Hypervirulent Klebsiella pneumoniae, a 5-year study in a French ICU

PURPOSE

Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a leading cause of severe community-acquired pneumonia, liver abscess and disseminated infection in the Far East. Data regarding the incidence, clinical features and microbiological characteristics related to hvKp infections in the Western world are scarce.

METHODOLOGY

The incidence, clinical features and microbiological characteristics of hvKp infections were investigated through a 5-year survey conducted in a single French intensive care unit. K. pneumoniae strains were screened for hypermucoviscosity based on a string test. Multilocus sequence typing and multiplex PCR analysis targeting virulence genes were performed on string test-positive strains.

RESULTS

Over a 53-month period, a total of 59 infections due to K. pneumoniae were identified including 26 community-onset infections. Twelve hvKp infections were documented, accounting for 46.1 % of community-acquired K. pneumoniae. Community-acquired pneumonia (n=6), aspiration pneumonia (n=4) and liver abscess (n=2) represented initial sites and mode of infection. Compared to non-hvKp infections, patients with hvKp infections displayed higher rates of multi-organ failure (83.3 % vs 35.7 %; P=0.04), but mortality rates were not different (50 % vs 35 %; P=0.71). Strains K1/ST23 (n=5) and K2/ST86 (n=5) predominated. All hvKp strains displayed wild-type susceptibility.

CONCLUSION

hvKp represent a potentially underestimated cause of fatal infections in the Western world.

[Hemolytic and uremic syndrome and related thrombotic microangiopathies: Epidemiology, pathophysiology and clinics]

Thrombotic microangiopathies (TMA) represent an eclectic group of conditions, which share hemolytic anemia and thrombocytopenia as a common defining basis. Remarkable breakthroughs in the physiopathological setting have allowed for a thorough recomposition of the disparate syndromes, which form the constellation of TMA. In this view, clinicians now discriminate thrombocytopenic thrombotic purpura (TTP) defined by a severe deficiency in ADAMTS13, which is rarely associated with a severe renal involvement and the hemolytic and uremic syndrome (HUS) in which renal impairment is the most prominent clinical feature. HUS can result from toxins stemming from bacterial infections of the digestive tract, alternate complement pathway abnormalities, metabolic or coagulation disorders or, lastly, drug and various toxic compounds. The diverse forms of HUS reflect the insights gained in the understanding of the pathophysiological mechanisms underpinning TMA. In this first part, a broad overview of the epidemiological, physiopathological and clinical aspects of HUS and related TMA syndromes is presented.

Pathogenic Variants in Complement Genes and Risk of Atypical Hemolytic Uremic Syndrome Relapse after Eculizumab Discontinuation

BACKGROUND AND OBJECTIVES

The complement inhibitor eculizumab has dramatically improved the outcome of atypical hemolytic uremic syndrome. However, the optimal duration of eculizumab treatment in atypical hemolytic uremic syndrome remains debated. We report on the French atypical hemolytic uremic syndrome working group's first 2-year experience with eculizumab discontinuation in patients with atypical hemolytic uremic syndrome.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

Using the French atypical hemolytic uremic syndrome registry database, we retrospectively identified all dialysis-free patients with atypical hemolytic uremic syndrome who discontinued eculizumab between 2010 and 2014 and reviewed their relevant clinical and biologic data. The decision to discontinue eculizumab was made by the clinician in charge of the patient. All patients were closely monitored by regular urine dipsticks and blood tests. Eculizumab was rapidly (24-48 hours) restarted in case of relapse.

RESULTS

Among 108 patients treated with eculizumab, 38 patients (nine children and 29 adults) discontinued eculizumab (median treatment duration of 17.5 months). Twenty-one patients (55%) carried novel or rare complement genes variants. Renal recovery under eculizumab was equally good in patients with and those without complement gene variants detected. After a median follow-up of 22 months, 12 patients (31%) experienced atypical hemolytic uremic syndrome relapse. Eight of 11 patients (72%) with complement factor H variants, four of eight patients (50%) with membrane cofactor protein variants, and zero of 16 patients with no rare variant detected relapsed. In relapsing patients, early reintroduction (≤48 hours) of eculizumab led to rapid (<7 days) hematologic remission and a return of serum creatinine to baseline level in a median time of 26 days. At last follow-up, renal function remained unchanged in nonrelapsing and relapsing patients compared with baseline values before eculizumab discontinuation.

CONCLUSIONS

Pathogenic variants in complement genes were associated with higher risk of atypical hemolytic uremic syndrome relapse after eculizumab discontinuation. Prospective studies are needed to identify biomarkers predictive of relapse and determine the best strategy of retreatment in relapsing patients.

Can we improve transthoracic echocardiography training in non-cardiologist residents? Experience of two training programs in the intensive care unit

BACKGROUND

To evaluate the diagnostic performances of two training programs for residents with no prior ultrasound experience to reach competences in extended basic critical care transthoracic echocardiography (CCE) including Doppler capabilities.

METHODS

This is a prospective observational study in two intensive care units of teaching hospitals. Group I (five residents) completed a short training program (4-h theory; 3-h practical); group II (six residents) completed a longer training program (6-h theory; 12-h practical). The residents and an expert examined all patients who required a transthoracic echocardiography. Their agreement studied by Cohen's κ coefficient, concordance coefficient correlation (CCC) and Bland-Altman plots was used as an indicator of program effectiveness.

RESULTS

Group I performed 136 CCEs (mean/resident 27; range 22-32; 65 in ventilated patients) in 115 patients (62 men; 64 ± 18 years; Simplified Acute Physiologic Score [SAPS] II 37 ± 18). Group II performed 158 CCEs (mean/resident 26; range 21-31; 65 in ventilated patients) in 108 patients (64 men; 58 ± 17 years; SAPS II 42 ± 22). Both groups adequately assessed left ventricular (LV) systolic function (κ 0.75, 95 % confidence interval [CI] 0.64-0.86; κ 0.77, 95 % CI 0.66-0.88, respectively) and pericardial effusion (κ 0.83, 95 % CI 0.67-0.99; κ 0.76, 95 % CI 0.60-0.93, respectively). Group II appraised severe right ventricular dilatation and significant left-sided valve disease with good to very good agreement (κ 0.80, 95 % CI 0.56-0.96; κ 0.79, 95 % CI 0.66-0.93, respectively). Regarding left ventricular ejection fraction, E/A ratio, E/e' ratio and aortic peak velocity assessed by group II, CCCs were all >0.70 and the bias (mean difference) ±SD on Bland-Altman analysis was 1.3 ± 8.8 %, 0 ± 0.3, 0.4 ± 2.2 and 0.1 ± 0.4 m/s, respectively. Detection of paradoxical septum (κ 0.65, 95 % CI 0.37-0.93), of heterogeneous LV contraction (κ 0.49, 95 % CI 0.33-0.65) and of respiratory variation of the inferior vena cava (κ 0.27, 95 % CI 0.09-0.45), as well as stroke volume measurement (CCC 0.65, 95 % CI 0.54-0.74; bias ± SD -1.4 ± 4.7 cm), was appraised by group II with moderate agreement requiring probably more comprehensive training.

CONCLUSIONS

Although a training program blending 6-h theory and 12-h practical may be adapted to achieve some essential competences, it seems to be insufficiently to perform a complete extended basic critical care transthoracic echocardiography including Doppler capabilities.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

Renal impairment an impediment to heart transplantation?

Chronic kidney disease and chronic heart failure are now recognized as closely intertwined entities. The noxious interactions between the heart and kidney systems as part of the so-called cardiorenal syndrome is a matter of great concern for heart transplant candidates. Not only is chronic kidney disease a commonly associated comorbidity, but its detrimental effect on the outcome of heart transplantation is now well established. In the more advanced stages of kidney disease, it may even deter physicians from carrying out heart transplantation in potential candidates. This review offers insights on epidemiological issues regarding chronic kidney disease among patients awaiting heart transplantation as well as its impact on the outcomes related with heart transplantations. Finally, emerging therapeutic opportunities which may benefit heart transplant candidates with the most severe renal impairment will be reviewed with a special emphasis on combined heart-kidney transplantation.

Use of High-Flow Nasal Cannula Oxygen Therapy in Subjects With ARDS: A 1-Year Observational Study

BACKGROUND

Beneficial effects of high-flow nasal cannula (HFNC) oxygen on oxygenation and respiratory parameters have been reported in a small number of subjects with acute respiratory failure (ARF). We aimed to evaluate its effect in subjects with ARDS.

METHODS

This was an observational single-center study. Prospectively obtained data were retrospectively analyzed. All patients admitted over 1 y to a university hospital medicosurgical ICU were included. Classification was according to the highest ventilatory support required. HFNC indications were reviewed, and demographics, clinical characteristics, and course of subjects with ARDS according to intubation need were compared.

RESULTS

Of 607 subjects admitted, 560 required ventilatory or oxygen support, among whom 180 received noninvasive ventilatory support. HFNC was used in 87 subjects and as first-line treatment in 51 subjects (29% of first-line noninvasively treated subjects), 45 of which had ARDS (PaO2 /FIO2 of 137 mm Hg; 22 men, 57.9 y of age). Pneumonia accounted for 82% of ARDS causes. The intubation rate in these subjects was 40%. Higher Simplified Acute Physiology Score II (SAPS II; 46 vs 29, P=.001), occurrence of additional organ failure (76% vs 26%, P=.002), mainly hemodynamic (50% vs 7%, P=.001) or neurological (22% vs 0, P=.01), and trends toward lower PaO2 /FIO2 and higher breathing frequency after HFNC initiation were evidenced in subjects who failed HFNC. Higher SAPS II scores were associated with HFNC failure in multivariate analysis.

CONCLUSIONS

In daily care, over one fourth of subjects requiring noninvasive ventilatory support were treated via HFNC, with a high success rate in subjects with severe ARDS. We conclude that HFNC may be considered as first-line therapy in ARF, including patients with ARDS.

Acute kidney injury in critical care: experience of a conservative strategy

PURPOSE

Renal replacement therapy (RRT) is a major supportive treatment of acute kidney injury (AKI) in intensive care unit (ICU), but the timing of its initiation remains open to debate.

MATERIALS AND METHODS

We retrospectively analyzed ICU patients who had AKI associated with at least one usual RRT criteria: serum creatinine concentration greater than 300 μmol/L, serum urea concentration greater than 25 mmol/L, serum potassium concentration greater than 6.5 mmol/L, severe metabolic acidosis (arterial blood pH<7.2), oliguria (urine output<135 mL/8 hours or <400 mL/24 hours), overload pulmonary edema. To estimate the risk of death associated with RRT adjusted for risk factors, we performed a marginal structural Cox model with inverse-probability-of-treatment-weighted estimator.

RESULTS

Among 4173 patients admitted to the ICU, 203 patients fulfilled potential RRT criteria. Ninety-one patients (44.8%) received RRT and 112 (55.2%) did not. Non-RRT and RRT patients differed in terms of severity of illness: Simplified Acute Physiology Score II (55±17 vs 60±19, respectively; P<.05) and Sequential Organ Failure Assessment score (8 [5-10] vs 9 [7-11], respectively; P=.01). Crude analysis indicated a lower ICU mortality for non-RRT compared with RRT patients (18% vs 45%; P<.001). In the marginal structural Cox model, RRT was associated with increased mortality (P<.01).

CONCLUSION

A conservative approach of AKI was not associated with increased mortality.

Use of desmopressin acetate in severe hyponatremia in the intensive care unit

BACKGROUND AND OBJECTIVES

Excessive correction of chronic and profound hyponatremia may result in central pontine myelinolysis and cause permanent brain damage. In the case of foreseeable or established hyponatremia overcorrection, slowing down the correction rate of sodium plasma levels (PNa) or reinducing mild hyponatremia may prevent this neurologic complication.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective and observational study was performed with 20 consecutive patients admitted to two intensive care units for severe hyponatremia, defined by PNa <120 mmol/L and/or neurologic complications ascribable to hyponatremia and subsequently treated by desmopressin acetate (DDAVP) during correction of hyponatremia when the rate of correction was overtly or predictably excessive. The primary endpoint was the effectiveness of DDAVP on PNa control.

RESULTS

DDAVP dramatically decreased the rate of PNa correction (median 0.81 mmol/L per hour [interquartile range, 0.46, 1.48] versus -0.02 mmol/L per hour [-0.16, 0.22] before and after DDAVP, respectively; P<0.001) along with a concurrent decrease in urine output (650 ml/h [214, 1200] versus 93.5 ml/h [43, 143]; P=0.003), and a rise in urine osmolarity (86 mmol/L [66, 180] versus 209 mmol/L [149, 318]; P=0.002). The maximal magnitude of PNa variations was also markedly reduced after DDAVP administration (11.5 mmol/L [8.25, 14.5] versus 5 mmol/L [4, 6.75]; P<0.001). No patient developed seizures after DDAVP or after subsequent relowering of PNa that occurred in 11 patients.

CONCLUSIONS

Desmopressin acetate is effective in curbing the rise of PNa in patients admitted in the intensive care unit for severe hyponatremia, when the initial rate of correction is excessive.

Severe Measles Infection: The Spectrum of Disease in 36 Critically Ill Adult Patients

France has recently witnessed a nationwide outbreak of measles. Data on severe forms of measles in adults are lacking. We sought to describe the epidemiologic, clinical, treatment, and prognostic aspects of the disease in adult patients who required admission to an intensive care unit (ICU). We performed a retrospective analysis of a cohort of 36 adults admitted to a total of 64 ICUs throughout France for complications of measles from January 1, 2009, to December 31, 2011. All cases of measles were confirmed by serologic testing and/or reverse transcription polymerase chain reaction.The cohort consisted of 21 male and 15 female patients, with a median age of 29.2 years (25th-75th interquartile range [IQR], 27.2-34.2 yr) and a median Simplified Acute Physiology Score (SAPS II) of 13 (IQR, 9-18). Among the 26 patients whose measles vaccination status was documented, none had received 2 injections. One patient had developed measles during childhood. Underlying comorbid conditions included chronic respiratory disease in 9 patients, immunosuppression in 7 patients, and obesity in 3 patients, while measles affected 5 pregnant women.Respiratory complications induced by measles infection led to ICU admission in 32 cases, and measles-related neurologic complications led to ICU admission in 2 cases. Two patients were admitted due to concurrent respiratory and neurologic complications.Bacterial superinfection of measles-related airway infection was suspected in 28 patients and was documented in 8. Four cases of community-acquired pneumonia, 6 cases of ventilator-associated pneumonia, 1 case of tracheobronchitis, and 2 cases of sinusitis were microbiologically substantiated.Of 11 patients who required mechanical ventilation, 9 developed acute respiratory distress syndrome (ARDS). Among the patients with ARDS, extraalveolar air leak complications occurred in 4 cases. Five patients died, all of whom were severely immunocompromised.On follow-up, 1 patient had severe chronic respiratory failure related to lung fibrosis, and 2 patients had mild lower limb paraparesis along with bladder dysfunction, both of which were ascribable to measles-induced encephalitis and myelitis. Among the 5 pregnant patients, the course of measles infection was uneventful, albeit 1 patient underwent emergent cesarean delivery because of fetal growth restriction.Measles is a disease with protean and potentially deceptive clinical manifestations, especially in the immunocompromised patient. Measles-associated pneumonitis and its complications, and less commonly postinfectious encephalomyelitis, are the main source of morbidity and mortality. In contrast with the usually benign course of the disease in immunocompetent patients, measles occurring in immunocompromised patients gives rise to lethal complications including ARDS, with or without bacterial superinfection. Other patients potentially at high risk for severe measles are young adults and pregnant women. Measles pneumonitis may predispose to air leak disease in patients using mechanical ventilation. To date, vaccination remains the most potent tool to control measles infection.