Critical Care

Epinephrine for Out of Hospital Cardiac Arrest

Despite its central role in ACLS, the use of Epinephrine and outcome has been controversial. A major study finds “the use of epinephrine resulted in a significantly higher rate of 30-day survival than the use of placebo, but there was no significant between-group difference in the rate of a favorable neurologic outcome because more survivors had severe neurologic impairment in the epinephrine group”.

Postulated mechanisms include impairment of microvascular cerebral blood flow or possible reperfusion injury. So Epinephrine may improve survival but at a cost. The most important message to reiterate is how vital rapid CPR and defibrillation are.

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High Flow Nasal Oxygen & Length of Stay

The enthusiasm for high flow nasal oxygen continues unabated. This study was on high‐risk patients with pre‐existing lung disease (COPD, asthma, recent lower respiratory tract infection), heavy smokers or morbidly obese patients (body mass index (BMI) ≥ 35 kg.m−2), who were expected to stay longer in ICU and hospital due to increased respiratory complications after cardiac surgery.

When compared with standard oxygen therapy care, prophylactic postoperative high‐flow nasal oxygen reduced hospital length of stay and intensive care unit re‐admission. The authors recommend routine use of high‐flow nasal oxygen after tracheal extubation in this cohort of patients and further testing of their hypothesis in large multi‐centre randomised trials.

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Medication Diluents, Volume and Hyperchloremia

When prescribing intravenous fluids, physicians don’t always take into consideration the amount contributed by medications. In this medical ICU study, 63% of all fluids came from medication diluents. This is an important source of ‘fluid creep’ that must be considered in de-resuscitation strategies ( blog link ).

The study focuses on the higher incidence of hypernatremia when using normal saline compared with 5% Dextrose, with a non-significant trend towards higher acute kidney injury. There was no higher incidence of hyponatremia, glucose levels or Insulin requirements in the D5% group.

Intensivists should monitor both medication fluids and their relation to electrolyte levels, with the increasing recognition of the association between 0.9% Saline and potential kidney injury, as well as medication diluent impact on overall fluid balance.

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De-resuscitation of Fluid Overload and ICU Mortality

A retrospective cohort study on iatrogenic fluid overload in critically ill ventilated patients shows that a positive cumulative fluid balance on day three was associated with a higher mortality.  The largest contributions to fluid excess were maintenance and medication fluids rather than resuscitation fluids. Negative fluid balance achieved in the context of deresuscitative measures was associated with lower mortality.

This study supports recent trends in actively limiting maintenance and medication fluids along with deresuscitative measures such as diuretic usage and renal replacement therapy after the initial resuscitation  to achieve a negative fluid balance around  day three in the critically ill.

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Inferior Vena Cava Filters and Mortality

Inferior vena cava filters are widely employed for thromboembolism where contraindications to anticoagulation exist. This study has the limitations of being retrospective and observational and as such is hypothesis generating, but its conclusions are important and concerning in suggesting a higher 30 day mortality with use of caval filters in those with contraindications to anticoagulation.

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ARDS Guidelines

Updated guidelines based on current evidence from the UK Intensive Care Society on ARDS.

EXECUTIVE SUMMARY

The British Thoracic Society supports the recommendations in this guideline.
Where mechanical ventilation is required, the use of low tidal volumes ( < 6 m l / k g ideal body weight) and airway pressures (plateau pressure < 30 cmH2O) was recommended. For patients with moderate/severe ARDS (PF ratio < 20kPa), prone positioning was recommended for at least 12 hours per day.
By contrast, high frequency oscillation is not recommended and it is suggested that inhaled nitric oxide is not used. The use of a conservative fluid management strategy was suggested for all patients, whereas mechanical ventilation with high positive end-expiratory pressure (PEEP) and the use of the neuro-muscular blocking agent cisatracurium for 48 hours was suggested for ARDS patients with PF ratios less than or equal to 27 and 20 kPa respectively.
Extra-corporeal membrane oxygenation (ECMO) was suggested as an adjunct to protective mechanical ventilation for patients with very severe ARDS. In the absence of adequate evidence, research recommendations were made for the use of corticosteroids and extra-corporeal carbon dioxide removal (ECCOR).

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Critical Burns and Hemodynamic Management

A review on the hemodynamic management of critical burns updates some concepts. The traditional Parkland formula often results in too much fluid as does reliance on central venous pressure or intra-thoracic blood volume. Excess fluids may risk ARDS, abdominal compartment syndrome or renal failure. The authors suggest more updated hemodynamic monitors such as arterial pressure waveform analysis, pulse pressure or stroke volume variation. They recommend balanced crystalloids rather than normal saline as is the case in other areas, with better renal outcomes; Albumin may have a role to play; vasopressors like Norepinephrine may limit over-resuscitation in the hyperdynamic sepsis-like phase. Some evidence is also presented on high dose Vitamin C and possibly steroids.

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