Letter to the Editor. Intracranial pressure monitoring: challenge beyond the threshold numerical value

Nícollas Nunes RabeloAtenas Medical School, Passos, MG, Brazil;

Search for other papers by Nícollas Nunes Rabelo in
Current site
Google Scholar
PubMed
Close
 MD
,
Mateus Gonçalves de Sena BarbosaAtenas Medical School, Passos, MG, Brazil;

Search for other papers by Mateus Gonçalves de Sena Barbosa in
Current site
Google Scholar
PubMed
Close
,
Matheus Pereira Silva LemosUNIFENAS Medical School, Alfenas, MG, Brazil;

Search for other papers by Matheus Pereira Silva Lemos in
Current site
Google Scholar
PubMed
Close
,
Sérgio BrasilHospital das Clínicas, School of Medicine, University of São Paulo, Brazil; and

Search for other papers by Sérgio Brasil in
Current site
Google Scholar
PubMed
Close
 MD, PhD
, and
Gustavo FrigieriBrain4Care, São Paulo, Brazil

Search for other papers by Gustavo Frigieri in
Current site
Google Scholar
PubMed
Close
 MD, PhD
Free access

TO THE EDITOR: We have read with great attention the article by Doron et al.1 (Doron O, Barnea O, Stocchetti N, et al. Cardiac-gated intracranial elastance in a swine model of raised intracranial pressure: a novel method to assess intracranial pressure–volume dynamics. J Neurosurg. Published online June 5, 2020. doi:10.3171/2020.3.JNS193262). We would like to congratulate the authors. Their paper is very relevant, and we agree with most of the authors’ statements, especially with the description of a possible new model for monitoring intracranial pressure (ICP).

Our team believes that one great global need nowadays is to make ICP monitoring accessible to the largest number of patients possible for use in the treatment of many neurological and clinical diseases, not only neurological injury, because we believe that more widespread use of this method may ensure a better overall prognosis for these patients.

The article in question presents a study that uses small animals and a very small sample, and therefore the scientific evidence for using this ICP model clinically in human patients is still hypothetical. In addition, the method used by the authors of insufflation-deflation of the balloon is able to generate only one mechanism of a pathological process. The study did not define the borderline values of intracranial elastance that are associated with clinical findings. Details about the methodology used are also lacking, as it is still unknown if this method may be adversely affected by other parameters, in addition to the physiological ones already mentioned, like intracranial mass, hydrocephalus, and other clinical conditions.

Despite the search for a numerical limit value for ICP and new alternative models of monitoring, such as volume dynamics, by many in the scientific community,2,3 we believe that the ICP waveform (ICPwf) as a method of assessing and monitoring patients provides more accurate information than just the ICP cutoff number. The use of the ICPwf was associated with intracranial compliance (ICC),4,5 and in 2017 Ballestero et al.6 observed for the first time the relation between the peaks obtained with ICPwf monitoring, the P2/P1 ratio, as a marker for studying hydrocephalus. This waveform can also be used in other cases, such as in patients with neoplasms, contusions, and intracranial trauma, in order to monitor ICC. Thus, the numerical values are more referential than conclusive, due to their variations and the limited information about the outcomes.

Technological advances in the medical field have allowed the creation of a new noninvasive model to monitor ICC, the B4C sensor (Braincare), which Ballestero et al.6 applied in their study. This model includes a tension meter and recorder connected to a mechanical device that touches the scalp surface in the frontoparietal area lateral to the sagittal suture. The ICP monitoring function of this instrument is based on the detection of brief changes in the measurements of the skull that result from pressure changes within it; that is, it relates the deformation of the skull with the detection of changes in mean ICP.6

We believe that this noninvasive ICPwf register technique would be of value to monitor neurocritical patients under various circumstances. Its advantages are affordability, efficiency, and simple and practical handling. Besides that, it does not trigger complications, such as infections or hemorrhages, which are frequent adverse effects from the use of invasive methods to monitoring ICP.

Disclosures

The authors report no conflict of interest.

References

  • 1

    Doron O , Barnea O , Stocchetti N , et al. Cardiac-gated intracranial elastance in a swine model of raised intracranial pressure: a novel method to assess intracranial pressure-volume dynamics . J Neurosurg . Published online June 5, 2020. doi:10.3171/2020.3.JNS193262 .

    • Search Google Scholar
    • Export Citation
  • 2

    Alperin NJ , Lee SH , Loth F , et al. MR-Intracranial pressure (ICP): a method to measure intracranial elastance and pressure noninvasively by means of MR imaging: baboon and human study . Radiology . 2000 ;217 (3 ):877 885 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Kiehna EN , Huffmyer JL , Thiele RH , et al. Use of the intrathoracic pressure regulator to lower intracranial pressure in patients with altered intracranial elastance: a pilot study . J Neurosurg . 2013 ;119 (3 ):756 759 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Okon MD , Roberts CJ , Mahmoud AM , et al. Characteristics of the cerebrospinal fluid pressure waveform and craniospinal compliance in idiopathic intracranial hypertension subjects . Fluids Barriers CNS . 2018 ;15 (1 ):21 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Westhout FD , Paré LS , Delfino RJ , Cramer SC . Slope of the intracranial pressure waveform after traumatic brain injury . Surg Neurol . 2008 ;70 (1 ):70 74 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Ballestero MFM , Frigieri G , Cabella BCT , et al. Prediction of intracranial hypertension through noninvasive intracranial pressure waveform analysis in pediatric hydrocephalus . Childs Nerv Syst . 2017 ;33 (9 ):1517 1524 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
Guy RosenthalHadassah-Hebrew University Medical Center, Jerusalem, Israel;

Search for other papers by Guy Rosenthal in
Current site
Google Scholar
PubMed
Close
 MD
,
Omer DoronHadassah-Hebrew University Medical Center, Jerusalem, Israel;

Search for other papers by Omer Doron in
Current site
Google Scholar
PubMed
Close
 MD
,
Nino StocchettiMilan University and Neuro ICU Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy; and

Search for other papers by Nino Stocchetti in
Current site
Google Scholar
PubMed
Close
 MD
, and
Ofer BarneaTel Aviv University, Tel Aviv, Israel

Search for other papers by Ofer Barnea in
Current site
Google Scholar
PubMed
Close
 PhD

Response

We were pleased to read the comments of Nunes Rabelo and colleagues regarding our article and concur that the model provides a potentially useful platform to study intracranial pressure (ICP) dynamics. An advantage of the model we reported is that a large-animal swine model is used that has direct translational potential for patients with traumatic brain injury. As we discuss in the work, an inherent limitation of the swine model is that it usually precludes the use of large numbers of animals. As Nunes Rabelo and colleagues pointed out in their comments, our preliminary study did not allow for the definition of intracranial elastance thresholds to determine when the limits of intracranial volume reserve capacity have been reached. We agree wholeheartedly that this will be a crucial goal if the technology is to be applied in the clinical realm.

In their comments, Nunes Rabelo and colleagues stress the importance of ICP waveform analysis in helping to assess intracranial compliance. Although we agree with this point, it is important to point out that ICP waveform analysis alone has inherent limitations in its ability to provide a complete picture of intracranial compliance or its inverse, elastance. This is because the pressure change induced by the entry of blood volume into the cranium that the intracranial pulse pressure and waveform represent result from the effects of two parameters, the intracranial elastance and the blood volume entering the cranium. Without a direct measure of the intracranial elastance, the differing effects of these two parameters cannot be assessed in isolation. Hyperemia with high cerebral blood flow may lead to a higher intracranial pulse pressure while intracranial elastance remains unchanged.

Lastly, we concur with the assertion that an important goal is for ICP monitoring to be readily available to as many neurocritically ill patients worldwide as possible. We believe that it may be possible to incorporate the technology we describe into routine monitoring without using much in the way of additional resources. In fact, we are currently working to adapt the technology in a way that it can be used with any functioning external ventricular drain. Nunes Rabelo and colleagues advocate a noninvasive approach for monitoring ICP in order to potentially be able to spread monitoring availability to a wider range of patients. We support all efforts to develop noninvasive technologies for ICP monitoring, but at the same time, we are cognizant of the technological difficulties of achieving accurate measurements of ICP without a monitor within the cranium. We certainly hope that the approach advocated by Nunes Rabelo et al. will bear fruit and lead to important clinical advances. Our feeling is that these efforts should be pursued in parallel with efforts like ours that utilize a direct measure of intracranial elastance.

  • Collapse
  • Expand

Illustration from Bährend et al. (pp 1409–1418). Copyright Katharina Faust. Published with permission.

  • 1

    Doron O , Barnea O , Stocchetti N , et al. Cardiac-gated intracranial elastance in a swine model of raised intracranial pressure: a novel method to assess intracranial pressure-volume dynamics . J Neurosurg . Published online June 5, 2020. doi:10.3171/2020.3.JNS193262 .

    • Search Google Scholar
    • Export Citation
  • 2

    Alperin NJ , Lee SH , Loth F , et al. MR-Intracranial pressure (ICP): a method to measure intracranial elastance and pressure noninvasively by means of MR imaging: baboon and human study . Radiology . 2000 ;217 (3 ):877 885 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Kiehna EN , Huffmyer JL , Thiele RH , et al. Use of the intrathoracic pressure regulator to lower intracranial pressure in patients with altered intracranial elastance: a pilot study . J Neurosurg . 2013 ;119 (3 ):756 759 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Okon MD , Roberts CJ , Mahmoud AM , et al. Characteristics of the cerebrospinal fluid pressure waveform and craniospinal compliance in idiopathic intracranial hypertension subjects . Fluids Barriers CNS . 2018 ;15 (1 ):21 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Westhout FD , Paré LS , Delfino RJ , Cramer SC . Slope of the intracranial pressure waveform after traumatic brain injury . Surg Neurol . 2008 ;70 (1 ):70 74 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Ballestero MFM , Frigieri G , Cabella BCT , et al. Prediction of intracranial hypertension through noninvasive intracranial pressure waveform analysis in pediatric hydrocephalus . Childs Nerv Syst . 2017 ;33 (9 ):1517 1524 .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation

Metrics

All Time Past Year Past 30 Days
Abstract Views 285 0 0
Full Text Views 611 459 53
PDF Downloads 317 211 16
EPUB Downloads 0 0 0