The study aims to explore if Maximum Inspiratory Pressure can predict postoperative breathlessness in obese patients receiving interscalene blocks for shoulder surgery.

The main question is: does baseline Maximum Inspiratory Pressure have any association with postoperative breathlessness after interscalene blocks in class 2 or higher obese patients (BMI>35).

Preoperative and postoperative lung volumes, pressures, breathlessness score and respiratory outcomes will be measured on participants already receiving shoulder surgery with interscalene blocks.

Inclusion Criteria Groups 1 and 2

• Adults >18 years of age receiving shoulder surgery with preoperative interscalene block and general anesthesia;
• Speak English;

Group 3

· Adults >18 years of age receiving cystoscopy or lower extremity procedures receiving general endotracheal anesthesia

Exclusion Criteria All Groups

• Less than 18 years of age;
• currently pregnant;
• currently incarcerated;
• those with significant neuromuscular disease, tracheo-bronchial structural abnormalities, severe respiratory or severe cardiovascular comorbidity;
• those undergoing intra-abdominal or intrathoracic surgeries due to the potential to independently effect breathing

Adult patients presenting for shoulder surgery with preoperative interscalene block (Groups 1 and 2). Group 3 includes adult patients presenting for non thoracic, non abdominal surgery under general anesthesia.