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Table of Contents    
LETTER TO EDITOR
Year : 2020  |  Volume : 68  |  Issue : 5  |  Page : 1246-1247

Response to Article “A Comparison of Hypertonic Saline (HTS) and Mannitol on Intraoperative Brain Relaxation in Patients with Raised Intracranial Pressure During Supratentorial Tumors Resection: A Randomized Control Trial”


Senior Consultant, Neurosurgery, Department of Neurosciences, Kokilaben Dhirubhai Ambani Hospital, Mumbai, Maharashtra, India

Date of Web Publication27-Oct-2020

Correspondence Address:
Dr. Hrishikesh Sarkar
Senior Consultant, Neurosurgery, Department of Neurosciences, Kokilaben Dhirubhai Ambani Hospital, Mumbai, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.299166

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How to cite this article:
Sarkar H. Response to Article “A Comparison of Hypertonic Saline (HTS) and Mannitol on Intraoperative Brain Relaxation in Patients with Raised Intracranial Pressure During Supratentorial Tumors Resection: A Randomized Control Trial”. Neurol India 2020;68:1246-7

How to cite this URL:
Sarkar H. Response to Article “A Comparison of Hypertonic Saline (HTS) and Mannitol on Intraoperative Brain Relaxation in Patients with Raised Intracranial Pressure During Supratentorial Tumors Resection: A Randomized Control Trial”. Neurol India [serial online] 2020 [cited 2020 Nov 30];68:1246-7. Available from: https://www.neurologyindia.com/text.asp?2020/68/5/1246/299166




Dear Editor,

This is in reference to the article titled “A Comparison of Hypertonic Saline (HTS) and Mannitol on Intraoperative Brain Relaxation in Patients with Raised Intracranial Pressure during Supratentorial Tumors Resection: A Randomized Control Trial” authored by Singla et al.[1] in Neurology India (Issue 68). Authors must be congratulated for their sincere efforts, rigorous blinding methodology, and meticulous documentation of their findings. We certainly need to know which is better in controlling raised intracranial pressure - salt or sugar? The study tries to answer that and conclude, with an advocacy toward using HTS. However, there are a few important aspects that have been underemphasized and have diluted the validity of the observed differences.

  1. Authors have considered HTS and Mannitol to be equimolar in their trial. They administered 300 mL (5mL/kg for 60 kgs) of the test solution per patient. Each infusion, therefore, had 307 mmol of HTS versus 329 mmols of Mannitol (20% mannitol with osmolarity = 1098 mOsm/andHTS with osmolarity = 1024 mOsm/l). Considering the normal range of serum osmolality between 285 and 295 mmol/L,[2] the baseline difference in the osmolarity of these two solutions becomes more significant and hence cannot be neglected
  2. Furthermore, rather than the osmolality, it is the osmotic pressure (OP) of a solution that drives movement of fluid. OP is measured by Vant Hoff equation,[3] according to which OP for ideal solution = iMRT where i is the Vant Hofffactor (Mannitol - 1, NaCl - 2), M (Moles/Litre), R = ideal gas constant(.08206 L atm mol-1K-1) and T is the temperature in Kelvin. Using this equation and assuming the mean temperature to be 37°C, OP of Mannitol used by the authors is 27.93 atm while for HTS it is 52.12 atm which is, twice more that of Mannitol. Such a large difference would negate unbiased comparison. The role of measuring temperature accurately also becomes an important variable
  3. Though the Hyperchloremic metabolic acidosis (HCMA) is more commonly seen with large volume saline resuscitation(>1 L), studies have shown that it can happen with HTS in volume as low as 250 mL.[4] HCMA may worsen brain swelling and paradoxically lessen the effect of brain relaxation. Measurement of serial Chloride ions and/or arterial pH would have been more helpful to assess this
  4. Conditions in which the blood–brain barrier is “leaky”, the degree of leakiness (which is difficult to quantify) may also determine the overall response to these hyperosmolar agents
  5. Sometimes, the brain relaxation is obtained quickly by draining tumor-associated cysts or adjacent arachnoid pockets. The listed baseline lesion/surgical characteristics do not cover these observations
  6. The mean blood pressure in the Mannitol group was noted to be low, although it was never low enough to affect cerebral blood flow. Whether any volume or inotropic adjustment was required is not known.


Therefore, more evidence needs to be gathered in a more elaborate manner to demonstrate superiority of one over another.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Singla A, Mathew PJ, Jangra K, Gupta SK, Soni SL. A comparison of hypertonic saline and mannitol on intraoperative brain relaxation in patients with raised intracranial pressure during supratentorial tumors resection: A randomized control trial. Neurol India 2020;68:141-5.  Back to cited text no. 1
[PUBMED]  [Full text]  
2.
Butcher BW, Liu KD. Hyponatremia and Hypernatremia - In Critical Care Secrets. 5th ed. Elsevier; 2013. p. 322-8.  Back to cited text no. 2
    
3.
Feher J. Plasma and Red Blood Cells - Quantitative Human Physiology - An Introduction. Elsevier; 2012. p. 428-36.  Back to cited text no. 3
    
4.
Bruegger D, Bauer A, Rehm M, Niklas M, Jacob M, Irlbeck M,et al. Effect of hypertonic saline dextran on acid-base balance in patients undergoing surgery of abdominal aortic aneurysm. Crit Care Med 2005;33:556-63.  Back to cited text no. 4
    




 

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