Effects of early hemodynamic resuscitation on left ventricular performance and microcirculatory function during endotoxic shock

Background

Microcirculation and macrohemodynamics are severely compromised during septic shock. However, the relationship between these two compartments needs to be further investigated. We hypothesized that early resuscitation restores left ventricular (LV) performance and microcirculatory function but fails to prevent metabolic disorders. We studied the effects of an early resuscitation protocol (ERP) on LV pressure/volume loops-derived parameters, sublingual microcirculation, and metabolic alterations during endotoxic shock.

Methods

Twenty-five pigs were randomized into three groups: LPS group: Escherichia coli lipopolysaccharide (LPS); ERP group: LPS + ERP based on volume expansion, dobutamine, and noradrenaline infusion; Sham group. LV pressure/volume-derived parameters, systemic hemodynamics, sublingual microcirculation, and metabolic profile were assessed at baseline and after completing the resuscitation protocol.

Results

LPS significantly decreased LV end-diastolic volume, myocardial contractility, stroke work, and cardiac index (CI). Early resuscitation preserved preload, and myocardial contractility, increased CI and heart rate (p < .05). LPS severely diminished sublingual microvascular flow index (MFI), perfused vascular density (PVD), and the proportion of perfused vessels (PPV), while increased the heterogeneity flow index (HFI) (p < .05). Despite MFI was relatively preserved, MVD, PVD, and HFI were significantly impaired after resuscitation (p < .05). The macro- and microcirculatory changes were associated with increased lactic acidosis and mixed venous O₂ saturation when compared to baseline values (p < .05). The scatter plot between mean arterial pressure (MAP) and MFI showed a biphasic relationship, suggesting that the values were within the limits of microvascular autoregulation when MAP was above 71 ± 6 mm Hg (R² = 0.63).

Conclusions

Early hemodynamic resuscitation was effective to restore macrohemodynamia and myocardial contractility. Despite MAP and MFI were relatively preserved, the persistent microvascular dysfunction could explain metabolic disorders. The relationship between micro- and systemic hemodynamia and their impact on cellular function and metabolism needs to be further studied during endotoxic shock.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-015-0049-y) contains supplementary material, which is available to authorized users.

Streptococcus pneumoniae translocates into the myocardium and forms unique microlesions that disrupt cardiac function

Hospitalization of the elderly for invasive pneumococcal disease is frequently accompanied by the occurrence of an adverse cardiac event; these are primarily new or worsened heart failure and cardiac arrhythmia. Herein, we describe previously unrecognized microscopic lesions (microlesions) formed within the myocardium of mice, rhesus macaques, and humans during bacteremic Streptococcus pneumoniae infection. In mice, invasive pneumococcal disease (IPD) severity correlated with levels of serum troponin, a marker for cardiac damage, the development of aberrant cardiac electrophysiology, and the number and size of cardiac microlesions. Microlesions were prominent in the ventricles, vacuolar in appearance with extracellular pneumococci, and remarkable due to the absence of infiltrating immune cells. The pore-forming toxin pneumolysin was required for microlesion formation but Interleukin-1β was not detected at the microlesion site ruling out pneumolysin-mediated pyroptosis as a cause of cell death. Antibiotic treatment resulted in maturing of the lesions over one week with robust immune cell infiltration and collagen deposition suggestive of long-term cardiac scarring. Bacterial translocation into the heart tissue required the pneumococcal adhesin CbpA and the host ligands Laminin receptor (LR) and Platelet-activating factor receptor. Immunization of mice with a fusion construct of CbpA or the LR binding domain of CbpA with the pneumolysin toxoid L460D protected against microlesion formation. We conclude that microlesion formation may contribute to the acute and long-term adverse cardiac events seen in humans with IPD.

Acute kidney injury in critically ill patients with 2009 influenza A (H1N1) viral pneumonia: an observational study

OBJECTIVE

To describe the incidence, risk factors, and impact on mortality of acute kidney injury (AKI) in patients with 2009 influenza A (H1N1) viral pneumonia requiring mechanical ventilation.

DESIGN

Observational cohort study.

PATIENTS AND METHODS

AKI was defined as risk, injury or failure, according to the RIFLE classification. Early and late AKI were defined as AKI occurring on intensive care unit (ICU) day 2 or before, or after ICU day 2, respectively. Demographic data and information on organ dysfunction were collected daily.

RESULTS

Of 84 patients, AKI developed in 43 patients (51%). Twenty (24%) needed renal replacement therapy. Early and late AKI were found in 28 (33%) and 15 (18%) patients, respectively. Patients with AKI, as compared with patients without AKI, had higher Acute Physiology and Chronic Health Evaluation (APACHE) II score and ICU mortality (72% versus 39%, p < 0.01) and presented on admission more marked cardiovascular, respiratory, and hematological dysfunction. Patients with early but not late AKI presented on admission higher APACHE II score and more marked organ dysfunction, as compared with patients without AKI. ICU mortality was higher in late versus early AKI (93% versus 61%, p < 0.001). On multivariate analysis, only APACHE II score and late but not early AKI [odds ratio (OR) 1.1 (95% confidence interval 1.0-1.1) and 15.1 (1.8-130.7), respectively] were associated with mortality.

CONCLUSIONS

AKI is a frequent complication of 2009 influenza A (H1N1) viral pneumonia. AKI developing after 2 days in ICU appears to be associated with different risk factors than early AKI, and is related to a higher mortality rate.

Clinical characteristics and outcomes of patients with 2009 influenza A(H1N1) virus infection with respiratory failure requiring mechanical ventilation

PURPOSE

The purpose of the study was to describe the clinical characteristics and outcomes of critically ill patients with 2009 influenza A(H1N1).

METHODS

An observational study of patients with confirmed or probable 2009 influenza A(H1N1) and respiratory failure requiring mechanical ventilation was performed.

RESULTS

We studied 96 patients (mean age, 45 [14] years [mean, SD]; 44% female). Shock and acute respiratory distress syndrome were diagnosed during the first 72 hours of admission in 43% and 72% of patients, respectively. Noninvasive positive pressure ventilation was used in 45% of the patients, but failed in 77% of them. Bacterial pneumonia was diagnosed in 33% of cases, 8% during the first week (due to community-acquired microorganisms) and 25% after the first week (due to gram-negative bacilli and resistant gram-positive cocci). Intensive care unit mortality was 50%. Nonsurvivors differed from survivors in the prevalence of cardiovascular, respiratory, and hematologic failure on admission and late pneumonia. Reported causes of death were refractory hypoxia, multiorgan failure, and shock (50%, 38%, and 12% of all causes of death, respectively).

CONCLUSIONS

Patients with 2009 influenza A(H1N1) and respiratory failure requiring mechanical ventilation often present with clinical criteria of acute respiratory distress syndrome and shock. Bacterial pneumonia is a frequent complication. Mortality is high and is primarily due to refractory hypoxia.

[Sporadic Creutzfeldt-Jakob disease: two cases in intensive care]

Prion diseases or spongiform encephalopathies are a family of rare neurodegenerative diseases characterized by long incubation periods associated with slow, irreversible and invariably fatal evolution. In humans, they are classified as sporadic, acquired and hereditary or genetic. Diagnosing sporadic "Creutzfeldt-Jakob Disease" (sCJD) is a real challenge for the intensive care physician, given the variability in its clinical presentation and its low incidence. The cases of two patients admitted to the Intensive Care Unit are presented. After ruling out other diseases, they were diagnosed with sCJD with a likelihood level according to the World Health Organization Classification. Clinical and laboratory diagnostic aspects of the disease were analyzed, highlighting the utility of 14-3-3 protein identification in the cerebrospinal fluid.

[Marchiafava-Bignami disease in Uruguay]

INTRODUCTION

Marchiafava-Bignami disease (MBD) is a rare complication of chronic alcoholism characterized by demyelination and necrosis of the corpus callosum that usually has a poor prognosis. It has an extensive clinical spectrum presentation and can presently be diagnosed in vivo with the computed tomography (CT) and magnetic resonance imaging (MRI).

CLINICAL CASES

We describe two cases of MBD disease with fatal outcome that presented with acute onset coma. Impairment of consciousness, hypertonia, and frontal release signs were the dominant clinical signs. One of the patients had optic neuropathy and the other had neuropsychiatric symptoms before onset of coma and pellagra-like skin lesion. The CT scan and MRI showed lesions of the white matter that were fundamentally in the corpus callosum.

CONCLUSIONS

The possibility of the existence of MBD should be investigated in all patients with chronic alcoholism who have prolonged confusional syndrome, stupor or coma. A prodromal stage with neuropsychiatric symptoms should be thoroughly investigated with a neuropsychological exploration including interhemispheric disconnection signs. Careful attention should be given to the corpus callosum in the image for the diagnosis of this probably underdiagnosed disease.

Propofol vs midazolam for ICU sedation : a Canadian multicenter randomized trial

STUDY OBJECTIVES

To determine whether sedation with propofol would lead to shorter times to tracheal extubation and ICU length of stay than sedation with midazolam.

DESIGN

Multicenter, randomized, open label.

SETTING

Four academic tertiary-care ICUs in Canada.

PATIENTS

Critically ill patients requiring continuous sedation while receiving mechanical ventilation.

INTERVENTIONS

Random allocation by predicted requirement for mechanical ventilation (short sedation stratum, < 24 h; medium sedation stratum, > or = 24 and < 72 h; and long sedation stratum, > or = 72 h) to sedation regimens utilizing propofol or midazolam.

MEASUREMENTS AND RESULTS

Using an intention-to-treat analysis, patients randomized to receive propofol in the short sedation stratum (propofol, 21 patients; midazolam, 26 patients) and the long sedation stratum (propofol, 4 patients; midazolam, 10 patients) were extubated earlier (short sedation stratum: propofol, 5.6 h; midazolam, 11.9 h; long sedation stratum: propofol, 8.4 h; midazolam, 46.8 h; p < 0.05). Pooled results showed that patients treated with propofol (n = 46) were extubated earlier than those treated with midazolam (n = 53) (6.7 vs 24.7 h, respectively; p < 0.05) following discontinuation of the sedation but were not discharged from ICU earlier (94.0 vs 63.7 h, respectively; p = 0.26). Propofol-treated patients spent a larger percentage of time at the target Ramsay sedation level than midazolam-treated patients (60.2% vs 44.0%, respectively; p < 0.05). Using a treatment-received analysis, propofol sedation either did not differ from midazolam sedation in time to tracheal extubation or ICU discharge (sedation duration, < 24 h) or was associated with earlier tracheal extubation but longer time to ICU discharge (sedation duration, > or = 24 h, < 72 h, or > or = 72 h).

CONCLUSIONS

The use of propofol sedation allowed for more rapid tracheal extubation than when midazolam sedation was employed. This did not result in earlier ICU discharge.

Thoracic complications of Lemierre syndrome

Lemierre syndrome is a severe, septicemic illness most commonly caused by the anaerobic Gram-negative bacillus Fusobacterium necrophorum. It is characterized by an acute oropharyngeal infection, with secondary septic thrombophlebitis of the internal jugular vein and frequent metastatic infections. This report of a patient with the Lemierre syndrome is complemented by a review of the literature on the subject.

The effect of sodium citrate in arterial catheters on acid-base and electrolyte measurements

OBJECTIVE

To compare the effects of heparin or sodium citrate used to anticoagulate indwelling arterial catheters on acid-base and electrolyte measurements.

DESIGN

Randomized controlled trial.

SETTING

Medical-surgical university-affiliated intensive care unit.

SUBJECTS

Twenty patients with indwelling arterial catheters.

INTERVENTIONS

Patients were randomly allocated to have ten 1-mL aliquots of blood sampled serially from an arterial catheter maintained with either heparin or sodium citrate. A sample then obtained by arterial puncture provided true measurement values. Acid-base and electrolyte measurements of whole blood were obtained from each sample by means of a Coming 860 analyzer.

MEASUREMENTS AND MAIN RESULTS

Contamination with sodium citrate lowered ionized calcium and pH but increased glucose and Pco2. Heparin produced negligible effects on those measurements. When sodium citrate was used, reliable measurements were not obtained for ionized calcium, pH, and glucose, even after 9 mL of blood had been discarded. However, reliable P(CO2) measurements were obtained after 2 mL of blood was discarded.

CONCLUSIONS

Sodium citrate used to maintain arterial catheters can contaminate blood samples. The result of that contamination can mimic severe hypocalcemia, metabolic acidosis, and mild hyperglycemia. Failure to recognize the effects of sodium citrate on acid-base and electrolyte measurements may lead to changes in treatment that could affect patient outcome adversely.

[Epidemic of gastroenteritis of viral origin associated with eating imported raspberries]

Several episodes of food poisoning affected the region of Quebec City in July and August 1997. In the first two episodes, the analysis of two cohorts (A and B) demonstrated that the consumption of a raspberry mousse with raspberry sauce increased the risk of contracting gastroenteritis (A, RR = 2.6 p = 0.001; B, RR = 4.7 p = 0.02). More than 200 people were sick after eating a raspberry dessert. The common ingredient of all those desserts was raspberries imported from Bosnia. Viral studies on the raspberry sauce (2) and stool samples (5) using the genome amplification method by PCR indicated the presence of genomic material compatible with a virus of the Caliciviruses family. Southern hybridization and sequence analysis showed that the nucleotide sequences found in the raspberry sauce and in the stool samples were identical. It is important to maintain active surveillance to detect and limit the spread of this kind of outbreak.

How accurate is spirometry at predicting restrictive pulmonary impairment?

OBJECTIVE

To determine the accuracy with which spirometric measurements of FVC and expiratory flow rates can diagnose the presence of a restrictive impairment.

DESIGN

The pulmonary function tests of 1,831 consecutive white adult patients who had undergone both spirometry and lung volume measurements on the same visit over a 2-year period were analyzed. The probability of restrictive pulmonary impairment, defined as a reduced total lung capacity (TLC) below the lower limit of the 95% confidence interval, was determined for each of several categoric classifications of the spirometric data, and additionally for each of several interval levels of the FVC and the FEV1/FVC ratio.

SETTING

A large clinical laboratory in a university teaching hospital using quality-assured and standardized spirometry and lung volume measurement techniques according to American Thoracic Society standards.

RESULTS

Two hundred twenty-five of 1,831 patients (12.3%) had a restrictive defect. The positive predictive value of spirometry for predicting restriction was relatively low; of 470 patients with a low FVC on spirometry, only 41% had restriction confirmed on lung volume measurements. When the analysis was confined to the 264 patients with a restrictive pattern on spirometry (ie, low FVC and normal or above normal FEV1/FVC ratio), the positive predictive value was 58%. Conversely, spirometry had a very favorable negative predictive value; only 2.4% of patients (32 of 1,361) with a normal vital capacity (VC) on spirometry had a restrictive defect by TLC measurement. The probability of a restrictive defect was directly and linearly related to the degree of reduction of FVC when the FVC was < 80% of predicted (p = 6.002). Combining the FVC and the FEV1/FVC ratio improved the predictive ability of spirometry; for all values of FVC < 80% of the predicted amount, the likelihood of restrictive disease increased as the FEV1/FVC ratio increased.

CONCLUSIONS

Spirometry is very useful at excluding a restrictive defect. When the VC is within the normal range, the probability of a restrictive defect is < 3%, and unless restrictive lung disease is suspected a priori, measurement of lung volumes can be avoided. However, spirometry is not able to accurately predict lung restriction; < 60% of patients with a classical spirometric restrictive pattern had pulmonary restriction confirmed on lung volume measurements. For these patients, measurement of the TLC is needed to confirm a true restrictive defect.

Functional magnesium deficiency in critically ill patients identified using a magnesium-loading test

OBJECTIVE

To determine the feasibility of the magnesium-loading test in the critically ill and to validate serum ionized magnesium assay using the magnesium-loading test as a reference in this same patient population.

DESIGN

Double-blind, randomized, controlled clinical investigation.

SETTING

Tertiary level intensive care unit.

PATIENTS

Forty-four consecutive critically ill patients without evidence of renal insufficiency.

INTERVENTION

Patients were randomly allocated to receive 30 mmol (7.5 g) of magnesium sulfate daily for 3 days, or an equivalent amount of normal saline.

MEASUREMENTS AND MAIN RESULTS

We recorded baseline characteristics, and serial serum biochemical measurements included creatinine, glucose, sodium, potassium, phosphate, total calcium, ionized calcium, total magnesium, and ionized magnesium. Serum assays were accompanied by 24-hr urine collections of creatinine and magnesium over the 3-day period. Baseline characteristics were comparable in both groups. In patients receiving magnesium, serum ionized magnesium and total magnesium concentrations were increased by 43% (p = .0001) and 59% (p = .0002), respectively, on day 1 as compared with the control group. Magnesium excretion in the control group averaged 4.8 +/- 2.3 mmol/day during the 3-day study period, while the magnesium excretion in the magnesium-loaded group was significantly increased to 22.7 +/- 10.9 mmol/day (p < .0001). Following day 1 magnesium loading, patients who excreted < 70% of the total magnesium (30 mmol infused magnesium plus 4.8 mmol basal excretion) were termed as functionally magnesium-deficient retainers (n = 12), and patients who excreted > 70% of the total magnesium were termed as nonretainers (n = 7). In addition, magnesium retainers on day 2 (nine of ten patients) and day 3 (five of six patients) excreted > 70% of the total magnesium, indicating a replenishment of body magnesium stores. In contrast, nonretainers on day 2 (four of five patients), and day 3 (four of four patients) continued to excrete excess amounts of magnesium. In the retainer group, only two patients had a low serum ionized magnesium concentration, while two other patients had low total serum magnesium values. In addition, magnesium retention was associated with low ionized calcium and high phosphate values.

CONCLUSIONS

The magnesium-loading test is feasible and appears to be valid based on its performance during the 3-day evaluation. Using the magnesium-loading test as a reference, serum ionized magnesium appears to be an insensitive biochemical marker of functional hypomagnesemia. Larger cohort studies using the magnesium-loading test will help establish the true prevalence of magnesium deficiency and its associated risk factors in critically ill patients.

Contribution of water condensation in endotracheal tubes to contamination of the lungs

We postulated that water condensate in endotracheal tubes (ETTs) transports bacteria in the ETTs into the lungs during mechanical ventilation. Thirty-two ETTs obtained from freshly extubated patients were studied under wet and dry conditions using a physiologic lung model. All bacteria expelled from the ETTs were collected on culture plates positioned beneath the ETT. The lung model was ventilated with saturated air at 37 degrees C over two time periods (60 min each), one in which condensation formation was prevented and the second in which condensation formed within the ETT. A mean of 457.6 colony-forming units (CFU)/h were expelled with condensation compared to a mean of 2.4 CFU/h without condensation. We concluded that bacteria were continuously transported from the ETT into the lungs during mechanical ventilation in water droplets. Prevention of water condensation abolishes this constant bacterial inoculation in a lung model.

Bacteriology of the oral cavity of BALB/c mice

To be used as a model in dental research, an animal must fulfil experimental needs and information on the composition and variation of its oral flora must be available. Only limited data are available on the indigenous oral bacterial flora of BALB/c mice. In this work, a total of 671 isolates from different sites (saliva, tongue, teeth, and mucosa) of the oral cavity of BALB/c mice were identified. Only 18 different species were isolated, which indicates the relative simplicity of the flora. The predominant species of the total cultivable flora were "Lactobacillus murinus" (38%), Staphylococcus aureus (37%), Streptococcus faecalis (8%), Staphylococcus sciuri (4%), and Escherichia coli (3%). The other species each represent less than 2% of the flora. "Lactobacillus murinus" is found in greater proportion on mucosa than in the other sites, Staph. aureus predominates in saliva, and Strep. faecalis was found in greater proportion in tooth samples. Statistical analyses, using the minimum percentage of similarity, indicate that there is some variation among the microflora of different mice but that this difference is smaller for mice from the same lot. These results set the basis for the study of the variations of the indigenous oral microflora of BALB/c mice under different conditions.

Laser interaction based on resonance saturation (LIBORS): an alternative to inverse bremsstrahlung for coupling laser energy into a plasma

Resonance saturation represents an efficient and rapid method of coupling laser energy into a gaseous medium. In the case of a plasma superelastic collision quenching of the laser maintained resonance state population effectively converts the laser beam energy into translational energy of the free electrons. Subsequently, ionization of the laser pumped species rapidly ensues as a result of both the elevated electron temperature and the effective reduction of the ionization energy for those atoms maintained in the resonance state by the laser radiation. This method of coupling laser energy into a plasma has several advantages over inverse bremsstrahlung and could therefore be applicable to several areas of current interest including plasma channel formation for transportation of electron and ion beams, x-ray laser development, laser fusion, negative ion beam production, and the conversion of laser energy to electricity.