Airway management in an obese patient
Airway management (VA) It is one of the fundamental elements in patient care. It requires continuous training, maneuvering and the use of devices that allow adequate and safe ventilation.
Knowledge of the airway includes anatomy, causes of structural abnormalities and ways of permeating it. Nowadays, Difficulties during this procedure persist as causes of morbidity and mortality. associated with anesthesia.
Obesity and overweight consist of an accumulation of excessive fat in the body that can be harmful to health. They are risk factors for numerous chronic diseases, like diabetes, cardiovascular disease and cancer.
The diagnosis of difficult airways is often underestimated in people with obesity. The study of the abnormal airway is divided into two groups: congenital and acquired. The latter cites morbid obesity.
The accumulation of fat in the morbidly obese patient can cause difficulties in laryngoscopy and intubation. It is because of that it is necessary to evaluate excessive fatty tissue, both internal (mouth, pharynx, abdomen) and external (breasts, neck, chest wall and abdomen).
Next, reference is made to a series of characteristics present in morbidly obese people to take into account in the management of the airway. The key is to anticipate the difficulty and execute an action plan.
Anatomy of obese patients
In an obese patient both fat distribution and weight itself influence. In the case of airway management in these patients Fat distribution is more important than patient weight.
It was demonstrated, by means of nuclear magnetic resonance in morbidly obese patients with and without Obstructive Sleep Apnea Syndrome (OSAS), that SOS patients have a greater amount of fatty tissue in the areas surrounding the collapsible segments of the pharynx.
Thanks to these results, it was possible to explain why Airway management in some patients is easy and in others it is not. The occipital arrangement of fat can decrease neck extension, making laryngoscopy difficult.
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Physiology of obese patients
Different studies have been carried out that show that obese patients have increased muscle tone. By decreasing the tone during anesthesia, the airway can be obstructed, making it difficult to ventilate with a face mask.
In addition, obese people have decreased functional reserve capacity and total lung capacity. Due, oxygen consumption is increased; Therefore, they are predisposed to desaturation after induction of anesthesia.
Pharmacology in airway management
One of the keys to safety during airway management of obese patients is achieve an adequate level of anesthetic depth prior to mask ventilation.
Attempted ventilation of a patient with superficial anesthesia can lead to false diagnoses of ventilation failure.
Read also: Bullard laryngoscope intubation
Most of the drugs used in induction are fat soluble. For this reason, the initial distribution in the effect compartment may be low.
In the case of obese patients, the use of adapted doses is recommended instead of those established for those that have an ideal weight.
Difficult Airway or VAD
Today, the percentage of obese patients with VAD (Difficult Airway) is 15.8% compared to 5.8% of the normal population.
A BMI (Body Mass Index) greater than 30 and the SAOS they are factors that induce a difficult handling of the airways. However, it is not shown to hinder intubation.
There are other studies that use more specific markers, such as the Difficult Intubation Scale. These studies support that obese patients have more VAD.
Aspiration and preoperative fasting
Obese patients usually have longer gastric emptying time. However, they have not been seen to have a higher incidence of aspiration nor of reflux disease.
So, it is not recommended to give them additional measures of fasting or bronchial aspiration prophylaxis when they are going to undergo some technique of airway management.