Donald Mathews

Sedation for medical procedures is provided in a variety of clinical settings by medical personnel with differing levels of education and training. Although generally a safe practice, there is a degree of morbidity and mortality associated with sedation practice. Monitoring standards continue to be refined by professional societies with the goal of improving care. The depth of sedation should be monitored with clinical criteria. Processed electroencephalographic monitors currently do not contribute significantly to sedation care. Monitoring ventilation using pulse oximetry should be abandoned for more direct methods, such as capnography-transcutaneous carbon dioxide, respiratory acoustical and thoracic impedance monitoring could also play a role. Propofol has become widely utilized for sedation, although there are concerns about its margin of safety and synergistic interactions with other agents. Dexmedetomidine and propofol/ketamine also have utility. Patient-controlled sedation pu...

Assess the utility of a respiratory volume monitor (RVM) to reduce the incidence of low minute ventilation events in procedural sedation. Randomized control trial SETTING: Endoscopy suite PATIENTS: Seventy-three total patients (ASA Physical Status 1-3) undergoing upper endoscopies were analyzed. Patients were randomized into two groups using a computer generated randomization table: Control (n=41): anesthesia provider was unable to see the screen of the RVM; RVM (n=32): anesthesia provider had access to RVM data to assist with management of the case. Minute ventilation (MV), tidal volume, and respiratory rate were continuously recorded by the RVM. MV is presented as percent of Baseline MV (MV), defined during a 30s period of quiet breathing prior to sedation. We defined Low MV as MV<40% MV, and calculated the percentage of procedure spent with Low MV. Patients in the RVM group were stratified based on whether the anesthesiologist rated the RVM as "not useful", "som...

Utilization of fuel in clinical conditions has become an important area of interest to the clinician. Injury and sepsis cause predictable changes in the metabolism of fuel, favoring a shift toward the oxidation of fat. Similar considerations apply to the tumor-bearing host.

Successful ambulatory surgery begins with proper selection and screening of patients. It then requires intelligent perioperative management of the medical issues that have been identified during the preoperative evaluation. Both of these areas, preoperative evaluation and perioperative management, are constantly evolving, and maintaining a current knowledge base is a challenge for the busy ambulatory anesthesiologist.

Endoscopic procedures performed under conscious sedation require careful monitoring of respiratory status to prevent adverse outcomes. This study utilizes a non-invasive respiratory volume monitor (RVM) that provides continuous real-time measurements of minute ventilation (MV), tidal volume and respiratory rate (RR) to assess the adequacy of ventilation during endoscopy. Digital respiratory traces were collected from 51 patients undergoing upper endoscopy with propofol sedation using an impedance-based RVM. Baseline MV for each patient was derived from a 30 s period of quiet breathing prior to sedation (MVBASELINE). Capnography data were also collected. Because RR from capnography was frequently unavailable, the RVM RR's were used for analysis. RR rate values were compared the MV measurements and sensitivity and specificity of RR to predict inadequate ventilation (MV <40 % MVBASELINE) were calculated. Initial analysis revealed that there is a weak correlation between an MV measurement and its corresponding RR measurement (r = 0.05). If MV is an actual indictor of respiratory performance, using RR as a proxy is grossly inadequate. Simulating a variety of RR alarm conditions [4-8 breaths/min (bpm)] showed that a substantial fraction of low MV measurements (MV <40 % MVBASELINE) went undetected (at 8 bpm, >70 % low MV measurements were missed; at 6 bpm, >82 % were missed; and at 4 bpm, >90 % were missed). A cut-off of 6 bpm had a sensitivity of only 18.2 %; while <40 % of all RR alarms would have coincided with a low MV (39.4 % PPV). Low RR measurements alone do not reflect episodes of low MV and are not sufficient for accurate assessment of respiratory status. RVM provides a new way to collect MV measurements which provide more comprehensive data than RR alone. Further work is ongoing to evaluate the use of MV data during procedural sedation.

Observational studies on pediatric anesthesia neurotoxicity have been unable to distinguish long-term effects of general anesthesia (GA) from factors associated with the need for surgery. A recent study on elementary school children who had received a single GA during the first year of life demonstrated an association in otherwise healthy children between the duration of anesthesia and diminished test scores and also revealed a subgroup of children with "very poor academic achievement" (VPAA), scoring below the fifth percentile on standardized testing. Analysis of postoperative cognitive function in a similar cohort of children anesthetized with an alternative to GA may help to begin to separate the effects of anesthesia from other confounders. We used a novel methodology to construct a combined medical and educational database to search for these effects in a similar cohort of children receiving spinal anesthesia (SA) for the same procedures. We compared former patients with a control population of students matched by grade, gender, year of testing, and socioeconomic…

ABSTRACT Patient Safety PostersSESSION TYPE: Original Investigation PosterPRESENTED ON: Wednesday, October 30, 2013 at 01:30 PM - 02:30 PMPURPOSE: Upper endoscopic procedures are generally performed under conscious sedation which requires careful monitoring of respiratory status to prevent adverse outcomes. Effective monitoring remains difficult with current technology. While both capnography and pulse oximetry are capable of detecting severe adverse events, neither is sensitive enough to detect early signs of hypoventilation. This study evaluates the use of a novel, non-invasive Respiratory Volume Monitor (RVM) to quantify ventilation before, during, and after endoscopic procedures. The RVM has been shown to be capable of detecting changes in ventilation potentially predicting and preventing life-threatening hypoventilation.METHODS: Thirteen patients (age: 54 ± 5 years, BMI: 29 ± 2 kg/m2) undergoing endoscopic procedures were monitored using an RVM (ExSpiron™, Respiratory Motion, Inc., Waltham, MA). During the study, real-time minute ventilation (MV), tidal volume (TV), and respiratory rate (RR) were recorded. All patients were sedated with propofol and airway maneuvers (chin-lifts and jaw-thrusts) were performed as needed to maintain airway patency during the procedure. These procedures included endoscopic ultrasound (n = 4), esophagogastroduodenoscopy (n = 5), gastroscopy (n = 1), and endoscopic retrograde cholangiopancreatography (n = 3).RESULTS: Prior to sedation (baseline), the RVM recorded an average MV of 10.3 ± 0.9 L/min, TV of 710 ± 70 mL, and RR of 15.6 ± 1.2 breaths/min. A nadir in ventilation occurred 25 minutes after the last dose of propofol with a significant reduction in MV to 6.8 ± 1.0 L/min, (-30%±9%, p<0.05) and TV to 470 ± 50 mL (-22%±10%, p<0.05) with a small, non-significant reduction in RR to14.3 ± 1.5 breaths/min, (-4.8%±10%, p=0.48) relative to baseline. In 10 of the patients, 20 airway maneuvers were performed to improve ventilation. MV was significantly increased immediately following an airway maneuver (from 5.1 ± 0.7 L/min to 6.7 ± 0.8 L/min, an increase of 31%, p<0.05).CONCLUSIONS: These results show that the RVM can be a useful tool to assess the adequacy of ventilation in the endoscopic environment.CLINICAL IMPLICATIONS: Continuous non-invasive monitoring with the RVM can help clinicians quantify the degree of respiratory depression induced by sedatives and narcotics, as well as evaluate the effectiveness of airway management in real time, potentially minimizing adverse outcomes and improving patient safety.DISCLOSURE: Lisa Campana: Employee: Respiratory Motion, Inc. Diane Ladd: Employee: Respiratory Motion, Inc. Jonathan Lee: Employee: Respiratory Motion. Inc. The following authors have nothing to disclose: Katherine Holley, Donald Mathews, Howard SchapiroNo Product/Research Disclosure Information.

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A 34-yr-old man, possibly opiate tolerant, underwent the second part of a scoliosis repair. We describe a narcotic titration protocol by using facial electromyography data derived from the bispectral index monitor that resulted in a good clinical outcome.

The administration of nitrous oxide (N2O) may be associated with side effects and toxicities. Remifentanil shares characteristics with N2O, including MAC-reducing and antinociceptive effects and a rapid decrease in clinical effect when discontinued. We compared the outcome after ambulatory orthopedic surgery with desflurane and fentanyl supplemented with clinically equivalent doses of either N2O or remifentanil. Seventy patients undergoing ambulatory orthopedic surgery were studied. Thirty-five received 66% N2O and 35 received remifentanil 0.085 microg x kg(-1) x min(-1) in addition to desflurane, titrated to a bispectral index (BIS) value of 50, and a fentanyl infusion. The principle outcome measure was time to awakening to verbal stimulation. Secondary outcome measures included neuropsychological testing, time to orientation, hemodynamic values, pain and nausea visual analog scores, discharge times, and satisfaction scores. The average end-tidal desflurane concentration and fentanyl effect-site concentration were determined. The median time (interquartile range) to awakening to verbal stimulation, 3.0 min (3.0-5.0 min) in the remifentanil group and 4.6 min (3.0-8.1 min) in the N2O group was not significantly different. Median time to orientation was significantly faster in the remifentanil group: 6.0 min (5.0-8.5 min) compared with 8.0 min (5.0-12.8 min) for the N2O group. There was no difference between groups in desflurane or fentanyl administration, neuropsychological testing, or any other outcome measure. This study demonstrates that a remifentanil infusion of 0.085 microg x kg(-1) x min(-1) may be substituted for 66% N2O during desflurane/fentanyl anesthesia without any clinically significant change in outcome.