Limitation in monitoring depth of anesthesia: a case report

Abstract

Although we describe a clinical situation that most likely occurs in hundreds of operatory rooms in the world, we report this case as provocation. It concerns an unexpected awakening from an appropriate depth of anesthesia, although the BIS monitor showed a BIS index of less than 50 for a prolonged period before and after the event. Approximately 30 min after induction of anesthesia, the patient had a hypothetic sudden arousal of consciousness, with spontaneous movements, facial muscle activation, intolerance to the tracheal tube, and tearing. After immediate intravenous administration of midazolam (4 mg), the patient returned to a depth of anesthesia status, and surgery was completed uneventfully. The patient had no recall of the event when questioned during the episode, at emergence, or at 24 h, 36 h, and 7 days after surgery. Were these events spinal reflexes to pain or stimulation although the cortex was still anesthetized? Maybe this is the more rational explanation. Was the patient awake but not aware? Is it possible that our patient experienced only a transient arousal from consciousness, and that he did not have recall because the arousal time was short and we blocked memory consolidation? The latter hypothesis provides an opportunity to discuss the evidence that at the moment there is no device to assess the depth of anesthesia. We also focus on the possibility of interfering with memory processing under anesthesia.

The utility of bispectral index monitoring for prevention of rocuronium-induced withdrawal movement in children

“…In this situation, there may be a risk for an episode of anesthesia awareness due to pain or stimulation of rocuronium injection and thus the use of BIS monitoring can also be effective for preventing anesthesia awareness. [22] Although no single component of anesthesia such as hypnosis can be used to define overall “anesthetic depth” considering the underlying mechanisms of general anesthesia, [23] the hypnotic depth is the primary endpoint of anesthesia and this has become the focus of contemporary depth of anesthesia monitoring. [10] Therefore, we hypothesized that rocuronium-induced WMs might be considerably suppressed if rocuronium is administered not at the loss of eyelash reflex but once a deep hypnotic state with BIS values lower than 40 has been achieved.…”

Electroencephalography: Clinical Applications During the Perioperative Period

“…In 1929, Hans Berger made the first observation of spontaneous electrical activity in the human brain (2). Berger defined two different frequency bands of wakefulness: alpha waves (8)(9)(10)(11)(12), predominant in the waking state with eyes closed, and beta waves (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), which often occur during mental concentration (Figure 1). In most of the population, closing the eyes results in a marked shift from predominately beta waves to alpha waves.…”

“…FIGURE 1 | EEG recordings performed in patients. The waveform can be mathematically decomposed into different frequency bands: delta rhythm (0.5-3 Hz), theta rhythm (4-7 Hz), alpha rhythm (8)(9)(10)(11)(12), beta rhythm (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and gamma rhythm (>30 Hz).…”

Anesthetic dreaming, anesthesia awareness and patient satisfaction after deep sedation with propofol target controlled infusion: A prospective cohort study of patients undergoing day case breast surgery

“…In a large cohort of cancer patients we detected an incidence of AAWR of 1:10,550 [ 16 ]. While AAWR occurs in extremely rare cases [ 17 - 19 ], patients could experience this complication with procedures that do not necessarily involve general anesthesia, but performed under a different degree of sedation. According to the American Society of Anesthesiology (ASA), in these clinical settings there would be an advantage in brain-function monitoring, especially when used in association with clinical and standard instrumental monitoring of the anesthesia [ 20 ].…”