December Case of The Month
Topic: Total Muscle Rigidity, an Important Sign of MH
8 year old female with a previous surgical history of strabismus correction presented to the operating room for a supracondylar fracture repair. The mother informed the anesthesia provider that following her last surgery, the patient took more than 16 hours to “wake up from the anesthesia” without any explanation. The patient had something to eat 4 hours before surgery and presented to the OR without IV access. Following inhalation induction with nitrous, O2 and sevoflurane, the patient developed general rigidity and pulse oximeter indicated desaturation (70-80%). Unable to mask ventilate the lungs and without IV access, the anesthesia provider administered succinylcholine (2 mg/kg) intramuscularly. However the muscle rigidity worsened and hypoventilation became an issue as the pulse oximeter disappeared and the patient’s mucosal tissues became blue. While the surgical nurse and surgeon were trying to obtain intravenous (IV) or intraosseous (IO) access, the anesthesia provider attempted a difficult, but successful on second attempt, endotracheal intubation. Breaths sounds were weak bilaterally and peak airway pressure (40 mmH2O) were required to ventilate the patient’s lungs. Bradycardia did not develop and the pulse oximeter reading appeared again and rose slowly and gradually to upper 80s % despite ventilating the lungs with 100% FIO2. Meanwhile, IO access was obtained and bilateral chest wheeze were auscultated. Endotracheal suctioning was performed and “small” amounts of food residual were noted. Mechanical ventilation continued with high peak airway pressure that improved following discontinuing the sevoflurane. Albuterol was administered endotracheally that improved the lungs’ wheeze. Diagnosing “status asthmaticus” another anesthesia provider suggested deepening the anesthetic by re-administering sevoflurane in high concentrations (5%). However and within a minute of re-administering sevoflurane, the patient’s chest rigidity worsened and desaturation continued. ABG obtained at that time were as follows: PH: 7.15, PCO2: 40 mmHg, PO2: 56 mmHg. Chest X-ray obtained and demonstrated some haziness but was “acceptable”. Temperature remained within normal limits.
As the anesthesia location did not have a pediatric ICU, arrangements for transfer to a Children’s Hospital were made. While waiting on the transport team, a decision was made to place a pin in the fracture under sevoflurane anesthesia. Towards the end of the procedure, chest rigidity was noted again and desaturation developed. Sevoflurane was discontinued and another chest x-ray was obtained. Bilateral haziness in the lung’s fields was noted. Furosemide (0.5 mg/kg) was administered and a Foley catheter was inserted. The urine appeared foggy and unclear with rusty iron color.
1) What is your diagnosis?
A- Definitely MH
B- Probably MH
C- Aspiration
D- B&C
2) What action should be taken now?
A- Administer dantrolene 2.5 mg/kg i.v.
B- Actively cool the patient
C- Extubate the trachea
D- Administer antibiotics for aspiration pneumonia
3) the most sensitive and useful monitor for the early diagnosis of a hypermetabolic event is:
A- EKG
B- Temperature monitor
C- ETCO2
D- Pulse oximeter
E- Blood pressure monitor
4) When faced with a master spasm, the anesthesia provider should do all the following except?
A- Ventilate with a face mask
B- Tracheal intubation
C- Discontinue all triggering agents
D- Monitor the patient in the recovery room for 4 hours at least
E- Check for myoglobinuria in 6-12 hours
5) Should this child be referred for MH biopsy testing?
A- No
B- Yes
C- Get more information from the family
6) Caffeine halothane contracture testing is indicated in all the following except?
A- Clinical history suspicions for malignant hyperthermia
B- A first-degree relative of a patient with documented MH
C- Unexplained muscular rigidity with MH suspicion
D- Sudden cardiac arrest on induction of anesthesia
Narrative:
The symptoms of muscle rigidity and desaturation that worsened with sevoflurane and succinylcholine in a patient with previous history of post anesthetic complication following a strabismus correction surgery are more likely of MH. Aspiration pneumonia can not be ruled out especially that the anesthesia provider aspirated food particles from the ETT in a child who fasted for 4 hours only. As most of MH episodes, this patient presented with one of the MH classical findings, muscle rigidity. Administering succinylcholine worsened the rigidity which was a red flag at that time. If a patient received succinylcholine and his/her jaw can not be opened or the patient has peripheral muscle rigidity, the clinician should assume this is an MH event and immediately begin MH treatment. Masseter (jaw) muscle rigidity (MMR) may occur after the administration of succinylcholine, particularly in children. MMR presages MH in approximately 15% of cases. When a patient develops MMR, triggering agents should be discontinued and ventilation should be established with a face mask as direct tracheal intubation is impossible due to a closed mouth. Currently, the in vitro contracture test (IVCT) is the gold standard for diagnosing MH. However, the IVCT is very expensive, requires a surgical procedure that can only be performed on-site in one of approximately 10 specialized testing centers in the
Answers
1. D
2. A
3. C
4. B
5. B
6. D
Mohanad Shukry, MD
Children's Hospital of Oklahoma
Oklahoma City, OK
