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.

Implementation of a Goal-Directed Mechanical Ventilation Order Set Driven by Respiratory Therapists Improves Compliance With Best Practices for Mechanical Ventilation

PURPOSE

Data regarding best practices for ventilator management strategies that improve outcomes in acute respiratory distress syndrome (ARDS) are readily available. However, little is known regarding processes to ensure compliance with these strategies. We developed a goal-directed mechanical ventilation order set that included physician-specified lung-protective ventilation and oxygenation goals to be implemented by respiratory therapists (RTs). We sought as a primary outcome to determine whether an RT-driven order set with predefined oxygenation and ventilation goals could be implemented and associated with improved adherence with best practice.

METHODS

We evaluated 1302 patients undergoing invasive mechanical ventilation (1693 separate episodes of invasive mechanical ventilation) prior to and after institution of a standardized, goal-directed mechanical ventilation order set using a controlled before-and-after study design. Patient-specific goals for oxygenation partial pressure of oxygen in arterial blood (Pao ₂), ARDS Network [Net] positive end-expiratory pressure [PEEP]/fraction of inspired oxygen [Fio ₂] table use) and ventilation (pH, partial pressure of carbon dioxide) were selected by prescribers and implemented by RTs.

RESULTS

Compliance with the new mechanical ventilation order set was high: 88.2% compliance versus 3.8% before implementation of the order set ( P < .001). Adherence to the PEEP/Fio ₂ table after implementation of the order set was significantly greater (86.0% after vs 82.9% before, P = .02). There was no difference in duration of mechanical ventilation, intensive care unit (ICU) length of stay, and in-hospital or ICU mortality.

CONCLUSIONS

A standardized best practice mechanical ventilation order set can be implemented by a multidisciplinary team and is associated with improved compliance to written orders and adherence to the ARDSNet PEEP/Fio ₂ table.

Anesthetic Management of the Adult Patient with Concomitant Cardiac and Pulmonary Disease

Several common diseases of the cardiac and pulmonary systems and the interactions of the two in disease and anesthetic management are discussed. Management of these disease processes in isolation is reviewed and how the management of one organ system impacts another is then explored. For example, in a patient with acute lung injury and right heart failure, lung-protective ventilation may directly conflict with strategies to minimize right heart afterload. Such challenging clinical scenarios require appreciation of each disease entity, their appropriate management, and the balance between competing priorities.

Perioperative Glucose Management: Point-of-Care Testing and Pseudohypoglycemia

Perioperative hypoglycemia has been associated with adverse outcomes. Consequently, perioperative monitoring of blood glucose using convenient point-of-care (POC) monitors is frequently used. Although venous or arterial glucose POC testing has been cleared for use in critically ill hospitalized patients, the results of capillary glucose POC testing should be interpreted with caution because capillary POC samples are usually less reliable than those obtained from arterial or venous sites. We describe a case of pseudohypoglycemia using such testing. This case highlights the importance of individualizing perioperative glucose management to venous or arterial rather than capillary sampling in certain clinical situations.