Rapid, highly discriminatory binary genotyping to demonstrate methicillin-resistant Staphylococcus aureus transmission in a tertiary care intensive care unit.

OBJECTIVES: No previous studies of methicillin-resistant Staphylococcus aureus (MRSA) epidemiology in adult intensive care units (ICUs) have assessed the utility of rapid, highly discriminatory strain typing in the investigation of transmission events. DESIGN: Observational. SETTING: A 22-bed medical-surgical adult ICU. Patients Those admissions MRSA-positive on initial screening and all admissions <48 hours in duration were excluded, leaving a cohort of 653 patients (median age, 61 years; APACHE-II, 19). METHODS: We conducted this study of MRSA transmission over 1 year (August 1, 2011 to July 31, 2012) using a multiplex PCR-based reverse line blot (mPCR/RLB) assay to genotype isolates from surveillance swabs obtained at admission and twice weekly during ICU stays. MRSA prevalence and incidence rates were calculated and transmission events were identified using strain matching. Colonization pressure was calculated daily by summation of all MRSA cases. RESULTS: Of 1,030 admissions to ICU during the study period, 349 patients were excluded. MRSA acquisition occurred during 31 of 681 (4.6%) remaining admissions; 19 of 31(61%) acquisitions were genotype-confirmed, including 7 (37%) due to the most commonly transmitted strain. Moving averages of MRSA patient numbers on the days prior to a documented event were used in a Poisson regression model. A significant association was found between transmission and colonization pressure when the average absolute colonization pressure on the previous day was ≥3 (χ2=7.41, P=0.01). CONCLUSIONS: mPCR/RLB characterizes MRSA isolates within a clinically useful time frame for identification of single-source clusters within the ICU. High MRSA colonization pressure (≥3 MRSA-positive patients) on a given day is associated with an increased likelihood of a transmission event.

Training for cricothyroidotomy.

Cricothyroidotomy is infrequently performed in the intensive care unit but may be a lifesaving procedure. The aim of this study was to determine the number of attempts required by trainees to gain adequate skills for a successful cricothyroidotomy (defined as lung inflation <60 seconds). The effect of training on time to completion of cricothyroidotomy was also studied. After viewing a demonstration video on the procedure, each participant attempted cricothyroidotomy five times consecutively on a manikin with a pre-assembled Melker cricothyroidotomy kit. Time from 'skin' palpation to 'lung' inflation was recorded for 30 participants. Time to completion of cricothyroidotomy decreased over consecutive attempts within each participant (F4df=39.6; P <0.001) and between participant variability in times recorded at each attempt also decreased (P=0.04). Overall improvement in time to completion was seen even between the fourth and fifth attempts (mean difference -6.3 seconds; P <0.001). All participants were successful by the fifth attempt, by which stage all but two had been successful on two consecutive attempts. Age, years of postgraduate practice and level of seniority appeared to be associated with earlier success. Consecutive attempts on a manikin led to an improvement in the time to completion of cricothyroidotomy and rate of a successful outcome (<60 seconds). We recommend that clinicians undergo at least five training attempts on a manikin to gain proficiency in cricothyroidotomy.

Lewy-like aggregation of α-synuclein reduces protein phosphatase 2A activity in vitro and in vivo.

α-synuclein (α-Syn) is a chaperone-like protein that is highly implicated in Parkinson's disease (PD) as well as in dementia with Lewy bodies (DLB). Rare forms of PD occur in individuals with mutations of α-Syn or triplication of wild type α-Syn, and in both PD and DLB the intraneuronal inclusions known as Lewy bodies contain aggregated α-Syn that is highly phosphorylated on serine 129. In neuronal cells and in the brains of α-Syn overexpressing transgenic mice, soluble α-Syn stimulates the activity of protein phosphatase 2A (PP2A), a major serine/threonine phosphatase. Serine 129 phosphorylation of α-Syn attenuates its stimulatory effects on PP2A and also accelerates α-Syn aggregation; however, it is unknown if aggregation of α-Syn into Lewy bodies impairs PP2A activity. To assess for this, we measured the impact of α-Syn aggregation on PP2A activity in vitro and in vivo. In cell-free assays, aggregated α-Syn had ∼50% less PP2A stimulatory effects than soluble recombinant α-Syn. Similarly in DLB and α-Syn triplication brains, which contain robust α-Syn aggregation with high levels of serine 129 phosphorylation, PP2A activity was also ∼50% attenuated. As α-Syn normally stimulates PP2A activity, our data suggest that overexpression of α-Syn or sequestration of α-Syn into Lewy bodies has the potential to alter the phosphorylation state of key PP2A substrates; raising the possibility that all forms of synucleinopathy will benefit from treatments aimed at optimizing PP2A activity.

Experience with high frequency oscillation ventilation during the 2009 H1N1 influenza pandemic in Australia and New Zealand.

During the 2009 H1N1 pandemic, large numbers of patients had severe respiratory failure. High frequency oscillation ventilation was used as a salvage technique for profound hypoxaemia. Our aim was to compare this experience with high frequency oscillation ventilation during the 2009 H1N1 pandemic with the same period in 2008 by performing a three-month period prevalence study in Australian and New Zealand intensive care units. The main study end-points were clinical demographics, care delivery and survival. Nine intensive care units contributed data. During 2009 there were 22 H1N1 patients (17 adults, five children) and 10 non-H1N1 patients (five adults, five children), while in 2008, 18 patients (two adults, 16 children) received high frequency oscillation ventilation. The principal non-H1N1 high frequency oscillation ventilation indication was bacterial or viral pneumonia (56%). For H1N1 patients, the median duration of high frequency oscillation ventilation was 3.7 days (interquartile range 1.8 to 5) with concomitant therapies including recruitment manoeuvres (22%), prone ventilation (41%), inhaled prostacyclins (18%) and inhaled nitric oxide (36%). Seven patients received extracorporeal membrane oxygenation, six having H1N1. Three patients had extracorporeal membrane oxygenation concurrently, two as salvage therapy following the commencement of high frequency oscillation ventilation. In 2008, no high frequency oscillation ventilation patient received extracorporeal membrane oxygenation. Overall hospital survival was 77% in H1N1 patients, while survival in patients having adjunctive extracorporeal membrane oxygenation was similar to those receiving high frequency oscillation ventilation alone (65% compared to 71%, P = 1.00). Survival rates were comparable to published extracorporeal membrane oxygenation outcomes. High frequency oscillation ventilation was used successfully as a rescue therapy for severe respiratory failure. High frequency oscillation ventilation was only available in a limited number of intensive care units during the H1N1 pandemic.

Cricothyroidotomy: comparison of three different techniques on a porcine airway.

We compared three different cricothyroidotomy techniques on a cadaveric porcine airway model to determine the most rapid, successful and safe method in emergency situations. In this observational comparative bench-test, surgical or scalpel cricothyroidotomy (ST), Cook Melker Cricothyrotomy Kit (CM) and Portex Cricothyroidotomy Kit (PCK) were evaluated. After a familiarisation program, four operators performed five procedures using each of the techniques. A dissected pig airway was housed in an airway training manikin. Time to successful completion of the procedure, complications and anatomical variations in the pig larynx were recorded. A patent airway was established in 20 of 20 (100%) attempts with CM technique, 11 of 20 (55%) with ST and six of 20 (30%) with PCK technique. The CM technique was associated with a higher success rate (P <0.001). There was no significant difference (P=0.4) in the median time (interquartile range) taken to achieve a patent airway; CM 50 seconds (40 to 57), ST 47 seconds (41 to 55) and PCK 63 seconds (41 to 150). There was a higher rate of posterior tracheal wall injury with the PCK technique (n=11) and ST technique (n=5). No complications were observed with CM technique. There were no significant anatomical variations in the pig larynxes. We conclude that the CM technique is safe, rapid and has a significantly higher success rate in achieving an artificial airway in this airway model. Overall, all the participants in our study preferred to use this kit in an emergency situation.

Atrial fibrillation in a tertiary care multidisciplinary intensive care unit--incidence and risk factors.

Atrial fibrillation is a common arrhythmia in an intensive care unit. We performed a prospective observational study over a period of three months, to study the incidence, risk factors and outcome of patients who develop atrial fibrillation in a multidisciplinary intensive care unit. All patients above the age of 50 years were eligible. Exclusion criteria were: cardiac or oesophageal surgery during current hospitalisation, atrial fibrillation at admission, implanted pacemaker and expected intensive care unit stay of less than 24 hours. Sixty-one patients were included in the study. Eighteen patients (29.5%, confidence interval 18-40) developed atrial fibrillation. Incidence of atrial fibrillation was 4.02 episodes per 100 patient days. Patients who developed atrial fibrillation had higher age (71.3 years vs. 63.2 years, P=0.001), severity of illness (APACHE II 25.4 vs. 20.0, P=0.005) and sepsis at admission (9/18 vs. 9/43, P=0.01). They also had higher in-hospital mortality (Risk ratio 2.7, 95% confidence interval 1.3-5.4). Standardised mortality ratio was higher in patients who developed atrial fibrillation (1.08 vs. 0.63). Patients who developed atrial fibrillation required a longer period of mechanical ventilation and inotropic support. Multivariate logistic regression analysis showed age >75 years, APACHE II score >20 and sepsis at admission were independent predictors for development of atrial fibrillation in critically ill patients. Although atrial fibrillation by itself is unlikely to be the cause of higher mortality, it is likely to be a marker for increased mortality and resource utilisation in the intensive care unit.

A review of the use of heliox in the critically ill.

Heliox, a mix of oxygen and helium, has a number of potential medical applications resulting from its relatively lower density. This paper reviews the physics underlying its utility and considers the evidence for its use. While there are studies that support its role, particularly in patients with exacerbations of asthma and chronic obstructive pulmonary disease (COPD), the data are inconclusive.

Procalcitonin: a marker of bacteraemia in SIRS.

A number of European studies have documented the ability of procalcitonin (PCT), a novel inflammatory marker, to discriminate patients with sepsis from those with other causes of systemic inflammatory response syndrome (SIRS). The aim of this study was to assess procalcitonin's performance in an Australian intensive care unit (ICU) setting to examine whether it could discriminate between these two conditions. One hundred and twenty-three consecutive adult ICU patients fulfilling criteria for SIRS were enlisted in the study. Over a period of five days, daily serum PCT and C-reactive protein (CRP) levels were measured. At least two sets of cultures were taken of blood, sputum/broncho-alveolar lavage (BAL) and urine. Other cultures were taken as clinically indicated. Questionnaires to ascertain clinical suspicion of sepsis were prospectively answered by the ICU senior registrars. PCT values were ten times higher in patients with positive blood cultures; CRP values were also significantly higher in the bacteraemic patients. Both PCT and CRP had a good ability to discriminate bacteraemia from non-infectious SIRS, with the area under receiver operating characteristics (ROC) curves for PCT being 0.8 and for CRP being 0.82. However neither PCT or CRP was able to discriminate patients with localized sepsis from those without. Utilizing both tests resulted in a more sensitive screen than either one alone, while PCT was a more accurate diagnostic test for bacteraemia than CRP. The PCT value also differed between those who died in hospital and those who survived. Measurement of PCT alone or in combination with CRP can aid discrimination of septicaemia/bacteriemia with associated SIRS from non-infectious SIRS in an Australian ICU setting.