Ventilation and difficulties related to obesity

Obesity is considered a global epidemic. It’s continuous increase in prevalence places the anesthestist in conflict with consequences of this condition. The most prominent alteration in the respiratory system is the reduction of the residual functional capacity, which occurs mainly due to the reduction of the chest and lung complacence. This impacts on the mechanic respiratory and on gas exchange. There are several strategies to minimize this impact on general anesthesia. Proclive position increases the apnea time during induction. One should avoid to the maximum the Trendelenburg and lithotomy positions, since they worsen the respiratory function. Maximum caution should be taken in airway management due to the increased risk of difficulties of ventilation and intubation in the obese. Before intubation, the patient should be positioned properly. Another strategy is the use of CPAP during the pre-oxigenation phase and the application of alveolar recruitment maneuver in intraoperative period, followed by PEEP, which increases the PaO2/FiO2 ratio and the system respiratory complacence, without any significant change in hemodynamic. There is no proved substantial difference among ventilatory modes, pressure-control or volume-control. Protective pulmonar ventilation (Volume tidal < 8 mL/Kg of predicted body weight with alveolar recruitment followed by PEEP > 5 cm H20) has been indicated. Before extubation, it should be done: raise the back of the surgery table to 30° or place the table at reverse Trendelenburg; reduce FiO2 by 40%, if Ventilation and difficulties related to obesity Raphael Grossi Rocha1, Carlos Leonardo Alves Boni2, Walkiria Wingester Vilas Boas3 Ventilação e dificuldades relacionadas à obesidade DOI: 10.5935/2238-3182.20140122