Sodium Bicarbonate in Different Critically Ill Conditions: From Physiology to Clinical Practice

Common pitfalls in the use of hypertonic sodium bicarbonate for cardiac toxic drug poisonings

BACKGROUND

Hypertonic sodium bicarbonate is advocated for the treatment of sodium channel blocker poisoning, but its efficacy varies amongst different sodium channel blockers. This Commentary addresses common pitfalls and appropriate usage of hypertonic sodium bicarbonate therapy in cardiotoxic drug poisonings.

SODIUM BICARBONATE WORKS SYNERGISTICALLY WITH HYPERVENTILATION

Serum alkalinization is best achieved by the synergistic effect of hypertonic sodium bicarbonate and hyperventilation (PCO2 ∼ 30-35 mmHg [0.47-0.6 kPa]). This reduces the dose of sodium bicarbonate required to achieve serum alkalinization (pH ∼ 7.45-7.55) and avoids adverse effects from excessive doses of hypertonic sodium bicarbonate.

VARIABILITY IN RESPONSE TO SODIUM BICARBONATE TREATMENT

Tricyclic antidepressant poisoning responds well to sodium bicarbonate therapy, but many other sodium channel blockers may not. For instance, drugs that block the intercellular gap junctions, such as bupropion, do not respond well to alkalinization. For sodium channel blocker poisonings in which the expected response is unknown, a bolus of 1-2 mmol/kg sodium bicarbonate can be used to assess the response to alkalinization.

SODIUM BICARBONATE CAN EXACERBATE TOXICITY FROM DRUGS ACTING ON MULTIPLE CARDIAC CHANNELS

Hypertonic sodium bicarbonate can cause electrolyte abnormalities such as hypokalaemia and hypocalcaemia, leading to QT interval prolongation and torsade de pointes in poisonings with drugs that have mixed sodium and potassium cardiac channel properties, such as hydroxychloroquine and flecainide.

THE GOAL FOR HYPERTONIC SODIUM BICARBONATE IS TO ACHIEVE THE ALKALINIZATION TARGET (∼PH 7.5), NOT COMPLETE CORRECTION OF QRS COMPLEX PROLONGATION

Excessive doses of hypertonic sodium bicarbonate commonly occur if it is administered until the QRS complex duration is < 100 ms. A prolonged QRS complex duration is not specific for sodium channel blocker toxicity. Some sodium channel blockers do not respond, and even when there is a response, it takes a few hours for the QRS complex duration to return completely to normal. In addition, QRS complex prolongation can be due to a rate-dependent bundle branch block. So, no further doses should be given after achieving serum alkalinization (pH ∼ 7.45-7.55).

MAXIMAL DOSING FOR HYPERTONIC SODIUM BICARBONATE

A further strategy to avoid overdosing patients with hypertonic sodium bicarbonate is to set maximum doses. Exceeding 6 mmol/kg is likely to cause hypernatremia, fluid overload, metabolic alkalosis, and cerebral oedema in many patients and potentially be lethal.

RECOMMENDATION FOR THE USE OF HYPERTONIC SODIUM BICARBONATE IN SODIUM CHANNEL BLOCKER POISONING

We propose that hypertonic sodium bicarbonate therapy be used in patients with sodium channel blocker poisoning who have clinically significant toxicities such as seizures, shock (systolic blood pressure < 90 mmHg, mean arterial pressure <65 mmHg) or ventricular dysrhythmia. We recommend initial bolus dosing of hypertonic sodium bicarbonate of 1-2 mmol/kg, which can be repeated if the patient remains unstable, up to a maximum dose of 6 mmol/kg. This is recommended to be administered in conjunction with mechanical ventilation and hyperventilation to achieve serum alkalinization (PCO2∼30-35 mmHg [4-4.7 kPa]) and a pH of ∼7.45-7.55. With repeated bolus doses of hypertonic sodium bicarbonate, it is imperative to monitor and correct potassium and sodium abnormalities and observe changes in serum pH and on the electrocardiogram.

CONCLUSIONS

Hypertonic sodium bicarbonate is an effective antidote for certain sodium channel blocker poisonings, such as tricyclic antidepressants, and when used in appropriate dosing, it works synergistically with hyperventilation to achieve serum alkalinization and to reduce sodium channel blockade. However, there are many pitfalls that can lead to excessive sodium bicarbonate therapy and severe adverse effects.

Emergent Management of Severe Hypothermia, Acidemia, and Coagulopathy in Operative Penetrating Ballistic Cranial Trauma

Hypothermia in a trauma patient has been associated with increased morbidity and mortality and is more frequently seen in those sustaining traumatic brain injuries (TBIs). Acidosis is an important consequence of hypothermia that leads to derangements across the spectrum of the coagulation cascade. Here, we present a case of a 31-year-old male presented after suffering a right parietal penetrating ballistic injury with an associated subdural hematoma and 7 mm midline shift requiring decompressive craniectomy and external ventricular drain (EVD) placement in the setting of severe hypothermia (28°C) and acidosis (pH 7.12). With aggressive rewarming intraoperatively, the use of full-body forced-air warming, warmed IV fluids, and increasing the ambient room temperature, the patient's acidosis and hypothermia improved to pH 7.20 and 34°C. Despite these aggressive attempts to rewarm the patient, he developed coagulopathy in the setting of concurrent hypothermia and acidosis. This case highlights the importance of prompt reversal of hypothermia due to its potentially fatal effects, particularly in the setting of severe TBIs. We discuss the critical aspects of surgical management of the injury and anesthetic management of hypothermia, acidosis, and coagulopathy perioperatively.

Adverse Impact of Sodium Bicarbonate Administration on Multiple Outcomes in Acute Pancreatitis Patients With Hyperlactatemia

OBJECTIVE

Hyperlactatemia is likely to occur among patients with acute pancreatitis (AP). Sodium bicarbonate (SB) therapy could be applied to correct potential detrimental acidic disturbances, but the exact impact of SB treatment is unknown. This study aims to investigate the impact of SB on AP patients complicated with hyperlactatemia.

METHODS

The study was conducted based on the database named Medical Information Mart for Intensive Care-IV (MIMIC-IV). Propensity matching (PSM) and inverse probability weighting (IPTW) were used to balance the baseline differences. Multivariate regression and marginal structural Cox models were performed to investigate the association between SB and multiple outcomes.

RESULTS

Three hundred fifty-three AP patients with hyperlactatemia (initial serum lactate, >2.0 mmol/L) were extracted from the MIMIC-IV database. We found that SB treatment was significantly associated with worse multi-outcomes of AP patients with hyperlactatemia (in-hospital mortality: hazard ratio, 2.46; 95% confidence interval, 1.38-4.39; P < 0.01). Further analysis through marginal structural Cox models showed that SB had adverse impact on in-hospital prognosis of patients with severe lactic acidosis (pH < 7.15,lactate > 2.0 mmol/L).

CONCLUSION

Sodium bicarbonate might not be an appropriate treatment for AP patients with hyperlactatemia (lactate > 2.0 mmol/L) or with severe lactic acidosis (pH < 7.15, lactate > 2.0 mmol/L).

Tris-Hydroxymethyl Aminomethane in Critically Ill Adults: A Systematic Review

Tris-hydroxymethyl aminomethane (THAM) is an amino alcohol used clinically to buffer acid loads and raise pH in acidotic conditions. Unlike sodium bicarbonate, which increases plasma sodium levels with use and produces carbon dioxide (CO 2 ) as part of the buffering process, THAM does neither. Although not widely used in modern critical care and unavailable for clinical use in 2016, THAM has been available in the United States since 2020. Clinical experience and existing literature suggest that THAM may have clinical utility in acid-base management in conditions such as liver transplantation where rising sodium levels during perioperative care may be dangerous, and in managing acid-base derangements during care of patients with acute respiratory distress syndrome (ARDS). To clarify the evidence base supporting the clinical use of THAM, we conducted a systematic review to assess the efficacy and safety of THAM as a buffering agent in critically ill adults using Ovid EBM Reviews, Ovid Embase, Ovid Medline, Scopus, and Web of Science Core Collection. Randomized-, crossover-, retrospective cohort-, parallel-designed clinical trials, case series, and case reports of adult patients who received THAM in the operative or critical care setting were included. Conference abstracts of qualifying study designs were also included. Two independent reviewers extracted the data regarding the study details, demographics, treatment, and outcomes data. A third reviewer adjudicated discrepancies. A total of 21 studies including 3 randomized controlled trials, 5 observational studies, 4 case series, and 9 case reports met inclusion criteria. Eight studies (38%) were abstracts published in conference proceedings. In total, 417 critically ill patients received THAM to treat acidosis in critically ill surgical and nonsurgical patients, during liver transplantation, and in ARDS. In general, THAM corrected acidosis with an efficacy equivalent to sodium bicarbonate and did so with less hypercarbia and hypernatremia. Adverse effects of THAM included hyperkalemia, hypoglycemia, ventilator depression, and tissue damage with extravasation. We conclude that THAM may have potential advantages in some critical care settings, but that clinical evidence is limited, and high-quality evaluations are necessary.

Paraneoplastic syndrome in malignant lymphoma: A case report

Hypercalcaemia associated with malignancy is a complication of advanced tumors. Lactic acidosis is also an extremely rare paraneoplastic syndrome of malignancy, and the presence of both usually indicates an extremely poor prognosis for the tumour. Diffuse large B-cell lymphoma is the most common type of non-Hodgkin's lymphoma and is also a common aggressive lymphoma. It is extremely rare for patients with diffuse large B-cell lymphoma to develop both hypercalcaemia and severe lactic acidosis. In this article, we report a case of CD5 positive diffuse large B-cell lymphoma with hypercalcaemic crisis and persistent lactic acidosis, in which calcium was rapidly reduced to normal after rehydration, diuresis, calcitonin and zoledronate, and continuous renal replacement therapy (CRRT). After correction of acidosis with sodium bicarbonate, diuresis, vitamin B1 and CRRT, the patient's lactate remained at a high level. The aim of this article is to analyse the experience of the combination of hypercalcaemia and intractable lactic acidosis, which should be considered as a serious electrolyte disorder possibly associated with abnormal metabolism of malignant tumors, and to identify and treat the primary lesion as early as possible.

Serum Bicarbonate Deficiency in Dogs with Acute and Chronic Kidney Disease

Serum bicarbonate deficiency is a disorder frequently found in human patients with acute (AKI) and chronic (CKD) kidney disease, due to abnormalities in kidney generation and reabsorption of bicarbonate. Although alkali supplementation is usually performed in both humans and veterinary CKD patients, data regarding the frequency of bicarbonate disorders in AKI and CKD dogs are scarce. The aim of the present study is to assess the frequency and the severity of bicarbonate deficiency of dogs affected by AKI, acute chronic kidney disease (ACKD), and CKD, and to investigate its possible association with the IRIS grade/stage as well as with disorders of calcium phosphate metabolism. A retrospective evaluation of the serum biochemical panels of all dogs with diagnoses of AKI, ACKD, and CKD referred to the nephrology and urology service of the Veterinary Teaching Hospital of the University of Pisa, between January 2014 and January 2022, was performed. Bicarbonate deficiency was defined as serum bicarbonate < 22 mmol/L and classified as moderate (between 18 and 22 mmol/L) or severe (<18 mmol/L). Serum bicarbonate deficiency was found in 397/521 dogs (76%), of which 142/397 (36%) showed moderate deficiency, and 255/397 (64%) severe deficiency. Dogs with AKI and ACKD showed a significantly higher frequency of bicarbonate deficiency (p = 0.004) and severe forms compared to CKD dogs (p = 0.02). In AKI and ACKD dogs, a negative linear correlation was found between serum bicarbonate and serum creatinine, urea, and phosphate. The frequency of bicarbonate deficiency was higher in the later stages of the disease in both AKI (p = 0.01), ACKD (p = 0.0003), and CKD dogs (p = 0.009). Dogs with serum CaxP ≥ 70 mg²/dL² showed a higher frequency of bicarbonate deficiency (p = 0.01) and showed severe forms (p = 0.01) compared to dogs with CaxP < 70 mg²/dL². Serum bicarbonate deficiency seems to be a very frequent disorder in both AKI, ACKD, and CKD dogs, with an increasing frequency and severity in more advanced stages of kidney disease. The higher frequency and severity of bicarbonate deficiency in AKI and ACKD may be caused by a more severe and sudden loss of kidney function, or extra-renal factors. Finally, the association between frequency and severity of bicarbonate deficiency and abnormal CaxP may suggest a potential connection between metabolic acidosis and bone mineral disorders.

Evaluation of Different Contrast Agents for Regional Lung Perfusion Measurement Using Electrical Impedance Tomography: An Experimental Pilot Study

Monitoring regional blood flow distribution in the lungs appears to be useful for individually optimizing ventilation therapy. Electrical impedance tomography (EIT) can be used at the bedside for indicator-based regional lung perfusion measurement. Hypertonic saline is widely used as a contrast agent but could be problematic for clinical use due to potential side effects. In five ventilated healthy pigs, we investigated the suitability of five different injectable and clinically approved solutions as contrast agents for EIT-based lung perfusion measurement. Signal extraction success rate, signal strength, and image quality were analyzed after repeated 10 mL bolus injections during temporary apnea. The best results were obtained using NaCl 5.85% and sodium-bicarbonate 8.4% with optimal success rates (100%, each), the highest signal strengths (100 ± 25% and 64 ± 17%), and image qualities (r = 0.98 ± 0.02 and 0.95 ± 0.07). Iomeprol 400 mg/mL (non-ionic iodinated X-ray contrast medium) and Glucose 5% (non-ionic glucose solution) resulted in mostly well usable signals with above average success rates (87% and 89%), acceptable signal strength (32 ± 8% and 16 + 3%), and sufficient image qualities (r = 0.80 ± 0.19 and 0.72 ± 0.21). Isotonic balanced crystalloid solution failed due to a poor success rate (42%), low signal strength (10 ± 4%), and image quality (r = 0.43 ± 0.28). While Iomeprol might enable simultaneous EIT and X-ray measurements, glucose might help to avoid sodium and chloride overload. Further research should address optimal doses to balance reliability and potential side effects.

Effects of Peripherally Inserted Central Catheter (PICC) Catheterization Nursing on Bloodstream Infection in Peripheral Central Venous Catheters in Lung Cancer: A Single-Center, Retrospective Study

Background. Peripherally inserted central catheter (PICC), as one of the important intravenous routes for the rescue and treatment of critically ill patients, has been widely used in the fluid resuscitation of critically ill patients in intensive care. In particular, PICC can be widely used in the treatment of cancer patients. With the wide application of peripheral central venous catheterization, the clinical findings of bloodstream infection complications caused by PICC have gradually attracted the attention of doctors and patients. Aims. To investigate the effect of specialized placement and PICC placement care on patients with lung cancer who underwent PICC puncture. Patients were selected and divided into a comparison group and an observation group of 40 patients each according to the randomized residual grouping method. In the comparison group, routine PICC placement and catheter maintenance were performed, while the observation group was provided with specialized placement and PICC placement care. The differences in immune and tumor marker levels and nursing compliance between the two groups were observed and compared before and after nursing care. Results. There was no significant difference in the comparison of tumor marker levels between the two groups of patients before care, while the levels of CYFRA21-1, CA125, and VGEF in the observation group were significantly lower than those in the comparison group after care, and this difference was statistically significant ( $P<0.05$ ). There was no statistically significant difference in the comparison of immune levels between the two groups before care ( $P>0.05$ ), while the comparison of CD4+, CD3+, and CD4+/CD8+ after care was significantly different and higher in the observation group than in the comparison group, and the comparison was statistically significant ( $P<0.05$ ). The compliance rate of 93.8% in the observation group was significantly higher than that of 77.9% in the comparison group, and this difference was statistically significant for comparison ( $P<0.05$ ). Conclusion. PICC placement care is more effective in patients with lung cancer and performing PICC puncture, significantly improves patients’ immune and tumor marker levels, improves patients’ negative emotions, reduces disease uncertainty, and improves nursing compliance.