Insensible Water Loss Research Articles

Neonatal warming devices: What can be recommended for low-resource settings when skin-to-skin care is not feasible?

Hypothermia occurs frequently among clinically unstable neonates who are not suitable to place in skin-to-skin care. This study aims to explore the existing evidence on the effectiveness, usability, and affordability of neonatal warming devices when skin-to-skin care is not feasible in low-resource settings. To explore existing data, we searched for (1) systematic reviews as well as randomised and quasi-randomised controlled trials comparing the effectiveness of radiant warmers, conductive warmers, or incubators among neonates, (2) neonatal thermal care guidelines for the use of warming devices in low-resource settings and (3) technical specification and resource requirement of warming devices which are available in the market and certified medical device by the US Food and Drug Administration or with a CE marking. Seven studies met the inclusion criteria, two were systematic reviews comparing radiant warmers vs. incubators and heated water-filled mattresses vs. incubators, and five were randomised controlled trials comparing conductive thermal mattresses with phase-change materials vs. radiant warmers and low-cost cardboard incubator vs. standard incubator. There was no significant difference in effectiveness between devices except radiant warmers caused a statistically significant increase in insensible water loss. Seven guidelines covering the use of neonatal warming devices show no consensus about the choice of warming methods for clinically unstable neonates. The main warming devices currently available and intended for low-resource settings are radiant warmers, incubators, and conductive warmers with advantages and limitations in terms of characteristics and resource requirements. Some devices require consumables which need to be considered when making a purchase decision. As effectiveness is comparable between devices, specific requirements according to patients' characteristics, technical specification, and context suitability must play a primary role in the selection and purchasing decision of warming devices. In the delivery room, a radiant warmer allows fast access during a short period and will benefit numerous neonates. In the neonatal unit, warming mattresses are low-cost, effective, and low-electricity consumption devices. Finally, incubators are required for very premature infants to control insensible water losses, mainly during the first one to two weeks of life, mostly in referral centres.

Management of Hypernatremia Dehydration in Three Neonates with Ichthyosis

Introduction: Ichthyosis is an epidermal disruption that increases insensible water loss. Hypernatremic dehydration is a consequence of skin disruption. This study reviewed the treatment of hypernatremic dehydration in patients with ichthyosis comparing to patients with intact skin. Case Presentation: We studied five neonates with hypernatremia, including three ichthyosis cases and two normal-skin neonates. This case-series study showed that the sodium correction rate is slower in infants with ichthyosis than in infants with normal skin. The first and second neonates needed less sodium than fluid intake than normal skin infants, although fluid requirement was lower in the third ichthyosis infant than in others due to less skin disruption in this infant. Conclusions: Fluid therapy in hypernatremic dehydration in ichthyosis patients is different from neonates with intact skin because of excessive insensible water loss in these patients. It may be needed to give more fluid and less sodium depending on the degree of skin disruption, which may not be determined by physical examination.

Evaluation and management of hypernatremia in adults: clinical perspectives.

Hypernatremia is an occasionally encountered electrolyte disorder, which may lead to fatal consequences under improper management. Hypernatremia is a disorder of the homeostatic status regarding body water and sodium contents. This imbalance is the basis for the diagnostic approach to hypernatremia. We summarize the eight diagnostic steps of the traditional approach and introduce new biomarkers: exclude pseudohypernatremia, confirm glucose-corrected sodium concentrations, determine the extracellular volume status, measure urine sodium levels, measure urine volume and osmolality, check ongoing urinary electrolyte free water clearance, determine arginine vasopressin/copeptin levels, and assess other electrolyte disorders. Moreover, we suggest six steps to manage hypernatremia by replacing water deficits, ongoing water losses, and insensible water losses: identify underlying causes, distinguish between acute and chronic hypernatremia, determine the amount and rate of water administration, select the type of replacement solution, adjust the treatment schedule, and consider additional therapy for diabetes insipidus. Physicians may apply some of these steps to all patients with hypernatremia, and can also adapt the regimens for specific causes or situations.

Incubator humidity and temperature control in infants born at 22–23 weeks' gestation

BackgroundPreterm infants, especially those born at ≤23 gestational weeks (GW), present with extremes in insensible water loss (IWL) and changes in water balance. AimsTo prevent water loss from the skin and achieve skin maturation without infection, we investigated transepidermal water loss (TEWL), IWL from the skin (IWL-s), and electrolyte balance with differences in high incubator humidity and temperature control from birth to postnatal 1 month in 22–23 GW and 24–25 GW infants. Study designProspective cohort study. SubjectsExtremely preterm infants born at 22–23 GW (n = 11) and 24–25 GW (n = 11), admitted to the neonatal intensive care unit between September 2018 and October 2019. Outcome measuresTotal fluid intake (TFI), fluid output volume, TEWL, IWL-s, and electrolyte balance were compared between the two groups with controlled incubator humidity and temperature, gradually decreasing the humidity and ambient temperature from 95% to 50% and from 37.0 to 34.0 °C, respectively, while maintaining the central body temperature at 36.5–37.5 °C. ResultsTEWL and IWL-s between the 22–23 and 24–25 GW was not significantly different for infants at postnatal age. No significant difference in electrolyte imbalance was noted between the two groups, within the first 7 days. Differences in TEWL and IWL-s were eliminated with corresponding humidity and temperature adjustments. ConclusionsIncubator humidity and temperature control should aid management of 22–23 GW infants to reduce IWL, facilitate skin maturation, and prevent infection.

The impact of heat on kidney stone presentations in South Carolina under two climate change scenarios

The risk of kidney stone presentations increases after hot days, likely due to greater insensible water losses resulting in more concentrated urine and altered urinary flow. It is thus expected that higher temperatures from climate change will increase the global prevalence of kidney stones if no adaptation measures are put in place. This study aims to quantify the impact of heat on kidney stone presentations through 2089, using South Carolina as a model state. We used a time series analysis of historical kidney stone presentations (1997–2014) and distributed lag non-linear models to estimate the temperature dependence of kidney stone presentations, and then quantified the projected impact of climate change on future heat-related kidney stone presentations using daily projections of wet-bulb temperatures to 2089, assuming no adaptation or demographic changes. Two climate change models were considered—one assuming aggressive reduction in greenhouse gas emissions (RCP 4.5) and one representing uninibited greenhouse gas emissions (RCP 8.5). The estimated total statewide kidney stone presentations attributable to heat are projected to increase by 2.2% in RCP 4.5 and 3.9% in RCP 8.5 by 2085–89 (vs. 2010–2014), with an associated total excess cost of ~ $57 million and ~ $99 million, respectively.

Overview on Fluid, Electrolyte and Nutrition Management of the Newborn and Pre-term Newborns

Often in extremely preterm newborns in the early postnatal daysproblems in fluid and electrolyte balance occur Due to excessive insensible water loss and renal immaturity. The dietary care of newborn newborns is challenged by the demands of growth and organ development. The stress of a serious disease makes it much more difficult to get enough nourishment. Newborns andespecially premature newborns must be assessed thoroughly for fluid and electrolytes balance. Calculating the fluid and electrolyte demand for sustaining metabolic activities, replacing losses (evaporative, third space, external), and considering pre-existing fluid imbalance are all part of effective fluid and electrolyte management. When a neonate's size or condition prevents them from receiving enteral nutrition, parenteral nutrition can help them grow and thrive. Although eating through the gastrointestinal tract is the recommended method of nutritional management, some situations necessitate the use of PN as an adjuvant or sole treatment. In this article we discuss fluid electrolytes and Nutritional management using parenteral nutrition.

ENDOCRINOLOGY IN THE TIME OF COVID-19-2021 UPDATES: The management of diabetes insipidus and hyponatraemia.

COVID-19 has changed the nature of medical consultations, emphasizing virtual patient counselling, with relevance for patients with diabetes insipidus (DI) or hyponatraemia. The main complication of desmopressin treatment in DI is dilutional hyponatraemia. Since plasma sodium monitoring is not always possible in times of COVID-19, we recommend to delay the desmopressin dose once a week until aquaresis occurs allowing excess retained water to be excreted. Patients should measure their body weight daily. Patients with DI admitted to the hospital with COVID-19 have a high risk for mortality due to volume depletion. Specialists must supervise fluid replacement and dosing of desmopressin. Patients after pituitary surgery should drink to thirst and measure their body weight daily to early recognize the development of postoperative SIAD. They should know hyponatraemia symptoms. Hyponatraemia in COVID-19 is common with a prevalence of 20–30% and is mostly due to SIAD or hypovolaemia. It mirrors disease severity and is an early predictor of mortality. Hypernatraemia may also develop in COVID-19 patients, with a prevalence of 3–5%, especially in ICU, and derives from different multifactorial reasons, for example, due to insensible water losses from pyrexia, increased respiration rate and use of diuretics. Hypernatraemic dehydration may contribute to the high risk of acute kidney injury in COVID-19. IV fluid replacement should be administered with caution in severe cases of COVID-19 because of the risk of pulmonary oedema.

IMPACT OF INORGANIC FERTILIZATION ON SORGHUM FORAGE QUALITY AND GROWTH PERFORMANCE OF BARKI LAMBS

The present study was conducted at Maryout Research Station, Desert Research Center. It was applied in two experiments (Agronomy and fodder evaluation experiment and animal growth experiment) to determine the response of sorghum quality and consequently the animal performance to the application of combined N and P fertilizer in newly reclaimed soil. The first experiment was for evaluating sorghum fodder (Sorghum bicolor L.) that sorted with nine treatment combinations (from T1 up to T9) comprising of three nitrogen (N) and phosphorus (P) fertilizers levels (N80.4, N100.5 and N120.6 kg/feddan vs. P20.2, P30.2 and P40.3 kg/feddan) in factorial randomized block design with three replications. The results of the agronomy experiment with considering the ISDMD, NEg and the cost of treatments, showed that two treatments (N120P30 and N100P40) could be nominated to the second experiment which was their evaluation as feeds for the growing Barki lambs as compared to control treatment (N80P20). So, two treatments and control were sorting again in the next summer season to evaluate their nutritive values by using 15 growing Barki lambs (5 lambs/ treatment) in a completely randomized block design. Lambs were on average 22.83 ± 0.29 kg as the initial body weight and aged 5 months. All animals fed concentrate feed mixture to cover 70% of their growth requirements (Kearl, 1982). However, the experimental fodders were offered ad lib. So the experimental animal groups were allowed for three rations for 85d as follows; R1: CFM + sorghum forage of T1 (N80P20) ad lib., (served as a control), R2: CFM + sorghum forage of T6 (N120P30) ad lib, and R3: CFM + sorghum forage of T8 (N100P40) ad lib. The results indicated that; Average daily gain differed significantly (P= 0.016) being values 158, 185 and 192g for lambs fed R1, R2 and R3, respectively. Animals in R2 and R3 consumed a higher (P=0.042) amount of sorghum compared with the control one. There is a significant effect (P 0.05) by the experimental rations. Both R2 and R3 were the better (P 0.05) amounts of calcium. However, higher P content in sorghum of R2 and R3 revealed significantly higher P intake (P<0.05) and also P retained (P<0.05). The revealed insensible water loss (IWL) of the three groups was significantly different being values 144, 172 and 176 g/kg0.82 for R1, R2 and R3, respectively. The rumen pH value of animal group fed control ration (R1) was significantly (P≤0.001) higher than other groups at all the sampling time. Animals who received R2 ration showed the highest NH3-N values at 3h (P<0.01) and 6h (P<0.05) post-feeding as compared to the other groups; however R3 group showed the highest (P<0.05) value at zero hour post-feeding as compared to the groups. At 6h post-feeding, animals fed R2 showed the highest (P<0.05) TVFA value (22.14meq/dl) as compared to the other groups (19.68 and 21.45 meq/dl for R1 and R3, respectively). It could be concluded that both of the sorghum treatments; N120P30 and N100P40 kg/fed; are in the same nutritive values and similar growth rate for Barki lambs but because of higher P drain away to the land below in case of N100P40 ration so it is recommended for N120P30 to be a better fertilizer rate for the fodder consumed by the Barki lambs and also for its potential to reduce the environmental pollution with the high level of P compared to the other treatment.

Did human evolution in skin of color enhance the TEWL barrier?

United States will soon be a nation of color; however, much of our knowledge of normal skin disease, and treatment thereof is based on white skin. We and others have attempted to elucidate any potential differences and advantages/disadvantages in skin function that have emerged during homo sapiens evolution post major migration from Eastern Africa. We investigated differences in one stratum corneum function by examining transepidermal water loss (TEWL) measurements in skin of color compared to Caucasian skin. TEWL, a measure of insensible water loss through stratum corneum, plays a major role in human survival. A comprehensive literature search was conducted to procure relevant papers that measured baseline TEWL in skin of color and Caucasian skin. The data show wide contradiction in results for all skin of color groups and white skin and, therefore, no conclusion can be made based on this question. We suggest this variation may be due to experimental confounding variables that impact TEWL quantification, such as anatomic site and sample size subject to further analysis and focus.

Significance of Hypernatremia Due to SARS-CoV-2 Associated ARDS in Critically Ill Patients.

Background and ObjectivesSARS-CoV-2-induced ARDS is a new entity that should be characterized as it appears to be different from standard ARDS. Hypernatremia is a biological alteration that seems to occur very often in this population without any clear cause. The present study aims to clarify the possible causes of hypernatremia and evaluate its impact on patient outcome.Patients and MethodsWe conducted a retrospective one-day prevalence study in 2 intensive care units, which only treated COVID-19 patients with moderate to severe ARDS. We measured blood and urine electrolytes in all the patients. Patients with chronic renal failure or renal replacement therapy were excluded from the study. Hypernatremia was defined as plasma sodium levels above 145 mmol/L.ResultsInclusion criteria were met in 17 out of 24 patients. Hypernatremia was present in 52% patients. All had a natriuresis higher than 20 mmol/L and a urine osmolality above 600 mOsm/L. Hypernatremia was acquired in ICU as all the patients had a normal serum sodium level at admission.ConclusionThe incidence of hypernatremia was elevated and appears to be linked to significant insensible water losses. This should trigger us to optimize the maintenance fluid therapy in critically ill patients with SARS-CoV-2-induced ARDS.

ENDOCRINOLOGY IN THE TIME OF COVID-19: Management of diabetes insipidus and hyponatraemia.

COVID-19 has changed the nature of medical consultations, emphasizing virtual patient counseling, with relevance for patients with diabetes insipidus (DI) or hyponatraemia. The main complication of desmopressin treatment in DI is dilutional hyponatraemia. Since plasma sodium monitoring is not always possible in times of COVID-19, we recommend to delay the desmopressin dose once a week until aquaresis occurs allowing excess retained water to be excreted. Patients should measure their body weight daily. Patients with DI admitted to the hospital with COVID-19 have a high risk for mortality due to volume depletion. Specialists must supervise fluid replacement and dosing of desmopressin. Patients after pituitary surgery should drink to thirst and measure their body weight daily to early recognize the development of the postoperative syndrome of inappropriate antidiuresis (SIAD). They should know hyponatraemia symptoms. The prevalence of hyponatraemia in patients with pneumonia due to COVID-19 is not yet known, but seems to be low. In contrast, hypernatraemia may develop in COVID-19 patients in ICU, from different multifactorial reasons, for example, due to insensible water losses from pyrexia, increased respiration rate and use of diuretics. Hypernatraemic dehydration may contribute to the high risk of acute kidney injury in COVID-19. IV fluid replacement should be administered with caution in severe cases of COVID-19 because of the risk of pulmonary oedema.

Effects of crude protein and sodium intake on water turnover in cats fed extruded diets.

The comprehension of strategies to increase urine production may be important, especially in kibble diets to prevent urolithiasis in cats. The effects of increasing amounts of crude protein (CP) and sodium on the water turnover of cats were evaluated using the water balance (WB) method and the deuterium dilution technique. The study followed a randomized block design, with three blocks of eight cats, two cats per food type in each block, and six cats per food. Four extruded diets with different amounts of CP and sodium were evaluated (on DM basis): 28% CP and 0.58% sodium; 39% CP and 0.64% sodium; 52% CP and 0.76% sodium; and 64% CP and 0.87% sodium. Cats were individually housed in cages for 8days to measure WB, urea excretion, and faecal and urine characteristics. Deuterium oxide was used to evaluate water turnover, and during the period cats were housed in a collective cattery. The data were analysed by an F test, and the means were compared by polynomial contrasts. The ɑ level of significance was set at 0.05. The methods were compared by Pearson correlation, and Bland and Altman analysis. The increase in the CP content elevated linearly the renal excretion of urea (p<.001), and, together with the higher sodium intake, elevated the renal solute load, which resulted in a linear increase in urine production and water intake (p<.01). The urine density, metabolic water, and faecal and insensible water losses did not differ (p>.05). The water flux increased linearly when using the deuterium method (p<.001), but the obtained values were 20.85±11.11ml/cat/day higher than those verified using the WB method (p=.001). Higher CP and sodium amounts in dry diets increased the urine production and water consumption of cats, and this can be explored as a possible option to increase urination.

Dry Fasting Physiology: Responses to Hypovolemia and Hypertonicity

Objective: The aim of this study was to provide a deeper insight into dry fasting (DF) physiology. Design: Ten participants performed DF for 5 consecutive days. Methods: The following parameters were monitored daily: cortisol, aldosterone, high-sensitivity C-reactive protein (CRP), erythropoietin, albumin, uric acid, and vitamin C in serum; vasopressin (ADH), adrenocorticotropic hormone (ACTH), renin, angiotensin II, and total antioxidant capacity (TAC) in plasma; hematocrit and erythrocytes in whole blood; osmolality, noradrenaline, dopamine, adrenaline, Na⁺, and K⁺ in 24-h urine; waist circumference and body, urine, and stool weight. Results: The following parameters increased: ADH (60 ± 11%), ACTH (176 ± 34%), cortisol (495 ± 75%), urine osmolality (20 ± 4%), CRP (167 ± 77%), renin (315 ± 63%), angiotensin II (74 ± 21%), aldosterone (61 ± 21%), TAC (80.4 ± 17%), uric acid (103 ± 19%), albumin (18.4 ± 2.4%), erythrocytes (13.4 ± 2.2%), hematocrit (11 ± 1.8%), and the excretion of noradrenaline (40.3 ± 10%) and dopamine (17 ± 5%). The following parameters decreased: waist circumference (8.20 ± 0.61 cm), body weight (7.010 ± 0.3 kg), erythropoietin (65 ± 18%), and the excretion of adrenaline (38 ± 4%) and Na⁺ (60 ± 16%). The excretion of K⁺ remained unchanged. Vitamin C decreased, showing a half-life of 4.8 ± 0.7 days. The percent ratios of lost weight components were: urine (52.2 ± 3.7%), insensible water loss (32.2 ± 1.4%), stool (5 ± 0.3%), and respiratory gases, i.e., expired CO₂ – incorporated O₂ (10.6 ± 5.4%). Conclusion: The mechanisms underlying the hypertonicity and hypovolemia compensation and the ratio analysis of lost weight components were presented. DF demonstrated short-term antioxidant, anti-ischemic, immune-stimulating, anti-edematous, and anti-inflammatory effects. The results may have an impact on developing new concepts for the treatment of edema, obesity, and inflammatory and ischemic diseases.

Does control of insensible evaporative water loss by two species of mesic parrot have a thermoregulatory role?

Insensible evaporative water loss (EWL) at or below thermoneutrality is generally assumed to be a passive physical process. However, some arid zone mammals and a single arid zone bird can control their insensible water loss, so we tested the hypothesis that the same is the case for two parrot species from a mesic habitat. We investigated red-rumped parrots (Psephotus haematonotus) and eastern rosellas (Platycercus eximius), measuring their EWL, and other physiological variables, at a range of relative humidities at ambient temperatures of 20 and 30°C (below and at thermoneutrality). We found that, despite a decrease in EWL with increasing relative humidity, rates of EWL were not fully accounted for by the water vapour deficit between the animal and its environment, indicating that the insensible EWL of both parrots was controlled. It is unlikely that this deviation from physical expectations was regulation with a primary role for water conservation because our mesic-habitat parrots had equivalent regulatory ability as the arid habitat budgerigar (Melopsittacus undulatus). This, together with our observations of body temperature and metabolic rate, instead support the hypothesis that acute physiological control of insensible water loss serves a thermoregulatory purpose for endotherms. Modification of both cutaneous and respiratory avenues of evaporation may be involved, possibly via modification of expired air temperature and humidity, and surface resistance.

Two lines of evidence for physiological control of insensible evaporative water loss by a tiny marsupial.

We present two independent lines of evidence that a tiny dasyurid marsupial, the ningaui (Ningaui spp.), has acute physiological control of its insensible evaporative water loss below and within thermoneutrality. Perturbation of the driving force for evaporation by varying relative humidity, and therefore the water vapour pressure deficit between the animal and the ambient air, does not have the expected physical effect on evaporative water loss. Exposure to a helox atmosphere also does not have the expected physical effect of increasing evaporative water loss for live ningauis (despite it having the expected effect of increasing heat loss for live ningauis), but increases evaporative water loss for dead ningauis. We discuss the relative advantages and disadvantages of both experimental approaches for demonstrating physiological control of insensible evaporative water loss. An appreciation of physiological control is important because insensible evaporative water loss contributes to both water and heat balance, is clearly under environmental selection pressure, and potentially impacts the distribution of endotherms and their response to environmental change.

Central diabetes insipidus: A rare complication of IVH in a very low birth weight preterm infant

A 710 g male infant was born at a referring hospital at a gestational age of 23 weeks and 2 days via vaginal delivery and was transferred to our facility at 14 days of age. His delivery was complicated by the breech presentation with difficult head extraction. The infant's initial course was significant for respiratory distress syndrome, grade III-IV intraventricular hemorrhage (IVH), acute kidney injury, and large PDA. On the day of life 29, a gradual increase in serum sodium level refractory to increasing total fluid volume was noted. The combination of persistent hypernatremia (150-160 mmol/l), polyuria (8.4 ml/kg/hr), high plasma osmolality (323 mosm/kg), hyposthenuria (75 mosm/kg) and an undetectable serum ADH (<0.8 pg/ml) confirmed the diagnosis of central diabetes insipidus (CDI). Serum sodium and urine output decreased and urine osmolality increased after subcutaneous DDAVP administration.CDI is an uncommon cause of hypernatremia in the neonatal period. The diagnosis can be difficult as excessive urine output and high serum sodium can often be attributed to high insensible water loss in the extremely premature newborn. CDI in our patient was thought to be due to grade III-IV IVH complicated by post-hemorrhagic hydrocephalus.In conclusion, the diagnosis of central DI should be considered as a complication of severe IVH in the extremely premature neonate who demonstrates persistent hypernatremia, polyuria, decreased urine osmolality, and increased plasma osmolality. Serum ADH levels can be helpful in confirming the central origin of DI and subcutaneous desmopressin can be an effective treatment in the preterm infant.

Causes and Consequences of Sodium Imbalances in the First Week of Life in Very Low-Birthweight Infants

Abstract Background: Sodium imbalance is common in the first week of life in very low-birthweight infants (VLBWI) and may be associated with poor outcome. Objective: To determine the incidence and outcomes of both hypo- and hypernatraemia in VLBWI (500–1500 g birthweight) in the first week of life. Methods: This was a retrospective cross-sectional descriptive study evaluating sodium abnormalities in VLBWI in the first week of life. Subjects included all VLBWI born at Charlotte Maxeke Johannesburg Academic Hospital between 1 January 2013 and 31 July 2013. The causes and complications associated with sodium abnormalities and their outcomes were reviewed. Results: Sodium imbalances were found in 29.1% (85/292) VLBWI. Hypernatraemia was present in 27.1% (79/292) and hyponatraemia in 2.0% (6/292). There was no difference in birthweight or gestational age between hyponatraemic and hypernatraemic VLBWI. Within the hypernatraemic VLBWI, mortality was significantly increased in much smaller and more preterm infants (p &lt; 0.001) and in infants with higher sodium levels (p &lt; 0.005). The main causes of hypernatraemia were insensible water loss through the skin (73.9% of babies born via normal vaginal delivery) and respiratory system (60% of babies were on continuous positive airway pressure (CPAP)). Conclusion: Hypernatraemia is common in the first week of life in VLBWI. Prevention of prematurity and measures to prevent sodium abnormalities should be implemented at birth, especially in very small preterm infants to decrease the mortality and morbidity.

Neonatal skin: Handle with care: A case series

The neonatal skin is fragile and should be handled with maximal care. The thin stratum corneum and attenuated rete ridges in neonatal skin makes them vulnerable to physical injury, insensible water loss, thermal instability and infection. The widespread use of Intensive Care Unit facilities for taking specialized care of the neonate brings along with it a better prognosis for survival but has introduced the caveat of many an iatrogenic skin disorder. Most of these iatrogenic disorders are potentially preventable by providing more inclusive rigorous training of neonatal health care providers and observation of utmost vigilance and care.

Estimation of sodium and chloride storage in critically ill patients: a balance study

BackgroundNonosmotic sodium storage has been reported in animals, healthy individuals and patients with hypertension, hyperaldosteronism and end-stage kidney disease. Sodium storage has not been studied in ICU patients, who frequently receive large amounts of sodium chloride-containing fluids. The objective of our study was to estimate sodium that cannot be accounted for by balance studies in critically ill patients. Chloride was also studied. We used multiple scenarios and assumptions for estimating sodium and chloride balances.MethodsWe retrospectively analyzed patients admitted to the ICU after cardiothoracic surgery with complete fluid, sodium and chloride balance data for the first 4 days of ICU treatment. Balances were obtained from meticulously recorded data on intake and output. Missing extracellular osmotically active sodium (MES) was calculated by subtracting the expected change in plasma sodium from the observed change in plasma sodium derived from balance data. The same method was used to calculate missing chloride (MEC). To address considerable uncertainties on the estimated extracellular volume (ECV) and perspiration rate, various scenarios were used in which the size of the ECV and perspiration were varied.ResultsA total of 38 patients with 152 consecutive ICU days were analyzed. In our default scenario, we could not account for 296 ± 35 mmol of MES in the first four ICU days. The range of observed MES in the five scenarios varied from 111 ± 27 to 566 ± 41 mmol (P < 0.001). A cumulative value of 243 ± 46 mmol was calculated for MEC in the default scenario. The range of cumulative MEC was between 62 ± 27 and 471 ± 56 mmol (P = 0.001 and P = 0.003). MES minus MEC varied from 1 ± 51 to 123 ± 33 mmol in the five scenarios.ConclusionsOur study suggests considerable disappearance of osmotically active sodium in critically ill patients and is the first to also suggest rather similar disappearance of chloride from the extracellular space. Various scenarios for insensible water loss and estimated size for the ECV resulted in considerable MES and MEC, although these estimates showed a large variation. The mechanisms and the tissue compartments responsible for this phenomenon require further investigation.

Insensible water loss volume during Simulated Cardiopulmonary Bypass

Insensible water loss volume during Simulated Cardiopulmonary Bypass