCLUSION

On average, hyperemic long-lasting rCBF values frequently occur in the cortex located beneath an evacuated SDH and seem to be associated with unfavorable outcome.

Risk stratification and outcomes in hemodynamically stable patients with acute pulmonary embolism: a prospective, multicentre, cohort study with three months of follow-up

BACKGROUND

The role of risk stratification in normotensive patients with acute pulmonary embolism (PE) is still unclear.

OBJECTIVES

We evaluated, in these patients, the usefulness of six prognostic markers for predicting in-hospital adverse events related to PE and 3-month mortality.

PATIENTS/METHODS

Two hundred and one consecutive patients with confirmed acute PE and normal blood pressure, who were administered conventional anticoagulation, were recruited in a multicentre prospective cohort study with 3 months of follow-up. At baseline, they received a comprehensive risk-evaluation including echocardiographic assessment of right ventricular dysfunction, determination of troponin I, brain natriuretic peptide and D-dimer, arterial blood gas analysis and a clinical score. Primary outcome of the study was PE-related in-hospital death or clinical deterioration. Secondary outcomes were in-hospital and 3-month all-cause mortality.

RESULTS

The primary outcome occurred in one patient (0.5%), who died from PE during hospitalization. The in-hospital and 3-month all-cause mortality were 2% and 9%, respectively. None of the prognostic markers was predictive of the primary outcome. Clinical score, troponin I and hypoxemia predicted in-hospital all-cause mortality (P = 0.02, 0.01 and < 0.01, respectively). Clinical score (HR, 4.7; 95% CI, 1.9-12.0), D-dimer (4.8; 1.4-16.3), hypoxemia (5.7; 2.1-15.1) and troponin I (7.5; 2.5-22.7) were predictors of 3-month all-cause mortality on univariate analysis. On multivariate analysis clinical score and troponin I remained independently predictive.

CONCLUSIONS

We did not find prognostic markers useful as predictors of in-hospital PE-related adverse events. Clinical score, troponin I and hypoxemia predicted in-hospital all-cause mortality. Clinical score and troponin I independently predicted 3-month all-cause mortality.

Determinants of tracheostomy decannulation: an international survey

Background

Although tracheostomy is probably the most common surgical procedure performed on critically ill patients, it is unknown when a tracheostomy tube can be safely removed.

Methods

We performed a cross-sectional survey of physicians and respiratory therapists with expertise in the management of tracheostomized patients at 118 medical centers to characterize contemporary opinions about tracheostomy decannulation practice and to define factors that influence these practices.

Results

We surveyed 309 clinicians, of whom 225 responded (73%). Clinicians rated patient level of consciousness, ability to tolerate tracheostomy tube capping, cough effectiveness, and secretions as the most important factors in the decision to decannulate a patient. Decannulation failure was defined as the need to reinsert an artificial airway within 48 hours (45% of respondents) to 96 hours (20% of respondents) of tracheostomy removal, and 2% to 5% was the most frequent recommendation for an acceptable recannulation rate (44% of respondents). In clinical scenarios, clinicians who worked in chronic care facilities (30%) were less likely to recommend decannulation than clinicians who worked in weaning (47%), rehabilitation (53%), or acute care (55%) facilities (p = 0.015). Patients were most likely to be recommended for decannulation if they were alert and interactive (odds ratio [OR] 4.76, 95% confidence interval [CI] 3.27 to 6.90; p < 0.001), had a strong cough (OR 3.84, 95% CI 2.66 to 5.54; p < 0.001), had scant thin secretions (OR 2.23, 95% CI 1.56 to 3.19; p < 0.001), and required minimal supplemental oxygen (OR 2.04, 95% CI 1.45 to 2.86; p < 0.001).

Conclusion

Patient level of consciousness, cough effectiveness, secretions, and oxygenation are important determinants of clinicians' tracheostomy decannulation opinions. Most surveyed clinicians defined decannulation failure as the need to reinsert an artificial airway within 48 to 96 hours of planned tracheostomy removal.

Metabolic treatment of critically ill patients: energy balance and substrate disposal

Oxidation of substrates is the main biochemical process used by the human body to produce energy. Different substrates (carbohydrates, lipids, and proteins) have different effects on oxygen consumption and carbon dioxide production: during the critical phase of pathologies it could be relevant pay attention to the use of various nutrients, that have some altered effect respect to the normal subjects metabolism, and during the length of metabolic treatment, too. Generally, nutrition lead to replenish body stores, while endogenous substrates are used to be oxidized. Critically ill patients show a preference for prompt energy availability (i.e. glucose) to avoid endogenous protein catabolism; lipids are shown to have a more pronounced storage effect. Adequate amount of energy intake in carbohydrates determine an increase of RQ, that means a shift from a more lipid-based to a more glucose-based oxidation. Composition of dietary intake can be usefully different for each pathology, and also for different periods of the same pathology, because critically ill patients have a variety of metabolic needs during their stay in ICU.

Nipple leiomyoma in man: a case report

We describe a rare case of a man, 38 year old, with a nipple leiomyoma, and report the presentation as a small nodule of the areola spreading the nipple, the symptoms, the clinical signs, the treatment that includes a complete excision; free margins should be histologically established to prevent recurrence.

Stabilities of N-acetyl-beta-D-glucosaminidase (NAG) isoenzymes in urine: advantage of NAG isoenzyme B measurement in clinical applications

N-Acetyl-beta-D-glucosaminidase (NAG) is a widely used urinary enzyme for the assessment of renal diseases. We studied the stabilities of NAG isoenzymes in urine at 37 degrees C by enzyme assay and ELISA using a model simulating in vivo conditions. The stabilities were found to be affected by the pH. Under mild acidic condition (about pH 6), there was no significant loss of enzymatic activity of NAG isoenzyme A, enzymatic activity of NAG isoenzyme B and immunological activity of NAG isoenzyme B even after 8 h incubation. In contrast, under alkaline condition (about pH 8), the enzymatic activity of NAG isoenzyme A was rapidly lost, whereas both enzymatic and immunological activities of NAG isoenzyme B were maintained at more than 80% of their initial values. Also, we found that the ratios of endogenous NAG isoenzyme B to total NAG were elevated in alkaline urine samples. These results indicate that NAG isoenzyme A, which is a major isoenzyme in normal urine (pH 5-7), seems to be inactivated in alkaline urine. Our results suggest that for alkaline urine, NAG isoenzyme B should be measured to avoid misinterpretation of total NAG enzymatic activities.

[Respiratory failure caused by myopathy in severe sepsis]

OBJECTIVE

To describe a generalized myopathic disorder occurred in the convalescence phase of illness of a critically ill patient.

SETTING

Neurological Intensive Care Unit.

PATIENT

A 43-year-old man with acute leukoencephalopathy and severe sepsis complicated by sustained and prolonged cardiovascular, respiratory and renal failure. After 15 days of complete respiratory autonomy, the patient presented an acute ventilatory failure associated with generalized muscle weakness. Neither a relapse of sepsis nor neurological worsening were detected.

MEASUREMENTS AND RESULTS

Electromyogram resulted in normal conduction velocity in both motor and sensitive nervous fibers. Muscular biopsy showed marked fiber size variability with several hypotrophic fibers type II fiber grouping, several areas of degeneration-necrosis with macrophage invasion, dishomogeneous oxidative enzymatic activity, no increase in glycogen or lipid content.

CONCLUSIONS

These results excluded critical illness polyneuropathy and all the other known myopathies. Prolonged period of sepsis with multiple organ failure can result in a direct generalized myopathy. This possibility should be kept in mind while treating long term critically ill survivors.

[Energy metabolism and metabolite flow from muscle tissue during TPN of trauma patients]

AIM

We evaluated muscle-visceral interorgan flux of substrates in 8 critically ill patients in the flow phase after injury.

SETTING

This study was conducted on critically ill patients admitted in ICU.

PATIENTS

8 patients were studied immediately after injury.

RESULTS

We measured leg flux for oxygen, amino acids, glucose, lactate pyruvate, keton bodies, free fatty acids (FFA), free and total carnitine, and whole body oxygen consumption, nitrogen (N) balance and 3-methyl hystidine (3MEH) excretion during fasting and the second day of metabolic treatment (10.7 +/- 0.06 g x N x m-2 e 1035.5 +/- 3.9 kcal x m-2 x die). During fast the leg shows a net release of N, pyruvate, FFA and free carnitine while glucose, lactate and keton bodies fluxes are not different from zero. The energy balance of the leg is markedly negative (substrate for 79 kcal x m-2 burned for leg energy requirement and 347 kcal x m-2 released as a such). Assuming the body muscle tissue 4.5 times the leg tissue and knowing whole body energy balance, we were able to assess that the non muscular (visceral) part of the body resulted in a consistently positive energy balance. The metabolic treatment is able to match the energy expenditure and the substrate efflux of the leg (and the whole body muscle tissue). In fact the efflux of amino acids and FFA is reduced pyruvate blunted while glucose is remarkably taken up (the uptake of the whole muscle tissue accounted for 72% of the daily load). At the same time, the treatment blunts leg free carnitine and reduces body 3MEH output. Moreover, the caloric balance of the non muscular part of the body remains positive even if the qualiquantitative uptake of substrates is different from fasting.

CONCLUSION

Substrates for energy requirements of visceral tissue came from muscular tissue. The metabolic treatment is able to modulate this process.

Simple, rapid spectrophotometry of urinary N-acetyl-beta-D-glucosaminidase, with use of a new chromogenic substrate

We have developed a new spectrophotometric assay for urinary N-acetyl-beta-D-glucosaminidase (NAGase) with use of sodio m-cresolsulfonphthaleinyl N-acetyl-beta-D-glucosaminide (MCP-NAG). MCP-NAG was synthesized from acetochloro-glucosamine and m-cresolsulfonphthalein (MCP) in four steps. MCP-NAG reacts well with NAGase (Km = 0.41 mmol/L) and is highly water soluble. The absorption maximum and molar absorptivity of the aglycone MCP are 580 nm and 40 670, respectively. Spectral overlap of interfering substances at 580 nm is almost negligible, so that the urine blank can be omitted from the assay procedure. The high molar absorptivity of MCP gives sufficient analytical sensitivity at a reaction time of 15 min. The correlation between the MCP-NAG method (y) and the fluorimetric method (x) involving 4-methylumbelliferyl N-acetyl-beta-D-glucosaminide is represented by the equation y = 0.995x - 0.669 (r = 0.991). Thus, the present method provides practical advantages over conventional methods, for use in the routine laboratory.

Simple, rapid spectrophotometry of urinary N-acetyl-beta-D-glucosaminidase, with use of a new chromogenic substrate

We have developed a new spectrophotometric assay for urinary N-acetyl-beta-D-glucosaminidase (NAGase) with use of sodio m-cresolsulfonphthaleinyl N-acetyl-beta-D-glucosaminide (MCP-NAG). MCP-NAG was synthesized from acetochloro-glucosamine and m-cresolsulfonphthalein (MCP) in four steps. MCP-NAG reacts well with NAGase (Km = 0.41 mmol/L) and is highly water soluble. The absorption maximum and molar absorptivity of the aglycone MCP are 580 nm and 40 670, respectively. Spectral overlap of interfering substances at 580 nm is almost negligible, so that the urine blank can be omitted from the assay procedure. The high molar absorptivity of MCP gives sufficient analytical sensitivity at a reaction time of 15 min. The correlation between the MCP-NAG method (y) and the fluorimetric method (x) involving 4-methylumbelliferyl N-acetyl-beta-D-glucosaminide is represented by the equation y = 0.995x - 0.669 (r = 0.991). Thus, the present method provides practical advantages over conventional methods, for use in the routine laboratory.