Journal of Medical Sciences

: 2020  |  Volume : 40  |  Issue : 5  |  Page : 248--250

Is analgesia nociception index monitor suitable for post-heart transplant patients under general anesthesia?

Shih-Yu Chen1, Zhi-Fu Wu2, Meng-Ta Yang3, Hou-Chuan Lai1, Nan-Kai Hung1,  
1 Department of Anesthesiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
2 Department of Anesthesiology, Chi Mei Medical Center, Tainan, Taiwan
3 Department of Anesthesiology, Tri-Service General Hospital, National Defense Medical Center, Taipei; Department, Division of Anesthesiology, Hualien Armed Forced General Hospital, Hualien, Taiwan

Correspondence Address:
Dr. Nan-Kai Hung
Department of Anesthesiology, Tri-Service General Hospital, National Defense Medical Center, #325, Section 2, Chenggung Road, Neihu, Taipei 114

How to cite this article:
Chen SY, Wu ZF, Yang MT, Lai HC, Hung NK. Is analgesia nociception index monitor suitable for post-heart transplant patients under general anesthesia?.J Med Sci 2020;40:248-250

How to cite this URL:
Chen SY, Wu ZF, Yang MT, Lai HC, Hung NK. Is analgesia nociception index monitor suitable for post-heart transplant patients under general anesthesia?. J Med Sci [serial online] 2020 [cited 2020 Nov 27 ];40:248-250
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Full Text

Dear Editor,

The anesthetic approach for heart transplant recipients undergoing noncardiac surgery can be challenging for anesthesiologists. Although transplanted patients can present with more optimal myocardial function, anesthesiologists should carefully consider the effects of heart denervation; preoperative, intraoperative, and postoperative pain management; the impact of immunosuppressant therapy; and subsequent patient immunosuppression. Poorly managed perioperative pain is associated with quality-of-life impairment, delayed recovery of time, long-term negative consequences, and increased morbidity in surgical patients, especially in adults after heart transplantation undergoing noncardiac surgery.

Analgesia Nociception Index (ANI) is a noninvasive pain monitoring system during anesthesia. The ANI system provides a continuous measurement of parasympathetic tone, which is derived from heart rate variability (HRV).[1],[2] Use of the ANI system may decrease intraoperative analgesia doses and seems to have an advantage over standard clinical practice of analgesia management during general anesthesia (GA).[3] However, the accuracy of ANI monitoring in patients after a heart transplantation remains unknown. Here, we are the first to communicate the procedural findings of ANI monitoring in a patient who underwent GA after heart transplantation surgery.

A 56-year-old male who had a history of dilated cardiomyopathy with end-stage congestive heart failure received a heart transplant in September 2018. Six months after the heart transplantation, the patient had recurrent cholecystitis and decided to undergo laparoscopic cholecystectomy (LC). Accordingly, the patient was classified by the American Society of Anesthesiologists as Physical Status Class III. Standard monitoring using a three-lead electrocardiogram and measurements of noninvasive blood pressure (BP), pulse oximetry oxygen saturation, and end-tidal carbon dioxide were performed. In addition, the bispectral index (BIS; BIS Vista, Aspect medical System, Inc. now Medtronic, USA.) and Mdoloris Analgesia Nociception Index (Physiodoloris®, MDoloris Medical Systems, Loos, France) monitoring were applied during the process of GA. GA was induced with a combination of fentanyl (50 μg), propofol (50 mg), and rocuronium (40 mg), and maintained with 1%–3% sevoflurane under fresh gas flow of 1 L/min and adjusted by BIS. Initially, the ANI dropped from 58 to 17 after the start of surgery, including incision of the skin and pneumoperitoneum. Fifty micrograms of fentanyl was administered due to an ANI <50 Hz and an increase in HR and/or systolic BP >20% of baseline,[4] and subsequently, the ANI scores increased to within normal range [Figure 1]. The BIS and ANI were kept within the ranges of 40–60 and 50–70, respectively. The hemodynamic status remained relatively stable, and HR ranged between 90 and 100 beats/min during the procedure [Table 1]. The operation was uncomplicated and required about 60 min, and the patient was sent to the postanesthesia care unit with a Visual Analog Pain Scale (0 to 10 scale, with 0 denoting “no pain” and 10 as the “worst pain imaginable”) for one to two. Finally, the patient was moved to the regular ward with stable vital signs after an hour of postanesthesia care.{Figure 1}{Table 1}

The ANI scores were derived from HR variation with respiration and are affected by parasympathetic tone. The heart has its own rhythm regulated by the sinus node. The sinus node, located in the right atrial tissue, is connected to the autonomic nervous system by both sympathetic and parasympathetic branches. However, the transplanted heart is a partially denervated organ, lacking both sympathetic and parasympathetic innervations. Compared to a normal heart, it has a higher resting HR, a similar maximum HR, a higher minimum HR, and a reduced HRV.[5] Because our patient had residual HRV after heart transplantation, our ANI monitoring system could be used.[6] As such, when the changes in ANI values in our patient's case were likened to other patients undergoing LC, the differences were insignificant [Figure 1].

The “energy” in a Mdoloris ANI monitor is used to confirm the reliability of indices composed of three HRV parameters, including high frequency, low frequency, and very low frequency. The valid range of energy in ANI should be within 0.05–2.5 Hz. Once the energy measurement is out of this range, the quality is poor and the ANI score is unreliable. One notable thing in our case is that the average energy score of our patient was 0.30 Hz, which is within normal range but lower than the scores of other patients. This outcome may be a result of the lack of sympathetic and parasympathetic innervations and/or circulating catecholamines or intrinsic mechanisms regulating HRV.[7] In addition, the energy was occasionally observed below 0.05 Hz in this case, therefore, the ANI index should be interpreted carefully during GA. Further study is necessary to clarify the reliability of ANI monitoring in the denervated heart.

In conclusion, anesthesiologists should carefully consider the use of ANI in patients after heart transplant surgery to avoid any misinterpretation during anesthesia.

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Conflicts of interest

There are no conflicts of interest.


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