Differences in acid-base behavior between intensive care unit survivors and nonsurvivors using both a physicochemical and a standard base excess approach: a prospective, observational study

Impact of Postoperative ABG Analysis and ICU Weaning Protocol in Surgical Outcome of Atlanto-Axial Dislocation: It's not the Towering Sail, but the Unseen Wind that Moves the Ship

Background

The outcome in patients of atlanto-axial dislocation (AAD) depends on multiple factors like preoperative optimization, intraoperative distractio and cord manipulation. Certain unfocussed factors such as respiratory reserve and compensatory acclimatization to hypoxia warrant consideration.

Aims

The purpose of this study is to find the association of postoperative arterial blood gas (ABG) analysis and respiratory reserve in patients of AAD with clinical outcome.

Study Design

We retrospectively analyzed the available records of patients, operated for AAD, at our institute (n = 66), from January 2014 to November 2018.

Materials and Methods

Preoperative pulmonary function test (PFT) and the postoperative ABG analysis was noted. Timing of extubation, duration of intensive care unit (ICU) stays, and clinical outcomes (Nurick grade) were noted from the inpatient record and the last outpatient follow up. An independent t-test and analysis of variance were used to find significance.

Results

In total, 41% (n = 27) patients had body mass index of less than 18.5, and 50% (n = 33) had breath holding time of less than 20 minutes. There was improvement in mean Nurick grade from 3.17 ± 0.8 to 2.76 ± 0.7 in follow up. A trend suggesting that patients with poor preoperative PFT has more ICU duration and worse outcome. In patients with mild acid-base disorders, extubation was possible within 24 hours. Out of 26 patients with ICU duration less than 2 days, 23 patients had "good" outcome, whereas ten out of 40 patients with ICU duration of more than or equal to 2 days had "bad" outcome (P = 0.00).

Conclusion

Patients having moderate to severe primary or mixed acid-base disorder have a probability of re-intubation or delayed extubation. A strong correlation was seen with the novel grading system (grade >6 had worse outcome).

Does Chloride Intake at the Early Phase of Septic Shock Resuscitation Impact on Renal Outcome?

INTRODUCTION

Fluid administration is one of the first lines of treatment for hemodynamic management of sepsis and septic shock. Studies investigating the effects of chloride-rich fluids including normal saline on renal function report controversial findings.

METHODS

This is a prospective, observational, multicenter study. Patients with septic shock, defined according to Sepsis-2 definition, were eligible. A "high-dose" of chloride was defined as a chloride intake greater than 18 g administrated within the first 48 h of septic shock management. The purpose of this study was to investigate the impact of cumulative chloride infusion within the first 48 h of septic shock resuscitation on acute kidney injury (AKI).

RESULTS

Two hundred thirty-nine patients with septic shock were included. Patients who received a "high-dose" of chloride had significantly higher Sequential Organ Failure Assessment score at the time of enrolment (P < 0.001). Cumulative chloride load was higher in patients requiring renal replacement therapy (RRT) (31.1 vs. 25.2 g/48 h; P < 0.005). Propensity score-weighted regression did not find any association between "high-dose" of chloride and AKI requiring RRT (OR: 0.97 [0.88-1.1]; P = 0.69). There was no association between "high-dose" of chloride and worsening kidney function at H48 (OR: 0.94 [0.83-1.1]; P = 0.42). There was also no association between "high-dose" of chloride and ICU length of stay (P = 0.61), 28-day mortality (P = 0.83), or hospital mortality (P = 0.89).

CONCLUSION

At the early stage of resuscitation of critically ill patients with septic shock, administration of "high-dose" of chloride (> 18 g/48 h) was not associated with renal prognosis.

Bedside clinical data subphenotypes of critically ill COVID-19 patients: a cohort study

Objective

To identify more severe COVID-19 presentations.

Methods

Consecutive intensive care unit-admitted patients were subjected to a stepwise clustering method.

Results

Data from 147 patients who were on average 56 ± 16 years old with a Simplified Acute Physiological Score 3 of 72 ± 18, of which 103 (70%) needed mechanical ventilation and 46 (31%) died in the intensive care unit, were analyzed. From the clustering algorithm, two well-defined groups were found based on maximal heart rate [Cluster A: 104 (95%CI 99 - 109) beats per minute versus Cluster B: 159 (95%CI 155 - 163) beats per minute], maximal respiratory rate [Cluster A: 33 (95%CI 31 - 35) breaths per minute versus Cluster B: 50 (95%CI 47 - 53) breaths per minute], and maximal body temperature [Cluster A: 37.4 (95%CI 37.1 - 37.7)°C versus Cluster B: 39.3 (95%CI 39.1 - 39.5)°C] during the intensive care unit stay, as well as the oxygen partial pressure in the blood over the oxygen inspiratory fraction at intensive care unit admission [Cluster A: 116 (95%CI 99 - 133) mmHg versus Cluster B: 78 (95%CI 63 - 93) mmHg]. Subphenotypes were distinct in inflammation profiles, organ dysfunction, organ support, intensive care unit length of stay, and intensive care unit mortality (with a ratio of 4.2 between the groups).

Conclusion

Our findings, based on common clinical data, revealed two distinct subphenotypes with different disease courses. These results could help health professionals allocate resources and select patients for testing novel therapies.

Admission Serum Bicarbonate Predicts Adverse Clinical Outcomes in Hospitalized Cirrhotic Patients

A low serum bicarbonate (SB) level is predictive of adverse outcomes in kidney injury, infection, and aging. Because the liver plays an important role in acid-base homeostasis and lactic acid metabolism, we speculated that such a relationship would exist for patients with cirrhosis. To assess the prognostic value of admission SB on adverse hospital outcomes, clinical characteristics were extracted and analyzed from a large electronic health record system. Patients were categorized based on admission SB (mEq/L) into 7 groups based on the reference range (22-25) into mildly (18-21), moderately (14-17), and severely (<14) decreased groups and mildly (26-29), moderately (30-33), and severely (>30) increased groups, and the relationship of SB category with the frequency of complications (acute kidney injury/hepatorenal syndrome, portosystemic encephalopathy, gastrointestinal bleeding, ascites, and spontaneous bacterial peritonitis) and hospital metrics (length of stay [LOS], admission to an intensive care unit [ICU], and mortality) was assessed. A total of 2,693 patients were analyzed. Mean SB was 22.9 ± 4.5 mEq/L. SB was within the normal range (22-25 mEq/L) in 1,072 (39.8%) patients, and 955 patients (36%) had a low SB. As the SB category decreased, the incidence of complications progressively increased (p < 0.001). Increased MELD-Na score and low serum albumin also correlated with frequency of complications (p < 0.001). As the SB category decreased, LOS, ICU admission, and mortality progressively increased (p < 0.001). On multivariate analysis, the association of decreased SB with higher odds of complications, LOS, ICU admission, and mortality persisted. Conclusion. Low admission SB in patients with cirrhosis is associated with cirrhotic complications, longer LOS, increased ICU admissions, and increased hospital mortality.

Urinary chloride concentration as a prognostic marker in critically ill patients

AIM

Associations have been reported among serum chloride concentration, mortality and incidence of acute kidney injury (AKI) in intensive care units (ICU). This study aimed to examine associations among urinary chloride, mortality, and AKI incidence in ICU patients.

METHODS

A retrospective observational study was conducted among medical-surgical ICU in a tertiary hospital wherein 170 consecutive ICU patients were evaluated from October 2015 to March 2016 and 116 patients were enrolled. Serial data of serum and urine electrolytes from day 1 to day 4 of ICU admission were examined. The primary and secondary outcomes were ICU mortality and incidence of AKI in the ICU, respectively.

RESULTS

Among the 116 enrolled patients, 15 (13%) died during their ICU stay. Although serum and urinary sodium and potassium on day 1 did not significantly differ between ICU survivors and non-survivors, urinary chloride concentration on day 1 was significantly lower in non-survivors. Receiver operating characteristic analysis showed that the cutoff value of day 1 urinary chloride concentration for prediction of ICU mortality was 53 mEq/L. The lower urinary chloride concentration group on day 1 showed a significantly lower survival rate, even in long-term follow-up, compared with the higher urinary chloride group. Addition of day 1 urinary chloride concentration improved prediction of AKI incidence in the ICU by Sequential Organ Failure Assessment score alone.

CONCLUSION

Lower urinary chloride concentration was associated with increased mortality and incidence of AKI in the ICU. Further investigation is necessary to clarify the mechanism of urinary chloride regulation.

Evidence-based guidelines for supportive care of patients with Ebola virus disease

The 2013-16 Ebola virus disease outbreak in west Africa was associated with unprecedented challenges in the provision of care to patients with Ebola virus disease, including absence of pre-existing isolation and treatment facilities, patients' reluctance to present for medical care, and limitations in the provision of supportive medical care. Case fatality rates in west Africa were initially greater than 70%, but decreased with improvements in supportive care. To inform optimal care in a future outbreak of Ebola virus disease, we employed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology to develop evidence-based guidelines for the delivery of supportive care to patients admitted to Ebola treatment units. Key recommendations include administration of oral and, as necessary, intravenous hydration; systematic monitoring of vital signs and volume status; availability of key biochemical testing; adequate staffing ratios; and availability of analgesics, including opioids, for pain relief.

Is There a Role for Balanced Solutions in Septic Patients?

The use of fluid bolus infusion is the cornerstone for hemodynamic resuscitation of critically ill patients. Recently, the clinical use of colloids has lost strength with the publication of several trials suggesting no benefit, and possible harm of its use.On the other hand, the so-called balanced solutions, with low chloride concentrations, have emerged as an alternative with potential physiological benefits over traditional saline solution. Normal saline carries a high amount of chloride which has been associated with an increased incidence of metabolic acidosis, renal vasoconstriction, and reduced urine output. Recent observational studies associated the use of saline with acute kidney injury, which was not observed in a single prospective randomized controlled trial.The present review summarizes available literature regarding the potential clinical and laboratorial benefits of balanced solutions in septic patients.

Metabolic acidosis and the role of unmeasured anions in critical illness and injury

Acid-base disorders are frequently present in critically ill patients. Metabolic acidosis is associated with increased mortality, but it is unclear whether as a marker of the severity of the disease process or as a direct effector. The understanding of the metabolic component of acid-base derangements has evolved over time, and several theories and models for precise quantification and interpretation have been postulated during the last century. Unmeasured anions are the footprints of dissociated fixed acids and may be responsible for a significant component of metabolic acidosis. Their nature, origin, and prognostic value are incompletely understood. This review provides a historical overview of how the understanding of the metabolic component of acid-base disorders has evolved over time and describes the theoretical models and their corresponding tools applicable to clinical practice, with an emphasis on the role of unmeasured anions in general and several specific settings.

Metabolic acid-base adaptation triggered by acute persistent hypercapnia in mechanically ventilated patients with acute respiratory distress syndrome

Objective

Hypercapnia resulting from protective ventilation in acute respiratory distress syndrome triggers metabolic pH compensation, which is not entirely characterized. We aimed to describe this metabolic compensation.

Methods

The data were retrieved from a prospective collected database. Variables from patients' admission and from hypercapnia installation until the third day after installation were gathered. Forty-one patients with acute respiratory distress syndrome were analyzed, including twenty-six with persistent hypercapnia (PaCO₂ > 50mmHg > 24 hours) and 15 non-hypercapnic (control group). An acid-base quantitative physicochemical approach was used for the analysis.

Results

The mean ages in the hypercapnic and control groups were 48 ± 18 years and 44 ± 14 years, respectively. After the induction of hypercapnia, pH markedly decreased and gradually improved in the ensuing 72 hours, consistent with increases in the standard base excess. The metabolic acid-base adaptation occurred because of decreases in the serum lactate and strong ion gap and increases in the inorganic apparent strong ion difference. Furthermore, the elevation in the inorganic apparent strong ion difference occurred due to slight increases in serum sodium, magnesium, potassium and calcium. Serum chloride did not decrease for up to 72 hours after the initiation of hypercapnia.

Conclusion

In this explanatory study, the results indicate that metabolic acid-base adaptation, which is triggered by acute persistent hypercapnia in patients with acute respiratory distress syndrome, is complex. Furthermore, further rapid increases in the standard base excess of hypercapnic patients involve decreases in serum lactate and unmeasured anions and increases in the inorganic apparent strong ion difference by means of slight increases in serum sodium, magnesium, calcium, and potassium. Serum chloride is not reduced.

Fluid and electrolyte overload in critically ill patients: An overview

Fluids are considered the cornerstone of therapy for many shock states, particularly states that are associated with relative or absolute hypovolemia. Fluids are also commonly used for many other purposes, such as renal protection from endogenous and exogenous substances, for the safe dilution of medications and as “maintenance” fluids. However, a large amount of evidence from the last decade has shown that fluids can have deleterious effects on several organ functions, both from excessive amounts of fluids and from their non-physiological electrolyte composition. Additionally, fluid prescription is more common in patients with systemic inflammatory response syndrome whose kidneys may have impaired mechanisms of electrolyte and free water excretion. These processes have been studied as separate entities (hypernatremia, hyperchloremic acidosis and progressive fluid accumulation) leading to worse outcomes in many clinical scenarios, including but not limited to acute kidney injury, worsening respiratory function, higher mortality and higher hospital and intensive care unit length-of-stays. In this review, we synthesize this evidence and describe this phenomenon as fluid and electrolyte overload with potentially deleterious effects. Finally, we propose a strategy to safely use fluids and thereafter wean patients from fluids, along with other caveats to be considered when dealing with fluids in the intensive care unit.

Metabolic acidosis and strong ion gap in critically ill patients with acute kidney injury

Purpose. To determine the influence of physicochemical parameters on survival in metabolic acidosis (MA) and acute kidney injury (AKI) patients. Materials and Methods. Seventy-eight MA patients were collected and assigned to AKI or non-AKI group. We analyzed the physiochemical parameters on survival at 24 h, 72 h, 1 week, 1 month, and 3 months after AKI. Results. Mortality rate was higher in the AKI group. AKI group had higher anion gap (AG), strong ion gap (SIG), and apparent strong ion difference (SIDa) values than non-AKI group. SIG value was higher in the AKI survivors than nonsurvivors and this value was correlated serum creatinine, phosphate, albumin, and chloride levels. SIG and serum albumin are negatively correlated with Acute Physiology and Chronic Health Evaluation IV scores. AG was associated with mortality at 1 and 3 months post-AKI, whereas SIG value was associated with mortality at 24 h, 72 h, 1 week, 1 month, and 3 months post-AKI. Conclusions. Whether high or low SIG values correlate with mortality in MA patients with AKI depends on its correlation with serum creatinine, chloride, albumin, and phosphate (P) levels. AG predicts short-term mortality and SIG value predicts both short- and long-term mortality among MA patients with AKI.

Arterial pH, bicarbonate levels and base deficit at presentation as markers of predicting mortality in acute pancreatitis: a single-centre prospective study

Background. Arterial blood gas (ABG) parameters such as pH form part of multi-parameter scoring systems for predicting severe acute pancreatitis; however, literature on detailed evaluation of ABG alone in this context is scarce.

Methods. Patients with acute pancreatitis presenting to our unit between January 2012 and November 2013 were prospectively studied. ABG analysis was done at admission and development of organ failure, any need for intervention, and mortality were noted. The association between various parameters of ABG analysis and the development of organ failure or local complications, need for interventions (endoscopic/radiological/surgical) and mortality were analysed.

Results. Two hundred and five patients (mean age: 39.33 ± 13.85 years; 61.0% males) were prospectively studied. The aetiology of acute pancreatitis was alcohol in 93 patients (45.4%) and gall stone disease in 73 (35.6%). Organ failure developed in 71.2% patients and 83.9% had local complications. In 18% of patients, endoscopic/radiological/surgical interventions were needed and 14.6% died. The patients (n = 35) with metabolic acidosis (pH <7.35) suffered higher frequency of organ failure, need for interventions and mortality. Patients with low arterial bicarbonate levels, as well as higher base deficit, also displayed higher frequency of organ failure, need for interventions and mortality. The receiver operating characteristic (ROC) curves for pH <7.35, bicarbonate <22 meq/L and base deficit of >−4 meq/L for prediction of mortality were 0.771 (95% CI: 0.664–0.878), 0.707 (95% CI: 0.622–0.791) and 0.780 (95% CI: 0.693–0.867), respectively.

Conclusion. Arterial pH, bicarbonate levels, and base deficit at presentation are useful early markers for predicting adverse outcome in acute pancreatitis.

Different contribution of splanchnic organs to hyperlactatemia in fecal peritonitis and cardiac tamponade

Background. Changes in hepatosplanchnic lactate exchange are likely to contribute to hyperlactatemia in sepsis. We hypothesized that septic and cardiogenic shock have different effects on hepatosplanchnic lactate exchange and its contribution to hyperlactatemia. Materials and Methods. 24 anesthetized pigs were randomized to fecal peritonitis (P), cardiac tamponade (CT), and to controls (n = 8 per group). Oxygen transport and lactate exchange were calculated during 24 hours. Results. While hepatic lactate influx increased in P and in CT, hepatic lactate uptake remained unchanged in P and decreased in CT. Hepatic lactate efflux contributed 20% (P) and 33% (CT), respectively, to whole body venous efflux. Despite maintained hepatic arterial blood flow, hepatic oxygen extraction did not increase in CT. Conclusions. Whole body venous lactate efflux is of similar magnitude in hyperdynamic sepsis and in cardiogenic shock. Although jejunal mucosal pCO₂ gradients are increased, enhanced lactate production from other tissues is more relevant to the increased arterial lactate. Nevertheless, the liver fails to increase hepatic lactate extraction in response to rising hepatic lactate influx, despite maintained hepatic oxygen consumption. In cardiac tamponade, regional, extrasplanchnic lactate production is accompanied by hepatic failure to increase oxygen extraction and net hepatic lactate output, despite maintained hepatic arterial perfusion.

A balanced view of balanced solutions

The present review of fluid therapy studies using balanced solutions versus isotonic saline fluids (both crystalloids and colloids) aims to address recent controversy in this topic. The change to the acid-base equilibrium based on fluid selection is described. Key terms such as dilutional-hyperchloraemic acidosis (correctly used instead of dilutional acidosis or hyperchloraemic metabolic acidosis to account for both the Henderson-Hasselbalch and Stewart equations), isotonic saline and balanced solutions are defined. The review concludes that dilutional-hyperchloraemic acidosis is a side effect, mainly observed after the administration of large volumes of isotonic saline as a crystalloid. Its effect is moderate and relatively transient, and is minimised by limiting crystalloid administration through the use of colloids (in any carrier). Convincing evidence for clinically relevant adverse effects of dilutional-hyperchloraemic acidosis on renal function, coagulation, blood loss, the need for transfusion, gastrointestinal function or mortality cannot be found. In view of the long-term use of isotonic saline either as a crystalloid or as a colloid carrier, the paucity of data documenting detrimental effects of dilutional-hyperchloraemic acidosis and the limited published information on the effects of balanced solutions on outcome, we cannot currently recommend changing fluid therapy to the use of a balanced colloid preparation.