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16 - Remifentanil in morbidly obese patients
- from Section 5 - Pharmacology
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- By A.O. Alvarez, Medical Director, IMETCO (Instituto Multidisciplinario Especializado en el Tratamiento y Cirugía de la Obesidad), Buenos Aires, Argentina
- Edited by Adrian O. Alvarez
- Edited in association with Jay B. Brodsky, Stanford University School of Medicine, California, Martin A. Alpert, George S. M. Cowan
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- Book:
- Morbid Obesity
- Published online:
- 17 August 2009
- Print publication:
- 04 November 2004, pp 223-240
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Summary
Introduction
The use of opioids is almost essential in the anesthesiological practice nowadays. Many clinical benefits can be observed by the use of morphins, such as autonomic stability, blocking response to surgical stress, good to excellent hemodynamic conditions to improve myocardial oxygenation and capability to reduce the required doses of other agents (such as hypnotics) between others. Unfortunately, use of opioids in this particular population (principally in large doses or long lasting infusions) is limited and even dangerous due to pharmacokinetic and -dynamic alterations (see Chapter 15).
Latter distribution might result in variable adverse effects, such as delay in recovery, respiratory depression, muscle rigidity, cardiac dysfunction, nausea, vomiting and “resedation phenomenon”. This is related to the redistribution of lipophilic/sedative agents from the fatty tissue back into the bloodstream. The resedation phenomenon is compounded by the very high risk of obstructive sleep apnea (OSA) and upper airway resistance syndrome (UARS) seen in these patients.
Respiratory system function is significantly altered in the obese (see Chapter 4). It has been noted that a body mass index (BMI) of one standard deviation above the mean is associated with a 4-fold increased risk of obstructive sleep apnea syndrome (OSAS).
Prevalence of OSAS in general USA population is 2% in women and 4% in men, but increases up to 3–25% in women and 40–78% in men if they are morbidly obese.
1 - Introduction to peri-operative management: reasons for a multidisciplinary approach
- from Section 1 - General aspects
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- By A.O. Alvarez, Medical Director, IMETCO (Instituto Multidisciplinario Especializado en el Tratamiento y Cirugía de la Obesidad), Buenos Aires, Argentina, A. Baltasar, Chairman, Department of Surgery, Hospital Virgen de los Lirios, Alcoy, Spain; Past-President, International Federation for the Surgery of Obesity (IFSO)
- Edited by Adrian O. Alvarez
- Edited in association with Jay B. Brodsky, Stanford University School of Medicine, California, Martin A. Alpert, George S. M. Cowan
-
- Book:
- Morbid Obesity
- Published online:
- 17 August 2009
- Print publication:
- 04 November 2004, pp 3-12
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- Chapter
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Summary
Introduction
Morbid obesity has always been a challenge to the anesthesiologist and surgeon. In the past, it was frequent to avoid any surgical procedure due to the increased risk observed among these subjects. It was common to hear, “if you do not lose weight you cannot be operated …”.
But this situation have changed, mainly in the last two decades.
Morbid obesity is actually one of the most prominent medical problems in the world. Two aspects support this concept: quantitative and qualitative.
Quantitative
Obesity prevalence is increasing. It has been recently reported that the incidence of all classes of obesity, those with body mass indexes (BMI) of 30, 40, or 50 kg/m2 have shown a dramatic growth from 1986 to 2000. One in five patients has a BMI over 30, one in 50 over 40, and one in 400 has a BMI over 50.
Similar incidence and tendency have been observed in the rest of the world.
Qualitative
Morbid obesity is a life-threatening situation in the long term. BMI over 40 if not treated, significantly shortens the individual's life expectancy. Apart from the increased morbidity associated with obesity, the excess mortality is substantial. It is principally caused by death from coronary heart disease, stroke, and diabetes mellitus, although sudden unexplained death, malignancies, and fatal accidents are also more prevalent in the obese.
23 - Total intravenous anesthesia
- from Section 7 - Intra-operative management
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- By A.O. Alvarez, Medical Director, IMETCO (Instituto Multidisciplinario Especializado en el Tratamiento y Cirugía de la Obesidad), Buenos Aires, Argentina
- Edited by Adrian O. Alvarez
- Edited in association with Jay B. Brodsky, Stanford University School of Medicine, California, Martin A. Alpert, George S. M. Cowan
-
- Book:
- Morbid Obesity
- Published online:
- 17 August 2009
- Print publication:
- 04 November 2004, pp 305-324
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Summary
Introduction: anesthetic planning, selection of the anesthetic technique (Why total intravenous anesthesia for the morbidly obese?)
As in every surgical—anesthetic practice, anesthesia for the morbidly obese has to be based upon pathophysiological patient's condition. After knowing how morbidly obese body behaves (and according to this; considering the most frequent risks) anesthetic targets have to be defined. Finally in order to get the best approach to those targets, technique and tactic could be reasonably planned. So the logical line of thoughts should be chronologically developed as follows:
Pathophysiological considerations.
Frequent risks and complications.
Anesthetic targets.
Anesthetic planning.
Pathophysiological considerations and frequent risks have been already considered in other chapters (see Chapters 2, 4, 5 and 8). Anyway, it should be remembered that the most frequent and prominent risks are:
gastric aspiration;
difficult mask ventilation and tracheal intubation;
rapid development of hypoxemia after apnea;
pulmonary atelectasis;
hemodynamic instability;
reduced capability to face stress situations (increments of stress hormones could develop hyperglycemia, hypertension, cardiac failure, arrhythmias and myocardial ischemia);
delay in recovery;
post-operative respiratory dysfunction;
deep venous thrombosis.
Accordingly basic anesthetic targets should be:
smooth and quick induction;
rapid and secure airway control;
prominent hemodynamic stability;
high versatility to manage changing levels of surgical stimuli to avoid increments in catecholamine activity;
fast and successful recovery, and ambulating capacity.
30 - Anesthesia and morbid obesity: present and future
- from Section 9 - Conclusions
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- By A.O. Alvarez, Medical Director, IMETCO (Instituto Multidisciplinario Especializado en el Tratamiento y Cirugía de la Obesidad), Buenos Aires, Argentina
- Edited by Adrian O. Alvarez
- Edited in association with Jay B. Brodsky, Stanford University School of Medicine, California, Martin A. Alpert, George S. M. Cowan
-
- Book:
- Morbid Obesity
- Published online:
- 17 August 2009
- Print publication:
- 04 November 2004, pp 399-406
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- Chapter
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Summary
Obesity a growing medical problem
Conclusions regarding the disease: morbid obesity
Obesity is a major healthcare problem, and the prevalence is increasing. Recently it has been informed that its prevalence has grown dramatically from 1996 to 2000, and is expected that it will rise to 40% by 2025. Actually 20% of patients have a body mass index (BMI) over 30, 2% over 40 and 0.25% over 50. Morbid obesity is a life-threatening situation in the long term and BMI over 40 if not treated, significantly shortens the individual's life expectancy.
The World Health Report for 2002 estimated that there were more than 2.5 million annual deaths due to weight-related problems, with 220,000 of those deaths in Europe and more than 300,000 obesity-related deaths in the US.
Deaths between the obese population are principally caused by coronary heart disease, stroke and diabetes mellitus, although sudden unexplained death, malignancies and fatal accidents are also more prevalent when compared with lean people. It has been shown that there is a 12-fold excess mortality in men in the age group 25–34 years and a 6-fold in those aged 35–44 years. In addition, the prevalence and severity of co-existing diseases has shown a clear correlation with the duration of obesity, therefore, it is advisable to provide a successful weight reduction treatment as early in the patient's life as possible.