“Time to scrub in,” says Dr. Hodges. The appendectomy you are about to observe is your

second surgical case in surgical technician school. The patient, David Sims, is an 18-

year-old male who was healthy until two days ago when he began having severe

abdominal pain, fever, and vomiting resulting in a diagnosis of appendicitis. David is in

excellent health and has never had surgery before, so you anticipate the procedure to go

smoothly.

Your instructor asked the anesthesiologist, Dr. Hodges, if you can observe her today

during the procedure. “All of the patient’s vital signs and lab work are within normal

limits so we are good to go,” says Dr. Hodges as David is brought into the operating

room. You help get David ready by applying the heart monitor, oxygen saturation

monitor, and blood pressure cuff. After David has been sedated, Dr. Hodges places a

special tube down his esophagus to measure his core body temperature and another in his

trachea (an endotracheal tube) to help him breathe during the procedure. While Dr.

Hodges places the endotracheal tube, she comments, “His jaw muscles are a bit tight so it

is very important to check and record his vital signs every 10 minutes. That is your job

today while I monitor his respiratory status.”

The case has been in progress for about 20 minutes when you notice David’s heart rate

jump up to 120bpm, setting off the ECG alarm on the monitor. You are concerned and

ask, “Can he feel what is happening? His heart rate just went up.” Dr. Hodges looks at

you and asks, “What is his core temperature?” You show her the chart and see that

David’s temperature has gradually begun to rise and is now 101.8° F (38.8° C). Dr.

Hodges’ face turns serious and she says, “His exhaled carbon dioxide levels have also

begun to rise. We need to get the malignant hyperthermia cart right away!”

David is now two days post-operative and is recovering in the Surgical Intensive Care

Unit. You recall all of the activity that occurred to save his life by treating his malignant

hyperthermia. You researched this condition and discovered that it is an inherited disease.

While under general anesthesia, the affected person will experience a rapid rise in body

temperature and severe muscle contractions. Dr. Hodges drops by to see David and says

to you, “I was impressed how you handled yourself during a very stressful situation.

Good job.”

Short Answer Questions:

1. David’s body temperature rises above normal during the surgery (hyperthermia).

How does skeletal muscle tissue contribute to body temperature?

2. During malignant hyperthermia, there is an increased amount of calcium released

into the sarcoplasm of skeletal muscle cells.

a. What organelle stores calcium in muscles cells?

b. Describe the events that must occur in the muscle cell before calcium is

released from this organelle.

3. Jaw muscle contraction (masseter spasm) is one of the key physical findings seen

in David’s case of malignant hyperthermia. Explain how calcium functions to

cause contraction of a skeletal muscle cell.

4. Dr. Hodges notes that David’s exhaled carbon dioxide levels are elevated. List all

the metabolic pathways that function to synthesize ATP for skeletal muscle

contraction. Which of these pathways produces carbon dioxide as a by-product?

5. Malignant hyperthermia causes a hypermetabolic state in skeletal muscle, which

is triggered by high demands for ATP during uncontrolled muscle contractions.

a. What is the role of ATP in cross bridge cycling?

b. What is the role of ATP in generating a resting membrane potential?

c. What is the role of ATP in maintaining calcium concentration gradients?

6. Dantrolene is the only drug available to treat malignant hyperthermia. It works by

inhibiting calcium channels of the terminal cisterns of the sarcoplasmic reticulum.

Explain how this inhibition helps to terminate skeletal muscle contraction. What

effect would this have on David’s body temperature?

The post Dantrolene is the only drug available to treat malignant hyperthermia. It works by inhibiting calcium channels of the terminal cisterns of the sarcoplasmic reticulum. Explain how this inhibition helps to terminate skeletal muscle contraction. What effect would this have on David’s body temperature?Discuss appeared first on Essay Quoll.

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