Trace element requirements in critically ill burned patients

Critically ill burned patients are characterized by a strong oxidative stress, an intense inflammatory response, and months-long hypermetabolism, all of which are proportional to the severity of injury. Trace element (TE) deficiencies have repeatedly been described. The clinical course is complicated by organ failures, infections, and delayed wound healing, which can be partly attributed to TE deficiencies.Among critically ill patients, TE deficiencies are the most severe in major burns, who suffer a specific copper deficiency. Plasma TE concentrations are low during any critical illness, as a result of TE losses in biological fluids, low intakes, dilution by fluid resuscitation, and redistribution from plasma to tissues mediated by the inflammatory response. The large exudative losses cause negative TE balances. Intravenous supplementation trials show that early substitution improves recovery, reduces infectious complications (particularly nosocomial pneumonia), normalize thyroid function, normalize skin tissue levels, improve wound healing and shorten hospital stay.Nevertheless, prolonged high dose delivery may be deleterious, as TE have potential for toxicity. In major burns, supplements up to 4 mg of Cu/day, 500 mg Se/day and 40 mg Zn/day for 3 weeks have been found to be safe and effective. The intravenous route appears the only way to deliver the doses required to achieve antioxidant and clinical effects. Further research is required to determine the optimal combination and doses for different severities of injury.     

Effects of ambulance transport in critically ill patients.

Two groups of critically ill patients were transferred by ambulance from other hospitals to a central intensive therapy unit. The effect of transport was reviewed retrospectively in 46 patients and prospectively in 20 patients. Of the 46 patients reviewed retrospectively six became hypotensive, six became hypertensive, and seven developed delayed hypotension. One patient developed fits and six out of 13 patients had a rise in arterial PCO-2 of 1-6-4-1 kPa (12-31 mm Hg). Of the 20 patients reviewed prospectively, one patient became hypertensive due to overtransfusion, one had a fit, but none became hypotensive. Three out of four cases of delayed hypotension were related to starting intermittent positive pressure ventilation. Arterial PCO-2 fell in one patient and arterial PCO-2 rose in two, each change being related to changed oxygen therapy or narcotics. There were no changes in other cardiovascular or respiratory indices, body temperature, or urine production. Earlier transfer, resuscitation before transfer, continuing medical care during the journey, and hence a slower smoother journey seemed to be important factors in the management of these patients. Our findings, may have important implications in the future regional organization of the care of critically ill patients.     

Cardiopulmonary interactions during mechanical ventilation in critically ill patients

Cardiopulmonary interactions induced by mechanical ventilation are complex and only partly understood. Applied tidal volumes and/or airway pressures largely mediate changes in right ventricular preload and afterload. Effects on left ventricular function are mostly secondary to changes in right ventricular loading conditions. It is imperative to dissect the several causes of haemodynamic compromise during mechanical ventilation as undiagnosed ventricular dysfunction may contribute to morbidity and mortality.     

Clinical spectrum of invasive candidiasis in critically ill non-neutropenic patients

Invasive Candida spp. infections in non-neutropenic critically ill patients admitted to intensive care units can be classified as focal and systemic. Both types of infection usually occur after episodes of candidemia, although some focal infections may be of exogenous development, like those occurring after trauma or be device-related.The clinical spectrum of invasive Candida spp. infections includes focal urinary tract, abdominal, ocular, respiratory tract, renal and hepato-biliary infections, as well as systemic infections like candidemia and acute systemic candidiasis with multiorgan involvement after hematogenous seeding. Candida spp. isolates in "significant" samples, like synovial fluid, cerebrospinal fluid and blood cultures, represent true infection. However, the diagnosis of invasive infection based on "non-significant" samples, like surgical drains and digestive tract exudates, requires additional criteria. The total number of isolates from different sites, the presence of risk factors, the clinical host response, as well as severity of illness need to be taken into account for the diagnosis of invasive candidiasis. The clinical signs of systemic infection due to Candida spp. are completely non-specific and cannot be differentiated from bacterial peritonitis, urinary tract infection or bacteremia. These infections may be associated with signs of sepsis,severe sepsis, septic shock or multiorgan dysfunction. In the future clinical multicentre observational and interventional studies are necessary to reach agreement on clinical definitions and classification of invasive Candida spp. infections in critically ill non-immunocompromised patients.     

Increased carbon monoxide in exhaled air of critically ill patients

Heme oxygenase produces carbon monoxide (CO) during breakdown of heme molecules primarily in liver and spleen. Recent data suggest that CO is also produced in the lungs. CO is excreted by exhalation via the lungs. A number of inflammatory agents induce the expression of heme oxygenase, possibly leading to increased CO production. To investigate whether critical illness results in increased CO production we measured the CO concentration in exhaled air in 30 critically ill patients and in healthy controls (n = 6). Critically ill patients showed a significantly higher CO concentration in exhaled air (median 2.4 ppm, 95% CI 1.0-7.0 ppm vs median 1.55 ppm, 95% CI 1.2-1.7 ppm, P = 0.01) as well as total CO production (median 20 ml/min, 95% CI 8 to 90 ml/min vs median 13.5 ml/min, 95% CI 11 to 19 ml/min, P = 0.026) compared to healthy controls. No correlation was found between CO concentration in exhaled air and carboxyhemoglobin concentration in arterial and central venous blood (P > 0.05). The increase of CO concentration in exhaled air in critical illness suggests an induction of inducible heme oxygenase (HO-1) and might reflect the severity of illness.     

Risk factors for vancomycin-resistant enterococci colonisation in critically ill patients

Vancomycin-resistant enterococci (VRE) are important hospital pathogens and have become increasingly common in patients admitted to the intensive care unit (ICU). To determine the incidence and the risk factors associated with VRE colonisation among ICU patients, active surveillance cultures for VRE faecal carriages were carried out in patients admitted to the ICU of the University Hospital of Uberlandia, Minas Gerais, Brazil. Risk factors were assessed using a case-control study. Seventy-seven patients (23.1%) were found to be colonised with vanC VRE and only one patient (0.3%) was colonised with vanA VRE. Independent risk factors for VRE colonisation included nephropathy [odds ratio (OR) = 13.6, p < 0.001], prior antibiotic use (OR = 5.5, p < 0.03) and carbapenem use (OR = 17.3, p < 0.001). Our results showed a higher frequency (23.1%) of Enterococcus gallinarum and Enterococcus casseliflavus, species that are intrinsically resistant to low levels of vancomycin (vanC), without an associated infection, associated with prior antibiotic use, carbapenem use and nephropathy as comorbidity. This study is the first to demonstrate the risk factors associated with vanC VRE colonisation in ICU hospitalised patients. Although vanA and vanB enterococci are of great importance, the epidemiology of vanC VRE needs to be better understood. Even though the clinical relevance of vanC VRE is uncertain, these species are opportunistic pathogens and vanC VRE-colonised patients are a potential epidemiologic reservoir of resistance genes.     

Decision making in critically ill patients with hematologic malignancy.

Hematologic neoplasms that were previously considered fatal are now potentially curable with techniques such as bone marrow transplantation. Such therapies also carry significant morbidity and mortality. With the increasing application of these therapies, a growing number of physicians are using medical decision making regarding critical care for these patients. The process by which ethical decisions are reached for these critically ill patients may be baffling because of several factors: rapidly evolving treatments, uncertain probabilities of the cure of the malignant disorder, the relatively young age of many of these patients, and the poor prognosis with critical illness. I discuss a process to reach acceptable decisions, providing a case example of the application of the process. This process is derived from the ethical principles that drive decision making in general medicine and attempts to maximize patients'' autonomy. It involves a consideration of accurate information regarding the disease process and the prognosis, a clear delineation of the goals of the medical care, and communication with patients. Appropriate, ethical, and consistent decisions regarding the critical care of patients with hematologic malignancy can be reached when these considerations are addressed.     

Ophtalmoscopic examination in critically ill non-neutropenic patients: Candida endophtalmitis

Invasive Candida (IC) infection is the most common cause of endogenous endophthalmitis. Ocular candidiasis develops within three days and at least two weeks of fungemia. There are two characteristic ocular signs: Candida chorioretinitis defined as retina and choroid lesions without vitreal involvement, and Candida endophthalmitis defined as chorioretinitis with extension into the vitreous with characteristic fluffy balls. The most common initial visual symptoms are blurred vision and floaters. Amphotericin B, fluconazole and voriconazole are effective in the treatment of chorioretinitis; however, when vitreous is involved vitrectomy seems necessary. Early antifungal systemic treatment at first evidence of infection in patients at risk of IC, appears to decrease dramatically the incidence of endogenous fungal endophthalmitis, probably healing minimal chorioretinal infections. Routine ophthalmoscopic examination seems of little value in patients with positive blood culture, with early implementation of antifungal treatment, without symptoms of ocular infection and without impairment of the level of consciousness during the episode. However, periodic ophthalmoscopic examination should be performed in children with candidemia and critically ill patients with documented deep Candida infection.     

Early prolonged neutrophil activation in critically ill patients with sepsis

We hypothesised that plasma concentrations of biomarkers of neutrophil activation and pro-inflammatory cytokines differ according to the phase of rapidly evolving sepsis. In an observational study, we measured heparin-binding protein (HBP), myeloperoxidase (MPO), IL-6 and IL-8 in 167 sepsis patients on intensive care unit admission. We prospectively used the emergence of the first sepsis-associated organ dysfunction (OD) as a surrogate for the sepsis phase. Fifty-five patients (of 167, 33%) developed the first OD > 1 h before, 74 (44%) within ± 1 h, and 38 (23%) > 1 h after intensive care unit admission. HBP and MPO were elevated at a median of 12 h before the first OD, remained high up to 24 h, and were not associated with sepsis phase. IL-6 and IL-8 rose and declined rapidly close to OD emergence. Elevation of neutrophil activation markers HBP and MPO was an early event in the evolution of sepsis, lasting beyond the subsidence of the pro-inflammatory cytokine reaction. Thus, as sepsis biomarkers, HBP and MPO were not as prone as IL-6 and IL-8 to the effect of sample timing.     

Assessment of body cell mass at bedside in critically ill patients

Critical illness affects body composition profoundly, especially body cell mass (BCM). BCM loss reflects lean tissue wasting and could be a nutritional marker in critically ill patients. However, BCM assessment with usual isotopic or tracer methods is impractical in intensive care units (ICUs). We aimed to modelize the BCM of critically ill patients using variables available at bedside. Fat-free mass (FFM), bone mineral (Mo), and extracellular water (ECW) of 49 critically ill patients were measured prospectively by dual-energy X-ray absorptiometry and multifrequency bioimpedance. BCM was estimated according to the four-compartment cellular level: BCM = FFM - (ECW/0.98) - (0.73 × Mo). Variables that might influence the BCM were assessed, and multivariable analysis using fractional polynomials was conducted to determine the relations between BCM and these data. Bootstrap resampling was then used to estimate the most stable model predicting BCM. BCM was 22.7 ± 5.4 kg. The most frequent model included height (cm), leg circumference (cm), weight shift (Δ) between ICU admission and body composition assessment (kg), and trunk length (cm) as a linear function: BCM (kg) = 0.266 × height + 0.287 × leg circumference + 0.305 × Δweight - 0.406 × trunk length - 13.52. The fraction of variance explained by this model (adjusted r(2)) was 46%. Including bioelectrical impedance analysis variables in the model did not improve BCM prediction. In summary, our results suggest that BCM can be estimated at bedside, with an error lower than ±20% in 90% subjects, on the basis of static (height, trunk length), less stable (leg circumference), and dynamic biometric variables (Δweight) for critically ill patients.