Tale of two sites: capillary versus arterial blood glucose testing in the operating room

Low preoperative hemoglobin A1c level is a predictor of perioperative infectious complications after esophagectomy: A retrospective, single-center study

This retrospective, single-center study aimed to evaluate the impact of blood glucose (BG) markers on perioperative complications after esophagectomy in a cohort of 176 patients. Study analyses included the correlation of daily maximum BG level and hemoglobin A1c (HbA1c) with clinicopathological factors. Maximum BG levels were significantly higher on postoperative day (POD) 0 than on PODs 2, 3, 5, and 7 (p < 0.05). Additionally, maximum BG levels on PODs 1, 2, and 7 were significantly higher in patients with preoperative HbA1c levels of ≥ 5.6% than in those with preoperative HbA1c levels of < 5.6% (p < 0.05 for all). The rates of any complications and infectious complications were higher in patients with preoperative HbA1c levels of < 5.6% than in those with preoperative HbA1c levels of ≥ 5.6% (p < 0.05 for both). A preoperative HbA1c level of < 5.6% was a significant predictor of infectious complications after esophagectomy by logistic regression analysis (p < 0.05). Maximum BG level after esophagectomy remained high in patients with high preoperative HbA1c levels, whereas a normal HbA1c level was an independent risk factor for infectious complications.

Error traps in the perioperative management of children with type 1 diabetes

Patients with type 1 diabetes mellitus (T1D) require insulin administration at all times to maintain euglycemia and metabolic stability. Insulin administration in the perioperative period is complicated by fasting requirements and perioperative stressors that can change the patient's insulin needs. In addition, many anesthesia providers are not familiar with insulin dosing strategies and technology, such as insulin pumps and continuous glucose monitors (CGMs), that are commonly used by patients with T1D. Errors in perioperative insulin administration can lead to hypoglycemia, hyperglycemia, and diabetic ketoacidosis. This article reviews common errors of associated with the perioperative management of patients with T1D, including failure to assess and coordinate patient care preoperatively; failure to understand diabetes management and technology; failure to monitor blood glucose and recognize dysglycemia; and failure to appropriately administer basal insulin.

Feasibility of intraoperative continuous glucose monitoring: An observational study in general surgery patients

BACKGROUND

Perioperative hyperglycemia is associated with adverse outcomes in surgical patients, and major societies recommend intraoperative monitoring and treatment targeting glucose <180-200 mg/dL. However, compliance with these recommendations is poor, in part due to fear of unrecognized hypoglycemia. Continuous Glucose Monitors (CGMs) measure interstitial glucose with a subcutaneous electrode and can display the results on a receiver or smartphone. Historically CGMs have not been utilized for surgical patients. We investigated the use of CGM in the perioperative setting compared to current standard practices.

METHOD

This study evaluated the use of Abbott Freestyle Libre 2.0 and/or Dexcom G6 CGMs in a prospective cohort of 94 participants with diabetes mellitus undergoing surgery of ≥3 h duration. CGMs were placed preoperatively and compared to point of care (POC) BG checks obtained by capillary samples analyzed with a NOVA glucometer. Frequency of intraoperative blood glucose measurement was at the discretion of the anesthesia care team, with a recommendation of once per hour targeting BG of 140-180 mg/dL. Of those consented, 18 were excluded due to lost sensor data, surgery cancellation, or rescheduling to a satellite campus resulting in 76 enrolled subjects. There were zero occurrences of failure with sensor application. Paired POC BG and contemporaneous CGM readings were compared with Pearson product-moment correlation coefficients, and Bland-Altman plots.

RESULTS

Data for use of CGM in perioperative period was analyzed for 50 participants with Freestyle Libre 2.0, 20 participants with Dexcom G6, and 6 participants with both devices worn simultaneously. Lost sensor data occurred in 3 participants (15%) wearing Dexcom G6, 10 participants wearing Freestyle Libre 2.0 (20%) and 2 of the participants wearing both devices simultaneously. The overall agreement of the two CGM's utilized had a Pearson correlation coefficient of 0.731 in combined groups with 0.573 in Dexcom arm evaluating 84 matched pairs and 0.771 in Libre arm with 239 matched pairs. Modified Bland-Altman plot of the difference of CGM and POC BG indicated for the overall dataset a bias of -18.27 (SD 32.10).

CONCLUSIONS

Both Dexcom G6 and Freestyle Libre 2.0 CGMs were able to be utilized and functioned well if no sensor error occurred at time of initial warmup. CGM provided more glycemic data and further characterized glycemic trends more than individual BG readings. Required time of CGM warm up was a barrier for intraoperative use as well as unexplained sensor failure. CGMs had a fixed warm of time, 1 h for Libre 2.0 and 2 h for Dexcom G6 CGM, before glycemic data obtainable. Sensor application issues did not occur. It is anticipated that this technology could be used to improve glycemic control in the perioperative setting. Additional studies are needed to evaluate use intraoperatively and assess further if any interference from electrocautery or grounding devices may contribute to initial sensor failure. It may be beneficial in future studies to place CGM during preoperative clinic evaluation the week prior to surgery. Use of CGMs in these settings is feasible and warrants further evaluation of this technology on perioperative glycemic management.

Capillary blood for point-of-care testing

Clinically, blood sample analysis has been widely used for health monitoring. In hospitals, arterial and venous blood are utilized to detect various disease biomarkers. However, collection methods are invasive, painful, may result in injury and contamination, and skilled workers are required, making these methods unsuitable for use in a resource-limited setting. In contrast, capillary blood is easily collected by a minimally invasive procedure and has excellent potential for use in point-of-care (POC) health monitoring. In this review, we first discuss the differences among arterial blood, venous blood, and capillary blood in terms of the puncture sites, components, sample volume, collection methods, and application areas. Additionally, we review the most recent advances in capillary blood-based commercial products and microfluidic instruments for various applications. We also compare the accuracy of microfluidic-based testing with that of laboratory-based testing for capillary blood-based disease diagnosis at the POC. Finally, we discuss the challenges and future perspectives for developing capillary blood-based POC instruments.

Correlation Between Capillary and Venous Blood Glucose in the Lactose Tolerance Test

BACKGROUND

The lactose tolerance test is a classic method for the study of lactose malabsorption. However, the methodology used has not been standardized, and this leads to differences in results.

AIM

The aim of this report was to analyze whether capillary blood glucose measurement is in agreement with venous blood glucose when performing lactose tolerance test.

METHODS

This is a prospective study of consecutive patients with suspected lactose malabsorption who had lactose tolerance test performed in venous and capillary blood simultaneously, using a load of 50 g lactose. Agreement was measured using the concordance correlation coefficient of Lin (95 % CI) and Bland-Altman plots. The degree of agreement was measured using the Kappa index. A value of p < 0.05 was considered statistically significant.

RESULTS

Eighty-four patients (68 % women) were included. The concordance correlation coefficient showed very poor agreement between the two techniques: 0.68 (0.58-0.77), 0.72 (0.62-0.8), and 0.77 (0.69-0.83) for baseline, 30, and 60 min, respectively. The Bland-Altman plots showed that capillary blood glucose measurements result in higher levels than venous blood glucose measurements, with mean differences of 0.39, 0.77, and 1.1 mmol/L at baseline, 30, and 60 min, respectively. The degree of agreement was low, with a Kappa index of 0.59 (p < 0.001).

CONCLUSIONS

The test measured in venous blood is not in agreement with the measurement obtained from capillary blood. It is likely that the diagnostic accuracy attributed without distinction to lactose tolerance test in different studies for lactose malabsorption is incorrect, making it necessary to specify the analysis method.

Suitability of capillary blood glucose analysis in patients receiving vasopressors

BACKGROUND

Glycemic control in critically ill patients decreases infection and mortality. Patients receiving vasopressors have altered peripheral perfusion, which may affect accuracy of capillary blood glucose values measured with point-of-care devices.

OBJECTIVES

To compare capillary and arterial glucose values measured via point-of-care testing (POCT) with arterial glucose values measured via clinical chemistry laboratory testing (CCLT) in patients after cardiothoracic surgery. To determine if vasopressors or diminished peripheral perfusion influence the accuracy of POCT values.

METHODS

In a prospective, convenience sample of 50 adult postoperative cardiothoracic patients receiving insulin and vasopressors, 162 samples were obtained simultaneously from capillary and arterial sites during insulin infusion and tested via both POCT and CCLT. Clarke error grid analysis and ISO 15197 were used to analyze level of agreement. Two-way analysis of variance was used to analyze differences in glucose values with respect to vasopressor use and peripheral perfusion.

RESULTS

An unacceptable level of agreement was found between the capillary POCT results and arterial CCLT results (only 88.3% of values fell in zone A, or within the ISO 15197 tolerance bands). Arterial POCT results showed acceptable (94.4%) agreement with CCLT results. Vasopressor use had a significant effect on the accuracy of arterial blood glucose values (F=15.01; P<.001).

CONCLUSIONS

Even when the more accurate POCT with arterial blood is used, blood glucose values are significantly less accurate in patients receiving more than 2 vasopressors than in patients receiving fewer vasopressors. CCLT may be safer for titrating insulin doses in these patients.