Marc J. Bloom, M.D., Ph.D.

Isoproternol increases BIS and arousal during catheter ablation of atrial fibrillation
O'Neill D.K.; Rose E.; Linton P.; Hull M.; Aizer A.; Bloom M.
2011 ;112(5 SUPPL 1):?-?, Anesthesia & analgesia
Introduction : With the increase in anesthesia utilization in the electrophysiology laboratory, there is greater potential for arrhythmia suppression during electrophysiology study. Intravenous isoproterenol is frequently used to counteract the significant antiadrenergic impact of anesthesia, as well as induce arrhythmias and identify reconnection of pulmonary vein conduction. The effects of isoproterenol on cerebral and respiratory function during the sedated state have not been well studied. The Bispectral (BIS) Vista TM Monitor is a non-invasive device that measures electrical activity of the brain and computes a BIS value, which corresponds to a level of consciousness. The purpose of this study was to determine changes in BIS values during isoproterenol administration. Methods : Twenty consecutive patients underwent electrophysiology study under total intravenous anesthesia using propofol and remifentanil infusions. Isoproterenol was infused at a rate of 5mcg/kg/min and escalated to up to 20mcg/kg/min over 20 minutes. BIS levels were recorded before and throughout isoproterenol administration. Results : Patients demonstrated significant elevation in BIS value during isoproterenol infusion. The mean difference between pre- and post- BIS values was 21.3 [5.4, 37.2] (p = 0.00013). The isoproterenol doses which triggered a BIS spike ranged from 10.8 mcg to 90.8 mcg. The median effective isoproternol dose was 25.2 mcg. The median onset time for an isoproternol stimulated BIS spike was 6.9 minutes with rates from 2 to 20 mcg/minute. Discussion : Isoproterenol significantly increases BIS values during sedated electrophysiology study. Monitoring BIS values may be helpful in assessing the isoproterenol dosage required to overcome the suppressive effects of anesthesia on arrhythmia induction, as well as the potential need for additional anesthetics to prevent patient arousal. Conversely, decreasing BIS values are known to correlate with hypotensive episodes signaling cerebral hypoperfusion. This may be relevant in cases of hemodynamically unstable tachycardias. BIS appears to be an important tool for the optimization of anesthesia when isoproterenol is administered during electrophysiology study
— id: 146278, year: 2011, vol: 112, page: ?, stat: Journal Article,

The effect of dexmedetomidine on perioperative hemodynamics in patients undergoing craniotomy
Bekker, Alex; Sturaitis, Mary; Bloom, Marc; Moric, Mario; Golfinos, John; Parker, Erik; Babu, Ramesh; Pitti, Abishabeck
2008 Oct;107(4):1340-1347, Anesthesia & analgesia
BACKGROUND: The perioperative course of patients undergoing intracranial surgery is frequently complicated by hypertensive episodes. Dexmedetomidine (DEX), an alpha-2 adrenoreceptor agonist, is gaining popularity in neuroanesthesia, because its sympatholytic and antinociceptive properties may improve hemodynamic stability at critical moments of surgery. We designed this study to assess the efficacy of DEX in controlling hypertensive responses in patients undergoing intracranial surgery. METHODS: Patients scheduled for elective craniotomy were randomly assigned to receive either sevoflurane-opioid or sevoflurane-opioid-DEX anesthesia. Bispectral index was used to maintain a similar level of hypnosis in both groups (40-50). Opioids, sevoflurane, and vasoactive medications were titrated in a routine manner, at the discretion of the blinded anesthesiologist managing the case, to maintain systolic blood pressure (SBP) targeted within 90-130 mm Hg and heart rate (HR) between 50 and 90 bpm. Hemodynamic variables were continuously recorded and stored on a computer for analysis. Efficacy of the anesthetic technique in controlling SBP or HR is inversely proportional to the area under the curve (AUC) outside the targeted range. Areas under the curves above and below targeted ranges for SBP-time (AUCsbp mm Hg*min/h) and HR-time (bpm*min/h) were compared. Coefficient of variation was used to assess hemodynamic stability. RESULTS: Seventy-two patients were recruited for the study. Computerized records of 56 patients only were analyzed because of technical problems with data collection in 14 cases. AUCsbp for above the targeted range was significantly lower for patients in the DEX group (P=0.044). The coefficient of variation for SBP or HR did not differ between groups. A significantly smaller proportion of patients in the DEX group required treatment with antihypertensive medications (12 of 28, 42% vs 24 of 28, 86%, P=0.0008). The DEX group required fewer opioids in the intraoperative period, but there were no differences in the use of sevoflurane. In the postanesthesia care unit, patients in the DEX group had fewer hypertensive episodes (1.25+/-1.55 vs 2.50+/-2.00, P=0.0114) and were discharged earlier (91+/-17 vs 130+/-27 min, P<0.0001). There were no differences in the requirement for postoperative opioids or antiemetics. CONCLUSIONS: By using indices, which assess a global hemodynamic stability of the anesthetic, we determined that intraoperative DEX infusion was effective for blunting the increases in SBP perioperatively. The use of DEX did not increase the incidence of hypotension or bradycardia, common side effects of the drug
— id: 87811, year: 2008, vol: 107, page: 1340, stat: Journal Article,

The use of bispectral index monitoring in the anesthetic management of a patient with Rett syndrome undergoing scoliosis surgery
Kim, Jung T; Muntyan, Igor; Bashkirov, Ignat L; Bloom, Marc; Hartmannsgruber, Maximilian W B
2006 Mar;18(2):161-162, Journal of clinical anesthesia
— id: 68740, year: 2006, vol: 18, page: 161, stat: Journal Article,

On the use of multivariable piecewise-linear models for predicting human response to anesthesia
Lin, Hui-Hing; Beck, Carolyn L; Bloom, Marc J
2004 Nov;51(11):1876-1887, IEEE transactions on biomedical engineering
The standard modeling paradigm used to describe the relationship between input anesthetic agents and output patient endpoint variables are single-input single-output pharmacokinetic-pharmacodynamic (PK-PD) compartment models. In this paper, we propose the use of multivariable piecewise-linear models to describe the relations between inputs that include anesthesia, surgical stimuli and disturbances to a variety of patient output variables. Subspace identification methods are applied to clinical data to construct the models. A comparison of predicted and measured responses is completed, which includes predictions from PK-PD models, and piecewise-linear time-invariant models
— id: 68741, year: 2004, vol: 51, page: 1876, stat: Journal Article,

Dexmedetomidine infusion and somatosensory evoked potentials
Bloom M; Beric A; Bekker A
2001 Oct;13(4):320-322, Journal of neurosurgical anesthesiology
Intraoperative neurophysiologic monitoring requires information on the effects of anesthetic drugs because these drugs can directly alter evoked potentials, thus interfering with monitoring. We report on our evaluation of the effect of the recently introduced alpha2-adrenergic agonist, dexmedetomidine, on the somatosensory evoked potentials in two patients undergoing cervico-occipital fusion. Our results suggest that, although dexmedetomidine can affect the later cortical peaks of somatosensory evoked potentials (SSEPs), consistent and reproducible potentials can be recorded
— id: 26547, year: 2001, vol: 13, page: 320, stat: Journal Article,

Electroencephalography and Monitoring of Anesthetic Depth
Bloom MJ
Clinical monitoring : practical applications for anesthesia and critical care Philadelphia : London : W. B. Saunders, 2001,
— id: 2762, year: 2001, vol: , page: 92, stat: Chapter,

The recovery of cognitive function after remifentanil-nitrous oxide anesthesia is faster than after an isoflurane-nitrous oxide-fentanyl combination in elderly patients
Bekker AY; Berklayd P; Osborn I; Bloom M; Yarmush J; Turndorf H
2000 Jul;91(1):117-122, Anesthesia & analgesia
We tested the hypothesis that remifentanil-nitrous oxide (N(2)O) anesthesia shortens postoperative emergence and recovery compared with an isoflurane-N(2)O-fentanyl combination in elderly patients undergoing spinal surgery. A total of 60 patients (>65 yr old) were randomly assigned to one of two groups for maintenance of anesthesia. After the induction with 3.6 +/- 1.2 mg/kg IV thiopental and endotracheal intubation facilitated with 1.4 +/- 0.5 mg/kg succinylcholine, patients were maintained with either 0.5%-1.5% isoflurane, 70% N(2)O, and up to 7 microg/kg fentanyl (iso/fent group) or 48 +/- 11 microg/kg remifentanil and 70% N(2)O (remi group). A mini-mental status examination was used to assess cognitive ability preoperatively, at 15, 30, and 60 min after arrival at the postanesthesia care unit and again 12-24 h postoperatively. The time from the conclusion of anesthesia to spontaneous respiration was similar in both groups. Times to eye opening (4.8 +/- 2.6 vs 2.3 +/- 1.1 min), extubation (6.8 +/- 3.8 vs 3.2 +/- 2.1 min), and verbalization (9.9 +/- 6.2 vs 3.9 +/- 2.6 min) were significantly shorter for the remi group (P < 0.05). Postoperative mini-mental status examination scores were significantly lower in the iso/fent group at 15 (16.3 +/- 5.8 vs 23. 7 +/- 3.3), 30 (20.2 +/- 5.2 vs 26.3 +/- 2.7), and 60 min (23.5 +/- 4.4 vs 27.5 +/- 2.0) (P < 0.001); however, the scores equalized after 12 h. Requirements for postoperative analgesics were similar in the two groups. More patients in the remi group were treated with antiemetics (21 vs 7, P = 0.06). Use of remifentanil-N(2)O for maintenance did not shorten the overall length of stay in the postanesthesia care unit; a stay is often related to multiple administrative issues, rather than cognitive recovery. IMPLICATIONS: Maintenance of anesthesia with remifentanil-nitrous oxide (N(2)O), compared with isoflurane-N(2)O-fentanyl, can safely shorten postoperative recovery of cognitive function in a geriatric population. Earlier recovery may facilitate postoperative neurological assessment. Use of remifentanil-N(2)O for maintenance did not shorten the overall length of stay in the postanesthesia care unit, a stay often related to multiple administrative issues, rather than cognitive recovery
— id: 11636, year: 2000, vol: 91, page: 117, stat: Journal Article,

Bispectral analysis measures sedation and memory effects of propofol, midazolam, isoflurane, and alfentanil in healthy volunteers
Glass PS; Bloom M; Kearse L; Rosow C; Sebel P; Manberg P
1997 Apr;86(4):836-847, Anesthesiology
BACKGROUND: The bispectral index (BIS), a value derived from the electroencephalograph (EEG), has been proposed as a measure of anesthetic effect. To establish its utility for this purpose, it is important to determine the relation among BIS, measured drug concentration, and increasing levels of sedation. This study was designed to evaluate this relation for four commonly used anesthetic drugs: propofol, midazolam, isoflurane, and alfentanil. METHODS: Seventy-two consenting volunteers were studied at four institutions. Volunteers were given either isoflurane, propofol, midazolam, or alfentanil. Each volunteer was administered a dose-ranging sequence of one of the study drugs to achieve predetermined target concentrations. A frontal montage was used for continuous recording of the EEG. At each pseudo-steady-state drug concentration, a BIS score was recorded, the participant was shown either a picture or given a word to recall, an arterial blood sample was obtained for subsequent analysis of drug concentration, and the participant was evaluated for level of sedation as determined by the responsiveness portion of the observer's assessment of the alertness/ sedation scale (OAAS). An OAAS score of 2 or less was considered unconscious. The BIS (version 2.5) score was recorded in real-time and the BIS (version 3.0) was subsequently derived off-line from the recorded raw EEG data. The relation among BIS, measured drug concentration, responsiveness score, and presence or absence of recall was determined by linear and logistic regression for both the individual drugs and, when appropriate, for the pooled results. The prediction probability was also calculated. RESULTS: The BIS score (r = 0.883) correlated significantly better than the measured propofol concentration (r = -0.778; P < 0.05) with the responsiveness score. The BIS provided as effective correlation with responsiveness score of the OAAS as did the measured concentration for midazolam and isoflurane. None of the volunteers given alfentanil lost consciousness and thus were excluded from the pooled analysis. The pooled BIS values at which 50% and 95% of participants were unconscious were 67 and 50, respectively. The prediction probability values for BIS ranged from 0.885-0.976, indicating a very high predictive performance for correctly indicating probability of loss of consciousness. CONCLUSIONS: The BIS both correlated well with the level of responsiveness and provided an excellent prediction of the loss of consciousness. These results imply that BIS may be a valuable monitor of the level of sedation and loss of consciousness for propofol, midazolam, and isoflurane
— id: 27216, year: 1997, vol: 86, page: 836, stat: Journal Article,

Electrographic tachyphylaxis to etomidate and ketamine used for refractory status epilepticus controlled with isoflurane
Kofke WA; Bloom MJ; Van Cott A; Brenner RP
1997 Jul;9(3):269-272, Journal of neurosurgical anesthesiology
Etomidate and ketamine controlled seizures but acute tachyphylaxis occurred. Isoflurane was then used to control seizures
— id: 26366, year: 1997, vol: 9, page: 269, stat: Journal Article,

Monitoring for cerebrovascular surgery
Bloom MJ; Kofke WA; Nemoto E; Whitehurst S
1996 Summer;34(3):137-147, International anesthesiology clinics
— id: 26367, year: 1996, vol: 34, page: 137, stat: Journal Article,

Perioperative diuresis and ICP
Bagshaw RJ; Smith DS; Bloom MJ; Mitchell RL; Young ML
1984 Jul;61(1):107-108, Anesthesiology
— id: 26370, year: 1984, vol: 61, page: 107, stat: Journal Article,

Sudden hypotension with a test dose of chymopapain
Bruno LA; Smith DS; Bloom MJ; Domino K; Bagshaw RJ; Star AM; Cohen AM; Lupo SE
1984 May;63(5):533-535, Anesthesia & analgesia
— id: 26371, year: 1984, vol: 63, page: 533, stat: Journal Article,