Episode #62 Manifolds and Malignant Hyperthermia, Oh My!

Hello and welcome back to the Anesthesia Patient Safety Podcast.  My name is Alli Bechtel and I am your host. Thank you for joining us for another show. We have an exciting show for you today about Malignant Hyperthermia. It is an Articles Between the Issues article from August 2020. But before we get to that, we are going to talk about a patient safety threat related to IV manifold use in the operating room for medication administration.

Before we dive into today’s episode, we’d like to recognize Masimo, a major corporate supporter of APSF. Masimo has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Masimo – we wouldn’t be able to do all that we do without you!”

First up, we are talking about a rapid response article from the June 2018 APSF Newsletter. It is called, “Not All Manifolds are the Same: Lessons in Intravenous Drug Administration.” Thank you to Ravish Kapoor for submitting this rapid response and to Jan Hodges from Quest Medical for her response. To follow along with us, head over to APSF.org. Click on the Newsletter heading. 5^th one down is Newsletter archives. Scroll down and click on the June 2019 Newsletter. From here, scroll down until you see the Rapid Response section in the left hand column and click on our featured article. I will include a link in the show notes as well.

Kapoor writes in about an event that occurred while administering IV medications through a manifold in the Operating room. The event occurred while taking care of a patient in the OR who required additional port sites attached to a blood set. A Quest Medical six cannel manifold was positioned in line with a stopcock placed in the tubing between the patient and the manifold. Check out Figure one in the article to see the IV tubing set up with the manifold, followed by the downstream stopcock positioned closest to the patient. During the case, the patient required a transfusion of packed red blood cells. Due to significant hypotension, a 20ml syringe was attached to the stopcock to be able to aspirate the blood and then rapidly inject the blood back to the patient. While administering the blood through this pumping action, the patient’s blood pressure increased suddenly. A quick inspection revealed that a syringe of Phenylephrine with 2mls remaining in the syringe was attached to the manifold and these 2mls were now missing from the syringe. Thus, the patient received an unintended bolus of 200mcg of Phenylephrine leading to the temporary dramatic rise in blood pressure. The increased blood pressure was always within 20% of the patient’s baseline blood pressure and returned to normal within a few minutes.

Anesthesia professionals need to be aware that there is a risk for inadvertent administration of medications from syringes that are attached to a manifold from downstream aspiration, and this is more likely when the manifolds do not contain built in stopcocks. Figure 2 in the article depicts downstream aspiration of medications from the manifold using colored dyes in the syringes. Figure 3 then shows that this does not occur when the syringes are attached to a manifold with stopcocks in place that are turned OFF to the patient. Go check out these figures for a visual representation of how this event occurred. There is a risk for a medication error if anesthesia professionals do not remove syringes from manifold port sites especially when there are no stopcocks in place to prevent inadvertent downstream aspiration and administration. Stopcocks positioned in the OFF position can help to prevent this from occurring as well.

Jan Hodges with Quest Medical provided a reply to this rapid response. She writes that the check valves found within the multiport device are passive or a “floating disc” design which open or close depending on the pressure differential. This design prevents drugs and fluids that are injected through one port from entering a different port on the manifold. However, the design of the passive check valve on the manifold port will not prevent positive flow if negative pressure is generated downstream of the manifold as in the original case. Thus, the manifold performed as intended. Hodges writes that quest medical offers different manifolds that may be more suitable for this unique use.

Anesthesia professionals need to be familiar with different IV manifold set-ups and be aware when the supply changes in the OR. Stay vigilant when using manifolds for IV medication administration to help keep patients safe.

Let’s take a quick break to refresh your cup of coffee before we jump into our next article!

[Coffee Machine Sounds]

Plus, we will also do a plug for the Malignant Hyperthermia Association of the United States. Check out their website which I will link to into the show notes and you can call their 24 hour emergency MH Hotline if you have a suspected case of MH.

Now, we are ready to discuss an article about a hot topic in anesthesia patient safety, Malignant Hyperthermia. Let’s head back over to APSF.org and click on the Newsletter heading. Second one down is Articles Between Issues. Then go ahead and put August 2020 into the drop down menu at the top and then click on the featured article, “MH Survival Without Dantrolene” by Simmons and colleagues published online on August 25, 2020. The article kicks off with several well-known statements about Malignant hyperthermia: First, that intraoperative treatment usually involves IV Dantrolene and Second, that treatment with IV Dantrolene brings that mortality from over 80% down to less than 10%. But what happens to patient survival if malignant hyperthermia is encountered and Dantrolene is not available. We are going to hear about 3 cases from a hospital in China when patients survived MH without Dantrolene treatment.

Before we get to the cases of survival without Dantrolene therapy, the authors review MH and the recommended treatment. Remember, MH is a rare and life-threatening disorder of uncontrolled calcium release from the sarcoplasmic reticulum by way of the ryanodine receptor in response to a triggering agent. Triggering agents include inhaled general anesthetics, Desflurane, Enflurane, Ether, Halothane, Isoflurane, Sevoflurane, and Succinylcholine. The first step for treatment in patients with suspected MH is to immediately stop administering the trigger agent, start hyperventilation, and give Dantrolene as a bolus dose of 2.5mg/kg IV followed by 1 mg/kg every 4-6 hours with continued monitoring of clinical status. It is important to provide  treatment the patients resultant hypercarbia and acidosis quickly while also taking action to treat the resultant hyperthermia as well. Treatment for hyperthermia is necessary to avoid worse patient outcomes and may include skin cooling, ice packing, forced air cooling, circulating cool water blankets, cold IV fluid administration, ice-water immersion. Invasive temperature management strategies include instillation of iced saline into the bladder and peritoneal cavity as well as cardiopulmonary bypass or ECMO.

Have you ever had to treat MH when Dantrolene was not available? These 3 cases occurred in healthy teenage patients who underwent scoliosis surgery. Dantrolene was not available and not administered and all 3 patients survived. Induction of anesthesia for all of the patients included midazolam, propofol, fentanyl, vecuronium, and remifentanil. Maintenance of anesthesia included isoflurane for 2 patients and sevoflurane for 1 patient. The patients that received isoflurane presented with clinical signs of increased CO2 and tachycardia about 1 hour into the case and the patient who received sevoflurane developed these signs 3 hours after induction. Initial treatment included hyperventilation. Hyperthermia was seen later and at that point, there was concern for MH and the triggering agents were removed followed by active cooling with ice packs, cooling blankets, and alcohol sponge baths to multiple body locations including head, axillae, and groin, with chilled saline IV boluses. Treatment for the metabolic acidosis included administration of sodium bicarbonate as well as electrolyte maintenance. Volume resuscitation and vasopressor administration was needed in order to maintain hemodynamic stability with mechanical ventilation for respiratory support. One patient arrested and required CPR with return of spontaneous circulation. Diuretics were given to help remove tubular myoglobin for 2 patients and 1 patient required continuous renal replacement therapy. Remember, all 3 of these patients did not receive Dantrolene and the good news is that all 3 patients survived the event without sustaining major morbidity.

So, what steps need to be taken when there is a case of suspected MH? First, it is imperative to discontinue any triggering agents and call for help. Next, patients will need significant respiratory support including hyperventilation with 100% oxygen. Don’t forget to turn the flows up to the maximum fresh gas flows and aim to increase minute ventilation to about 2-3 times normal with a goal of attaining normal end-tidal CO2. Treatment of hyperthermia is needed with a goal of reducing body temperature back down to 38.5 degrees Celsius measured by a reliable core temperature. This is a crisis event in the OR. It is a good time to use any available emergency manuals with MH treatment guidelines or go to MHAUS.org and use their diagnostic and treatment protocols for reference.

For these 3 cases, review of the cases revealed that the inhalational agents were the most likely MH triggers. DNA analysis was not available for confirmation of MH susceptibility, but the Clinical Grading Scale for MH was used. 2 of the patients in this report were in category 6 which is consistent with almost certain MH and the 3^rd patient was in category 5 or the very likely group. This Clinical Grading Scale was first developed in 1994 by Larach and colleagues and published in Anesthesiology. I will include the reference in the show notes as well. There are 6 processes and several other indicators used for the clinical scoring. The 6 processes are rigidity, muscle breakdown, respiratory acidosis, temperature increase, and cardiac involvement. The first step for using the grading scale is to review the clinical indicators and add the appropriate points for indicators that are present. There is a double counting rule for this grading scale that states that if there is more than one indicator for a specific process, you should use the indicator with the highest score. The exception is the other indicator category so if there are any other relevant indicators from the other indicators category, these should be added to the final score and are not considered double counting. In addition, keep in mind that process VI should only be used to determine MH susceptibility and should not be used for scoring a potential MH event. The scoring system involves points between 3-15 points for the specific clinical signs. Then, you can determine the raw score range between 0 and over 50 to determine the MH rank between 1 and 6. The rank level has an associated likelihood of MH from MH rank of 0 or Almost never likelihood to and MH rank of 6 or an almost certain likelihood.

For all of these cases with the resultant good outcomes required active cooling, careful evaluation of volume status as well as acid-base and electrolyte balance. Keep in mind that this is a rare event. This hospital had these 3 cases out of the 7000 scoliosis surgeries that were performed over an 11-year time period. The additional good news for patient safety is that as a result of these cases, protocols were established that could be used for patients in the future with suspected MH in order to improve outcomes and decrease the risk of morbidity and mortality which is especially helpful when dantrolene is not available.

Before we wrap up for today, I want to highlight a recent article from BMC Anesthesiology published in April 2021 by Gong, called “Malignant Hyperthermia when dantrolene is not readily available.” I will include the reference in the show notes as well. This study provides additional information about cases of malignant hyperthermia that were not able to be treated with dantrolene. The 92 cases of malignant hyperthermia due to anesthesia come from databases in China from 1985 to 2020 with survival in 50 of the patients in this report. Mortality was increased between 1985 and 2010 with only 9 cases of mortality between 2011 and 2020. The author did not find significant differences in the cases of patients who survived compared with those who died. The analysis did reveal that the mortality cases had higher maximum end-tidal PCO2, higher maximum arterial PCO2, higher first abnormal temperature measurement as well as a higher maximum temperature measurement. These cases also had higher potassium levels with a worse metabolic acidosis. The author leaves us with a call to action that when dantrolene is not available to treat MH, then it is imperative to be vigilant for early signs, be able to establish a diagnosis, and provide effective alternative metabolic and physical treatments to improve patient outcomes and survival.

If you have any questions or comments from today’s show, please email us at [email protected].

Visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.  On the website, you can check out the current APSF Newsletter and don’t forget to subscribe to receive the APSF Newsletter by email! The next Newsletter will be here before you know it, so subscribe now! You can also check out the guide for authors and consider contributing to the APSF Newsletter in the future. We might be hearing from you as an author on this podcast with the latest in anesthesia patient safety!

Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

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