Diagnostic accuracy of venous blood gas electrolytes for identifying diabetic ketoacidosis in the emergency department

Effect of short-term ketogenic diet on end-tidal carbon dioxide

BACKGROUND & AIMS

Previous studies have shown that end-tidal carbon dioxide (EtCO₂) is lower with the presence of supraphysiological ketones as in the case of chronic ketogenic diet (KD) and diabetic ketoacidosis (DKA). This study aimed to determine changes in EtCO₂ upon short term KD.

METHODS

Healthy subjects were screened not to have conditions that exerts abnormal EtCO₂ nor contraindicated for KD. Subjects underwent seven days of KD while the EtCO2 and blood ketone (beta-hydroxybutyrate; β-OHB) parameters were sampled at day zero (t0) and seven (t7) of ketosis respectively. Statistically, the t-test and Pearson's coefficient were conducted to determine the changes and correlation of both parameters.

RESULTS

12 subjects completed the study. The mean score ± standard deviation (SD) for EtCO₂ were 35.08 ± 3.53 and 35.67 ± 3.31 mm Hg for t0 and t7 respectively. The mean score ±SD for β-OHB were 0.07 ± 0.08 and 0.87 ± 0.84 mmol/L for t0 and t7 respectively. There was no significant difference of EtCO₂ between the period of study (p > 0.05) but the β-OHB increased during t7 (p < 0.05). There was also no correlation between the parameters.

CONCLUSIONS

These findings suggest that EtCO₂ may not be utilized to determine short term nutritional ketosis.

Confidence at 100%: Characteristics of Likelihood Ratio Confidence Intervals in the Emergency Medicine Diagnostics Literature

OBJECTIVE

We hypothesized that "perfect" 100% sample sensitivity or specificity (PSSS) is common in the emergency medicine (EM) literature. When results yield PSSS, calculating the likelihood ratio (LR) 95% confidence interval (CI) has been challenging. Consequently, we also hypothesized that studies with PSSS would be less likely to report the LR and associated CI, and those that did would use imperfect methods.

METHODS

We searched PubMed or Scopus for all articles reporting diagnostic test results in the 20 top EM journals from 2011 to 2016 and randomly sampled 124 articles. Trained researchers coded the articles as having PSSS or not ("controls"). We separately sampled 100 articles with PSSS and compared them to 100 controls in terms of their reporting of diagnostic tests and associated CIs.

RESULTS

Of the 124 articles, 19.4% (95% CI = 13% to 27.6%) feature a diagnostic test with PSSS. The LR is reported significantly less often in PSSS studies versus control studies: 18 of 100 articles (18% [95% CI = 11.3% to 27.2%]) versus 34 of 100 articles (34% [95% CI = 25% to 44.2%]), with an odds ratio (OR) of 0.43 (95% CI = 0.21 to 0.86). The LR 95% CI is also reported less often in PSSS versus control studies: five of 100 articles (5% [95% CI = 1.9% to 11.8%]) versus 27 of 100 articles (27% [95% CI = 18.8% to 37%]), with an OR of 0.11 (95% CI = 0.02 to 0.44). Five articles with perfect sample sensitivity reported their negative LR CI. The bootstrap method resulted in CIs that were 42.7% smaller on average (range = 16.6% to 63.6%).

CONCLUSION

This analysis provides systematic evidence of diagnostic test reporting in the EM literature. Sample sensitivity or specificity of 100% is common. LRs and their associated 95% CIs are infrequently reported, particularly for PSSS samples. When the LR CI is reported in this scenario, it is overly wide. Improved reporting and methods can enhance the utility and confidence in diagnostic tests in EM.

New Test, Old Disease: A Case Series of Diabetic Ketoalkalosis

BACKGROUND

Diabetic ketoalkalosis (DKAlk) was first described in 1967 as a rare complication of diabetic ketoacidosis with normal or elevated pH/bicarbonate and elevated anion gap (AG) from high β-hydroxybutyrate (BHB).

OBJECTIVE

We report a case series of patients with DKAlk to show how venous blood gas (VBG) electrolytes alone may misdiagnose these patients.

METHODS

This was a case series of DKAlk patients with concomitant VBG and basic metabolic panel (BMP) electrolytes who met the following criteria for DKAlk: BMP hyperglycemia (glucose >250 mg/dL), elevated AG (>15 mEq/L), elevated BHB (>1.2 mmol/L), and high Delta (Δ) gap (>6 mEq/L [bicarbonate gap (BG): measured bicarbonate - 24] - [AG - 12]). Data are reported as median with interquartile range (IQR) (25%, 75%) and group comparisons utilized Mann-Whitney U test (two-tailed, α = 0.05).

RESULTS

We found 10 patients with DKAlk in 2 months. Patients ranged in age from 13 to 77 years, 50% were male, and all were African American. Most patients (8 of 10) were vomiting with hyperglycemia (350 to >600 mg/dL). DKAlk BMP AG ranged from 18 to 34 mmol/L and BHB from 1.74 to 9.09 mmol/L. For bicarbonate, we found no significant difference between VBG (24 mmol/L) and BMP (22 mmol/L) (p = 0.796). VBG chloride (98 mmol/L) was significantly higher than BMP chloride (88 mmol/L) (p < 0.005). This falsely elevated VBG chloride resulted in undervaluing of all VBG AGs, missing almost all of the patients with DKAlk.

CONCLUSIONS

We found that DKAlk is more common than previously reported. We recommend screening with BMP electrolytes and BHB levels for hyperglycemic ED patients who are vomiting or suspected of hypovolemia.

Comparison of bicarbonate values from venous blood gas and chemistry panels measured at the time of diagnosis and resolution of diabetes ketoacidosis

Objective

To determine if bicarbonate values from venous blood gas (VBG) and plasma chemistry samples provided agreement in determining the bicarbonate criteria for the diagnosis and/or resolution of diabetic ketoacidosis (DKA).

Methods

A retrospective chart review of data from patients admitted to a tertiary care hospital with a diagnosis of DKA over a four year period was performed. Paired bicarbonate values from a VBG and chemistry panel, if drawn within 60 minutes of each other, were compared.

Results

At the time of diagnosis of DKA, 197 paired bicarbonate values were available for analysis with the mean difference between the two methods of testing of 2.5 mmol/L. 16 of the 197 (8%) paired values were discordant in meeting criteria for diagnosis of DKA. At the time of resolution of DKA, 83 paired bicarbonate samples were compared. The mean difference was 2.3 mmol/L. 20 of the 83 (24%) paired bicarbonate values showed discordance with regards to meeting the bicarbonate criteria for resolution of DKA.

Conclusion

Discordance between bicarbonate results from different analysis methods may lead to different determinations as to whether or not a patient meets the biochemical definition for diagnosis and resolution of DKA.

Utilizing serum bicarbonate instead of venous pH to transition from intravenous to subcutaneous insulin shortens the duration of insulin infusion in pediatric diabetic ketoacidosis

Background Standard therapy of diabetic ketoacidosis (DKA) in pediatrics involves intravenous (IV) infusion of regular insulin until correction of acidosis, followed by transition to subcutaneous (SC) insulin. It is unclear what laboratory marker best indicates correction of acidosis. We hypothesized that an institutional protocol change to determine correction of acidosis based on serum bicarbonate level instead of venous pH would shorten the duration of insulin infusion and decrease the number of pediatric intensive care unit (PICU) therapies without an increase in adverse events. Methods We conducted a retrospective (pre/post) analysis of records for patients admitted with DKA to the PICU of a large tertiary care children's hospital before and after a transition-criteria protocol change. Outcomes were compared between patients in the pH transition group (transition when venous pH≥7.3) and the bicarbonate transition group (transition when serum bicarbonate ≥15 mmol/L). Results We evaluated 274 patient records (n=142 pH transition group, n=132 bicarbonate transition group). Duration of insulin infusion was shorter in the bicarbonate transition group (18.5 vs. 15.4 h, p=0.008). PICU length of stay was 3.2 h shorter in the bicarbonate transition group (26.0 vs. 22.8 h, p=0.04). There was no difference in the number of adverse events between the groups. Conclusions Transitioning patients from IV to SC insulin based on serum bicarbonate instead of venous pH led to a shorter duration of insulin infusion with a reduction in the number of PICU therapies without an increase in the number of adverse events.

Initial blood pH during cardiopulmonary resuscitation in out-of-hospital cardiac arrest patients: a multicenter observational registry-based study

BACKGROUND

When an out-of-hospital cardiac arrest (OHCA) patient receives cardiopulmonary resuscitation (CPR) in the emergency department (ED), blood laboratory test results can be obtained by using point-of-care testing during CPR. In the present study, the relationship between blood laboratory test results during CPR and outcomes of OHCA patients was investigated.

METHODS

This study was a multicenter retrospective analysis of prospective registered data that included 2716 OHCA patients. Data from the EDs of three university hospitals in different areas were collected from January 2009 to December 2014. Univariate and multivariable analyses were conducted to elucidate the factors associated with survival to discharge and neurological outcomes. A final analysis was conducted by including patients who had no prehospital return of spontaneous circulation and those who underwent rapid blood laboratory examination during CPR.

RESULTS

Overall, 2229 OHCA patients were included in the final analysis. Among them, the rate of survival to discharge and a good Cerebral Performance Categories Scale score were 14% and 4.4%, respectively. The pH level was independently related to survival to hospital discharge (adjusted OR 6.287, 95% CI 2.601-15.197; p < 0.001) and good neurological recovery (adjusted OR 15.395, 95% CI 3.439-68.911; p < 0.001). None of the neurologically intact patients had low pH levels (< 6.8) or excessive potassium levels (> 8.5 mEq/L) during CPR.

CONCLUSIONS

Among the blood laboratory test results during CPR of OHCA patients, pH and potassium levels were observed as independent factors associated with survival to hospital discharge, and pH level was considered as an independent factor related to neurological recovery.

The value of venous blood gas analysis in the diagnosis of diabetic ketoacidosis

BACKGROUND & AIM

Newer blood gas analyzers have the ability to report electrolyte values and glucose in addition to pH, so this diagnostic process could be condensed in diagnosing diabetic ketoacidosis (DKA). We aimed to assess the accuracy of the venous blood gas (VBG) analysis with electrolytes for diagnosing DKA.

METHODS

This study prospectively identified a convenience sample of (60 patients) presented with DKA and tested their VBG and serum electrolytes. The diagnosis of DKA was made according to American Diabetes Association criteria. Serum chemistry electrolyte values were considered to be the criterion standard. Sensitivity and specificity of VBG electrolytes results were compared against this standard. In addition, correlation coefficients for individual electrolytes between VBG electrolytes and laboratory chemistry electrolytes were calculated.

RESULTS

Paired VBG and serum chemistry panels were available for 60 patients, only 49 patients were included, In this study; 20% of cases were newly diagnosed diabetes mellitus. The total number of diabetic ketoacidosis was 14 patients (28.5%). The sensitivity and specificity of the VBG and electrolytes for diagnosing DKA was 92.9% (95% confidence interval [CI]=89% to 99%) and 97.1% (95% CI=92% to 100%), respectively. Correlation coefficients between VBG and serum chemistry were 0.91, 0.47, 0.61, 0.65, and 0.58 for blood sugar, sodium, potassium, chloride, and creatinine respectively.

CONCLUSIONS

Findings of this study offer preliminary support for the possibility of using VBG sample rather than VBG sample and serum chemistry electrolytes together to rule out diabetic ketoacidosis.

Use of Serum Bicarbonate to Substitute for Venous pH in New-Onset Diabetes

OBJECTIVE

To investigate whether serum bicarbonate (HCO3) levels can be used to accurately diagnose diabetic ketoacidosis (DKA) and classify its severity in children with new-onset diabetes mellitus (NODM).

METHODS

Retrospective study of all patients with NODM presenting to Boston Children's Hospital from October 1, 2007, to July 1, 2013. DKA was defined as blood glucose ≥200 mg/dL, venous pH (vpH) <7.3, and urine ketones ≥2+, and severe DKA as vpH <7.1. Linear regression was used to assess serum HCO3 as a predictor of vpH, and logistic regression to evaluate serum HCO3 as a predictor of DKA and severe DKA.

RESULTS

Of 690 study cohort subjects (47% girls, age 10.8 ± 4.3 years, 76.7% white), 19.4% presented with DKA. The relationship between serum HCO3 and vpH was log-linear (r = 0.87, 95% CI 0.85-0.89, P < .001). HCO3 predicted vpH (R(2) 0.75, P < .001) using the formula vpH = 6.81301 + (0.17823*ln[HCO3]) and DKA and severe DKA (c-statistic 0.97 [95% CI 0.96-0.99, P < .001] and 0.99 [95% CI 0.991-0.999, P < .001], respectively). HCO3 cutoffs of <18 and <8 mmol/L had sensitivities of 91.8% and 95.2%, and specificities of 91.7% and 96.7%, respectively, to diagnose DKA and severe DKA. Findings were similar in a validation cohort of 197 subjects.

CONCLUSIONS

Serum HCO3 concentration alone can substitute for vpH to diagnose DKA and classify severity in children with NODM. It is suggested as an alternative to reliance on vpH, especially in settings in which access to vpH measurement is limited.

Clinical features, mortality, hospital admission, and length of stay of a cohort of adult patients with diabetic ketoacidosis attending the emergency room of a tertiary hospital in Spain

AIM

To assess the clinical features, length of stay, incidence rate, mortality, and hospital admissions of patients with episodes of diabetic ketoacidosis (DKA).

PATIENTS

It was conducted retrospective, cross-sectional study of 164 consecutive admissions of adult patients (2008-August 2012), with type 1 or type 2 diabetes already known or new onset.

RESULTS

Mortality rate was 1.2%. The DKA episodes were mild (18.9%), moderate (31.7%), or severe (49.4%). The cumulative incidence was 2.66 cases/1000 patients with diabetes (DM) in 4.5 years. The most common causes triggering DKA were infection (33.2%) and dietary transgression and/or insulin dose omission (30.7%). A total of 12.8% of patients had new onset DM, 56.7% type 1, and 26.8% type 2 DM. Patients with type 2 DM were older and had at admission higher creatinine, BUN, osmolality, sodium, and anion gap levels. Patients with new-onset of DM had higher levels of glucose and sodium, but lower potassium levels. No differences were found in pH or bicarbonate. Admission to the intensive care unit (ICU) was required in >50% of cases (p<0.001), and 86.6% of patients were finally admitted to a medical ward (p=0.005). The length of stay at the ICU (p<0.001) and hospital (p=0.013) was significantly different depending on DKA severity.

CONCLUSIONS

Most DKA episodes require hospital admission, but mortality is <2%, and length of stay at the ER and medical ward depends on type of DM and initial severity of the episode.

Diabetic ketoacidosis in the pediatric emergency department

Despite many advances, the incidence of pediatric-onset diabetes and diabetic ketoacidosis (DKA) is increasing. Diabetes mellitus is 1 of the most common chronic pediatric illnesses and, along with DKA, is associated with significant cost and morbidity. DKA is a complicated metabolic state hallmarked by dehydration and electrolyte disturbances. Treatment involves fluid resuscitation with insulin and electrolyte replacement under constant monitoring for cerebral edema. When DKA is recognized and treated immediately, the prognosis is excellent. However, when a patient has prolonged or multiple courses of DKA or if DKA is complicated by cerebral edema, the results can be devastating.