Evaluate whether discrete landmarks of the proximal humerus can be identified using ultrasound in patients with various body habitus and BMI.

There are three main forms of vascular access: peripheral intravenous (PIV), Central venous (CV) and intraosseous (IO). Of the different types of vascular access PIV and CV access have drawbacks when used during resuscitation, because they can be difficult to obtain when patients are volume depleted as in cases of trauma. Attempting CV access has numerous risks with complications occurring in up to 33% of attempts. These include failed placement (22%), arterial puncture (5%), catheter malposition (4%), pneumothorax (1%) and asystolic cardiac arrest (<1%). Attempting to obtain CV access may also disrupt chest compressions in cases of cardiac arrest. Intraosseous access has been used in scenarios where PIV and CV access is difficult or impossible to obtain. Pharmacokinetic studies and standard practice support the bioequivalence of intraosseous and intravenous administration of common medications. Intravascular depletion does not hinder attempts at IO access, and as the insertion sites are peripheral to the heart, insertion can be done avoiding interruptions in chest compressions. Obtaining proximal humerus interosseous (PHIO) access may also be faster than obtaining both PIV and CV access with a relatively low complication rate. In one survey, complications of IO included difficulty in identifying correct anatomical site (3%), extravasation (3.7%), displacement after insertion (8.5%), and very rarely late complications including compartment syndrome (0.6%), osteomyelitis (0.4%) and skin infection (0.3%).

Inclusion Criteria:

• Males or females 18 years of age or older undergoing general, cardiac, thoracic or vascular surgery.
• BMI >= 18.5 kg/m^2

Exclusion Criteria:

• Limited mobility/ range of motion of arms
• Prior surgical intervention on shoulder or humerus
• History of arm dislocation with internal rotation
• History of arm fracture
• BMI in ranges: 25.1 - 29.9, 35.1 - 39.9

Participants will be selected after chart review of current patients undergoing general, cardiac, thoracic, or vascular surgery. Patients will be approached in the preoperative clinic or during their hospitalization (preoperatively or postoperatively). Informed consent will be obtained prior to performing the study.

Participants will be separated into 3 cohorts based on BMI. The number of participants in each cohort is as follows: 10 patients with BMI 18.5 - 25 kg/m2; 10 patients with BMI 30-35 kg/m2, 10 patients with BMI > 40 kg/m2.