A new continuous noninvasive finger cuff device (Vitalstream) for cardiac output that communicates wirelessly via bluetooth or Wi-Fi.

BACKGROUND: The new noninvasive Vitalstream (VS) continuous physiological monitor (Caretaker Medical LLC, Charlottesville, Virginia), allows continuous cardiac output by a low pump-inflated, finger cuff that pneumatically couples arterial pulsations via a pressure line to a pressure sensor for detection and analysis. Physiological data are communicated wirelessly to a tablet-based user interface via Bluetooth or Wi-Fi. We evaluated its performance against thermodilution cardiac output in patients undergoing cardiac surgery. METHODS: We compared the agreement between thermodilution cardiac output to that obtained by the continuous noninvasive system during cardiac surgery pre and post-cardiac bypass. Thermodilution cardiac output was performed routinely when clinically indicated by an iced saline cold injectate system. All comparisons between VS and TD/CCO data were post-processed. In order to match the VS CO readings to the averaged discrete TD bolus data, the averaged CO readings of the ten seconds of VS CO data points prior to a sequence of TD bolus injections was matched. Time alignment was based on the medical record time and the VS time-stamped data points. The accuracy against reference TD measurements was assessed via Bland-Altman analysis of the CO values and standard concordance analysis of the ΔCO values (with a 15% exclusion zone). RESULTS: Analysis of the data compared the accuracy of the matched measurement pairs of VS and TD/CCO VS absolute CO values with and without initial calibration to the discrete TD CO values, as well as the trending ability, i.e., ΔCO values of the VS physiological monitor compared to those of the reference. The results were comparable with other non-invasive as well as invasive technologies and Bland-Altman analyses showed high agreement between devices in a diverse patient population. The results are significant regarding the goal of expanding access to effective, wireless and readily implemented fluid management monitoring tools to hospital sections previously not covered because of the limitations of traditional technologies. CONCLUSION: This study demonstrated that the agreement between the VS CO and TD CO was clinically acceptable with a percent error (PE) of 34.5 to 38% with and without external calibration. The threshold for an acceptable agreement between the VS and TD was considered to be below 40% which is below the threshold recommended by others.

The application of a neural network to predict hypotension and vasopressor requirements non-invasively in obstetric patients having spinal anesthesia for elective cesarean section (C/S).

BACKGROUND: Neural networks are increasingly used to assess physiological processes or pathologies, as well as to predict the increased likelihood of an impending medical crisis, such as hypotension. METHOD: We compared the capabilities of a single hidden layer neural network of 12 nodes to those of a discrete-feature discrimination approach with the goal being to predict the likelihood of a given patient developing significant hypotension under spinal anesthesia when undergoing a Cesarean section (C/S). Physiological input information was derived from a non-invasive blood pressure device (Caretaker [CT]) that utilizes a finger cuff to measure blood pressure and other hemodynamic parameters via pulse contour analysis. Receiver-operator-curve/area-under-curve analyses were used to compare performance. RESULTS: The results presented here suggest that a neural network approach (Area Under Curve [AUC] = 0.89 [p < 0.001]), at least at the implementation level of a clinically relevant prediction algorithm, may be superior to a discrete feature quantification approach (AUC = 0.87 [p < 0.001]), providing implicit access to a plurality of features and combinations thereof. In addition, the expansion of the approach to include the submission of other physiological data signals, such as heart rate variability, to the network can be readily envisioned. CONCLUSION: This pilot study has demonstrated that increased coherence in Arterial Stiffness (AS) variability obtained from the pulse wave analysis of a continuous non-invasive blood pressure device appears to be an effective predictor of hypotension after spinal anesthesia in the obstetrics population undergoing C/S. This allowed us to predict specific dosing thresholds of phenylephrine required to maintain systolic blood pressure above 90 mmHg.

Continuous Non-invasive finger cuff CareTaker® comparable to invasive intra-arterial pressure in patients undergoing major intra-abdominal surgery.

BACKGROUND: Despite increased interest in non-invasive arterial pressure monitoring, the majority of commercially available technologies have failed to satisfy the limits established for the validation of automatic arterial pressure monitoring by the Association for the Advancement of Medical Instrumentation (AAMI). According to the ANSI/AAMI/ISO 81060-2:2013 standards, the group-average accuracy and precision are defined as acceptable if bias is not greater than 5 mmHg and standard deviation is not greater than 8 mmHg. In this study, these standards are used to evaluate the CareTaker® (CT) device, a device measuring continuous non-invasive blood pressure via a pulse contour algorithm called Pulse Decomposition Analysis. METHODS: A convenience sample of 24 patients scheduled for major abdominal surgery were consented to participate in this IRB approved pilot study. Each patient was monitored with a radial arterial catheter and CT using a finger cuff applied to the contralateral thumb. Hemodynamic variables were measured and analyzed from both devices for the first thirty minutes of the surgical procedure including the induction of anesthesia. The mean arterial pressure (MAP), systolic and diastolic blood pressures continuously collected from the arterial catheter and CT were compared. Pearson correlation coefficients were calculated between arterial catheter and CT blood pressure measurements, a Bland-Altman analysis, and polar and 4Q plots were created. RESULTS: The correlation of systolic, diastolic, and mean arterial pressures were 0.92, 0.86, 0.91, respectively (p < 0.0001 for all the comparisons). The Bland-Altman comparison yielded a bias (as measured by overall mean difference) of -0.57, -2.52, 1.01 mmHg for systolic, diastolic, and mean arterial pressures, respectively with a standard deviation of 7.34, 6.47, 5.33 mmHg for systolic, diastolic, and mean arterial pressures, respectively (p < 0.001 for all comparisons). The polar plot indicates little bias between the two methods (90%/95% CI at 31.5°/52°, respectively, overall bias = 1.5°) with only a small percentage of points outside these lines. The 4Q plot indicates good concordance and no bias between the methods. CONCLUSIONS: In this study, blood pressure measured using the non-invasive CT device was shown to correlate well with the arterial catheter measurements. Larger studies are needed to confirm these results in more varied settings. Most patients exhibited very good agreement between methods. Results were well within the limits established for the validation of automatic arterial pressure monitoring by the AAMI.

Effects of dose ranging of adenosine infusion on electrocardiographic findings during and after general anesthesia.

PURPOSE: To assess changes in the electrocardiogram (ECG) associated with intraoperative infusion of adenosine in patients undergoing open abdominal gynecological surgery. METHODS: One hundred and sixty-six patients undergoing gynecological surgery were randomly assigned to receive one of four doses of adenosine infusion (25, 50, 100, or 200 µg/kg/min) or matching placebo. Study drug administration was started at skin incision and discontinued at end of surgery. A standardized general anesthetic regimen was used and adjusted based on hemodynamic and bispectral index values. Heart rate and rhythm variables, and PR, QRS, QT, and QTc intervals were recorded from 12-lead ECGs before anesthesia and immediately after patient arrival in the postanesthesia care unit. In addition, a rhythm strip was obtained during administration of the loading dose of the study drug. ECG variables were compared within and between groups. Incidence of ECG and hemodynamic abnormalities was recorded. RESULTS: One hundred and fifty-one subjects had a full set of electrocardiographic data: placebo (n = 38), group adenosine 25 µg/kg/min (n = 31), group adenosine 50 µg/kg/min (n = 29), group adenosine 100 µg/kg/min (n = 28), and group adenosine 200 µg/kg/min (n = 25). Statistically significant postoperative QTc prolongation was observed in all study groups when compared with baseline except for the adenosine 200 µg/kg/min group. However, these changes from baseline were not different among the groups. There were also no significant differences in PR, QRS, and QT intervals between the treatment groups. CONCLUSION: There was no difference in QTc prolongation following intraoperative administration of adenosine infusion compared with placebo during isoflurane general anesthesia. However, QTc prolongation is common following general anesthesia.

A Randomized Controlled Trial Comparing a Mapleson Circuit with Nasal Trumpet to Standard Oxygen Supplementation during EBUS Bronchoscopy under Monitored Anesthesia Care.

BACKGROUND: Endobronchial ultrasound (EBUS) procedures tend to be longer than routine bronchoscopies. Increased duration and sedative dosing put patients at increased risk for -hypoxic events. OBJECTIVE: To determine whether oxygen supplementation via a nasal trumpet connected to a Mapleson B circuit (NTM) was effective in decreasing hypoxic events when compared with the standard of care, oxygen supplementation with a nasal cannula (NC). METHODS: Patients referred for EBUS-guided transbronchial needle aspiration with monitored anesthesia care (MAC) were randomized 1:1 to NTM or to NC. Hypoxia-related procedural interruptions, the primary endpoint of the study, were documented for all patients. Patients in the NC group who had refractory desaturations were allowed to cross over to the NTM group. Secondary endpoints included: number of crossovers from NC to NTM, sedative dosing, total procedure times, whether procedure goals were achieved, complications apart from hypoxia, patient discharge status. RESULTS: Fifty-two patients were randomized to NC and 48 to NTM. Baseline characteristics were comparable. The NC group had significantly more interruptions than did the NTM group (p < 0.001). Procedure duration was also significantly (p < 0.03) shorter for the NTM group. Fourteen patients were crossed over from NC to NTM because of hypoxia. Thirteen out of the 14 completed the procedure with no interruptions. All procedures were successfully completed, and all goals were achieved. All patients returned to baseline status prior to discharge. Three minor complications of epistaxis occurred. CONCLUSION: For patients undergoing EBUS with MAC, oxygen supplementation with NTM significantly decreased the incidence of hypoxic events when compared with NC. NTM may also be of value for other subsets of patients who are at increased risk for desaturation when undergoing bronchoscopy.

Pain evaluation in patients receiving intravenous patient-controlled analgesia after surgery.

STUDY OBJECTIVE: To evaluate the effectiveness of intravenous patient-controlled analgesia (PCA) in patients after surgery. DESIGN: Prospective, observational study. SETTING: University teaching hospital. PATIENTS: Sixty patients with American Society of Anesthesiologists physical status I-III receiving intravenous PCA for postoperative pain. The PCA was programmed to deliver morphine 1 mg or hydromorphone 0.1-0.2 mg, with a lockout interval of 10 and 6 minutes for 80% and 20% of the patients, respectively. MEASUREMENTS AND MAIN RESULTS: Patients were asked, up to 4 times during PCA use and once within 4 hours after PCA use, to describe and rate their intensity of pain at rest and after activity. During the first 12 hours of intravenous PCA use, 75% of the patients reported moderate-to-severe pain > or = 5 on a verbal numeric rating scale) at rest, 80% after activity. Corresponding values, respectively, were 33% and 72% for the 12-24-hour period, 43% and 76% for the 24-36-hour period, and 36% and 64% for the 36-48-hour period of intravenous PCA use. Within 4 hours of stopping PCA, 30% and 58% of the patients had moderate-to-severe pain at rest and after activity, respectively. In approximately 50% of patients, presence of pain was described with words signifying sensory and affective dimensions of pain. Pain control was rated as good or very good by 54% of patients during the first 12 hours of intravenous PCA. Ratings of pain control tended to improve with time. CONCLUSION: Successful postoperative pain management using PCA is difficult to achieve on a consistent basis unless treatment is individualized. Our data support the hypothesis that small fixed doses fail to achieve adequate relief in many patients.

The number of injections does not influence absorption of bupivacaine after cervical plexus block for carotid endarterectomy.

STUDY OBJECTIVE: To investigate the efficacy and kinetics of bupivacaine when used for deep cervical plexus block (CPB), using either a single-injection or multiple-injections technique. DESIGN: Prospective, randomized, double-blind study. SETTING: Operating room of a university hospital. PATIENTS: Twenty-four adult patients (16 men, 8 women) scheduled for carotid endarterectomy. INTERVENTIONS: Patients were randomly assigned to receive CPB either by a single injection or after 3 injections. Patients in the multiple-injections group received a total dose of 15 mL of 0.5% bupivacaine (5 mL each deposited at C2, C3, and C4 over 2 minutes). Patients in the single-injection group received a single 15-mL injection of 0.5% bupivacaine. After the deep CPB, a superficial CPB was performed with 20 mL of 0.5% bupivacaine in all patients. MEASUREMENTS: An anesthesiologist and a surgeon graded the success of the block. Arterial plasma concentrations of bupivacaine were measured using liquid chromatography-mass spectroscopy. MAIN RESULTS: No significant differences were seen between the 2 groups with respect to the mean peak concentration of bupivacaine (single injection 2314 +/- 1385 ng/mL vs multiple injections 2255 +/- 1105 ng/mL) or time to reach the maximal concentration (time to maximum concentration [single injection 12.1 +/- 7.2 minutes vs multiple injections 12.5 +/- 3.9 minutes]). Furthermore, there were no significant differences in mean block scores between the single-injection and the multiple-injections groups, evaluated either by the anesthesiologists or the surgeon. CONCLUSIONS: The results of this study showed that the absorption of bupivacaine is independent of the number of injections after CPB, and that anesthesia for carotid endarterectomy may be accomplished successfully using either technique.

Bronchial stenosis secondary to epidermolysis bullosa successfully treated with bronchoscopic balloon dilatation.

Epidermolysis bullosa rarely affects lower airways. We present a case of lower airway involvement and stenosis successfully managed with flexible bronchoscopy and balloon dilation.

Polymerized bovine hemoglobin solution as a replacement for allogeneic red blood cell transfusion after cardiac surgery: results of a randomized, double-blind trial.

BACKGROUND: Blood loss leading to reduced oxygen-carrying capacity is usually treated with red blood cell transfusions. This study examined the hypothesis that a hemoglobin-based oxygen-carrying solution can serve as an initial alternative to red blood cell transfusion. METHODS: In a randomized, double-blind efficacy trial of HBOC-201, a total of 98 patients undergoing cardiac surgery and requiring transfusion were randomly assigned to receive either red blood cell units or HBOC-201 (Hemopure; Biopure Corporation, Cambridge, Mass) for the first three postoperative transfusions. Patients were monitored before and after transfusion, at discharge, and at 3 to 4 weeks after the operation for subsequent red blood cell use, hemodynamics, and clinical laboratory parameters. RESULTS: The use of HBOC-201 eliminated the need for red blood cell transfusions in 34% of cases (95% confidence interval 21%-49%). Patients in the HBOC group received a mean of 1.72 subsequent units of red blood cells; those who received red blood cells only received a mean of 2.19 subsequent units (P =.05). Hematocrit values were transiently lower in the HBOC group but were similar in the two groups at discharge and follow-up. Oxygen extraction was greater in the HBOC group (P =.05). Mean increases in blood pressure were greater in the HBOC group, but not significantly so. CONCLUSION: HBOC-201 may be an initial alternative to red blood cell transfusions for patients with moderate anemia after cardiac surgery. In a third of cases, HBOC-201 eliminated the need for red blood cell transfusion, although substantial doses were needed to produce this modest degree of blood conservation.

Analgesic and hemodynamic effects of a single 7.5-mg intravenous dose of morphine in patients with moderate-to-severe postoperative pain.

STUDY OBJECTIVES: To evaluate the analgesic and hemodynamic effects of a single dose of intravenous morphine 7.5 mg in patients experiencing moderate-to-severe postoperative pain, and to determine any gender differences in analgesic response. DESIGN: Randomized, double-blind, parallel-group, multicenter study. SETTING: Postanesthesia care unit of a university teaching hospital. PATIENTS: Eighty-eight patients who underwent total abdominal hysterectomy or prostatectomy. INTERVENTION: Thirty-seven patients received a single dose of morphine sulfate 7.5 mg and 51 patients received placebo, both administered intravenously for 1 minute. MEASUREMENTS AND MAIN RESULTS: Overall, morphine had no significant effect on systolic or diastolic blood pressure, heart rate, oxygen saturation, or respiratory rate. Compared with baseline, morphine significantly reduced pain intensity at 2, 5, and 10 minutes after administration (p<0.05). The difference in pain intensity between patients who received morphine and those who received placebo, however, was significant only at the 5-minute time point (p<0.02). Patients receiving morphine also reported mild pain relief at 2 and 5 minutes after its administration. Peak analgesic effect was reported 2 minutes after its administration in three quarters of the patients. Significant gender differences also were observed in response to analgesic effect. In women, no significant differences in pain intensity were seen at any time between the morphine and placebo groups, whereas in men receiving morphine, pain intensity was significantly less at 2, 5, and 10 minutes compared with baseline and that seen in the placebo group. Women were generally more satisfied with their pain treatment than were men. CONCLUSION: A single 7.5-mg intravenous bolus dose of morphine did not appear to provide adequate reduction in perceived pain intensity in patients with moderate-to-severe postoperative pain. In addition, in contrast to the findings of other experimental pain studies, our data suggest that women are more tolerant of postoperative pain than are men.

Simulation-based education with deliberate practice may improve intraoperative handoff skills: a pilot study.

STUDY OBJECTIVE: To examine the results of simulation-based education with deliberate practice on the acquisition of handoff skills by studying resident intraoperative handoff communication performances. DESIGN: Preinvention and postintervention pilot study. SETTING: Simulated operating room of a university-affiliated hospital. MEASUREMENTS: Resident handoff performances during 27 encounters simulating elective surgery were studied. Ten residents (CA-1, CA-2, and CA-3) participated in a one-day simulation-based handoff course. Each resident repeated simulated handoffs to deliberately practice with an intraoperative handoff checklist. One year later, 7 of the 10 residents participated in simulated intraoperative handoffs. All handoffs were videotaped and later scored for accuracy by trained raters. A handoff assessment tool was used to characterize the type and frequency of communication failures. The percentage of handoff errors and omissions were compared before simulation and postsimulation-based education with deliberate practice and at one year following the course. MAIN RESULTS: Initially, the overall communication failure rate, defined as the percentage of handoff omissions plus errors, was 29.7%. After deliberate practice with the intraoperative handoff checklist, the communication failure rate decreased to 16.8%, and decreased further to 13.2% one year after the course. CONCLUSIONS: Simulation-based education using deliberate practice may result in improved intraoperative handoff communication and retention of skills at one year.

Using Simulation Education With Deliberate Practice to Teach Leadership and Resource Management Skills to Senior Resident Code Leaders.

BACKGROUND: Cardiopulmonary arrests are rare, high-stakes events that benefit from using crisis resource management (CRM). Simulation-based education with deliberate practice can promote skill acquisition. OBJECTIVE: We assessed whether using simulation-based education to teach CRM would lead to improved performance, compared to a lecture format. METHODS: We tested third-year internal medicine residents in simulated code scenarios. Participants were randomly assigned to simulation-based education with deliberate practice (SIM) group or lecture (LEC) group. We created a checklist of CRM critical actions (which includes announcing the diagnosis, asking for help/suggestions, and assigning tasks), and reviewed videotaped performances, using a checklist of skills and communications patterns to identify CRM skills and communication efforts. Subjects were tested in simulated code scenarios 6 months after the initial assessment. RESULTS: At baseline, all 52 subjects recognized distress, and 92% (48 of 52) called for help. Seventy-eight percent (41 of 52) did not succeed in resuscitating the simulated patient or demonstrate the CRM skills. After intervention, both groups (n  =  26 per group) improved. All SIM subjects announced the diagnosis compared to 65% LEC subjects (17 of 26, P  =  .01); 77% (20 of 26) SIM and 19% (5 of 26) LEC subjects asked for suggestions (P < .001); and 100% (26 of 26) SIM and 27% (7 of 26) LEC subjects assigned tasks (P < .001). CONCLUSIONS: The SIM intervention resulted in significantly improved team communication and cardiopulmonary arrest management. During debriefing, participants acknowledged the benefit of the SIM sessions.

Case report: vibration response imaging findings following inadvertent esophageal intubation.

PURPOSE: We describe the effect that inadvertent esophageal intubation has on the images and on the vibration distribution of vibration response imaging (VRI). CLINICAL FEATURES: Vibration response imaging (VRI) is a novel, non-invasive, computer-based technology that measures vibration energy of lung sounds during respiration and displays regional intensity, in both visual and graphic format. Vibration response images, obtained prior to tracheal intubation (spontaneous breathing) and during endotracheal ventilation using a controlled mode, resulted in evenly distributed vibrations throughout the patient's lungs. During inadvertent esophageal ventilation, however, the majority of vibrations were detected in the upper regions of the image, compared to those of the lower (60% vs 8%, respectively). During spontaneous breathing and endotracheal ventilation, the midclavicular column of sensors, located over the centre of each lung, detected more vibrations compared to either the medial or the axillary column of sensors. During inadvertent esophageal ventilation, more vibrations were detected by the medial column of sensors (nearest to the midline/esophagus); and fewer were detected by the sensors that were positioned more laterally. CONCLUSION: This report illustrates the potential for a visual image of distribution of lung vibration energy to differentiate endotracheal intubation from inadvertent esophageal intubation.

A phase III, double-blind, placebo-controlled, multicenter study on the efficacy of recombinant human antithrombin in heparin-resistant patients scheduled to undergo cardiac surgery necessitating cardiopulmonary bypass.

BACKGROUND: The study evaluated the efficacy of recombinant human antithrombin (rhAT) for restoring heparin responsiveness in heparin resistant patients undergoing cardiac surgery. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled study in heparin-resistant patients undergoing cardiac surgery with cardiopulmonary bypass. Heparin resistance was diagnosed when the activated clotting time was less than 480 s after 400 U/kg heparin. Fifty-four heparin-resistant patients were randomized. One cohort received 75 U/kg rhAT, and the other received normal saline. If the activated clotting time remained less than 480 s, this was considered treatment failure, and 2 units fresh frozen plasma was transfused. Patients were monitored for adverse events. RESULTS: Only 19% of patients in the rhAT group received fresh frozen plasma, compared with 81% of patients in the placebo group (P < 0.001). During their hospitalization, 48% of patients in the rhAT group received fresh frozen plasma, compared with 85% of patients in the placebo group (P = 0.009). Patients in the placebo group required higher heparin doses (P < 0.005) for anticoagulation. There was no increase in serious adverse events associated with rhAT. There was increased blood loss 12 h postoperatively (P = 0.05) with a trend toward increased 24-h bleeding in the rhAT group (P = 0.06). There was no difference between the groups in blood and platelet transfusions. CONCLUSION: Treatment with 75 U/kg rhAT is effective in restoring heparin responsiveness and promoting therapeutic anticoagulation in the majority of heparin-resistant patients. Treating heparin-resistant patients with rhAT may decrease the requirement for heparin and fresh frozen plasma.