Salt of the earth or a drop in the ocean? A pathophysiological approach to fluid resuscitation

Trauma-related electrolyte disturbances: From resuscitation to rhabdomyolysis

Traumatic injury results in drastic changes to a patient's normal physiology. The hormonal stress response, as well as some treatment strategies, lead to significant disruptions in electrolyte homeostasis that are important for clinicians to understand. In addition, advances in fluid resuscitation and modern transfusion practices have led to their own unique set of consequences, which we are just beginning to appreciate. Special attention is placed on rhabdomyolysis, as this distinct entity represents an extreme example of injury induced electrolyte derangements. This review describes the physiologic response to trauma and highlights some of the important electrolyte abnormalities that can be encountered while caring for the injured patient.

Mechanisms of Post-critical Illness Cardiovascular Disease

Prolonged critical care stays commonly follow trauma, severe burn injury, sepsis, ARDS, and complications of major surgery. Although patients leave critical care following homeostatic recovery, significant additional diseases affect these patients during and beyond the convalescent phase. New cardiovascular and renal disease is commonly seen and roughly one third of all deaths in the year following discharge from critical care may come from this cluster of diseases. During prolonged critical care stays, the immunometabolic, inflammatory and neurohumoral response to severe illness in conjunction with resuscitative treatments primes the immune system and parenchymal tissues to develop a long-lived pro-inflammatory and immunosenescent state. This state is perpetuated by persistent Toll-like receptor signaling, free radical mediated isolevuglandin protein adduct formation and presentation by antigen presenting cells, abnormal circulating HDL and LDL isoforms, redox and metabolite mediated epigenetic reprogramming of the innate immune arm (trained immunity), and the development of immunosenescence through T-cell exhaustion/anergy through epigenetic modification of the T-cell genome. Under this state, tissue remodeling in the vascular, cardiac, and renal parenchymal beds occurs through the activation of pro-fibrotic cellular signaling pathways, causing vascular dysfunction and atherosclerosis, adverse cardiac remodeling and dysfunction, and proteinuria and accelerated chronic kidney disease.

Evaluation of Routine Postoperative Labs Following Robotic Assisted Partial Nephrectomy in Patients With Normal Preoperative Renal Function

OBJECTIVE

To evaluate predictors of abnormal routine postoperative day 1 (POD1) labs in patients with normal pre-operative renal function following robotic assisted partial nephrectomy (RAPN) and the associated clinical outcomes of these lab results.

METHODS

We analyzed 500 consecutive RAPN from a single surgeon series. Patients with chronic kidney disease (CKD) III or greater were excluded from the study. Three hundred ninty-three RAPN were included in the analysis. Routine POD1 lab tests including hemoglobin (Hgb), creatinine, potassium, and sodium were evaluated to determine rates of abnormal values and rates of clinical intervention. Abnormal Hgb at POD1 was defined as <8 g/dL or ≥3 g/dL decrease from the preoperative (baseline) value. Abnormal sodium (Na) preoperatively and postoperatively was defined as <135 mEq/L or >145 mEq/L. Abnormal potassium (K) was defined preoperatively and POD1 as <3.5 mEq/L or >5 mEq/L.

RESULTS

Of 37.4% (147/393) had one or more abnormal labs at POD1. Of the 101 patients with abnormal Hgb, 15 patients required blood transfusion. Twenty-six patients had abnormal sodium for which two were treated with IV fluids. Twenty-seven patients had potassium abnormalities (12/25 were hypokalemia). Acute kidney injury stage I was seen in 27 patients (6.9%) and stage II in 3 (0.8%). Patients with abnormal labs were more likely to have larger renal mass, higher R.E.N.A.L. scores, intraoperative complications, longer operative times, and higher EBL on multivariate analysis.

CONCLUSION

POD1 serum laboratory tests appear to be necessary following RAPN in patients with normal pre-operative renal function.

Electrolytes, albumin and acid base equilibrium during laparoscopic surgery

BACKGROUND

Surgery, causing inflammation, disrupts endothelial permeability leading to movement of fluids and albumin across the vascular barrier. Fluid therapy for restoring circulatory homeostasis may lead to positive fluid balance which has been shown to increase morbidity and mortality in surgical patients. The current investigation aims to describe physio-pathological changes in circulating albumin, fluid and electrolyte balance, and acidbase equilibrium in a cohort of patients undergoing laparoscopic surgery under general anesthesia.

METHODS

Single-center prospective observational study. Patients undergoing laparoscopic colorectal surgery were screened for eligibility.. Before surgery the baseline fasting conditions were homogenized. Hemoglobin, urinary and plasmatic were collected before surgery and then at pre-defined timepoints. Albumin/Creatinine ratio was measured before and after surgery. Expected and actual circulating Sodium concentrations were compared according to a physiological theoretical model. Assessment and quantification of changes in major electrolytes, albumin and acid-base balance was defined as the primary outcome of the study.

RESULTS

38 patients were enrolled in the protocol. Patients had a positive electrolytes (Na+ 295 [244-375] mmol, Cl- 234 [195-295] mmol, K+ 16.8 [12.0-21.4] mmol) and fluid balance (2165 [1727-2728] ml). The positive fluid balance was associated with stable chloride (105 [103-107], end study vs 103 [102-106] mmol/L, baseline, p=ns) and potassium (4.2 [3.8-4.4], end study vs 4.1 [3.6-4.4] mmol/L, baseline, p=ns) levels, but sodium concentrations decreased over time (138 [137-140], end study vs 139 [138-141] mmol/L, baseline, p<0.05). The Albumin/Creatinine ratio was higher at the end of surgery 134 [61-267] vs 7 [4-14], p<0.001).

CONCLUSIONS

Data from patients undergoing colorectal laparoscopic surgery showed a positive fluid balance, decreased circulating albumin and increased albuminuria. A positive sodium balance was not always associated with an increase in sodium plasma concentration.

Low- versus High-Chloride Content Intravenous Solutions for Perioperative Patients: A Systematic Review and Meta-Analysis

Background

Studies have shown complications of normal saline infusion because of its high-chloride content. Therefore, in the present study, we aimed to explore whether the use of low- versus high-chloride solutions benefited the unselected and specifically perioperative patients and was associated with different outcomes.

Methods

Studies on the use of low- versus high-chloride content intravenous solutions for perioperative patients, published up to July 15, 2019, were systematically reviewed, and primary and secondary outcomes were quantitatively summarized.

Results

A total of 14 eligible randomized controlled trials with 943 perioperative patients were included. Five studies reported all-cause mortality, and eight studies provided detailed data on renal replacement therapy (RRT). The pooled result suggested no statistically significant difference in the effect of low- versus high-chloride solutions on all-cause mortality (risk ratio (RR) = 1.39; 95%confidence interval (CI) = 0.23–8.26) and RRT (RR = 1.05; 95%CI = 0.63–1.76). The pooled results on acute kidney injury (AKI) and the use of allogenic blood transfusion (P > 0.05) were similar.

Conclusion

Among specific perioperative patients, the use of low- versus high-chloride content intravenous solutions did not reduce the all-cause mortality, risk of severe AKI, or rate of RRT use. Further large randomized clinical trials are needed to confirm or refute this finding.

Microalbuminuria assessment after thoracic surgery: Early identification of complication risks

INTRODUCTION

Microalbuminuria (MA) is considered a reflection of systemic capillary leak and an early marker of acute stress reaction to the surgical insult, proportional to the severity of the initiating condition and predictive of the individual response to surgical stress.

OBJECTIVES

We conducted a prospective study to assess for the variation of MA within 4 days after thoracic surgery. We correlated observed MA levels with both their respective PaO₂ /FiO₂ respiratory ratio and the onset of postoperative complications.

METHODS

This single-centre study enrolled 255 consecutive patients having an American Society of Anaesthesiologists (ASA) score ≤ 3. The mean age was 62 years with 67% male. All patients were scheduled for elective pulmonary resection. MA was measured in urine samples as the albumin-to-creatinine ratio (A/C), prior to, at and after extubation up to 96 hours. PaO₂ /FiO₂ was measured at extubation and on the first postoperative day.

RESULTS

Overall, preoperative A/C levels resulted normal, with a significant average increase at extubation which peaked 6 hours later (P < 0.001). Larger postoperative A/C increases were observed in patients who developed postoperative complications, compared to those without these complications (P < 0.019). Moreover, patients undergoing major open pulmonary resections had larger postoperative A/C increases, compared to those undergoing minor video-assisted thoracic surgery resections (P < 0.006). At the time of extubation, A/C was inversely related to the PaO₂ /FiO₂ ratio (r = -0.25; P = 0.038). Peak A/C > 61 mg/g (P = 0.0003) was associated with postoperative cardio-pulmonary complications (OR 3.85; P = 0.003).

CONCLUSION

Within 6 hours after extubation, MA assessment may be a rapid and relatively inexpensive method for better predicting perioperative risk in an ASA score ≤ 3 population.

Postoperative fluid retention after heart surgery is accompanied by a strongly positive sodium balance and a negative potassium balance

The conventional model on the distribution of electrolyte infusions states that water will distribute proportionally over both the intracellular (ICV) and extracellular (ECV) volumes, while potassium homes to the ICV and sodium to the ECV. Therefore, total body potassium is the most accurate measure of ICV and thus potassium balances can be used to quantify changes in ICV. In cardiothoracic patients admitted to the ICU we performed complementary balance studies to measure changes in ICV and ECV. In 39 patients, fluid, sodium, potassium, and electrolyte‐free water (EFW) balances were determined to detect changes in ICV and ECV. Cumulatively over 4 days, these patients received a mean ± SE infusion of 14.0 ± 0.6 L containing 1465 ± 79 mmol sodium, 196 ± 11 mmol potassium and 2.1 ± 0.1 L EFW. This resulted in strongly positive fluid (4.0 ± 0.6 L) and sodium (814 ± 75 mmol) balances but in negative potassium (−101 ± 14 mmol) and EFW (−1.1 ± 0.2 L) balances. We subsequently compared potassium balances (528 patients) and fluid balances (117 patients) between patients who were assigned to either a 4.0 or 4.5 mmol/L blood potassium target. Although fluid balances were similar in both groups, the additionally administered potassium (76 ± 23 mmol) in the higher target group was fully excreted by the kidneys (70 ± 23 mmol). These findings indicate that even in the context of rapid and profound volume expansion neither water nor potassium moves into the ICV.

Equine anaesthesia-associated mortality: where are we now?

OBJECTIVES

To review the literature concerning mortality associated with general anaesthesia in horses and to assess whether there is evidence for a reduction in mortality over the 20 years since the Confidential Enquiry into Perioperative Equine Fatalities (CEPEF).

DATABASES USED

PubMed, Scopus, Google Scholar. Search terms used: horse; pony; equine; anaesthesia; anesthesia; recovery; morbidity, and mortality.

CONCLUSIONS

The most recent studies, in which isoflurane and sevoflurane have been more commonly used for anaesthesia maintenance, report fewer intraoperative cardiac arrests than older studies in which halothane was favoured. Catastrophic fractures, however, have become the greatest cause of recovery-associated mortality.

Balanced and unbalanced solutions modulate the release of Matrix Metalloproteinase-9 (MMP-9) from neutrophils in response to inflammatory stimuli: an in vitro study

OBJECTIVES AND DESIGN

We investigated the effect of balanced (BS) and unbalanced (UBS) solutions in the absence or presence of hydroxyethyl starch (HES) on neutrophil functionality, evaluating the release of matrix metalloproteinase (MMP)-9, myeloperoxidase (MPO), and MMP-8.

MATERIALS AND METHODS

Neutrophils were isolated by gradient centrifugation and dextran sedimentation and incubated in BS or UBS without or with HES, in the absence or presence of Interleukin-8 (IL-8) or Lipopolysaccharide (LPS). MMP-9, MPO, and MMP-8 were assayed by commercially available ELISA kits.

RESULTS

There was not any influence of volume replacement solutions on the release of the enzymes from resting neutrophils. After IL-8 stimulation, the release of MMP-9 was higher in BS than in UBS or RPMI-1640, whereas HES enhanced its release regardless of the composition. After LPS stimulation, the release of MMP-9 was higher in both UBS and BS than RPMI-1640, but HES brought its release back to physiological conditions. No difference was found in the release of MPO and MMP-8 after stimulation with IL-8 or LPS.

CONCLUSION

Volume replacement solutions might have an impact on the release of MMP-9 depending on the inflammatory milieu, suggesting that the use of balanced or unbalanced solutions is not a neutral choice.

Effects of two different strategies of fluid administration on inflammatory mediators, plasma electrolytes and acid/base disorders in patients undergoing major abdominal surgery: a randomized double blind study

BACKGROUND

Administration of normal saline might increase circulating levels of pro-inflammatory cytokines and may cause variation of plasmatic electrolytic and hyperchloremic acidosis, which in turn can impair renal function. Hence the use of balanced solutions could influence the inflammatory cascade triggered by the surgical procedures, the plasmatic electrolyte concentration, the acid-base equilibrium, and the renal function.

METHODS

This is a double blind randomized trial. Forty patients undergoing major abdominal surgery (bowel cancer) were allocated in two groups, the balanced solution (BS) group in which the fluids administered were balanced solutions (colloids and crystalloids); and the unbalanced solution (UBS) group in which the fluids administered were unbalanced solutions (colloids and crystalloids). Measurements were performed after anaesthesia induction (T0), at the end of surgery (T1), within 2 h after surgery (T2) and 24 h after the beginning of surgery (T3). The following data were collected: 1) active matrix metalloproteinase 9 (MMP-9) and its tissue inhibitor (TIMP-1), IL-6, IL-8, IL-10; 2) blood gases variables; 3) electrolytes, albumin, total serum protein and the strong ion difference; 4) neutrophil gelatinase-associated lipocalin (NGAL) from urinary sample.

RESULTS

The BS group exhibited higher circulating level of IL-10 and TIMP-1 and lower level of active MMP-9. The UBS group experienced hypercloremia, hypocalcemia, hypomagnesemia, worse acid-base equilibrium and higher level of NGAL.

CONCLUSIONS

The use of balanced solutions was responsible of less alteration of plasmatic electrolytes, acid-base equilibrium, kidney function and it might be associated with an early anti-inflammatory mechanisms triggering.

TRIAL REGISTRATION

ClinicalTrials.gov (Ref: NCT01320891).

Changes in tissue perfusion parameters in dogs with severe sepsis/septic shock in response to goal-directed hemodynamic optimization at admission to ICU and the relation to outcome

OBJECTIVE

To evaluate the changes in tissue perfusion parameters in dogs with severe sepsis/septic shock in response to goal-directed hemodynamic optimization in the ICU and their relation to outcome.

DESIGN

Prospective observational study.

SETTING

ICU of a veterinary university medical center.

ANIMALS

Thirty dogs with severe sepsis or septic shock caused by pyometra who underwent surgery and were admitted to the ICU.

MEASUREMENTS AND MAIN RESULTS

Severe sepsis was defined as the presence of sepsis and sepsis-induced dysfunction of one or more organs. Septic shock was defined as the presence of severe sepsis plus hypotension not reversed with fluid resuscitation. After the presumptive diagnosis of sepsis secondary to pyometra, blood samples were collected and clinical findings were recorded. Volume resuscitation with 0.9% saline solution and antimicrobial therapy were initiated. Following abdominal ultrasonography and confirmation of increased uterine volume, dogs underwent corrective surgery. After surgery, the animals were admitted to the ICU, where resuscitation was guided by the clinical parameters, central venous oxygen saturation (ScvO(2)), lactate, and base deficit. Between survivors and nonsurvivors it was observed that the ScvO(2), lactate, and base deficit on ICU admission were each related independently to death (P = 0.001, P = 0.030, and P < 0.001, respectively). ScvO(2) and base deficit were found to be the best discriminators between survivors and nonsurvivors as assessed via receiver operator characteristic curve analysis.

CONCLUSION

Our study suggests that ScvO(2) and base deficit are useful in predicting the prognosis of dogs with severe sepsis and septic shock; animals with a higher ScvO(2) and lower base deficit at admission to the ICU have a lower probability of death.

The role of pre-hospital blood gas analysis in trauma resuscitation

Background

To assess, whether arterial blood gas measurements during trauma patient's pre-hospital shock resuscitation yield useful information on haemodynamic response to fluid resuscitation by comparing haemodynamic and blood gas variables in patients undergoing two different fluid resuscitation regimens.

Methods

In a prospective randomised study of 37 trauma patients at risk for severe hypovolaemia, arterial blood gas values were analyzed at the accident site and on admission to hospital. Patients were randomised to receive either conventional fluid therapy or 300 ml of hypertonic saline. The groups were compared for demographic, injury severity, physiological and outcome variables.

Results

37 patients were included. Mean (SD) Revised Trauma Score (RTS) was 7.3427 (0.98) and Injury Severity Score (ISS) 15.1 (11.7). Seventeen (46%) patients received hypertonic fluid resuscitation and 20 (54%) received conventional fluid therapy, with no significant differences between the groups concerning demographic data or outcome. Base excess (BE) values decreased significantly more within the hypertonic saline (HS) group compared to the conventional fluid therapy group (mean BE difference -2.1 mmol/l vs. -0.5 mmol/l, p = 0.003). The pH values on admission were significantly lower within the HS group (mean 7.31 vs. 7.40, p = 0.000). Haemoglobin levels were in both groups lower on admission compared with accident site. Lactate levels on admission did not differ significantly between the groups.

Conclusion

Pre-hospital use of small-volume resuscitation led to significantly greater decrease of BE and pH values. A portable blood gas analyzer was found to be a useful tool in pre-hospital monitoring for trauma resuscitation.