Perioperative response of leptin and the tumor necrosis factor alpha system in morbidly obese patients. Influence of cortisol inhibition by etomidate

Obesity, Hypertension, and Bariatric Surgery

PURPOSE OF REVIEW

Obesity increases the risk of hypertension. However, blood pressure decreases before any significant loss of body weight after bariatric surgery. We review the mechanisms of the temporal dissociation between blood pressure and body weight after bariatric surgery.

RECENT FINDINGS

Restrictive and bypass bariatric surgery lower blood pressure and plasma leptin levels within days of the procedure in both hypertensive and normotensive morbidly obese patients. Rapidly decreasing plasma leptin levels and minimal loss of body weight point to reduced sympathetic nervous system activity as the underlying mechanism of rapid blood pressure decline after bariatric surgery. After the early rapid decline, blood pressure does not decrease further in patients who, while still obese, experience a steady loss of body weight for the subsequent 12 months. The divergent effects of bariatric surgery on blood pressure and body weight query the role of excess body weight in the pathobiology of the obesity phenotype of hypertension. The decrease in blood pressure after bariatric surgery is moderate and independent of body weight. The lack of temporal relationship between blood pressure reduction and loss of body weight for 12 months after sleeve gastrectomy questions the nature of the mechanisms underlying obesity-associated hypertension.

Use of Etomidate for Rapid Sequence Intubation (RSI) in Pediatric Trauma Patients: An Exploratory National Survey

Objective, To survey the pediatric trauma programs to ascertain if and how etomidate is being used for rapid sequence intubation (RSI) in pediatric trauma patients. Design, A 25 question survey was created using REDCaps. A link to the survey was emailed to each of the pediatric and adult trauma programs that care for pediatric patients. Setting, Pediatric trauma programs and adult trauma programs caring for pediatric patients. Intervention, None. Measurements and Main Results, A total of 16% of programs responded (40/247). The majority of the centers that responded are urban, academic, teaching Level 1 pediatric trauma centers that provide care for > 200 pediatric trauma patients annually.  The trauma program directors were the most likely to respond to the survey (18/40).  33/38 respondents state they use etomidate in their RSI protocol but it is not used in all pediatric trauma patients.  26/38 respondents believe that etomidate is associated with adrenal suppression and 24/37 believe it exacerbates adrenal suppression in pediatric trauma patients yet 28 of 37 respondents do not believe it is clinically relevant. Conclusions, Based on the results of the survey, the use of etomidate in pediatric trauma patients is common among urban, academic, teaching, level 1 pediatric trauma centers.  A prospective evaluation of etomidate use for RSI in pediatric trauma patients to evaluate is potential effects on adrenal suppression and hemodynamics is warranted.

Obesity in anesthesia and intensive care

Obesity is a global epidemic increasingly affecting management of anesthesia as well as intensive care medicine. Possible improvements in therapy require consideration of the specific pathophysiology of the obese, their concomitant diseases, and the complications associated with morbid obesity. Systematic assessment of perioperative risk factors is essential for an appropriate management. Paradoxically, overweight and moderately obese patients undergoing surgery have a lower risk when compared to patients with normal weight. The highest mortality and morbidity rates in this setting are reported for underweight and morbidly obese patients. The better chance of survival when compared to normal-weight individuals in the perioperative setting has been described the obesity paradox. In particular, the commitment of all involved physicians to improve all aspects of care will reduce the perioperative risk in obese patients. Physiological and pharmacological characteristics of the obese should also be considered. Furthermore, adequate technical equipment and practical skills of all members of the anesthesia team significantly contribute to risk reduction and therapeutic success in obese patients.

The influence of obesity on postoperative inflammatory cytokine levels

Obesity is a chronic inflammatory state and adipose tissue serves as a source of inflammatory mediators. This study compared plasma levels of the proinflammatory cytokines interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) in 20 morbidly obese patients (group O) undergoing laparoscopic Roux-en-Y gastric bypass surgery and in 20 non-obese control patients (group C) undergoing laparascopic gastrectomy. Blood was sampled preoperatively and at 3 and 24 h postoperatively. Postoperative IL-6 levels increased significantly in both groups, but were significantly lower in group O than in group C. Age- and anaesthetic timeadjusted IL-6 levels showed a significant increase at 24 h postoperatively compared with preoperative values in both groups; changes were significantly greater in group C. TNF-α levels did not change significantly over time, but were significantly lower in group O at 3 h postoperatively compared with group C. In conclusion, postoperative changes in IL-6 and TNF-α levels in morbidly obese patients were lower than in non-obese patients. Adipose tissue appears not to contribute to the acute postoperative inflammatory response.

Leptin and the post-operative inflammatory response. More insights into the correlation with the clinical course and glucocorticoid administration

BACKGROUND

Cardiac surgery involving cardiopulmonary bypass (CPB) causes a systemic inflammatory process which can lead to multiple organ failure and postoperative morbidity. Recent animal and human studies suggested a possible involvement of leptin in the systemic inflammatory response.

AIM

To characterize the response of leptin to open heart surgery (OHS) and the relationship between the time course of leptin levels and the post-operative clinical course, and to examine the effect of exogenous glucocorticoids.

PATIENTS AND METHODS

Forty-seven pediatric patients, undergoing OHS for congenital heart disease were studied. Thirty-four patients (Group 1) received methylprednisolone during CPB while 13 (group 2) did not. Serial blood samples were collected perioperatively and up to 24 h after surgery, and assayed for leptin and cortisol.

RESULTS

All patients' leptin levels decreased significantly during CPB (to 44-48% of baseline, p<0.001); they then increased, peaking at 12 h post-operatively. The levels of groups 1 and 2 were similar up to 8 h post-operatively; thereafter, those of group 1 were significantly higher. Recovery of leptin levels in patients with a more complicated post-operative course was comparatively slower. Cortisol levels of all patients increased significantly during CPB (p<0.001), gradually decreasing afterwards. Cortisol and leptin levels were inversely correlated in both patients' groups.

CONCLUSIONS

CPB is associated with acute changes in circulating leptin levels. A complicated postoperative course is associated with lower leptin levels which are inversely correlated with cortisol levels. Leptin may participate in post-CPB inflammatory and hemodynamic responses.

Stress and body mass index each contributes independently to tumor necrosis factor-alpha production in prepubescent Latino children

This investigation extended prior work by determining if stress and body mass index (BMI) contributed independently to tumor necrosis factor-alpha (TNF-alpha) levels among prepubescent Latino children and if sex and family history of type 2 diabetes mellitus (T2DM) modified these relationships. Data were collected in South Florida from 112 nondiabetic school-aged Hispanic children, of whom 43.8% were obese (BMI >/= 95th percentile) and 51.8% presented with a family history of T2DM. Stressful life events were assessed via parental report using a life events scale. Plasma TNF-alpha levels were determined with enzyme-linked immunosorbent assay. The relative contributions of stress and BMI with TNF-alpha levels and the potential interaction effects of sex and family history of T2DM were analyzed with multiple linear regression analyses. Stress and BMI each accounted for a significant proportion of the unique variance associated with TNF-alpha. The association between stress and TNF-alpha was not modified by sex or family history of T2DM. These findings implicate BMI and stress as independent determinants of TNF-alpha (an inflammatory cytokine and adipocytokine) among Latino children. Future investigations should examine the potential roles of exercise, nutritional status, age, and growth hormone in explicating the relationship between TNF-alpha production and psychosocial distress and risk for infection among obese children.

Dissociation of thyrotropin and leptin secretion in acute surgical stress in severely obese patients

BACKGROUND

During illness, thyroid parameters undergo acute changes, which are known as non-thyroidal illness syndrome, the cause of which has not been elucidated. In vitro and in vivo data demonstrate that leptin regulates the expression of thyrotropin-releasing hormone (TRH)-mRNA in the paraventricular nucleus as well as the secretion of thyrotropin (TSH) in response to fasting in humans and animals. Moreover, in healthy adults, TSH and leptin have almost identical circadian rhythms. Our aim was to investigate the secretion of leptin and TSH, and their probable interaction, during the acute stress that is induced by surgery.

METHODS

We studied 18 severely obese but otherwise healthy men. All participants were admitted to the hospital in the morning after an overnight fast. On the following day, 14 of the participants underwent bariatric surgery at 0900. The remaining four participants did not undergo surgery and served as controls. Serum samples to measure the levels of TSH and leptin were collected from all participants, as follows: upon admission to the hospital (baseline values) and on the following day at 0900 and every 10 min, thereafter for 9 h.

RESULTS

The serum TSH increased during the first hour after skin incision (si) and then decreased gradually throughout the rest of the observation period. In contrast, during the first hour after si, the leptin levels remained unaltered. The leptin levels then decreased and reached a nadir at 4 h and 10 min post si after which they remained constant for approximately 1 h. Thereafter, while TSH continued to decrease, leptin started to increase and reached baseline values at 9 h post si. In control subjects, the TSH and leptin profiles seemed parallel each other.

CONCLUSIONS

During acute surgical stress, the secretion of TSH and leptin in severely obese men is asynchronous and causality could not be proven.

Acute adrenal insufficiency after a single dose of etomidate

Acute adrenocortical insufficiency is a critical care emergency characterized by hemodynamic instability, lethargy, and cardiovascular collapse. Acute adrenal insufficiency has many etiologies, from rapid withdrawal of exogenous glucocorticoids to adrenocortical destruction to poor adrenal reserve after administration of steroid synthesis inhibitors. Etomidate, a parenteral hypnotic agent, is a steroid synthesis inhibitor. Although the use of continuous etomidate infusion in the intensive care unit fell from favor secondary to reports of adrenal crisis, single-dose etomidate for induction of anesthesia is common for the hemodynamically unstable patient or in patients who may not tolerate wide variance in heart rate or blood pressure. A case is presented of acute adrenocortical insufficiency and crisis after a standard induction dose of etomidate. Acute adrenal insufficiency should be suspected in intensive care unit patients who have undergone general anesthesia with etomidate induction and present with hypotension refractory to standard vasopressor administration.

Similar effects of general and spinal anaesthesia on perioperative stress response in patients undergoing haemorrhoidectomy

Surgery induces release of neuroendocrine hormones (cortisol), cytokines (interleukin-6: IL-6, tumour necrosis factor-α: TNF-α), acute phase proteins (C-reactive protein: CRP, leptin). We studied the effects of general and spinal anaesthesia on stress response to haemorrhoidectomy. Patients were assigned to general and spinal anaesthesia groups (n = 7). Blood samples were drawn before induction and 24 hours after surgery. Perioperative levels of IL-6, TNF-α, CRP, cortisol, and leptin were comparable among the groups. Twenty four hours after surgery, TNF-α and cortisol did not change; IL-6 and CRP increased significantly in all patients. Significant increase in leptin levels was found in patients undergoing spinal anaesthesia. Except for the increase in leptin levels, there was no significant difference related to the effects of general and spinal anaesthesia.

Should we use etomidate as an induction agent for endotracheal intubation in patients with septic shock?: a critical appraisal

Etomidate is commonly used for the facilitation of endotracheal intubation. While etomidate possesses multiple qualities that are beneficial in hemodynamically unstable patients who require a sedative or amnestic, its potential to negatively impact corticosteroid production is well-documented. Given the frequency of relative adrenal insufficiency observed in the critically ill and the increasing use of corticosteroids in patients with septic shock, an appraisal of the status of etomidate as an induction agent in patients with evolving or established septic shock is indicated. A review of the relevant literature suggests that its use in this setting may be harmful. It is proposed that, pending the performance of a randomized, controlled clinical trial, considerable caution should accompany its administration in patients with evolving or established septic shock. The potential role for concomitant empiric steroid replacement and the comparability of alternative induction regimens are also discussed.

Lipid kinetics in obese patients undergoing laparoscopy. the impact of cortisol inhibition by etomidate

The aim of this study was to investigate the response of cortisol, insulin and lipid parameters [serum Lipoprotein Lipase activity, choleseryl-ester transfer protein, triglycerides, total Cholesterol, High Density Lipoprotein, Free Fatty Acids] during the perioperative period in obese patients undergoing laparoscopic cholecystectomy. Twenty obese patients were included and divided in two groups. In group A (n=10) patients were anaesthetized with propofol and group B (n=10) with etomidate. Blood samples were collected before induction in anaesthesia, just after the end of the operation and at one, two and three hours postoperatively. According to our results, in both groups serum LPL activity showed a significant decrease whereas serum Free Fatty Acids a potent increase over time. Likewise, both groups did not demonstrate significant changes over time in choleseryl-ester transfer protein activity, total cholesterol, triglycerides, High Density Lipoprotein or insulin concentrations in serum. Furthermore, cortisol release was significantly inhibited in the etomidate group while substantially enhanced in propofol group. Additionally, apart of triglycerides, no difference was found between the two groups in all the lipid parameters and insulin concentrations. In conclusion, serum Free Fatty Acids levels and Lipoprotein Lipase activity demonstrated significant alterations in obese patients underwent laparoscopic cholecystectomy and this result did not seem to be related with the anaesthetic agent used for induction in anaesthesia.