George Mychaskiw

Explicit intraoperative recall at a bispectral index of 47

The Bispectral Index (BIS) has become widely accepted as a measurement of hypnosis under anesthesia. It is derived from a processed electroencephalogram and computer algorithm that assigns a numerical value based on the probability of consciousness. Values ,60 correlate with a low probability of consciousness (1). We report a case wherein a patient experienced explicit recall of intraoperative events, despite a BIS of 47. Case Report A 28-yr-old, 85-kg male with a history of smoking, hypercholesterolemia, and hypertension presented to the operating room for three coronary artery bypass grafts, secondary to severe coronary artery disease with normal left ventricular function. There was no family history significant for heart disease. The patient was employed as a corrections officer and had no previous medical training or experience with cardiac surgery. He had no history of recreational drug use or alcohol abuse. His surgical history was previously negative. Monitors applied included an Aspect A-2000 BIS monitor (Aspect Medical Systems, Newton, MA). Anesthesia was induced with thiopental, 4 mg/kg, nitrous oxide, 70%, in oxygen and sevoflurane, 2‐3%, with paralysis induced by vecuronium. After endotracheal intubation, he was turned laterally, and preservative-free morphine, 5 mg/ kg, administered via a 22-gauge spinal needle at the L3-4 interspace. The patient was then returned to a supine position for the duration of surgery. During placement of the intrathecal morphine, the BIS sensor had become dislodged and was replaced after returning to the supine position. As the monitor was turned on, electrode impedances were automatically checked and within acceptable limits. Anesthesia was maintained with sevoflurane and nitrous oxide until the start of cardiopulmonary bypass (CPB), when it was changed to isoflurane in oxygen. At the conclusion of the case, the neuromuscular block from vecuronium was reversed, and the patient was awakened, tracheally extubated, and transferred to the cardiovascular intensive care unit in stable condition. He had an uneventful recovery and was discharged home on the fourth postoperative day. During his postanesthesia interview, 48 h after surgery, the patient reported that he could recall voices in the operating room, the sound of the sternal saw being tested, and could feel his chest being opened. The patient denied any pain, and did not recall anything after sternotomy. He clearly described the sound of the nitrogen-powered sternal saw to the anesthesiology resident conducting the postoperative evaluation. This was elicited spontaneously by the patient and not as a result of a specific inquiry about recall. The patient had no prior history of intraoperative recall. Review of the medical record revealed a BIS of 47 at the time of sternotomy, 35 min after induction of anesthesia. At the time of sternotomy, Fio2 was 0.26, Fin2o was 0.67, and inspired sevoflurane was 2%. The sevoflurane initially was started at 4%, and had been at 3% for most of the time before sternotomy. The patient’s heart rate and blood pressure were slowly decreasing after the induction, and the sevoflurane concentration was also slowly decreased to 2%, as noted. The vaporizer in use on the anesthesia machine had previously functioned well, and end-tidal sevoflurane was appropriately detected by a RASCAL gas-monitoring device (Ohmeda, Tewksbury, MA). Despite this, the patient was quite satisfied with his anesthetic and reported no psychological difficulties resulting from the awareness event.

Massive hemorrhage during radiofrequency ablation of a pulmonary neoplasm.

IMPLICATIONS Radiofrequency ablation is a new investigational therapy for primary and secondary neoplasms. In this article, the authors describe the anesthetic management of the radiofrequency ablation of a pulmonary neoplasm complicated by massive hemorrhage.

Sildenafil (viagra) facilitates weaning of inhaled nitric oxide following placement of a biventricular-assist device.

Sildenafil is a selective phosphodiesterase type 5 inhibitor used in the treatment of erectile dysfunction. We report the use of sildenafil to blunt the rebound pulmonary hypertension seen following withdrawal of inhaled nitric oxide (NO) and milrinone. The relatively long duration of sildenafils action on pulmonary artery pressures and lack of systemic hemodynamic effect make it an attractive option to facilitate weaning of inhaled NO.

Metabolic acidosis associated with a New formulation of Propofol

PROPOFOL is used for the intravenous induction of anesthesia and for sedation in the intensive care unit. Two formulations of propofol are available in the United States: Diprivan brand (Zeneca Pharmaceuticals, Wilmington, DE) and Propofol (Baxter Pharmaceutical Products, Inc., New Providence, NJ). The formulary of the University of Mississippi School of Medicine recently changed from the Zeneca product to the Baxter product for economic reasons. We report a case of severe metabolic acidosis associated with the new product.

Interaction of an implanted pacemaker with a transesophageal atrial pacemaker: report of a case

We report an interaction of a transesophageal atrial pacemaker (TAP) with a permanently implanted pacemaker in a cardiac patient who had undergone ablative therapy for atrial tachyarrhythmia 5 years earlier. The patients permanent A-V pacemaker was completely inhibited by the TAP, and there was loss of ventricular contractions and blood pressure. The patient required epicardial A-V pacing to overcome the programmed heart rate of 76 bpm. We describe alternative methods to epicardial pacing. We also recommend close inspection of the chest radiograph, which often can reveal the serial numbers of the implanted pacemaker, as a means of identifying the devices functions and programming.

In vitro effects of hyperbaric oxygen on sickle cell morphology.

STUDY OBJECTIVE To determine in vitro whether hyperbaric oxygen has any effect on the morphology of sickle cells. DESIGN Prospective, in vitro, study, with each patient sample serving as its own control. SETTING University medical center. PATIENTS 10 children known to be homozygous for hemoglobin S. INTERVENTIONS Blood samples were obtained from 10 children during routine visits to the University sickle cell clinic. Blood samples were exposed to room air to achieve maximal sickling. Each sample was divided into control and study aliquots, and the study portions placed in a research hyperbaric chamber with 100% oxygen at 3 atmospheres absolute pressure for 15 min. Then smears were prepared from all samples at regular intervals and examined by technicians in the sickle cell clinic who were blinded as to the details of this study. MEASUREMENTS Percentages of normal cells, sickle cells and sickle forms were reported. Data were interpreted using t-tests. MAIN RESULTS Hyperbaric oxygen appeared to have no effect on sickle cell morphology. Percentages of each cell type were unaffected by hyperbaric oxygen exposure. CONCLUSIONS Hyperbaric oxygen appears to have no effect on the morphology of sickle cells in vitro. Other mechanisms may account for the beneficial clinical effects of hyperbaric oxygen in sickle cell crisis, although in vivo studies are warranted.

Case Series or Uncontrolled Clinical Study

To the Editor:—We read with interest the article by Ramsay and Luterman and accompanying editorial discussing the use of high-dose dexmedetomidine as a single-agent intravenous anesthetic. We have several concerns, both with the technique described and the journal’s editorial position. As to the case series itself, we wonder what was the basis for the clinical choice to use doses of dexmedetomidine at more than 7 to 50 times the recommended dose range of 0.2–0.7 g·kg ·h 1 as the sole anesthetic. Ebert et al.’s work with volunteers was extremely limited and in no way established dexmedetomidine as a safe single-agent anesthetic. Indeed, doses of dexmedetomidine lower than those in the case series have been recently reported as “accidental overdose” and are accompanied by guidelines for the management of same. Although Ramsay and Luterman’s cases imply that the doses were increased when the patients could not tolerate the procedures at lower dose levels, there is no mention of the initial anesthetic plan. Did the authors undertake the anesthetics with the expectation of using dexmedetomidine at massive, unstudied doses? Given the properties of dexmedetomidine at its usual clinical dose range, it is unlikely that patients would be able to tolerate the procedures described without either supplementation or rapid escalation to massive doses, as actually occurred. We find no convincing evidence in the literature to believe that their course of action could be chosen with confidence in its safety and efficacy. The intraoperative management of the cases is also unusual. We fail to understand their need to avoid the use of supplemental oxygen except when absolutely necessary. The argument regarding electrocautery is unconvincing. It is almost as if the decreased margin of safety is used as a demonstration of dexmedetomidine’s properties with respect to maintenance of ventilation. In the two cases that did not receive supplemental oxygen, were the patients subsequently placed on oxygen in the postanesthesia care unit? Finally, we question the assertion that recovery time in these patients was not significantly prolonged when compared with many conventional anesthetic techniques. A recovery time and postanesthesia care unit stay of 2 to 3 h is considered by many to be significantly prolonged and is not a desirable side effect. We are therefore concerned that ANESTHESIOLOGY tacitly endorses this anesthetic technique by calling it “another arrow for the clinician’s quiver” in the accompanying editorial. On the basis of Ebert et al.’s two volunteers and the three cases described by Ramsay and Luterman, are we to assume that this is now an acceptable practice? Certainly, we all daily administer many medications “off-label” in a safe and reasonable manner. There comes a point, however, when the off-label use of a drug crosses the line of “reasonable” and becomes a deviation from the standard of care. Until properly controlled, Institutional Review Board reviewed clinical studies (with appropriate informed patient consent) are conducted addressing safety and efficacy issues of the doses in question, it is premature to call single-agent intravenous dexmedetomidine “another arrow for the clinician’s quiver.” A case report or small series of cases should highlight an unusual occurrence, pathology, or unanticipated anesthetic intervention, rather than act as a proving ground for new anesthetic techniques. There is nothing in the article to suggest that the patients involved provided informed consent as to the unusual nature of the anesthetic. Similarly, it does not appear that an Institutional Review Board or hospital ethics committee was consulted regarding this “case series.” The practice of anesthesiology is neither a contest of skills nor a game of what one can get away with. The essence of the practice of anesthesiology is the planning and administration of the safest and most efficient anesthetic for a given individual patient using principles grounded in science and controlled clinical studies. An unusual technique that worked in three patients does not rise to this standard and sidesteps the checks and balances of ethical scientific investigation. Finally, the lack of complete disclosure of conflicts of interest on Dr. Ebert’s part is disturbing. The attestation states, “Dr. Ebert is not supported by, nor maintains any financial interest in, any commercial activity that may be associated with the topic of this editorial.” This may be true only in the strictest and most limited interpretation of the statement, but ignores Dr. Ebert’s long and close association with Abbott Laboratories (Abbott Park, IL) and previous substantial financial support and honoraria. In fact, the study cited by Ebert in the editorial, examining high-dose dexmedetomidine in volunteers, was itself supported by a grant from Abbott Laboratories. At best, this is disingenuous. The casual reader of the journal should be fully aware that an unproven anesthetic technique, utilizing an expensive drug manufactured by Hospira, Inc. (Lake Forest, IL), a wholly-owned spin-off company of Abbott Laboratories, is advocated by an Abbott-funded investigator and is trumpeted by editorial writers with a long history of close association and support from Abbott Laboratories. It is difficult to understand how one can consider this an objective review of scientific data.

Halogenated Anesthetics and Intensive Care Unit Sedation: A Note of Caution

clinician’s serious consideration. Lebard et al. also express surprise at the 19.5% mortality we observed in patients with PPC, finding it high; they suggest that overlapping postoperative cardiovascular complications (CVC) might have played a role. In fact, however, high mortality is not unusual in patients with PPC: mortality was 27% and 21% in two studies by Arozullah et al. Nonetheless, we did record postoperative CVC in detail in our study, finding them in 36.6% of the patients with a PPC. Thirty-day mortality in this subgroup was 33.3%, which was similar to mortality in the study of Lawrence et al. and in sharp contrast with the rate of 11.5% we saw in patients with a PPC but no added CVC. Meanwhile, mortality in patients with a CVC but no PPC was low in our study (3.4%). We therefore think that although the cooccurrence of a PPC and a CVC is an ominous event, the PPC still play a large role in increasing risk of death. We emphasize that, although we analyzed factors associated with PPC, it was not our aim to examine how they might have arisen. Generally speaking, if a patient first develops a PPC, the clinical course that culminates in death may also include the development of cardiovascular or other complication that will influence the outcome. Conversely, if a PPC is not the first complication to appear, its later development nonetheless will play a role. Marret and Jaber suggest that anesthetic technique may play role in the development of PPC, and they specifically ask about the effect of combining general anesthesia with an epidural block. This subgroup accounted for 8.4% of our study population undergoing general anesthesia (n 1,336) and comprised patients who on average were older, in a poorer state of health, and undergoing more aggressive and longer-lasting surgical procedures. In a post hoc analysis of our data, we compared a group of 112 patients who underwent general anesthesia with another group of 112 who received combined general-epidural anesthesia, finding no significant differences in the incidence of PPC (18.8% vs. 20.5%, P 0.867) or pain intensity at 24 h (score of 3 or less on a visual analog pain scale, 56.3% vs. 67%, P 0.131) (statistical results from the ARISCAT database run on March 1, 2011). Thus, there seems to be no suggestion of a beneficial effect of combined anesthesia, although we must emphasize that our study was not designed to compare anesthetic strategies. We agree with Drs. Marret and Jaber that there is a possible influence of ventilatory settings on the development of PPC. The anesthesiologists in charge of care chose the settings in all cases in our study, and although our database includes recordings of positive end-expiratory pressures, alveolar recruitment maneuvers, and hyperoxygenation, we have no reliable information on tidal volume. Finally, with regard to fluid therapy and postoperative pain, we included both in the list of potential risk factors for PPC, but neither achieved statistical significance in the bivariable analysis. We agree with Drs. Marret and Jaber that different perioperative strategies might reduce risk; nonetheless, so far, systematic analysis has found that only a few have been shown to clearly or possibly do so, whereas others remain to be tried. We think controlled studies should now be designed to analyze the possible benefit of promising strategies given the impact of PPC on postoperative mortality. Our study has provided evidence of the magnitude of the problem in general surgical populations and the possibility of easily and reliably identifying patients at greater risk of PPC.

Failure of the Easy Cap II CO2 detector to indicate esophageal intubation

manufacturing defect. Recommendations for management of entrapped catheters have been derived largely from the management of entrapped epidural catheters [6,7]. As such, the literature suggests surgical intervention as the initial therapy of choice. In fact, surgery has been used almost exclusively in previous cases of entrapped Stimucath catheters. This case suggests the utility of consulting Interventional Radiology in removing entrapped peripheral nerve catheters before surgical intervention.