Letter to the Editor. Enteral volume loss and delayed cerebral ischemia

Lesheng WangZhongnan Hospital of Wuhan University, Wuhan, China

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TO THE EDITOR: I read with great interest the retrospective comparative study by Gelder et al.1 (Gelder CL, Bautista M, Awan SA, et al. Unaccounted for enteral volume loss linked to delayed cerebral ischemia after subarachnoid hemorrhage. Neurosurg Focus. 2022;52[3]:E5). The authors explored the relationship between developing enteral volume loss (i.e., diarrhea) and delayed ischemic neurological deficit (DIND) in patients with aneurysmal subarachnoid hemorrhage (aSAH). To confirm this conjecture, the authors conducted comparisons of age, sex, modified Fisher grade, World Federation of Neurosurgical Societies (WFNS) grade, and treatment modalities between patients with and without diarrhea. Subsequently, they concluded that enteral volume loss caused by osmotic laxative use is a potential risk factor for DIND following aSAH. This is a significant and conclusive study, and the presented data support the authors’ conclusions. However, we have to say that there are several limitations of this study and some factors remain to be advanced.

In the Methods section the following data were collected: age, sex, modified Fisher grade, WFNS grade, and treatment modalities. The authors assumed that at least one factor may be responsible for their hypothesis. Besides the factors included above, other such factors may be aneurysm locations, comorbidity, etc., which can very likely influence the development of DIND.

Furthermore, only univariate analysis was performed in the present study, which may compromise the accuracy of the conclusions. Hence, it is necessary to conduct multivariate analysis to specify whether the cause of enteral volume loss was related to DIND following aSAH.

Last but not least, the frequency or volume of laxative use is not clearly explained in this study, which may affect its conclusions.

In summary, the result of this very nice research work will contribute to the clinical practice of neurosurgeons and intensive care physicians in the management or prevention of delayed cerebral ischemia after aSAH. However, a large number of clinical randomized controlled trials investigating this conclusion are required for further verification.

Disclosures

The author reports no conflict of interest.

References

1

Gelder CL, Bautista M, Awan SA, Anderson IA. Unaccounted for enteral volume loss linked to delayed cerebral ischemia after subarachnoid hemorrhage. Neurosurg Focus. 2022;52(3):E5.

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Chloé Louise GelderLeeds General Infirmary, Leeds, United Kingdom

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Melissa BautistaLeeds General Infirmary, Leeds, United Kingdom

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Ian A. AndersonLeeds General Infirmary, Leeds, United Kingdom

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Sidra Arif AwanUniversity College London Hospital, London, United Kingdom

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Response

We thank Dr. Wang for the interest in our paper; we appreciate the time taken to respond to our findings. It is correct to surmise that we explored the relationship between enteral volume loss (i.e., diarrhea) and DIND in patients with aSAH. We concluded that enteral volume loss is a potential risk factor for DIND following aSAH. The univariate analysis confirmed this as a risk factor from our data; however, causation cannot be proven based on this alone. All of our patients received osmotic laxatives.

In the Methods section we collected data on age, sex, modified Fisher grade, WFNS grade, and treatment modalities. There is significant variability within the existing literature with regard to dependent variables linked with SAH and DIND, such as aneurysm location, hemodynamic status, and the presence of anemia, hypotension, leukocytosis, and hypokalemia—all of which might also have been collected.1 We selected our variables based on the opinion of our senior author that these are considered to be the most well established and straightforward.

We elected to conduct a univariate analysis instead of a multivariate or multivariate covariant analysis, because the only statistically significant difference between the cohorts was treatment modality and because there are many additional possible dependent variables. We were not able to obtain these other variables from our electronic health record system for this retrospective analysis, and therefore these could not have been incorporated into any multivariate analysis in any case.

Regarding the comment on the volume and/or frequency of laxative use, the dosing of each laxative was prescribed as per the recommendations from the British National Formulary2 and was not adjusted outside these standard doses. Given the retrospective nature of the data collection, the total duration of each laxative used was a particular challenge to demonstrate due to the way our hospital systems record this; however, we did collect data on the type of laxatives that each individual patient was prescribed (Fig. 1). Of note, all patients who had diarrhea had a Clostridium difficile screen performed, all of which were negative.

FIG. 1.
FIG. 1.

Graph showing the type of laxatives that patients with diarrhea were prescribed in those with and without DIND.

The possibility that another pathology, such as a global inflammatory response (which may or may not be linked to diarrhea), can make some patients more susceptible to DIND than others was discussed in the presentation of this work at the JNSPG March Journal Club’s virtual meeting.3

We are currently in the process of collecting further data, and Dr. Wang is correct in stating that a large number of clinical randomized controlled trials of this conclusion would be required for further verification.

References

  • 1

    Rumalla K, Lin M, Ding L, et al. Risk factors for cerebral vasospasm in aneurysmal subarachnoid haemorrhage: a population-based study of 8346 patients. World Neurosurgery. 2021;145:e233241.

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  • 2

    Joint Formulary Committee. (2019). British National Formulary (BNF 78). Pharmaceutical Press;2019.

  • 3

    JNSPG Journal Club March 2022 Update on Cerebrovasospasm. Journal of Neurosurgery Publishing Group. Accessed September 12, 2022. https://thejns.org/page/journal_club

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    FIG. 1.

    Graph showing the type of laxatives that patients with diarrhea were prescribed in those with and without DIND.

  • 1

    Gelder CL, Bautista M, Awan SA, Anderson IA. Unaccounted for enteral volume loss linked to delayed cerebral ischemia after subarachnoid hemorrhage. Neurosurg Focus. 2022;52(3):E5.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 1

    Rumalla K, Lin M, Ding L, et al. Risk factors for cerebral vasospasm in aneurysmal subarachnoid haemorrhage: a population-based study of 8346 patients. World Neurosurgery. 2021;145:e233241.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2

    Joint Formulary Committee. (2019). British National Formulary (BNF 78). Pharmaceutical Press;2019.

  • 3

    JNSPG Journal Club March 2022 Update on Cerebrovasospasm. Journal of Neurosurgery Publishing Group. Accessed September 12, 2022. https://thejns.org/page/journal_club

    • Search Google Scholar
    • Export Citation

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