Anaesthesia and BMI Recovery Complications in Patients with higher BMI
Origins ofAnaesthesia an ~ withoutaesthesis ~ sensation
Origins of Anaesthesia First AnaesthesiaOpium poppy capsules (herbal remedy) 4200 BC Sumerian Empire
General AnaesthesiaThe Common Forms of General Anaesthesia • Analgesia • Hypnosis • Amnesia • Relaxation
Modern AnaesthesiaMorpheusThe Greek God of dreams Morphine (Purified Alkaloid) Potent opiate analgesic drug. Also a natural endocrine product found in humans and other animals. Morphine acts on the central nervous system (CNS) to relieve pain,The efficacy of opioids have indicated that, in the management of severe pain, no other narcotic analgesic, other than Fentanyl (which has a higher potency, but is shorter acting), is more effective or superior to morphine.
Analgesic Agents Non Opioid• Barbiturates Thiopental• Benzodiazpines Midazolam Larazepam Diazepam• Propofol The most common IV drug to induce and maintain analgesia
Analgesic Agents Non-Opioid Based Midazolam LorazepamUsed to induce general anaesthesia but NOT pain relieving!!
Analgesic Agents Opioid Based Fentanyl RemifentanilUsed for the relief of pain in anaesthesia
Obesity Defined• A condition in which the natural energy reserve, stored in the fatty (adipose) tissue of humans, exceeds healthy limits.• Definition:- Body Mass Index (weight divided by height squared) 30 kg/m2 upwards in Obesity
Obesity Risks• Obesity has been identified as a significant risk factor in anaesthesia• BMI is only a guideline: Does not account for wide variations in body fat distribution and may not correspond to same degree of fatness in different people• Any extra fat deposited in the body demands its share of cardiac output. Every 100g of fat deposited increases cardiac output by 50 ml per minute (or roughly quarter of a cup of water)
Airway Problems in RecoveryNormal Airway – Low BMI Restricted Airway – High BMI
Airway Problems in Recovery Adipose Tissue Problems • Anaesthetics are “Lipophilic” • Lipophilic means “absorption in fats” • Anaesthetics stored in adipose tissue!
Airway Problems in Recovery Adipose Tissue Problems • Anaesthetics released back into blood • Effect: Resedation! • Be prepared! (Know your A.B.C’s!!) •Perform head-tilt / jaw thrust • Nasal / Oral airways nearby
Airway Problems in Recovery Adipose Tissue Problems • Anaesthetics and Patient Posture reduce vital capacity and diaphragmatic excursion • Effect: Hypoventilation and atelectasis (partial lung collapse!) • Solution: Address pulmonary function!
Posture Problems in Recovery Attention to Posture Adopt: Semi recumbent Positioning Encourage: Coughing, deep breathing, early ambulation Nausea risk: Pulmonary aspiration of gastric contents because of increased abdominal pressure, reflux and increased gastric volume
The Unexpected Drug dynamics Obesity affects drug performance and effectiveness Excess Fats and Cholesterol block action of drugs Greater kidney mass increases renal elimination diminishing drug effectiveness
Conclusion• Beware of abnormal patient recovery• Anaesthesia affects people differently, especially higher BMI rated people• Anaesthesia is held in adipose tissues and can be released back into the blood stream, causing more sedation and slower recovery times.• Prepare for emergencies, especially cardio and pulmonary complications – Know your ABC’s!• Consider Posture in high BMI patients ~ Semi Recumbent Position if possible• Appreciate the physiology of high BMI patients and the effects on drug dynamics
Thank you for your attention ~ A teaching session ~ Mark G. Hopewell: Under Graduate Adult Student Nurse ~ Cohort Sept 05 Venue Kidderminster Intervention Suite June 2008