Essay on Bariatric Anesthesia

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Abstract

In spite of the avalanche of medical publications on other medical and surgical developments and interventions, the chronic paucity of data on anesthetic considerations in bariatric surgery still persists. Largely reliant on retrospective data from past research publications for methodology design, the study involved a critical analysis of anesthetic considerations in bariatric surgery. The study established that among patients who had undergone restrictive bariatric surgery, weight loss was between 50% and 60% over a period of one year after operation in addition to considerable resolution of the comorbidities. With regard to positioning the study established that for a patient with morbid obesity, the direction for laryngoscopy an imaginary line originating from the sternal notch to the external auditory meatus aids in solving the problems associated with acute post operative airway pressure. In addition to presentations of induction, intubation and the maintenance of anesthesia, the paper also divulges into the use of anesthetics  Profol, Thiopental, Midazolam, Succinylcholine, Vecuronium, Rucoronium, Fentanyl , Sufentanyl, Remifentanil and Atracuranium and their pharmacokinetics.

Introduction

Obesity has been described as a global pandemic frustrating to both the afflicted and the medical practitioners. The National survey data shows an increase in prevalence of overweight and obese adults and children resulting from of  escalating body mass index(BMI) across the population(Woodward-Lopez et al 2006). According to the National Institutes of Health, the the extent of population affliction and the impacts of such widespread afflictions are predictable health implications  such as cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, joint diseases, dyslipidemia, social, economic and psychological impairment and a host of other debilitating conditions(Ogunnaike et al 2002). The risk of developing obesity and obesity related conditions are based on the classifications of the body mass index. BMI between 25–30 kg/m² is classified as low risk and BMI above 40 kg/m²

being classified as very high risk(Ogunnaike et al 2002).

The causes of obesity and overweight are as complex and complicated but are nonetheless accepted as interactions between the genetic and environmental predispositions to the disease. The genetic risks to obesity can not be used in explaining the dramatic rise in the incidence, prevalence and morbidities due to obesity and its associated complications since the population genetic makeup have not had any significant change over the last couple of decades. This leaves the environmental predispositions the likely cause of the current hikes in the fraction of the populace suffering from obesity and associated complications(Woodward-Lopez et al 2006). Studies on dietary determinants of bodily energy imbalance have clearly demonstrated that the current incidence and prevalence rates are a product of the changing consumption habits and lifestyle.

Owing to this understanding and synthesis of the accurate causative factors of obesity, individuals have been able to design strategies aimed at controlling the development of overweight phenomenon. In essence, these strategies have predominantly focussed on physical activity as an influential tool in restoring the bodies energy balance. Other interventions focus on cognitive and behavioral approaches and changes in lifestyle. While these non surgical options are recommendable and largely influential in reducing the negative impacts of obesity, they only achieve better results in the low risk category.

With the increasing progression of obesity from the low risk classification to high risk classifications, the diversity of non surgical procedures become obsolete and ineffective in ensuring a healthy weight loss regimen. As the paradigm shift occurs from the low risk to high risk, obesity attains the description of morbid obesity and surgical treatment becomes the only reliable treatment option despite its comparative ineffectiveness as a long term therapeutic intervention.

Indications of the necessity of bariatric surgery are derived from classifications of obesity. As outlined in the National Institutes of Health Consensus Development Conference Panel, an absolute BMI index that is more than 40 kg/m² or BMI of 35 kg/m² accompanied by cardiopulmonary problems and or diabetes melitus requires surgical treatment(NHI 1991). Additionally, patients opting for surgical weight loss should be in possession of failures of other medically supervised weight loss such as diet modification, medical therapy, exercise and non improvements in the severity of comorbid conditions.

Bariatric surgery can either be restrictive hence limiting the quantity of food ingested or malabsorbtive hence limiting the quantity of nutrients absorbed. In current surgical practice, malabsorbtive procedures include the biliopancreatic bypass and the jejuno-ileal bypass. These procedures becoming more rare as the restrictive procedures gain popular acceptance. These restrictive procedures are; the vertical banded gastroplasty and gastric banding. Gastric banding procedures are classified as either adjustable gastric banding or Roux-en-Y gastric bypass. All these three restrictive procedures are performed laparoscopically. However, in the weight category of < 60kg(class included in the study), the Roux-en-Y gastric bypass(RYGB) is the most common routine procedure in most hospitals.

However, surgical interventions are not without risks. Coupled to the medical risks of obesity and other associated complications, anesthesiologists have to identify these comorbidities and their respective influences on the preoperative and post operative outcomes(Samuels 2005). Dosing levels and choice of anesthetic drugs are critical in determining the safety of perianesthetic course. These drugs should be administered based on ideal body weights rather than the actual body weights of the patients. Given the fact that morbidly obese patients mostly present with obstructive sleep apnea hence making the necessity of continuous positive airway pressure necessary post operative anesthetic management requires clearly defined effective considerations in bariatric anesthesia. This can not be more true for patients who have been taken through laparoscopic gastric bypass.

Statement of the Problem

Due to the increasing need of definitive therapeutic intervention of morbid obesity over the course of the past four decades, novel procedures of weight loss and obesity management have been redefined and refined. The current bariatric procedures improve weight loss through a complex combination of malabsorption and food restriction. As a result of the efficiency of the Roux-en-Y gastric bypass and consequently its gold standard status, considerable successes in long term weight loss status and the resolution of the co-existing morbid pathological states have been achieved.

This evolution will most likely transcend to the next decade as novel technological and medical advances continue to shape the therapeutic scope. As a result of the complexity of the current surgical practices and the futuristic sophistication of bariatric surgery, the anesthesiologist will continually find himself at the care of a bariatric patient. In addition to this, the complexity of bariatric surgery and the uniqueness of morbid obesity management call onto all anesthesiologists to familiarize themselves with such a unique sub specialty and be able to guarantee optimal anesthetic care delivery. At the basic scale, such a care calls on adequate preparation, diligence, and vigilance. On the other hand, the intricacies of surgery and the dramatic changes in surgical operations yield fresh challenges that can only be adequately met with an in depth analysis of bariatric surgery and bariatric anesthesia and thereof the considerations involved and health care outcomes.

Objectives of the Study

General Objectives

1. To offer an in depth understanding on the efficiency of bariatric surgery on long term weight loss reduction and the resolution of associated comorbid diseases.
2. To divulge into the anesthetic therapeutics used during laparoscopic Roux-en-Y gastric bypass.
3. To present an analysis on proper positioning, induction, intubation and consequently the maintenance of the anesthesia with respect to post operative health outcomes

Main Objective

To provide the key anesthetic considerations for bariatric surgery

Hypothesis

In the presence and practice of effective key considerations in bariatric anesthesia, bariatric surgery yields positive health outcomes for patients with morbid obesity.

Methodology

Based on the surgical approaches of bariatric surgery such as the malabsorbtive and restrictive approach, the study has preliminarily synthesized the available data and eliminated the malabsorptive approaches that include the biliopancreatic bypass and jejuno-ileal bypass as a function of their rarity in current surgical procedures. The restrictive approaches included in the study include vertical banded gastroplasty(VGB) and gastric banding which is alternatively inclusive of adjustable gastric banding(AGB). The gold standard procedure in bariatric operations; the RYGB(Roux-en-Y gastric bypass) was more critically evaluated owing to its predominance in our institution. RYGB is a routine bariatric procedure for patients selected in the study(< 160 kg).

The decrease in body weight was measured over a span of one year in the postoperative period. The variables encompassed in the measurement of the outcome of bariatric surgery included, the duration of hospital stay, estimated blood loss, the proportion in need of intensive care, operative time, lengths of the surgical incision, complications within the first postoperative month and the weight loss measurements over the study period. Based on these measurements and the complications after the operation the research would evaluate the effectiveness of laparascopic Roux-en-Y gastric bypass.

Additionally, the study evaluated the effectiveness, mode of reactions and the effects of medical approved therapeutics for obesity. With regard to the aesthetic considerations for bariatric surgery the study enlisted key issues in preoperative evaluations on the obese patient, particularly the status of the cardiorespiratory system and the airway. Even though these analyses are critical in the decision of whether a patient should be taken through bariatric surgery, they are also very critical in anesthetic considerations even as concurrent and preoperative medications ensue prior to the surgery.

With regard to intraoperative considerations, the study also enlisted different positioning methods that are deemed to be more safe for anesthesia.

Since the effectiveness of positioning has profound effect on laparascopy and anesthesia, novel positions were divulged upon and the Trendelenburg position avoided because it worsens the systemic changes of pneumoperitoneum. These analyses were followed with monitoring of inversive arteries, followed by induction, intubation and consequently the maintenance of the anesthesia. The anesthetics used in the study(Profol, Thiopental, Midazolam, Succinylcholine, Vecuronium, Rucoronium, Fentanyl , Sufentanyl, Remifentanil and Atracuranium) were all analyzed on the basis of their effective dosing, pharmacokinetics and possible operative and post operative complications.

To help surgeons size the gastric pouch during postoperative surgery, the study carried out an observatory analysis of the roles of anesthesiologists in ensuring that there is proper placement of a nasogastric tube and an intragastric baloon. Their roles were also analyzed with specificity to the maintenance of anatomoticanastomotic

The use of bariatric surgery in the treatment of patients with morbid obesity is relatively safe and efficient in long term weight loss and the reduction of comorbities. This option is even more preferable that non surgical options because it entirely enlists patients who have been taken through non surgical obesity interventions and failed to generate any positive treatment outcome. However, in carrying out bariatric surgery, key anesthetic considerations need to be taken into account so as to optimize outcomes in the postoperative period. With reference to long term weight loss achieved from  laparascopic Roux-en-Y gastric bypass(50%-60% between the first and the second postoperative year), the benefits are thus more pronounced in comparison to the marginal successes of medical therapy which could only achieve a 5% to 10% weight loss over the same period.

These conclusions not only predict the futuristic preeminence of bariatric surgery in anesthetic morbid obesity treatment and management but also open the way for more research on better technological and therapeutic alternatives aimed at the improvement of overall health outcomes of patients who have undergone operative treatment options.

The use of laparascopic bariatric surgery was found to significantly reduce postoperative pulmonary dysfunction even though these patients still needed to be under overnight intensive care monitoring due to the possible threat of prolonged obstructive apnea especially in cases where parenteral narcotics had been used. In post operative analgesia it was established that epidural local narcotics and or anesthetics administered via the thoracic route were comparatively safe and effective.