RESEARCH ARTICLES

Predisposing factors for hypoglycemia: security measures for critical patients on intravenous insulin

Carina Teixeira Paixão^I; Raquel de Mendonça Nepomuceno^II; Manassés Moura dos Santos^III; Lolita Dopico da Silva^IV

^I PhD student in the Post-Graduate Nursing Program and Guest Professor of the Graduate Program in Intensive Nursing at the Rio de Janeiro State University. Nurse at the National Institute of cardiology. Rio de Janeiro, Brazil, Email: carinapaixao@gmail.com
^II PhD student in the Post-Graduate Nursing Program and Guest Professor of the Graduate Program in Intensive Nursing at the Rio de Janeiro State University. Nurse at the National Institute of cardiology. Rio de Janeiro, Brazil, Email: raquel.nepomuceno@gmail.com
^III Master's student in the Post-Graduate Nursing Program and Guest Professor of the Graduate Program in Intensive Nursing at the Rio de Janeiro State University Nurse of the National Cancer Institute. Rio de Janeiro, Brazil, Email: mana_moura@yahoo.com
^IV Standing Professor of the Post-Graduate Nursing Program and Intensive Nursing Program Coordinator at the Rio de Janeiro State University. Fellow Pro-scientist. Rio de Janeiro, Brazil, Email: lolita.dopico@gmail.com

DOI: http://dx.doi.org/10.12957/reuerj.2015.15098

ABSTRACT

Documentary, retrospective cross research aiming at describing the predisposing factors studied in critically ill patients receiving continuous insulin infusion. Tracking was made of five hundred and fifty (550) medical records for the years 2012 and 2013 of post-operative cardiac surgery patients who received intravenous insulin. Main results show that nearly half of the patients had at least one record of hypoglycemia, the majority were male (60.11%), elderly (md = 61.78), overweight (26,75Kg / m2), hypertense (78.57%), and ischemic (52.38%). Predisposing factors for hypoglycemia, with statistical significance identified among patients were as follows: diabetes (OR = 3.6); renal failure (OR = 5.4); and use of vasoactive amines (OR = 3.1). Conclusions identified security actions for patients in those conditions such as venous blood collection as well as the use of blood meters to assess glycemic levels.

Keywords: Insulin; glucose; hypoglycemia; nursing.

INTRODUCTION

During heart surgery, patients undergo significant variations in blood volume, body temperature, plasma composition and tissue blood flow with important physiopathological consequences. Aggressions such as cardiopulmonary bypass (CPB) and total circulatory arrest further contribute to aggravating the organic breakdown in the intraoperative period¹.

These patients are under a state of physiological stress due to the severity of their clinical condition, which predisposes them to various endocrine disorders such as hyperglycemia¹. Hyperglycemia causes deleterious effects micro and macrovascular complications, such as kidney diseases, immune system changes, electrolytic disorders, Neuropathies endotelias disorders that predisposes them to thrombogenesis. It is considered difficult to define the incidence of acute hyperglycemia; it may vary from 40 to 90% depending on the threshold used to define abnormal blood glucose levels¹ .

Thus, in recent years, intensive glycemic control achieved by continuous insulin infusion (CII) has taken began to occupy a prominent position in the management of critically ill patients. The premise is that the maintenance of normoglycemia is associated with lower rates of infections and organ failure. Insulin is the only hormone that makes this transport and without it, the cells are deprived of energy².

According to the Institute for Healthcare Improvement (IHI), insulin belongs to one of ten categories of medicinal products considered as high-risk Medications or Potentially Hazardous Drugs (PHDs), meaning that has greater potential to cause serious injury to patients when there is failure in its usage. The intravenous insulin requires care to ensure the efficiency and safety of its management because it has side effects, among the most important, hypoglycemia stands out, which if untreated, can cause irreversible brain damage³.

Hypoglycemia is considered the primary adverse event associated with continuous intravenous insulin therapy. Severe hypoglycemia occurs around 4% to 7% of patients, and despite the risk of hypoglycemia do not seem very high, the impact that this event has on the prognosis makes it mandatory to seek solutions that can contribute to reduce the occurrence of this event.

In daily practice it still often coexists with episodes of hypoglycemia during continuous intravenous infusion of insulin, despite monitoring by nursing, consisting of measure for digit-puncture the time of glucose in time, monitor the patient's vital signs. In addition, to maintaining a continuous source of glucose, both enteral and parenteral nutrition, all these guided by guided conduct protocols of the units⁴.

In Brazil, it falls to the nursing preparation and administration of insulin solution in most hospitals and should therefore be she aware of aspects that involve not only the management of insulin, but also monitoring to prevent the occurrence of severe hypoglycemia (<50mg/dl)².

In addition to these aspects, it is considered necessary to recognize the predisposing factors for hypoglycemia reported in the literature, because there are situations where even following the protocol with discipline and measuring blood glucose to time, some of the patients have hypoglycemia, events attributed to factors predisposing to hypoglycemia. There are many factors mentioned in the literature, and for being the most cited, will be those that this research will build; they are over the age 60, high blood pressure, diabetes mellitus, renal failure, absence of caloric intake and the use of vasoactive amines⁴.

This study aimed to describe the predisposing factors for hypoglycemia, found in critical patients in the postoperative period of cardiac surgery who received CII.

The contribution of this publication is based on the fact that it is for the nurse to supervision and / or medication, they are responsible for monitoring the patient receiving CII, and therefore know what the predisposing factors presented by the patient can contribute to a planning specific patient care, preventing adverse events that may compromise the results of drug therapy with intravenous insulin, in order to ensure safe management of insulin.

LITERATURE REVIEW

During heart surgery, patients undergo significant variations in blood volume, body temperature, plasma composition and tissue blood flow with important physiopathological consequences¹. Aggressions such as (CPB) and total circulatory arrest contribute by further aggravating the organic breakdown in the intraoperative period¹.

Endocrine changes and immune responses triggered leading to a set of metabolic changes to protect the main physiological functions². Hormonal changes cause stress to the excessive release of hormones such as glucagon, catecholamines and glucocorticoids, resulting in insulin deficiency to suppress hepatic gluconeogenesis, and commit to regulating insulin-glucose uptake. Hyperglycemia generated, long overlooked and taken as a secondary event is today recognized as a predictive factor of bad prognosis in the critical patient^5.6.

Thus, in recent years, the intensive glucose control achieved by continuous infusion of insulin came to occupy a prominent position in the management of critical patients. The premise is that the maintenance of normoglycemia is associated with lower rates of infections and organ failure. It is known that the maintenance of blood glucose values between 80 to 120 mg/dl, decreases the morbidity, mortality reduction promotes around 40% and also provides a reduction in length of stay, and decrease the incidence of complications and the development of organ dysfunction⁷.

Although insulin be among the PHDs, insulin therapy in the intensive glycemic control is a therapeutic possibility of impact on morbidity and mortality in critically ill patients and their implementation is low cost, mainly requiring proper training and discipline of the teams, especially nursing⁸.

METHODOLOGY

A survey conducted with epidemiological structure, retrospective documentary data collection charts of patients who received continuous infusion of insulin at a hospital, located in the State of Rio de Janeiro. The data were collected in the period from March to October 2014 and were selected all records of patients and postoperative intravenous insulin using in 2012 and 2013 and met the criteria for inclusion, namely: be patient over the age of 18 years; with at least two or more days of hospitalization; with record high populated or death and having received CII.

It was considered severe hypoglycemia when blood glucose was less than 50 mg/dL. As predisposing factors, the following were specified: diabetes, kidney disease; need of caloric intake and the use of vasoactive amines.

As the hospital does not have the electronic medical record, data were collected from clinical evolution, water balance, laboratory tests and prescriptions.

Statistical, descriptive measures and p ≤ 0.05 was considered significant. The p value was calculated by Fisher's exact test, in order to show statistical differences between the variables for each clinical characteristic. The p value expresses the statistical significance related to clinical characteristic and the occurrence of hypoglycemia. To quantify how much more likely is the occurrence of hypoglycemia in patients with clinical signs of hypoglycemia was used to calculate the risk ratio (RR). All ethical precepts relating to the development of research on human subjects regulated by Brazilian resolution 466/12 were followed in the development of this study. The project, referred to the Ethics and Research Committee of the Pedro Ernesto University Hospital, was approved under No. 3.083/2011

RESULTS

550 post-cardiac surgery records were screened, of which 168 patients received intravenous insulin (CII) on average for three days of which 74 (44.04%) patients had at least one episode of hypoglycemia severe hypoglycemia.

Among patients who used CII, the male predominated (60.11%) elderly (md = 61.78 years), overweight, with a median of 26.75 Kg/m²of body mass Index (BMI). Most were hypertensive (78.57%) and 52.38% were ischemic. The majority (80.35%) patients had discharge as the destination of hospitalization.

Among patients who have hypoglycemia, there was a predominance of males (29.16%), the majority had high (28.57%) and ischemic diseases (22.02%) were the largest cause of surgery, It is noteworthy that the only characteristic with significant statistical difference between the groups with and without hypoglycemia was to have had MI (p = 0.01345), as shown in Table 1.

ENTRA A TABELA 1

Table 2 shows the distribution of the predisposing factors mentioned in the literature that can promote hypoglycemia in patients who received continuous infusion of insulin.

ENTRA A TABELA 2

In this population, the predisposing factors for hypoglycemia with statistical significance were being diabetic, have kidney failure, using vasoactive amines.

In Table 3 is the Odds Ratio(OR) and the corresponding confidence interval for each predisposing factor found, noting that patients with diabetes are more likely to present 3.6 hypoglycemia than patients without diabetes. Renal failure is associated with a 5.4 times higher chance of hypoglycemia, and the use of vasoaminas increases the chance of hypoglycemia by up to three times.

ENTRA AQUI A TABELA 3

DISCUSSION

In the population researched were found the following factors predisposing to hypoglycemia: Diabetes (OR = 3.6), kidney disease (OR = 5.4) and use of vaosaminas (OR = 3.1).

Renal Failure

Patients with renal failure accounted for almost 15.47% of the population, of which 12% had hypoglycemia, with five times more likely to patients with kidney failure come to present hypoglycemia.

Kidneys are the main site of insulin degradation; in fact, the insulin needs of diabetic patients fall as kidney failure sets in. Thus, the patient who uses insulin or oral hypoglycemic, the occurrence of hypoglycemia can be explained by this mechanism and treated with insulin correction. However, some patients with renal dialysis may experience spontaneous hypoglycaemia. These patients have increased half-life of circulating insulin, and does not occur renal gluconeogenesis that works with 45% of the production of glucose. Hypoglycemia in people with kidney failure, who do dialysis and use insulin, is also the result of decreased clearance of insulin and reduced mobilization of neoglucogenic precursors in renal failure^9-11.

Hypoglycemia related to kidney failure involves one or more of several mechanisms, such as impaired hepatic gluconeogenesis, glycogenolysis changed, reduced renal gluconeogenesis, renal degradation and clearance of impaired insulin, malnutrition, and in some cases, deficiency of counter-regulatory hormones such as disability catecholamines, and glucagon^12,13. When these patients on dialysis, they have a higher insulin sensitivity by increasing the release of inflammatory molecules such as interleukins, leading to a greater risk of hypoglycemia. In this case, it is a correction and adaptation of the insulin dose¹⁴.

Diabetes

The presence of diabetes mellitus was a characteristic presented by almost 40% of the population of which 25% (n = 42) showed hypoglycemia, going on three times more likely than patients with diabetes will present hypoglycemia.

Hypoglycemia can be caused by various factors within the ICU as intravenous error in insulin dosage, medication changes, changes in blood glucose verification sites, and no decrease in caloric intake, insulin requirements after leaving the surgical stress situation¹⁵.

The poor control of blood glucose is related the worst hospital outcomes, not just in the diabetic patient, but also in non-diabetic. The stress induced by surgical procedure and by cardiopulmonary bypass in cardiac surgery can lead to important hyperglycemia. Blood glucose levels greater than 150 mg/dl in the operative period and higher than 350 mg/dl during extracorporeal circulation were related to increase of cardiovascular, respiratory, infectious, and neurological and kidney complications. Patients with deficient intraoperative glucose control may be seven times more likely compared to other complications. Hypoglycemia, especially in diabetics, lead to the deficiency counter-regulation mechanism, with decreased release of epinephrine and the alarm symptoms. Due to malnutrition, especially in ICUs liver glycogen stores may be compromised, which, in association with the deficit of catecholamines and cortisol, can also predispose the patient to a hypoglycemia¹⁶.

Vasoaminas

Almost half of the patients (49.4%) used vasoaminas, of whom 28.57% presented hypoglycemia, with three times more chances of these patients will present hypoglycemia.

Due to hemodynamic instability that can happen in the immediate postoperative period of cardiac surgery, the patient often need vasoactive drugs, as well as mechanical ventilation, circulatory support, with consequent increase of length of stay in intensive care¹⁷.

Hypoperfused patients in states of shock, with peripheral edema and use of vasoconstrictor drugs may have erroneously low blood glucose results by compromising the quality of the capillary sample.

Given these characteristics, it is recommended to collecting a venous sample. The venous sample is the most reliable, followed by arterial blood and finally the capillary. Due to the influence of various factors, the measured glycemic load diet by blood through capillary blood glucose monitoring system is not recommended as the sole method in patients, hemodynamically unstable and using vasoaminas¹⁸.

It is recommended that these nurses have laboratory confirmation of the extreme values of hypo-or hyperglycemia. However, it is known the difficulties of such a measure, such as the availability of the central laboratory in responding quickly to this demand and the definition of what glycemic value indicates the need of confirmation. Thus, it is believed that the repeating glucose by glucometer measurement with a different source sample before blood glucose levels less than 60 mg / dl or greater than 250 mg / dl, using hemogasometry is a more viable as in Brazilian intensive care units¹⁹.

In the context of intensive therapy, it is necessary that nurses contribute to the decrease of episodes of severe hypoglycemia, benefiting patients and hospital institutions on issues of patient safety that receives intravenous insulin²⁰.

CONCLUSION

To associate the presence of predisposing factors to the occurrence of hypoglycemia were investigated patients with more than 60years, with diabetes, renal failure, with caloric intake and use of vasoactive amines.

The predisposing factors that showed a positive association with the presence of hypoglycemia were kidney failure, diabetes and the use of vasoaminas, indicating that the presence of predisposing factor increased the chance of hypoglycemia.

Therefore, to ensure safe use on intravenous insulin infusion, it is recommended that nursing actions incorporate the identification of predisposing factors of each patient. The nurse should plan the procedures to avoid the delay or delay in performing tests that require fasting, performing dietary supply and the measurement of blood glucose at certain times.

In this sense, it is understood that the nurse, to take care of a patient receiving continuous infusion of insulin, must meet these main characteristics for the occurrence of hypoglycemia. Due to the multifactorial nature of the occurrence of hypoglycemia, the knowledge of the predisposing factors is critical to the adoption of preventive and therapeutic measures.

The limitations of the study refers mainly to the loss of data due to the quality of medical records, being an insurmountable factor, not only with regard to incomplete records, but also to information not always reliable, requiring the crossing of various patient data for the use of the clinical case.

We recommend further studies to test which nursing care would be effective as a barrier to episodes of hypoglycemia; which factors indicate the risk of measurement Glycemic doesn't detect hypoglycemia and what are predisposing factors that, when combined, indicate the patient with greater or lesser susceptibility to the occurrence of the adverse event during the CII.

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