Fractured Neck of Femur in an Elderly Patient

An 83-yr-old woman (70kg and 5′5″ tall) is admitted to the emergency room after a fall in her nursing home. She has fractured the neck of her femur, but otherwise there is no trauma. In addition, she has many medical problems, including coronary artery disease, hypertension, and chronic obstructive lung disease. On examination, she was cooperative and orientated for time and place. She has mild to moderate bilateral ankle and sacral edema. HR 100 atrial fibrillation, blood pressure (BP) 170/100. The electrocardiogram (ECG) shows old MI change with left-axis deviation. Room oxygen saturation is 91%. Her chest is clear, except for crepitations at the bases and increased respiratory wheeze. Because she is orientated for time and place, she requests a spinal anesthetic, as she is worried about going to sleep. You are happy to oblige and explain that she must either sit up or lie on her side for you to do the spinal. She absolutely refuses and claims this will be very painful. She has received morphine 10mg in the emergency room. You attempt to sit her up, but she complains of severe pain. You give her midazolam 0.5 mg and fentanyl 50mg, slowly. A little later she claims to feel better. However, her oxygen saturation has now fallen to 87% on room air. You give her supplemental oxygen and her saturation improves to 93%. You attempt to sit her up again, but she complains bitterly. You could use a small dose of ketamine so that you can place the spine in a lateral position, but you are concerned about a potentially unacceptable increase in BP with ketamine and the need to use atropine with its side effects. What else could you do to make her pain free, so that you can perform the spinal block?