Impact of resuscitation fluid bag size availability on volume of fluid administration in the intensive care unit

BACKGROUND

Iatrogenic fluid overload is associated with increased mortality in the intensive care unit (ICU). Decisions on fluid therapy may, at times, be based on other factors than physiological endpoints. We hypothesized that because of psychological factors volume of available fluid bags would affect the amount of resuscitation fluid administered to ICU patients.

METHODS

We performed a prospective intervention cross-over study at 3 Swedish ICUs by replacing the standard resuscitation fluid bag of Ringer's Acetate 1000 mL with 500 mL bags (intervention group) for 5 separate months and then compared it with the standard bag size for 5 months (control group). Primary endpoint was the amount of Ringer's Acetate per patient during ICU stay. Secondary endpoints were differences between the groups in cumulative fluid balance and change in body weight, hemoglobin and creatinine levels, urine output, acute kidney failure (measured as the need for renal replacement therapy, RRT) and 90-day mortality.

RESULTS

Six hundred and thirty-five ICU patients were included (291 in the intervention group, 344 in the control group). There was no difference in the amount of resuscitation fluid per patient during the ICU stay (2200 mL [1000-4500 median IQR] vs 2245 mL [1000-5630 median IQR]), RRT rate (11 vs 9%), 90-day mortality (11 vs 10%) or total fluid balance between the groups. The daily amount of Ringer's acetate administered per day was lower in the intervention group (1040 (280-2000) vs 1520 (460-3000) mL; P = .03).

CONCLUSIONS

The amount of resuscitation fluid administered to ICU patients was not affected by the size of the available fluid bags. However, altering fluid bag size could have influenced fluid prescription behavior.

Natalizumab for moderate to severe Crohn's disease in clinical practice: the Mayo Clinic Rochester experience

BACKGROUND

Not all patients with Crohn's disease (CD) respond or maintain response to anti-tumor necrosis factor (TNF) agents and alternative treatment is necessary. Natalizumab, a monoclonal antibody to alpha-4 integrin approved for CD, has demonstrated efficacy in randomized clinical trials. We describe our experience with natalizumab in clinical practice at Mayo Clinic Rochester.

METHODS

Consecutive patients prescribed natalizumab for active CD were invited to participate and were followed prospectively. Incidence of infection, hospitalization, neoplasm, or other adverse events were recorded. Clinical activity was assessed using the Harvey-Bradshaw Index at each 30-day infusion visit.

RESULTS

Between April 2008 and September 2010, 36 patients were prescribed natalizumab and 30 (83.3%) agreed to participate. Median disease duration was 9 years (range, 3-43). Twenty-three patients had prior exposure to two anti-TNF agents, seven to one agent. All patients experienced at least one adverse event; none of the 13 patients in whom natalizumab was stopped (43%) discontinued due to adverse events. Five patients had infusions held for infection. No patient developed progressive multifocal leukoencephalopathy (PML). Fourteen patients (46%) had clinical response. The cumulative probability of achieving complete response within 1 year was 56% (28%-73%). Four of seven patients were weaned off corticosteroids.

CONCLUSIONS

In our experience with natalizumab in clinical practice, adverse events were manageable and did not result in treatment cessation. No PML cases were seen and clinical response was similar to that in clinical trials. Natalizumab results in clinical benefit in patients who have active disease and have failed anti-TNF therapy.

Near-infrared spectroscopy: does it function in functional activation studies of the adult brain?

Changes in optical properties of biological tissue can be examined by near-infrared spectroscopy (NIRS). The relative transparency of tissues including the skull to near-infrared light is the prerequisite to apply the method to brain research. We describe the methodology with respect to its applicability in non-invasive functional research of the adult cortex. A summary of studies establishing the 'typical' response in NIRS vascular parameters, i.e. changes in the concentration of oxygenated and deoxygenated haemoglobin, over an activated area is followed by the validation of changes in the cytochrome-oxidase redox state in response to a visual stimulus. Proceeding from these findings a rough mapping of this metabolic response over the motion-sensitive extrastriate visual area is demonstrated. NIRS measures concentration changes in deoxygenated haemoglobin [deoxy-Hb] which are assumed to be the basis of fMRI BOLD contrast (blood oxygenation level-dependent). The method is therefore an excellent tool to validate assumptions on the physiological basis underlying the fMRI signal, due to its high specificity as to the parameters measured. Questions concerning the concept of 'activation'/'deactivation' and that of the linearity of the vascular response are discussed. To challenge the method we finally present results from a complex single-trial motor paradigm study testing the hypothesis, that premotor potentials (contingent negative variation) can be examined by functional techniques relying on the vascular response. Some of the work described here has been published elsewhere.

Determination of the wavelength dependence of the differential pathlength factor from near-infrared pulse signals

For the calculation of changes in oxyhaemoglobin, deoxyhaemoglobin and the redox state of cytochrome-c-oxidase from attenuation data via a modified Beer-Lambert equation the wavelength dependence of the differential pathlength factor (DPF(lambda)) has to be taken into account. The DPF, i.e. the ratio of the mean optical pathlength and the physical light source-detector separation at each wavelength, determines the crosstalk between the different concentrations and is therefore essential for a sensitive detection of chromophore changes. Here a simple method is suggested to estimate the wavelength dependence of the DPF(lambda) from pulse-induced attenuation changes measured on the head of adult humans. The essence is that the DPF is the ratio of the attenuation changes over absorption coefficient changes, and that the spectral form of the pulse correlated absorption coefficient change can be assumed to be proportional to the extinction coefficient of blood. Indicators for the validity of the DPF(lambda) derived for wavelengths between 700 and 970 nm are the stability of the calculated haemoglobin and cytochrome signals with variations of the wavelength range included for their calculation and its overall agreement with the data available from the literature.

Adding new information to semantic memory: how much learning is enough to produce automatic priming?

A series of experiments investigated the integration of new vocabulary words into semantic memory and the creation of new associations between preexisting, but previously unrelated, words. The ability of the newly learned vocabulary words and associations to facilitate lexical decisions when serving as primes under conditions associated with automatic processing was used to index integration. The results indicate that very extensive study is necessary for such integration to occur and that it is easier to add a new word to semantic memory than to establish a link between two formerly unconnected words already in semantic memory. The implications of these results for models of semantic memory and the episodic/semantic distinction are considered.

Adding new information to semantic memory: How much learning is enough to produce automatic priming?

A series of experiments investigated the integration of new vocabulary words into semantic memory and the creation of new associations between preexisting, but previously unrelated, words. The ability of the newly learned vocabulary words and associations to facilitate lexical decisions when serving as primes under conditions associated with automatic processing was used to index integration. The results indicate that very extensive study is necessary for such integration to occur and that it is easier to add a new word to semantic memory than to establish a link between two formerly unconnected words already in semantic memory. The implications of these results for models of semantic memory and the episodic/semantic distinction are considered.

[Autologous transfusion of blood deep frozen in the interim in childhood]

In the report we describe a method of reducing the number of transfusions of heterologous blood in patients with a surgical correction of chest walls. In 71 children between 2 and 17 years of age, 10-15% of total blood volume were withdrawn 3-4 weeks before the operation, deep frozen and thawed at the appropriate time to be ready for retransfusion. This arrangement reduced the need of heterologous blood significantly from 18.6% (prior to the introduction of the method) to 4.2%.

[Autologous transfusion in scoliosis operations: preoperative autologous blood donations and intraoperative mechanical autotransfusion]

Autologous transfusion was used to reduce the high demand for blood accompanied with scoliosis surgery. Half of the blood loss could be saved by intraoperative autotransfusion (35 patients). This resulted in a corresponding reduction in homologous transfusion. An elimination of the need for homologous blood could be achieved only by the combination of preoperative blood donation and intraoperative autotransfusion (37 patients). With freezing the predeposit blood was independent of storage time and autologous plasma was available. Thus, the risks of transfusion can be avoided.

[Cryopreservation at a modern blood transfusion center]

Transfusion of frozen blood has become a routine method. As the cost is high, the method is restricted to autologus transfusion and storage of rare blood groups. Transfusion of frozen platelets will become a routine method in near future. Especially large pools of HLA-identical platelets should be of great advantage in many cases.