Based on medical record review and interview, the Emergency Department physician did not ensure: 1) timely diagnosis and treatment of a patient who presented with a head injury; 2) timely treatment of a patient with critical value of potassium. These findings were noted in 2 (two) of 15 patients' medical records reviewed (Patient #2 and 3). The delay diagnosis and treatment of patients may have placed them at risk for harm. Findings include: 1. Review of Laboratory Panic reports on 5/5/16 for Patient #2 noted Critical value for Potassium 2.6 milliequivalents per liter (mEq/L) (Panic range for Potassium is less than or equal to 2.7 mEq/L and equal to or higher than 6.1 mEq/L) was verified by Laboratory Technologists (LT) on 5/4/16 at 5:33 PM. The LT documented the following in the Laboratory Information System on 5/4/16 at 5:33 PM: "Called no answer". Review of medical record for Patient #2 noted a [AGE]-year-old male with a history of [DIAGNOSES REDACTED], status post resection, and diverting colostomy. The Critical value for Potassium 2.6 mEq/L was acknowledged by a physician in a note on 5/4/15 at 9:20 PM; almost five (5) hours after the result was verified in the laboratory. There was no documentation of Potassium replacement therapy until on 5/5/16 at 4:49 AM. This was six (6) hours after the critical value for potassium was acknowledged and approximately eleven hours after the release of the critical value report. Review of medical record for Patient #3 noted 6-months-old male who was brought to the Emergency Department (ED) on 5/14/16 at 11:27 AM by his father with a chief complaint of status post fall with head injury. The triage assessment of the patient on 5/14/16 at 11:29 AM, noted the following: Infant alert, active, and playful. There are no neurological and respiratory systems deficits and stable vital signs. Physician order for CAT scan of the head on 5/14/16 at 1:03 PM was not completed until almost four hours later at 4:52 PM. The CAT scan report revealed "deformity of the right parietal skull. No fracture lines are demonstrated, no overlying soft tissues swelling. The lack of overlying soft tissue swelling suggests subacute or chronic skull fracture an acute fracture. No intracranial hemorrhage". The patient was transferred to another facility on 5/14/16 at 7:46 PM for pediatric neurological surgical consultation. At interview with Staff G, Attending Pediatric physician on 6/8/16 at 9:30 AM, she stated the following: the patient was evaluated within one hour of arrival, and she determined a CT scan was needed to rule out fracture. The plan was to attempt CAT scan of the head without sedation due to patient ' s neurological stability. During interview with Staff D, Chief Medical Officer on 6/8/16 at 9:45 AM, he concurred that the CAT scan could have been done sooner.