Spike in glucose levels after reperfusion during aortic surgery: assessment by continuous blood glucose monitoring using artificial endocrine pancreas

Time course changes in insulin sensitivity during cardiac surgery: A retrospective study on intraoperative glycemic management using an artificial pancreas

INTRODUCTION

Glycemic control is essential for improving the prognosis of cardiac surgery, although precise recommendations have not yet been established. Under a constant blood glucose level, the insulin infusion rate correlates with insulin resistance during glycemic control using an artificial pancreas (AP). We conducted this retrospective study to elucidate changes in intraoperative insulin sensitivity as a first step to creating glycemic control guidelines.

METHODS

Fifty-five cardiac surgery patients at our hospital who underwent intraoperative glycemic control using an AP were enrolled. Twenty-three patients undergoing surgical procedures requiring cardiac arrest under hypothermic cardiopulmonary bypass (CPB) with minimum rectal temperatures lower than 32°C, 13 patients undergoing surgical procedures requiring cardiac arrest under hypothermic CPB with minimum rectal temperatures of 32°C, eight patients undergoing on-pump beating coronary artery bypass grafting and 11 patients undergoing off-pump coronary artery bypass were assigned to groups A, B, C and D, respectively. We analyzed the time course of changes in the data derived from glycemic control using the AP.

RESULTS

Significant time course changes were observed in groups A and B, but not in groups C and D. Insulin resistance was induced after the start of hypothermic CPB in groups A and B, and the induced change was not resolved by the rewarming procedure, remaining sustained until the end of surgery.

CONCLUSIONS

Hypothermia is the predominant factor of the induced insulin resistance during cardiac surgery. Thus, careful glycemic management during hypothermic CPB is important. Prospective clinical studies are required to confirm the findings of this study.

Diode-pumped efficient high-power cascade Tm:GdVO4 laser simultaneously operating at ∼2 μm and ∼2.3 μm

The laser diode (LD)-pumped efficient high-power cascade Tm:GdVO4 laser simultaneously operating on the 3F4 → 3H6 (at ∼2 μm) and 3H4 → 3H5 (at ∼2.3 μm) Tm3+ transition was first reported in this paper. The cascade Tm:GdVO4 laser generated a maximum total continuous-wave (CW) laser output power of 8.42 W with a slope efficiency of 40%, out of which the maximum ∼2.3 μm CW laser output power was 2.88 W with a slope efficiency of 14%. To our knowledge, 2.88 W is the highest CW laser output power amongst the LD-CW-pumped ∼2.3 μm Tm3+-doped lasers reported so far.

Cascade lasing at ∼2 μm and ∼2.3 μm in a diode-pumped Tm:YVO4 laser

We report on the cascade continuous-wave operation of a diode-pumped Tm:YVO₄ laser on the ³F₄ → ³H₆ (at ∼2 μm) and ³H₄ → ³H₅ (at ∼2.3 μm) Tm³⁺ transitions. Pumped with a fiber-coupled spatially multimode 794 nm AlGaAs laser diode, the 1.5 at.% Tm:YVO₄ laser yielded a maximum total output power of 6.09 W with a slope efficiency of 35.7% out of which the ³H₄ → ³H₅ laser emission corresponded to 1.15 W at 2291-2295 and 2362-2371 nm with a slope efficiency of 7.9% and a laser threshold of 6.25 W.

Closed-loop artificial endocrine pancreas from Japan

The development of a closed-loop artificial pancreas (AP) in the Western countries and Japan is different. In Western countries, wearable AP with a closed-loop glycemic control system has been developed as a treatment for patients with type 1 and type 2 diabetes. On the contrary, in Japan, bedside closed-loop AP explored by a Japanese company (Nikkiso, Tokyo, Japan) has developed as perioperative glycemic control device in surgical patients and acute care patients with emergency. In this article, we reviewed the scientific evidence in the past and present and future prospects of perioperative glycemic control using bedside AP with a closed-loop system in Japan. Conventional perioperative strict glycemic controls have three major problems: hyperglycemia, hypoglycemia, and variability in blood glucose concentrations. In Japan, perioperative strict glycemic control using the current bedside AP STG-55 (Nikkiso, Tokyo, Japan) has been developed since 2010. This novel glycemic control method achieved not only stable glycemic control without hyperglycemia, hypoglycemia, and less variability of blood glucose concentrations but also reduced postoperative infectious complications in patients undergoing major surgeries. Among the rapidly increasing number of surgical or emergency patients with diabetes, frailty, and sarcopenia of intrinsic glucose intolerance, more sophisticated and smaller AP available easily in operating rooms and intensive care units will be warranted to promote improved therapeutic outcomes in such critically ill patients.

Pathophysiologic Mechanisms of Hypothermia-Induced Pancreatic Injury in a Rat Model of Body Surface Cooling

OBJECTIVE

The mechanisms underlying hypothermia-induced pancreatic injury are unclear. Thus, we investigated the pathophysiology of hypothermia-induced pancreatic injury.

METHODS

We created a normal circulatory model with body surface cooling in rats. We divided the rats into control (36°C-38°C), mild hypothermia (33°C-35°C), moderate hypothermia (30°C-32°C), and severe hypothermia (27°C-29°C) (n = 5 per group) groups. Then, we induced circulatory failure with a cooling model using high-dose inhalation anesthesia and divided the rats into control (36°C-38°C) and severe hypothermia (27°C-29°C) (n = 5 per group) groups. Serum samples were collected before the introduction of hypothermia. Serum and pancreatic tissue were collected after maintaining the target body temperature for 1 hour.

RESULTS

Hematoxylin and eosin staining of the pancreas revealed vacuoles and edema in the hypothermia group. Serum amylase (P = 0.056), lactic acid (P < 0.05), interleukin 1β (P < 0.05), interleukin 6 (P < 0.05), and tumor necrosis factor α (P = 0.13) levels were suppressed by hypothermia. The circulatory failure model exhibited pancreatic injury.

CONCLUSIONS

Hypothermia induced bilateral effects on the pancreas. Morphologically, hypothermia induced pancreatic injury based on characteristic pathology typified by vacuoles. Serologically, hypothermia induced protective effects on the pancreas by suppressing amylase and inflammatory cytokine levels.

Artificial endocrine pancreas with a closed-loop system effectively suppresses the accelerated hyperglycemic status after reperfusion during aortic surgery

OBJECTIVES

To control intraoperative hyperglycemia in patients who underwent aortic surgery using STG-55^® artificial endocrine pancreas and clarify the effectiveness of this device.

METHODS

Blood glucose control using the STG-55^® was performed in 18 patients (15 men and 3 women; age, 66 ± 10 years) who required hypothermic circulatory arrest (STG-55^® group). Seventeen patients (10 men and 7 women; age, 71 ± 8 years) whose blood glucose was controlled using the conventional method were included in the control group. Glucose concentration was controlled with the aim of maintaining it at 150 mg/dl.

RESULTS

In both groups, the blood glucose concentrations did not significantly change during the interruption of systemic perfusion; however, a sharp increase was noted immediately after reperfusion. Although the hyperglycemic status persisted after reperfusion in the control group, it was effectively suppressed in the STG-55^® group (STG^® vs. control group at 50 min after reperfusion: 180 ± 35 vs. 212 ± 47 mg/dl, p = 0.026) and blood glucose concentration reached the target value of 150 mg/dl at 100 min after reperfusion (STG^® vs. control group: 153 ± 29 vs. 215 ± 43 mg/dl, p = 0.0008). The total administered insulin dose was 175 ± 81 U and 5 ± 3 U in the STG^® and control groups, respectively (p < 0.0001).

CONCLUSIONS

To treat the accelerated hyperglycemic status in aortic surgery requiring circulatory arrest, strict glycemic control using an artificial endocrine pancreas might be beneficial.