Novel Use of a Gas Analyzer Can Reliably Predict the Arterial Oxygen among Emergency Department Patients Undergoing Rapid Sequence Intubation.

BACKGROUND: To our knowledge, no study has assessed the correlation of fraction of inspired oxygen (FiO2) and end-tidal oxygen (EtO2) values obtained from a gas analyzer during the preoxygenation period of rapid sequence intubation (RSI) to predict partial pressure of oxygen (PaO2) among patients requiring intubation in the emergency department (ED). OBJECTIVE: The purpose of this study was to determine whether a simple equation using EtO2 and FiO2 at time of induction could reliably estimate minimal PaO2 in ED patients undergoing RSI. METHODS: We conducted an observational pilot study performed in an adult ED utilizing a gas analyzer to obtain EtO2 and FiO2 values in ED patients undergoing RSI from data collectors blinded to our objective. The Pearson correlation coefficient was calculated between the equation's predicted PaO2 and the PaO2 drawn from an arterial blood gas shortly after intubation. A Bland-Altman plot analysis was performed to identify any additional bias. RESULTS: Seventy-five patients were enrolled. The equation's mean predicted minimal PaO2 and mean PaO2 from an arterial blood gas within 3 min after intubation was 178 mm Hg (95% confidence interval [CI] 145-211 mm Hg) and 209 mm Hg (95% CI 170-258 mm Hg), respectively. The Pearson correlation coefficient between the predicted minimal PaO2 and post-intubation PaO2 demonstrated a strong correlation (r2 = 0.89). The Bland-Altman plot indicated no bias affecting the correlation between the predicted and actual PaO2. CONCLUSIONS: Among ED patients undergoing RSI, the use of a gas analyzer to measure EtO2 and FiO2 can provide a reliable measure of the minimal PaO2 at the time of induction during the RSI phase of preoxygenation.

A retrospective analysis of the respiratory adjusted shock index to determine the presence of occult shock in trauma patients.

BACKGROUND: The shock index (SI), calculated as hear rate/systolic blood pressure, is a simple hemodynamic marker that may be used to assess for the presence of occult shock in trauma patients. The normal range for a healthy adult patient is 0.5 to 0.7. Recently, studies have demonstrated that tachypnea is the most important predictor of cardiac arrest in hospital wards and is an important indicator of derangements across multiple organ systems. As such, we have sought to determine whether the inclusion of the patient's respiratory rate (RR) to the already existing SI (called the Respiratory Adjusted Shock Index [RASI]), calculated as hear rate/systolic blood pressure*(RR/10), will improve the overall diagnostic accuracy of detecting patients in early occult shock. METHODS: A retrospective chart review over a 4-year period (2012-2016) at an urban, Level I trauma center was performed. All patients admitted to hospital for trauma were included in the study. Exclusion criteria were patients in traumatic arrest or in overt shock. Charts were reviewed for triage vital signs and point of care lactate drawn within 30 minutes of presentation. A lactate greater than 2 mmol/L was used to determine presence of hypoperfusion. The upper limit of normal for the RASI was calculated by multiplying the upper limit of the SI by 1.9 (RR of 19 divided by 10) and validated internally. RESULTS: A total of 3,093 patients were included in this study. There was no difference in SI for patients discharged versus patients admitted, 0.6 (95% CI, 0.5-0.7) versus 0.7 (95% CI, 0.5-0.8) and a significant difference between the same groups of patients (discharged vs. admitted) for the RASI, 1.1 (95% CI, 1.04-1.18) versus 1.46 (95% CI, 1.35-1.55), respectively. Area under the curve for SI was 0.58 and for the RASI score was 0.94. CONCLUSION: The RASI score improves diagnostic accuracy for detecting early occult shock in trauma patients when compared to the SI. LEVEL OF EVIDENCE: Diagnostic, level II.

Whole-body computed tomographic scanning leads to better survival as opposed to selective scanning in trauma patients: a systematic review and meta-analysis.

BACKGROUND: Traumatic injury in the United States is the Number 1 cause of mortality for patients 1 year to 44 years of age. Studies suggest that early identification of major injury leads to better outcomes for patients. Imaging, such as computed tomography (CT), is routinely used to help determine the presence of major underlying injuries. We review the literature to determine whether whole-body CT (WBCT), a protocol including a noncontrast scan of the brain and neck and a contrast-enhanced scan of the chest, abdomen, and pelvis, detects more clinically significant injuries as opposed to selective scanning as determined by mortality rates. METHODS: Scientific publications from 1980 to 2013 involving the study of the difference between pan scan and selective scan after trauma were identified. The Preferred Reporting Items for Systematic Reviews and Meta-analyses was used. Publications were categorized by level of evidence. Injury Severity Score (ISS) and pooled odds for mortality rate of patients who received WBCT scan versus those who received selective scans were compared. RESULTS: Of the 465 publications identified, 7 were included, composing of 25,782 trauma patients who received CT scan following trauma. Of the patients, 52% (n = 13,477) received pan scan and 48% (n = 12,305) received selective scanning. Overall ISS was significantly higher for patients receiving WBCT versus those receiving selective scan (29.7 vs. 26.4, p < 0.001, respectively). Overall mortality rate was significantly lower for WBCT versus selective scanning (16.9; 95% confidence interval [CI], 16.3-17.6 vs. 20.3; 95% CI, 19.6-21.1, p < 0.0002, respectively). Pooled odds ratio for mortality rate was 0.75 (95% CI, 0.7-0.79), favoring WBCT. CONCLUSION: Despite the WBCT group having significantly higher ISS at baseline compared with the group who received selective scanning, the WBCT group had a lower overall mortality rate and a more favorable pooled odds ratio for trauma patients. This suggests that in terms of overall mortality, WBCT scan is preferable to selective scanning in trauma patients. LEVEL OF EVIDENCE: Systematic review and meta-analysis, level III.

Mechanisms of glucagon degradation at alkaline pH.

Glucagon is unstable and undergoes degradation and aggregation in aqueous solution. For this reason, its use in portable pumps for closed loop management of diabetes is limited to very short periods. In this study, we sought to identify the degradation mechanisms and the bioactivity of specific degradation products. We studied degradation in the alkaline range, a range at which aggregation is minimized. Native glucagon and analogs identical to glucagon degradation products were synthesized. To quantify biological activity in glucagon and in the degradation peptides, a protein kinase A-based bioassay was used. Aged, fresh, and modified peptides were analyzed by liquid chromatography with mass spectrometry (LCMS). Oxidation of glucagon at the Met residue was common but did not reduce bioactivity. Deamidation and isomerization were also common and were more prevalent at pH 10 than 9. The biological effects of deamidation and isomerization were unpredictable; deamidation at some sites did not reduce bioactivity. Deamidation of Gln 3, isomerization of Asp 9, and deamidation with isomerization at Asn 28 all caused marked potency loss. Studies with molecular-weight-cutoff membranes and LCMS revealed much greater fibrillation at pH 9 than 10. Further work is necessary to determine formulations of glucagon that minimize degradation and fibrillation.

Nasal cannula end-tidal CO2 correlates with serum lactate levels and odds of operative intervention in penetrating trauma patients: a prospective cohort study.

BACKGROUND: Penetrating trauma patients in shock often require urgent operative intervention. Studies have demonstrated that variables obtained in the emergency department, such as lactate levels, can help the physician determine the presence of hemorrhagic shock, leading to more rapid intervention and improve prognosis in trauma patients. The purpose of the study is to determine if end-tidal (ET) CO2 correlates with serum lactate levels, a measure of tissue hypoxia and subsequently shock, in penetrating trauma patients. Secondarily, we sought to determine whether ET CO2 could be used to determine the patient's odds of requiring operative intervention. METHODS: A prospective observational cohort study was undertaken at an urban Level 1 trauma center. Baseline ET CO2 from nasal cannula and serum lactate level were recorded in all patients in whom the trauma team was activated. Outcomes defined were whether operative intervention was needed. Pearson correlation (R), correlation coefficient (r(2)), and odds ratio were calculated. RESULTS: One hundred five patients were enrolled. Pearson correlations and coefficients calculated for serum lactate level to ET CO2 were R = -0.86 (r(2) = 0.74, p < 0.0001). Of patients requiring operative intervention, 81.97% had abnormally low ET CO2 and 54.1% had abnormally high serum lactate levels. Odds ratios of patients needing an emergent operation with abnormally low ET CO2 was 20.4 (95% confidence interval, 7.47-55.96) and with abnormally high serum lactate levels was 4 (95% confidence interval, 1.68-5.93). CONCLUSION: ET CO2 has a strong inverse correlation to serum lactate levels. Abnormally low ET CO2 values were associated with greater increased odds compared with serum lactate levels of penetrating trauma patients requiring operative intervention. LEVEL OF EVIDENCE: Prognostic/diagnostic study, level I.

Stable liquid glucagon formulations for rescue treatment and bi-hormonal closed-loop pancreas.

Small doses of glucagon given subcutaneously in the research setting by an automated system prevent most cases of hypoglycemia in persons with diabetes. However, glucagon is very unstable and cannot be kept in a portable pump. Glucagon rapidly forms amyloid fibrils, even within the first day after reconstitution. Aggregation eventually leads to insoluble gels, which occlude pump catheters. Fibrillation occurs rapidly at acid pH, but is absent or minimal at alkaline pH values of ~10. Glucagon also degrades over time; this problem is greater at alkaline pH. Several studies suggest that its primary degradative pathway is deamidation, which results in a conversion of asparagine to aspartic acid. A cell-based assay for glucagon bioactivity that assesses glucagon receptor (GluR) activation can screen promising glucagon formulations. However, mammalian hepatocytes are usually problematic as they can lose GluR expression during culture. Assays for cyclic AMP (cAMP) or its downstream effector, protein kinase A (PKA), in engineered cell systems, are more reliable and suitable for inexpensive, high-throughput assessment of bioactivity.