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Perioperative abnormal electroencephalography in a later-stage elderly with septic shock: a case report

Abstract

Background

Patients with sepsis often exhibit abnormal patterns of electroencephalogram (EEG). We report an abnormal EEG pattern in a later-stage elderly patient with septic shock and EEG analysis results.

Case presentation

An 88-year-old woman with bowel perforation underwent emergency Hartmann surgery. On admission to the operating room, she exhibited septic shock. Her bispectral index value was 30 before anesthesia induction, and the EEG displayed slow waves without burst and suppression throughout the surgery. The relative slow-wave ratio [spectral power (0.5–8 Hz)/(0.5–30 Hz)] from anesthetic induction to the end of surgery was 95.1%, whereas the relative alpha frequency [spectral power (8–13 Hz)/(0.5–30 Hz)] was only 2.4%. Although without preoperative neurological abnormalities, she developed postoperative delirium after admission to the intensive care unit.

Conclusions

Intraoperative continuous EEG monitoring in elderly patients with sepsis may be useful to predict sepsis-associated encephalopathy. Therefore, continuous EEG monitoring may improve neurological outcomes.

Background

Delirium and sepsis are serious complications of critical illness. Sepsis-associated encephalopathy (SAE) is a systemic inflammatory reaction against infection to organs other than the central nervous system. The main symptom of SAE is delirium, and in severe cases, coma. Its diagnosis is based on the evaluation of the sedation and delirium scale after sepsis diagnosis.

Electroencephalogram (EEG) abnormalities, such as a decrease in alpha frequency band power and EEG amplitude, were found in 96% of patients with septic shock [1]. These inhibition degrees of change can reflect cerebral lesion, and changes in EEG may indicate brain damage. Continuous EEG (cEEG) monitoring may be useful to predict SAE, but the EEG of the elderly shows similarly low amplitude, with decreasing alpha waves and increasing slow waves [2].

Here, we report the case of an abnormal EEG pattern in a late elderly patient who suffered from septic shock caused by lower gastrointestinal perforations. We suggest that low-frequency dominant EEG at preinduction may indicate the possibility of SAE.

Case presentation

We have obtained a written informed consent from the patient and her family for the analysis of the EEG data and publication of this case report.

An 88-year-old woman (height, 150 cm; weight, 40 kg) was conservatively treated for multiple myeloma and diabetes mellitus for approximately 20 years. One day, she suffered from stomachache and subsequently consulted her family doctor. She was diagnosed with sigmoid volvulus and received endoscopic treatment to release the volvulus. She recovered after the treatment, but abdominal pain reoccurred after 3 days. The attending physician diagnosed the patient with bowel perforation caused by the endoscopic treatment and resulting in sepsis. Thus, she underwent emergency Hartmann surgery.

Upon admission to the operating room, she manifested septic shock; her blood pressure was 90/60 mmHg, and her heart rate was 100 beats per minute, with noradrenaline administration (0.3 μg/kg/min). Nevertheless, verbal communication was possible and the Glasgow Coma Scale was E3V4M6. Furthermore, we monitored the following variables continuously during anesthesia: electrocardiogram, pulse oximetry, end-tidal carbon dioxide concentration, direct arterial blood pressure, central venous pressure, body temperature (esophagus), and urinary output. EEG was monitored and recorded using a BSM monitor TM (NIHON KOHDEN, Tokyo, Japan) throughout the anesthesia period. Before anesthesia induction, the patient’s bispectral index (BIS) was 30, while her EEG displayed slow waves without burst and suppression (Fig. 1). Anesthesia was induced by intravenously injecting ketamine (20 mg) and rocuronium bromide (40 mg). We used ketamine (1 mg/kg/h), propofol (1–2 mg/kg/h), fentanyl (total dose, 200 μg), and rocuronium bromide to maintain general anesthesia as a total intravenous administration of anesthesia (TIVA). The anesthesia record is shown in Fig. 2a. The EEG waves, 95% spectral edge frequency (SEF95), and suppression ratio (SR) values at anesthetic induction, during surgery, and at the end of the surgery are shown in Fig. 2b–d, respectively. The stored EEG was retrospectively analyzed using the BIMTUS 2 software TM (KISSEI COMTEC, Tokyo, Japan). We extracted a sample frequency of 128 Hz with the BIMTUS 2 software TM. 3-min EEG frequency analysis at anesthetic induction, during surgery, and at the end of the surgery is shown in Fig. 2b–d, respectively. EEG predominantly consists of slow-wave components without burst and suppression throughout the surgery. The relative slow-wave ratio [spectral power (0.5–8 Hz)/spectral power (0.5–30 Hz)] from before anesthesia induction to the end of surgery was 95.1%, whereas the relative alpha frequency ratio [spectral power (8–13 Hz)/spectral power (0.5–30 Hz)] was only 2.4% (Fig. 3).

Fig. 1
figure1

Electroencephalogram before anesthetic induction. This EEG shows lower frequency dominance that is not observed in the healthy elderly

Fig. 2
figure2

Anesthesia record. EEG waves and frequency analysis at each point. Anesthetic record is shown in (a). The BIS value remained from 30 to 40 throughout the perioperative period. Anesthesia was induced by intravenously injecting ketamine (20 mg) and rocuronium bromide (40 mg) at that period. The EEG at lower frequency below 8 Hz was dominant (b). The EEG pattern was continuous throughout the surgery (c, d). Abbreviations: HR, heart rate; sBP, systolic blood pressure; dBP, diastolic blood pressure; BIS, bispectral index; SEF95 (Hz), 95% spectral edge frequency; SR (%), suppression ratio

Fig. 3
figure3

A frequency analysis for the EEG from anesthetic induction to end of surgery. A frequency analysis for the EEG from anesthetic induction to end of surgery is shown. The relative slow-wave ratio [spectral power (0.5–8 Hz)/spectral power (0.5–30 Hz)] from before anesthesia induction to the end of surgery was 95.1%, whereas the relative alpha frequency ratio [spectral power (8–13 Hz)/spectral power (0.5–30 Hz)] was only 2.4%

Although the patient received minimum amounts of intraoperative anesthetic drugs, she remained immobile and unconscious intraoperatively with BIS values of 30 to 40. She was then admitted to the intensive care unit with tracheal intubation and received ventilator management and continuous hemodiafiltration. After tracheal extubation, she developed postoperative delirium. Nonetheless, her cognitive dysfunction improved as her systemic condition recovered on postoperative day 5.

Discussion

This case report represents two issues of clinical importance. First, the EEG of this elderly patient with septic shock showed apparent abnormal patterns before anesthesia induction through surgery. Second, the neurological behaviors, such as delirium, of this patient with abnormal EEG may have been induced by perioperative invasion. Therefore, intraoperative cEEG monitoring may predict SAE even if septic shock patients do not have any symptoms.

The BIS of our patient was 30 and EEG displayed slow waves without burst and suppression before anesthesia induction, indicating that she already had SAE at that time. In patients with delirium, routine EEG commonly shows an increased slow-wave activity and a slow and disrupted alpha rhythm [3,4,5,6]. Nielsen et al. revealed that delirious episodes in patients with sepsis are associated with the disappearance of high-frequency electrographic cEEG activity and increased in power of low-frequency activity [7]. They also reported the association of EEG and the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Normal CAM-ICU scores were associated with continuous or nearly continuous high-frequency cEEG beta activity, preserved cEEG reactivity, and normal cEEG background activity. Conversely, patients with CAM-ICU scores of delirium exhibited a suppressed background cEEG actively. The suppressed cEEG was not observed in any patient without delirium. Although there are reports of patients with sepsis in the ICU [7], there are few reports of EEG during anesthesia in patients with sepsis.

Cerebral rhythmic EEG activity reflects the cortical neurons’ ability to synchronize input from thalamocortical and corticocortical neurons. Generation of high-frequency cortical activity requires fast spiking of high energy–demanding somatostatin-positive interneurons [8].

Ketamine is commonly used for patients with shock. Ketamine, which is an N-methyl-d-aspartate antagonist, activates the EEG, despite its sedative effects. Some features of EEG activation by ketamine, such as increases in β-activity, BIS, and SEF95, have already been described [9]. Ketamine also increases the alpha peak frequency, with simultaneous shifting of the bicoherence peak [10]. In this case, such features could not be observed, despite performing TIVA with ketamine as the primary anesthetic.

The abnormal neurological behaviors of this patient may have been induced by not only sepsis but also surgical invasion. Elderly patients with sepsis may be sensitive to anesthetics. An aged brain is significantly vulnerable to immune stimuli compared with a younger brain. Microglia of the aged brain take on a “primed” or “sensitized” phenotype, characterized by dystrophic morphology, progressive accumulation of metabolic stress, increased cell-surface expression of antigen recognition molecules, and an exaggerated inflammatory response to immune challenge [11]. Primed microglia show an increased production of proinflammatory cytokines in response to immune stimulation with a peripheral inflammatory challenge [12]. This patient’s EEG might reflect neuroinflammation. Her neurological behaviors with abnormal EEG may have been induced by surgical invasion and preexisting gastrointestinal perforation itself. Perioperative procedures requiring general anesthesia prolonged neuroinflammation, probably resulting in delirium. The initial processes involved in SAE could lead to cerebral damage [13]; hence, it is important to detect the presence of SAE earlier.

In conclusion, intraoperative cEEG monitoring in elderly patients with sepsis may be useful to predict SAE. The applicability of BIS monitoring for assessing the depth of anesthesia in elderly patients with sepsis should be performed carefully. Predicting SAE from perioperative EEGs may help improve neurological outcomes.

Availability of data and materials

Please contact the author for data requests.

Abbreviations

EEG:

Electroencephalogram

SAE:

Sepsis-associated encephalopathy

cEEG:

Continuous electroencephalogram

BIS:

Bispectral index

TIVA:

Total intravenous administration of anesthesia

SEF95:

95% spectral edge frequency

BSR:

Burst and suppression ratio

CAM-ICU:

Confusion Assessment Method for the Intensive Care Unit

References

  1. 1.

    Ma Y, Ouyang B, Guan X. Use of quantitative electroencephalogram in patients with septic shock. Zhonghua Yi Xue Za Zhi. 2016;96:195–8.

    PubMed  Google Scholar 

  2. 2.

    Purdon PL, Pavone KJ, Akeju O, Smith AC, Sampson AL, Lee J, et al. The ageing brain: age-dependent changes in the electroencephalogram during propofol and sevoflurane general anaesthesia. Br J Anaesth. 2015;115(Suppl 1):i46–57.

    Article  Google Scholar 

  3. 3.

    Koponen H, Partanen J, Paakkonen A, Mattila E, Riekkinen PJ. EEG spectral analysis in delirium. J Neurol Neurosurg Psychiatry. 1989;52:980–5.

    CAS  Article  Google Scholar 

  4. 4.

    van Der Kooi AW, Zaal IJ, Klijn FA, Koek HL, Meijer RC, Leijten FS, et al. Delirium detection using EEG: what and how to measure. Chest. 2015;147:94–101.

    Article  Google Scholar 

  5. 5.

    van Dellen E, van Dellen E, van der Kooi AW, Numan T, Koek HL, Klijn FA, Buijsrogge MP, et al. Decreased functional connectivity and disturbed directionality of information flow in the electroencephalography of intensive care unit patients with delirium after cardiac surgery. Anesthesiology. 2014;121:328–35.

    Article  Google Scholar 

  6. 6.

    van der Kooi AW, Leijten FSS, van der Wekken RJ, Slooter AJC. What are the opportunities for EEG-based monitoring of delirium in the ICU? J Neuropsychiatry Clin Neurosci. 2012;24:472–7.

    Article  Google Scholar 

  7. 7.

    Nielsen RM, Urdanibia-Centelles O, Vedel-Larsen E, Thomsen KJ, Møller K, Olsen KS, et al. Continuous EEG monitoring in a consecutive patient cohort with sepsis and delirium. Neurocrit Care. 2020;32:121–30.

    Article  Google Scholar 

  8. 8.

    Chen G, Zhang Y, Li X, Zhao X, Ye Q, Lin Y, et al. Distinct inhibitory circuits orchestrate cortical beta and gamma band oscillations. Neuron. 2017;96:1403–1418.e6.

    CAS  Article  Google Scholar 

  9. 9.

    Soloan TB. Anestheric effects on electrophysiologic recordings. J Clin Neurophysiol. 1998;15:217–26.

    Article  Google Scholar 

  10. 10.

    Hayashi K, Tsuda N, Sawa T, Hagihira S. Ketamine increases the frequency of electroencephalographic bicoherence peak on the alpha spindle area induced with propofol. Br J Anaesth. 2007;99:389–95.

    CAS  Article  Google Scholar 

  11. 11.

    Niraula A, Sheridan JF, Godbout JP. Microglia priming with aging and stress. Neuropsychopharmacology. 2017;42:318–33.

    Article  Google Scholar 

  12. 12.

    Kawano T, Eguchi S, Iwata H, Tamura T, Kumagai N, Yokoyama M. Impact of preoperative environmental enrichment on prevention of development of cognitive impairment following abdominal surgery in a rat model. Anesthesiology. 2015;123:160–70.

    Article  Google Scholar 

  13. 13.

    Widmann CN, Heneka MT. Long-term cerebral consequences of sepsis. Lancet Neurol. 2014;13:630–6.

    Article  Google Scholar 

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Acknowledgements

We would like to thank Concierge Editing (https://www.quicktranslate.com/conci/editing) for the English language editing.

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HK anesthetized the patient and wrote the first draft of the manuscript. TK anesthetized the patient and revised the manuscript. DT and KH supervised the anesthesia management. All authors read and approved the final manuscript for submission.

Corresponding author

Correspondence to Hirotaka Kinoshita.

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A written informed consent was obtained from the patient for the publication of this case report.

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Kinoshita, H., Kushikata, T., Takekawa, D. et al. Perioperative abnormal electroencephalography in a later-stage elderly with septic shock: a case report. JA Clin Rep 7, 5 (2021). https://doi.org/10.1186/s40981-020-00409-5

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Keywords

  • Electroencephalogram
  • Sepsis
  • Sepsis-associated encephalopathy
  • Ketamine
  • Postoperative delirium