Dexmedetomidine infusion for analgesia up to 48 hours after lung surgery performed by lateral thoracotomy

Patients undergoing a lateral thoracotomy for pulmonary resection have moderate to severe pain postoperatively that is often treated with opioids. Opioid side effects such as respiratory depression can be devastating in patients with already compromised respiratory function. This prospective double-blinded clinical trial examined the analgesic effects and safety of a dexmedetomidine infusion for postthoracotomy patients when administered on a telemetry nursing floor, 24 to 48 hours after surgery, to determine if the drug's known early opioid-sparing properties were maintained. Thirty-eight thoracotomy patients were administered dexmedetomidine intraoperatively and overnight postoperatively and then randomized to receive placebo or dexmedetomidine titrated from 0.1 to 0.5 μg·kg·h(-1) the day following surgery for up to 24 hours on a telemetry floor. Opioids via a patient-controlled analgesia pump were available for both groups, and vital signs including transcutaneous carbon dioxide, pulse oximetry, respiratory rate, and pain and sedation scores were monitored. The dexmedetomidine group used 41% less opioids but achieved pain scores equal to those of the placebo group. The mean heart rate and systolic blood pressure were lower in the dexmedetomidine group but sedation scores were better. The mean respiratory rate and oxygen saturation were similar in the two groups. Mild hypercarbia occurred in both groups, but periods of significant respiratory depression were noted only in the placebo group. Significant hypotension was noted in one patient in the dexmedetomidine group in conjunction with concomitant administration of a beta-blocker agent. The placebo group reported a higher number of opioid-related adverse events. In conclusion, the known opioid-sparing properties of dexmedetomidine in the immediate postoperative period are maintained over 48 hours.

Sedation levels during propofol administration for outpatient colonoscopies

The levels of sedation required for patients to comfortably undergo colonoscopy with propofol were examined. One hundred patients undergoing colonoscopy with propofol were enrolled. In addition to standard-of-care monitoring, sedation level was monitored with the Patient State Index (PSI) obtained from a brain function monitor, transcutaneous carbon dioxide (tcpCO2) was monitored with the TCM TOSCA monitor, and end-tidal carbon dioxide was monitored via nasal cannula. The Ramsay Sedation Score (RSS) was also assessed and recorded. After baseline data were obtained from the first 40 consecutive patients enrolled in the study, the remaining 60 patients were randomized into two groups. In one group the PSI value was blinded from the anesthesiologist and in the second group the PSI was visible and the impact of this information on the management of the sedation was analyzed. Overall 96% of patients reached levels of deep sedation and 89% reached levels of general anesthesia. When comparing the blinded to PSI versus unblinded groups, the blinded group had a significantly lower PSI and higher RSS and tcpCO2, indicating the blinded group was maintained at a deeper sedation level with more respiratory compromise than the unblinded group. Patients undergoing colonoscopy under propofol sedation delivered by a bolus technique are frequently taken to levels of general anesthesia and are at risk for respiratory depression, airway obstruction, and hemodynamic compromise.

Incidence and severity of respiratory insufficiency detected by transcutaneous carbon dioxide monitoring after cardiac surgery and intensive care unit discharge

Patients undergoing coronary artery bypass surgery and/or heart valve surgery using a median sternotomy approach coupled with the use of cardiopulmonary bypass often experience pulmonary complications in the postoperative period. These patients are initially monitored in an intensive care unit (ICU) but after discharge from this unit to the ward they may still have compromised pulmonary function. This dysfunction may progress to significant respiratory failure that will cause the patient to return to the ICU. To investigate the severity and incidence of respiratory insufficiency once the patient has been discharged from the ICU to the ward, this study used transcutaneous carbon dioxide monitoring to determine the incidence of unrecognized inadequate ventilation in 39 patients undergoing the current standard of care. The incidence and severity of hypercarbia, hypoxia, and tachycardia in post-cardiac surgery patients during the first 24 hours after ICU discharge were found to be high, with severe episodes of each found in 38%, 79%, and 44% of patients, respectively.

Chylopericardium following orthotopic lung transplantation

Chylopericardium is an uncommon condition, reported to occur following routine cardiac surgery, orthotopic heart transplantation, cardiac trauma, intrathoracic tumors, or infection. It has not, to date, been reported following uncomplicated orthotopic lung transplantation. This article describes chylopericardium following bilateral orthotopic lung transplantation.

The accuracy, precision and reliability of measuring ventilatory rate and detecting ventilatory pause by rainbow acoustic monitoring and capnometry

BACKGROUND

Current methods for monitoring ventilatory rate have limitations including poor accuracy and precision and low patient tolerance. In this study, we evaluated a new acoustic ventilatory rate monitoring technology for accuracy, precision, reliability, and the ability to detect pauses in ventilation, relative to capnometry and a reference method in postsurgical patients.

METHODS

Adult patients presenting to the postanesthesia care unit were connected to a Pulse CO-Oximeter with acoustic monitoring technology (Rad-87, version 7804, Masimo, Irvine, CA) through an adhesive bioacoustic sensor (RAS-125, rev C) applied to the neck. Each subject also wore a nasal cannula connected to a bedside capnometer (Capnostream20, version 4.5, Oridion, Needham, MA). The acoustic monitor and capnometer were connected to a computer for continuous acoustic and expiratory carbon dioxide waveform recordings. Recordings were retrospectively analyzed by a trained technician in a setting that allowed for the simultaneous viewing of both waveforms while listening to the breathing sounds from the acoustic signal to determine inspiration and expiration reference markers within the ventilatory cycle without using the acoustic monitor- or capnometer-calculated ventilatory rate. This allowed the automatic calculation of a reference ventilatory rate for each device through a software program (TagEditor, Masimo). Accuracy (relative to the respective reference) and precision of each device were estimated and compared with each other. Sensitivity for detection of pauses in ventilation, defined as no inspiration or expiration activity in the reference ventilatory cycle for ≥30 seconds, was also determined. The devices were also evaluated for their reliability, i.e., the percentage of the time when each displayed a value and did not drop a measurement.

RESULTS

Thirty-three adults (73% female) with age of 45 ± 14 years and weight 117 ± 42 kg were enrolled. A total of 3712 minutes of monitoring time (average 112 minutes per subject) were analyzed across the 2 devices, reference ventilatory rates ranged from 1.9 to 49.1 bpm. Acoustic monitoring showed significantly greater accuracy (P = 0.0056) and precision (P- = 0.0024) for respiratory rate as compared with capnometry. On average, both devices displayed data over 97% of the monitored time. The (0.95, 0.95) lower tolerance limits for the acoustic monitor and capnometer were 94% and 84%, respectively. Acoustic monitoring was marginally more sensitive (P = 0.0461) to pauses in ventilation (81% vs 62%) in 21 apneic events.

CONCLUSIONS

In this study of a population of postsurgical patients, the acoustic monitor and capnometer both reliably monitored ventilatory rate. The acoustic monitor was statistically more accurate and more precise than the capnometer, but differences in performance were modest. It is not known whether the observed differences are clinically significant. The acoustic monitor was more sensitive to detecting pauses in ventilation. Acoustic monitoring may provide an effective and convenient means of monitoring ventilatory rate in postsurgical patients.

Use of dexmedetomidine versus general anesthesia for endovascular repair of abdominal aortic aneurysms

While abdominal aortic aneurysms have traditionally been treated with a major open surgical procedure, minimally invasive endovascular techniques are much less traumatic, with significantly less strain on the heart and vital organs. A sedation technique using dexmedetomidine, an alpha 2-adrenoreceptor agonist, was developed for this procedure. We retrospectively reviewed records of 231 patients who underwent endovascular repair of abdominal aortic aneurysms at the Baylor Jack and Jane Hamilton Heart and Vascular Hospital from January 1, 2001, until September 30, 2005. Intraoperative and early postoperative data of 14 patients who had endovascular repairs using the dexmedetomidine sedation technique were compared with those of 22 patients who received general endotracheal tube anesthesia for the procedure during the time period of January 1, 2003, through September 1, 2005. The surgery and anesthesia times were shorter in the dexmedetomidine group, and less opioid medication was required. In addition, the postoperative pain scores were lower, and the need for postoperative pain medication was less in the dexmedetomidine group. This retrospective analysis demonstrates that a dexmedetomidine sedation technique offers a successful alternative to routine general anesthesia for endovascular repair of abdominal aortic aneurysms.

Evaluation of the SEDline to improve the safety and efficiency of conscious sedation

Brain function monitors have improved safety and efficiency in general anesthesia; however, they have not been adequately tested for guiding conscious sedation for periodontal surgical procedures. This study evaluated the patient state index (PSI) obtained from the SEDline monitor (Sedline Inc., San Diego, CA) to determine its capacity to improve the safety and efficiency of intravenous conscious sedation during outpatient periodontal surgery. Twenty-one patients at the periodontics clinic of Baylor College of Dentistry were admitted to the study in 2009 and sedated to a moderate level using midazolam and fentanyl during periodontal surgery. The PSI monitoring was blinded from the clinician, and the following data were collected: vital signs, Ramsay sedation scale (RSS), medications administered, adverse events, PSI, electroencephalography, and the patients' perspective through visual analogue scales. The data were correlated to evaluate the PSI's ability to assess the level of sedation. Results showed that the RSS and PSI did not correlate (r = -0.25) unless high values associated with electromyographical (EMG) activity were corrected (r = -0.47). Oxygen desaturation did not correlate with the PSI (r = -0.08). Satisfaction (r = -0.57) and amnesia (r = -0.55) both increased as the average PSI decreased. In conclusion, within the limits of this study, PSI appears to correlate with amnesia, allowing a practitioner to titrate medications to that effect. It did not provide advance warning of adverse events and had inherent inaccuracies due to EMG activity during oral surgery. The PSI has the potential to increase safety and efficiency in conscious sedation but requires further development to eliminate EMG activity from confounding the score.

Tracheal resection in the morbidly obese patient: the role of dexmedetomidine

We present a case of respiratory distress in a morbidly obese woman, which was complicated by a severe tracheal stenosis of the third to sixth cartilage. She had a history of sleep apnea and could only breathe sitting upright. An anesthetic, technique using dexmedetomidine was selected because of its properties of anxiolysis and sedation, with lack of respiratory depression. No intraoperative or postoperative opioids were required. Dexmedetomidine in high doses offers another approach to managing the patient with a compromised airway. Opioids were avoided in this patient, who was at major risk of postoperative respiratory depression and sleep apnea.

Outcomes of a pain management educational initiative at Baylor University Medical Center

Baylor University Medical Center established a pain initiative group in 1996 to research the effectiveness of pain management throughout the hospital. After analyzing 300 patient surveys, the group undertook an intensive program to educate physicians, nurses, and patients regarding newer pain management techniques. The outcome of this educational initiative was reassessed in 2001 based on surveys completed by 100 patients after discharge. Results showed marked improvement in patient education regarding pain management. In 2001, 93% of patients were offered education and choices regarding pain management vs only 36% in 1996. Fewer patients were afraid to "bother" their nurses to ask for pain medication (3% in 2001 vs 14% in 1996). Waiting time for administration of analgesics decreased considerably. The number of patients reporting moderate to severe pain decreased significantly since 1996, yet the overall satisfaction with pain relief remained high and did not change significantly. The overall incidence of patients reporting moderate to severe pain was significantly less at Baylor than the national average. In conclusion, attitudes, misconceptions, and fears about pain management can be changed with intensive educational programs.

Pharmacokinetic analysis of rapacuronium and its metabolite during liver transplantation: an assessment of its potential as a pharmacodynamic probe

The liver extracts aminosteroidal neuromuscular blocking drugs. We hypothesized that the duration of action of these drugs might provide a pharmacodynamic probe for assessing graft function during orthotopic liver transplantation. The pharmacokinetics of rapacuronium and its active metabolite, ORG 9488, were prospectively studied in 11 patients. Rapacuronium (1.5 mg/kg) was administered at induction of anesthesia, 2 minutes after clamping the portal vein, and 5 minutes after reperfusion of the new graft. Blood samples were drawn at intervals, and an independent laboratory analyzed plasma for both rapacuronium and ORG 9488. Rapacuronium's pharmacokinetics were characterized for 3 stages of the transplant using NONMEM software to construct mixed-effects compartmental models. Rapacuronium plasma clearance during the first stage of orthotopic liver transplantation was 7.25 mL/kg/min. Clearance decreased by only 44% during the anhepatic stage, to 3.91 mL/kg/min, and remained decreased after reperfusion. This effect suggests that an alternate clearance pathway exists. The clearance for ORG 9488 was 13.5 mL/kg/min during the paleohepatic and anhepatic stages, but it decreased 83% on reperfusion, suggesting accumulation after reperfusion. This pharmacokinetic analysis suggests that rapacuronium may not be suitable for use as a pharmacodynamic probe.

Continuous transesophageal echo-Doppler assessment of hemodynamic function during laparoscopic cholecystectomy

STUDY OBJECTIVE

The objective of this study was to examine the utility of the transesophageal echo-Doppler device in evaluating hemodynamic changes during laparoscopic cholecystectomy.

DESIGN

This was a prospective, controlled, observational open study.

SETTING

The study took place in a university hospital.

PATIENTS

Twenty patients with ASA physical statuses II and III undergoing laparoscopic cholecystectomy were enrolled into the study.

INTERVENTIONS AND MEASUREMENTS

A standardized general anesthetic and surgical technique was used for all patients. Similar depth of hypnosis (using bispectral index monitoring) was maintained in all patients. Hemodynamic parameters including mean arterial pressure (MAP), cardiac index (CI), left ventricular (LV) ejection time interval indexed to the heart rate, maximum acceleration, peak velocity, and systemic vascular resistance (SVR) were recorded at predetermined intervals: before incision, after peritoneal CO(2) insufflation and head-up tilt, every 10 minutes thereafter, and after deflation of the abdomen and return to supine position.

MAIN RESULTS

The transesophageal echo-Doppler probe placement was achieved in 3 to 5 minutes in all patients, and the probe position was maintained after creation of pneumoperitoneum and change in positioning. Induction of pneumoperitoneum and head-up tilt resulted in a significant increase in MAP and SVR (P < .05) that remained higher until deflation. The CI, LV ejection time interval indexed to the heart rate (a measure of LV filling), and maximum acceleration (a measure of contractility and global ventricular function) remained stable.

CONCLUSIONS

The transesophageal echo-Doppler device can be used during laparoscopic cholecystectomy. The LV function, as determined by measurement of CI and maximum acceleration, was preserved during laparoscopic cholecystectomy despite significant increases in afterload (ie, MAP and SVR).

AANA journal course: update for nurse anesthetists. The SLAM Emergency Airway Flowchart: a new guide for advanced airway practitioners

Advanced airway practitioners in anesthesiology, emergency medicine, and prehospital care can suddenly and unexpectedly face difficult airway situations that can surface without warning during mask ventilation or tracheal intubation. Although tracheal intubation remains the "gold standard" in airway management, it is not always achievable, and, when it proves impossible, appropriate alternative interventions must be used rapidly to avoid serious morbidity or mortality. The SLAM Emergency Airway Flowchart (SEAF) is intended to prevent the 3 reported primary causes of adverse respiratory events (ie, inadequate ventilation, undetected esophageal intubation, and difficult intubation). The 5 pathways of the SEAF include primary ventilation, rapid-sequence intubation, difficult intubation, rescue ventilation, and cricothyrotomy. It is intended for use with adult patients by advanced airway practitioners competent in direct laryngoscopy, tracheal intubation, administration of airway drugs, rescue ventilation, and cricothyrotomy. The SEAF has limitations (eg, suitable only for use with adult patients, cannot be used by certain categories of rescue personnel, and depends heavily on assessment of Spo2). A unique benefit is provision of simple alternative techniques that can be used when another technique fails.

Hepatopulmonary syndrome and portopulmonary hypertension: a report of the multicenter liver transplant database

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PortoPH) are pulmonary vascular consequences of advanced liver disease associated with significant mortality after orthotopic liver transplantation (OLT). Data from 10 liver transplant centers were collected from 1996 to 2001 that characterized the outcome of patients with either HPS (n = 40) or PortoPH (n = 66) referred for OLT. Key variables (PaO2 for HPS, mean pulmonary artery pressure [MPAP], pulmonary vascular resistance [PVR], and cardiac output [CO] for PortoPH) were analyzed with respect to 3 definitive outcomes (those denied OLT, transplant hospitalization survivors, and transplant hospitalization nonsurvivors). OLT was denied in 8 of 40 patients (20%) with HPS and 30 of 66 patients (45%) with PortoPH. Patients with HPS who were denied OLT had significantly worse PaO2 compared with patients who underwent transplantation (47 vs. 52 mm Hg, P <.005). Transplant hospitalization survival was associated with higher pre-OLT PaO2 (55 vs. 37 mm Hg; P <.005). MPAP was significantly higher (53 vs. 45 mm Hg; P <.015) and PVR was significantly worse (614 vs. 335 dynes. s. cm(-5); P <.05) in patients with PortoPH who were denied OLT compared with patients who underwent transplantation. Transplant hospitalization mortality was 16% (5/32) in patients with HPS and 36% (13/36) in patients with PortoPH. All of the deaths in patients with PortoPH occurred within 18 days of OLT; 5 of the 13 deaths in patients with PortoPH occurred intraoperatively. We concluded that patients with HPS (based on a combination of low PaO2 and nonpulmonary factors) and patients with PortoPH (based on pulmonary hemodynamics) were frequently denied OLT because of pre-OLT test results and comorbidities. For patients who subsequently underwent OLT, transplant hospitalization mortality remained significant for both those with HPS (16%) and PortoPH (36%).

Intravascular thrombosis and thromboembolism during liver transplantation: antifibrinolytic therapy implicated?

This case report describes a patient who underwent orthotopic liver transplantation and developed extensive hyperacute venous and arterial intravascular thromboses and thromboemboli intraoperatively. The patient was receiving antifibrinolytic therapy with aprotinin. The safety of routine aprotinin therapy in liver transplantation is examined. The value of the thrombelastograph (TEG) as a qualitative assessment of the coagulation system is emphasized.

Straight talk. New approaches in healthcare. Managing medical research: strategies for success

Medical research programs are under significant pressure both from declines in the growth rates of government funding as well as from increases in government oversight of the privacy and safety of human research subjects. To cope, forward-thinking healthcare institutions are applying the same no-nonsense business rules to their research programs that they apply to other programs and departments. Modern Healthcare and PricewaterhouseCoopers present Straight Talk. In the session on medical research, we discuss how and why the world of medical research is changing, and what health systems should do to manage research programs successfully. The session was held on March 4, 2003 at Modern Healthcare's Chicago headquarters. Charles S. Lauer, publisher of Modern Healthcare, was the moderator.