Effect of isotonic versus hypotonic maintenance fluid therapy on urine output, fluid balance, and electrolyte homeostasis: a crossover study in fasting adult volunteers

Background. Daily and globally, millions of adult hospitalized patients are exposed to maintenance i.v. fluid solutions supported by limited scientific evidence. In particular, it remains unclear whether fluid tonicity contributes to the recently established detrimental effects of fluid, sodium, and chloride overload.

Methods. This crossover study consisted of two 48 h study periods, during which 12 fasting healthy adults were treated with a frequently prescribed solution (NaCl 0.9% in glucose 5% supplemented by 40 mmol litre⁻¹ of potassium chloride) and a premixed hypotonic fluid (NaCl 0.32% in glucose 5% containing 26 mmol litre⁻¹ of potassium) at a daily rate of 25 ml kg⁻¹ of body weight. The primary end point was cumulative urine volume; fluid balance was thus calculated. We also explored the physiological mechanisms behind our findings and assessed electrolyte concentrations.

Results. After 48 h, 595 ml (95% CI: 454–735) less urine was voided with isotonic fluids than hypotonic fluids (P<0.001), or 803 ml (95% CI: 692–915) after excluding an outlier with ‘exaggerated natriuresis of hypertension’. The isotonic treatment was characterized by a significant decrease in aldosterone (P<0.001). Sodium concentrations were higher in the isotonic arm (P<0.001), but all measurements remained within the normal range. Potassium concentrations did not differ between the two solutions (P=0.45). Chloride concentrations were higher with the isotonic treatment (P<0.001), even causing hyperchloraemia.

Conclusions. Even at maintenance rate, isotonic solutions caused lower urine output, characterized by decreased aldosterone concentrations indicating (unintentional) volume expansion, than hypotonic solutions and were associated with hyperchloraemia. Despite their lower sodium and potassium content, hypotonic fluids were not associated with hyponatraemia or hypokalaemia.

Clinical trial registration. ClinicalTrials.gov (NCT02822898) and EudraCT (2016-001846-24).

Mechanical and electrical equipment interference provokes a misleading Neurally Adjusted Ventilatory Assist (NAVA) EAdi signal

BACKGROUND

Neurally Adjusted Ventilatory Assist (NAVA) offers synchronized proportional pressure in accordance with the electrical activity of the diaphragm (EAdi). NAVA relies on the EAdi to trigger the respiratory cycle and then adjusts the ventilatory assist to the neural drive. The technique necessitates a catheter with bipolar microelectrodes positioned near the crural diaphragm where this signal can be captured. Capturing a reliable EAdi signal is a condition sine qua non for using NAVA as a mode of ventilation. The displayed signal represents the sum of the electrical activity of the muscle action potential of the diaphragm and is expressed in microvolts.

METHODS

A technical note illustrated by a case series in the intensive care unit (ICU) of a tertiary referral hospital with experience using NAVA.

RESULTS

Here, we report on three separate cases in which the use of an intra-aortic balloon catheter, a pacemaker and a heating device all resulted in a distortion of the EAdi signal, despite good positioning of the catheter. In a fourth case, we observed internal interference from leaking cardiac electrical activity due to the malpositioning of the EAdi catheter in a patient with atrial fibrillation.

CONCLUSION

We illustrate that the detection and therefore interpretation of the EAdi signal during NAVA can be influenced by mechanical and electrical interference by other equipment used in the ICU or from endogenous leaking cardiac activity.

A patient with interstitial lung disease secondary to dermatomyositis: a case report and review of the literature

We describe the case of a man with known dermatomyositis who presented with a dry cough and who early after admission rapidly evolved to respiratory insufficiency. Based on pathological and radiological findings, the diagnosis of diffuse alveolar damage was made. Postmortem examination also revealed infection with yeast, Torulopsis glabrata. Polymyositis (PM) and dermatomyositis (DM) are both auto-immune diseases, which are characterised by the presence of auto-antibodies and tissue-inflammation, mainly involving the muscles. Patients with PM/DM may have pulmonary complications, often responsible for higher morbidity and mortality. Interstitial lung disease can present itself in different shapes and forms (bronchiolitis obliterans organising pneumonia, non-specific organising pneumonia, usual interstitial pneumonia, acute interstitial pneumonia) and the diagnosis is made based on the combination of pathological examination and radiological findings.

Identification of modifiable risk factors for acute kidney injury after cardiac surgery

OBJECTIVES

Acute kidney injury (AKI) is a common problem after cardiac surgery and is associated with an increase in morbidity, mortality and duration of hospital stay. With this study we aimed to identify potential risk factors for cardiac surgery associated AKI (CS-AKI) in a single-centre population with a special focus on modifiable risk factors.

METHODS

Retrospective single-centre cohort study of 565 consecutive patients who underwent isolated coronary artery bypass grafting (CABG) with the use of cardiopulmonary bypass. AKI was defined by the AKIN classification. Known risk scores were applied when possible.

RESULTS

Of the population, 14.7% were diagnosed with AKI. When considering baseline characteristics we found a significant difference in age, preoperative estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD) stage and urgency of surgery between the CS-AKI group and the control population. Regarding the intraoperative characteristics, patients with CS-AKI had a significantly lower haematocrit and were more likely to receive a transfusion of packed cells. Postoperative administration of furosemide and packed cell transfusions were also associated with AKI. We found no differences in other characteristics (history of diabetes mellitus, history of congestive heart failure, sex, body mass index (BMI), history of cardiac surgery, low cardiac output and need for intra-aortic balloon pump (IABP), duration of cardiopulmonary bypass (CPB) and cross clamping).

CONCLUSION

In our series we could identify intraoperative administration of packed cells and postoperative administration of furosemide or packed cells as potentially modifiable risk factors in the development of AKI.

Impact of a standardized nurse observation protocol including MEWS after Intensive Care Unit discharge

BACKGROUND

Analysis of in-hospital mortality after serious adverse events (SAE's) in our hospital showed the need for more frequent observation in medical and surgical wards. We hypothesized that the incidence of SAE's could be decreased by introducing a standard nurse observation protocol.

AIM

To investigate the effect of a standard nurse observation protocol implementing the Modified Early Warning Score (MEWS) and a color graphic observation chart.

METHODS

Pre- and post-intervention study by analysis of patients records for a 5-day period after Intensive Care Unit (ICU) discharge to 14 medical and surgical wards before (n=530) and after (n=509) the intervention.

RESULTS

For the total study population the mean Patient Observation Frequency Per Nursing Shift (POFPNS) during the 5-day period after ICU discharge increased from .9993 (95% C.I. .9637-1.0350) in the pre-intervention period to 1.0732 (95% C.I. 1.0362-1.1101) (p=.005) in the post-intervention period. There was an increased risk of a SAE in patients with MEWS 4 or higher in the present nursing shift (HR 8.25; 95% C.I. 2.88-23.62) and the previous nursing shift (HR 12.83;95% C.I. 4.45-36.99). There was an absolute risk reduction for SAE's within 120h after ICU discharge of 2.2% (95% C.I. -0.4-4.67%) from 5.7% to 3.5%.

CONCLUSION

The intervention had a positive impact on the observation frequency. MEWS had a predictive value for SAE's in patients after ICU discharge. The drop in SAE's was substantial but did not reach statistical significance.

Localised plasma-cell type Castleman's disease and AA-amyloidosis cured by resection. A case report and review of the literature

Castleman's disease (CD) is a rare atypical lymphoproliferative disorder with frequent, yet less well known renal involvement. We describe the case of a 58-year-old woman with localised abdominal plasma-cell type CD complicated by nephrotic syndrome due to renal amyloidosis. 18Fluorodeoxyglucose (FDG) positron emission tomography (PET) confirmed the unicentric nature. Resection of the mass resulted in regression of the signs of inflammation, a negative FDG-PET and complete remission of the nephrotic syndrome. A review of the literature of renal involvement (incidence, clinical and pathological manifestations, treatment and prognosis) in CD is provided.