Download Patient State Index During a Cardiac Arrest in the Operating Room

CASE REPORTS
Patient State Index During a Cardiac Arrest in the
Operating Room
Ngo K. Nguyen,
MD,
Fima Lenkovsky,
PhD, MD,
and Girish P. Joshi,
MB, BS, MD, FFARCSI
Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center at Dallas, Texas;
and Dallas Veterans Affairs Medical Center, Dallas, Texas
A 53-yr-old man undergoing laparoscopic cholecystectomy experienced cardiac arrest intraoperatively.
Patient state index values decreased to single digits
T
he Patient State Index (PSI) (Physiometrix Inc.,
North Billerica, MA) is an electroencephalographic (EEG) derived variable used to monitor
the depth of hypnosis during general anesthesia (1– 4).
The PSI has a range of 0 to 100 with decreasing values
correlating with increasing depth of hypnosis (4). Adequate depth of hypnosis is reflected by a PSI value of
25–50 with a fully awake state of 100.
Another processed EEG device, bispectral index
(BIS) (Aspect Medical Systems, Natick, MA), which is
also used to assess depth of hypnosis, has been reported to track patient response to cardiopulmonary
resuscitation (CPR) as well as return of cerebral function after cardiac arrest (5,6). However, there are no
previous reports of PSI values during cardiac arrest
situations. We report the changes in PSI values during
the resuscitative efforts after a cardiac arrest event in
the operating room (OR).
Case Report
A 53-yr-old 70-kg man was scheduled for an elective laparoscopic cholecystectomy. His medical history was significant for a decade-long history of end-stage renal disease
secondary to chronic glomerulonephritis. He received dialysis three times a week via his left arm arteriovenous fistula
and was dialyzed the day before surgery. His only medications were simvastatin and aspirin. He reported allergies to
IV contrast. He denied previous anesthetic complications.
Just before transfer to the OR, he received midazolam
2 mg IV. On arrival at the OR, standard monitors were
Accepted for publication July 9, 2004.
Address correspondence to Girish P. Joshi, MB, BS, MD, FFARCSI,
Professor of Anesthesiology and Pain Management, University of
Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas,
TX 75390 –9068. Address e-mail to [email protected].
DOI: 10.1213/01.ANE.0000140247.16106.75
©2005 by the International Anesthesia Research Society
0003-2999/05
during the cardiac arrest and returned to baseline after successful cardiopulmonary resuscitation.
(Anesth Analg 2005;100:155–7)
placed. In addition, a Patient State Analyzer (PSA 4000;
Physiometrix Inc.) array was placed on the patient’s forehead per manufacturer instructions. The patient’s initial PSI
value was 98. After breathing oxygen, anesthesia was induced by fentanyl 150 ␮g, lidocaine 50 mg, propofol 140 mg,
and rocuronium 35 mg IV. After uneventful tracheal intubation, anesthesia was maintained with desflurane and 50%
nitrous oxide in oxygen. Cefazolin 2 g IV was administered
at the surgeon’s request.
After induction and subsequent tracheal intubation, the
PSI value was 23. The concentrations of desflurane were
titrated to maintain a PSI value between 25 and 50. Approximately 20 min after the induction of general anesthesia,
while the patient was being prepared and draped for surgery, he developed supraventricular tachycardia with the
heart rate increasing from 60 to 160 bpm. His arterial blood
pressure was 71/31 mm Hg. Immediately after, the patient
developed pulseless electrical activity (PEA) with the pulse
oximeter waveform and the arterial blood pressure becoming unobtainable. The ETco2 concentration decreased from
35 mm Hg to 15 mm Hg.
Desflurane was immediately discontinued, and ventilation
was controlled with a Fio2 of 1.0. An Advanced Cardiopulmonary Life Support (ACLS) protocol for PEA was immediately
initiated which included chest compressions and IV doses of
epinephrine 1 mg, two doses approximately 3 min apart. After
6 –7 min of initiation of the ACLS algorithm, the heart converted to sinus rhythm with a heart rate of 120 and an arterial
blood pressure of 131/73 mm Hg. The patient then remained
hemodynamically stable without requiring pharmacological
support. The surgery was cancelled.
The PSI values were being recorded during the cardiac
arrest state, with the lowest value registering at 3. As the
patient’s hemodynamics stabilized (arterial blood pressure
of 131/95), the PSI increased to 70. The end-tidal desflurane
concentration was 0.9% at this time. With the PSI values
increasing, we elected to reverse the residual neuromuscular
blockade with neostigmine 2 mg IV and glycopyrrolate
0.4 mg IV. The PSI value returned to baseline within a few
minutes. Once the patient was awake and responding to
verbal command as well as upon return of adequate neuromuscular function, the trachea was extubated. A printout of
Anesth Analg 2005;100:155–7
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CASE REPORTS
ANESTH ANALG
2005;100:155–7
Figure 1. Patient State Index (PSI) and
Suppression Ratio (SR) trends during
the case.
the PSI trend was obtained at the end of the case for further
analysis (Fig. 1). The patient was transferred to the intensive
care unit and had an uneventful course thereafter. He was
discharged home 3 days later without any cardiac or neurologic sequelae. On further questioning, the patient admitted to having an allergic reaction to amoxicillin 2 yr earlier
during which he developed hives.
Discussion
The PSI values were obtained before and during the
cardiac arrest period as well as during the recovery
of hemodynamic state. The PSI values were in single
digits during the arrest, reflecting a decrease in EEG
activity probably attributable to reduced cerebral
perfusion (7). As the hemodynamics normalized,
the PSI values increased and ultimately returned to
baseline as the patient returned to consciousness.
When the changes in the PSI values and the ETco2
concentrations (obtained from the computerized anesthesia record) were compared, it was observed
that the decrease in PSI values to single digits (and
a negative suppression ratio) (Fig. 1) occurred before the decrease in the ETco2 concentrations. Similarly, the increase in PSI values (and suppression
ratio becoming positive) occurred before return of
ETco2 concentration.
The EEG-based devices such as the PSA 4000 and
BIS monitors have been used during general anesthesia and sedation to titrate hypnotic drugs. The PSA
4000 EEG algorithm uses 4-channel multi-regional,
multi-frequency power and coherence relationships
for PSI calculations, which makes it sensitive to global
and regional changes (3). On the other hand, the BIS
monitor utilizes a single channel monopolar EEG for
BIS calculation, which provides information on focusing solely on global EEG changes.
Other applications for these EEG-based devices
have also been reported (5– 8). Hausman (8) reported a
significant decrease in PSI value in a progressively
worsening hypoglycemia in a patient undergoing insulinoma resection who showed no significant
changes in vital signs. On correction of the hypoglycemia intraoperatively, the PSI value increased from
17 to 48. England (5) reported a reduction in BIS
values during hypovolemic cardiac arrest and a return
to baseline values after successful resuscitation. Similarly, Szekely et al. (6) reported an increase in BIS
values after resuscitation from cardiac arrest. However, unlike our case, previous reports using BIS monitoring during cardiac arrests did not provide graphic
trends of BIS values.
Our case suggests that EEG-based monitors such as
the PSA 4000 device may be useful during a cardiac
arrest situation. Furthermore, the PSI values may be
used to assess the need for further diagnostic tests. For
example, if the patient’s hemodynamic status had returned to baseline with the PSI values still remaining
low, there might have been a need for further neurological testing. It should be noted, however, that the
PSA 4000 device is approved by the Food and Drug
Administration as a hypnotic monitor.
References
1. John ER, Prichep LS, Kox W, et al. Invariant reversible QEEG
effects of anesthetics. Conscious Cogn 2001;10:165– 83.
2. Gugino LD, Chabot RJ, Prichep LS, et al. Quantitative EEG
changes associated with loss and return of consciousness in
healthy adult volunteers anaesthetized with propofol or sevoflurane. Br J Anaesth 2001;87:421– 8.
3. Drover DR, Lemmens HJ, Pierce ET, et al. Patient state index:
titration of delivery and recovery from propofol, alfentanil, and
nitrous oxide anesthesia. Anesthesiology 2002;97:82–9.
ANESTH ANALG
2005;100:155–7
4. Prichep LS, Gugino LD, John ER, et al. The patient state index as
an indicator of the level of hypnosis under general anaesthesia.
Br J Anaesth 2004;92:393–9.
5. Engl MR. The changes in bispectral index during a hypovolemic
cardiac arrest. Anesthesiology 1999;91:1947–9.
6. Szekely B, Saint-Marc T, Degremont AC, et al. Value of bispectral
index monitoring during cardiopulmonary resuscitation. Br J
Anaesth 2002;88:443– 4.
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7. Clute HL, Levy WJ. Electroencephalographic changes during
brief cardiac arrest in humans. Anesthesiology 1990;73:821–5.
8. Hausman LM. Processed electroencephalographic changes associated with hypoglycemia during the resection of an insulinoma.
Anesthesiology 2002:97;1013– 4.