Thermodilution and esophageal Doppler ultrasound in the assessment of blood flow changes induced by endotoxin and dobutamine

BACKGROUND: Intermittent (IT) and continuous (CT) thermodilution and esophageal Doppler (ED), are all used for hemodynamic monitoring. The aim of this study was to test the agreement between these methods during endotoxin (ET) and dobutamine infusion. METHODS: Twenty-two pigs (39 +/- 1.8 kg body weight) were randomized to general anesthesia and either continuous ET (n = 9) or placebo (PL, n = 13) infusion. After 18 hours of ET or PL infusion, the animals were further randomized to receive dobutamine (n = 3 in ET, n = 5 in PL) or PL. A set of measurements using the three methods were obtained every hour, and the relative blood flow changes between two subsequent measurements were calculated. RESULTS: Bias or limits of agreement for flows were 0.73 L/min or 1.80 L/min for IT and CT, -0.33 L/min or 4.29 L/min for IT and ED, and -1.06 or 3.94 for CT and ED (n = 515, each). For flow changes they were 1% or 44%, 2% or 59%, and 3% or 45%, respectively. Bias and limits of agreement did not differ in ET- and PL-treated animals or in animals with or without dobutamine. Despite significant correlation between any two methods, the respective correlation coefficients (r) were small (IT vs. CT: 0.452; IT vs. ED: 0.042; CT vs. ED: 0.069; all p < 0.001). The same directional changes were measured by any two methods in 49%, 40%, and 50%. When IT flows >5 L/min were compared with IT flows 5 L/min.

The immediate and sustained effects of volume challenge on regional blood flows in pigs

BACKGROUND: The postoperative assessment of volume status is not straightforward because of concomitant changes in intravascular volume and vascular tone. Hypovolemia and blood flow redistribution may compromise the perfusion of the intraabdominal organs. We investigated the effects of a volume challenge in different intra- and extraabdominal vascular beds. METHODS: Twelve pigs were studied 6 h after major intraabdominal surgery under general anesthesia when clinically normovolemic. Volume challenges consisted of 200 mL rapidly infused 6% hydroxyethyl starch. Systemic (continuous thermodilution) and regional (ultrasound Doppler) flows in carotid, renal, celiac trunk, hepatic, and superior mesenteric arteries and the portal vein were continuously measured. The acute and sustained effects of the challenge were compared with baseline. RESULTS: Volume challenge produced a sustained increase of 22% +/- 15% in cardiac output (P < 0.001). Blood flow increased by 10% +/- 9% in the renal artery, by 22% +/- 15% in the carotid artery, by 26% +/- 15% in the superior mesenteric artery, and by 31% +/- 20% in the portal vein (all P < 0.001). Blood flow increases in the celiac trunk (8% +/- 13%) and the hepatic artery (7% +/- 19%) were not significant. Increases in regional blood flow occurred early and were sustained. Mean arterial and central venous blood pressures increased early and decreased later (all P < 0.05). CONCLUSIONS: A volume challenge in clinically euvolemic postoperative animals was associated with a sustained increase in blood flow to all vascular beds, although the increase in the celiac trunk and the hepatic artery was very modest and did not reach statistical significance. Whether improved postoperative organ perfusion is accompanied by a lower complication rate should be evaluated in further studies.

Percutaneous vertebroplasty, kyphoplasty and lordoplasty: implications for the anesthesiologist

PURPOSE OF REVIEW: Vertebroplasty, kyphoplasty and lordoplasty are minimally invasive procedures mainly performed for refractory pain due to osteoporotic vertebral body fractures. This review summarizes recent findings on outcome, complications and their impact on anesthetic management. RECENT FINDINGS: Despite an increasing number of publications on surgical technique, therapeutic efficacy and side effects of these interventions, anesthetic management per se is hardly investigated. All three treatments provide similar pain relief. Adverse effects include local cement leakage and new fractures adjacent to augmented vertebrae. Asymptomatic pulmonary cement embolism occurs in 4.6-6.8% of patients depending on cement viscosity, injection pressure and number of injected vertebrae. Potentially life-threatening embolism of cement or fat may occur. Kyphoplasty and lordoplasty aim at correcting vertebral deformity and are equally effective; lordoplasty is substantially less expensive, however. The incidence of systemic cement or fat embolism is similar to that in vertebroplasty. Whereas vertebroplasty is mostly performed under local anesthesia and sedation, general anesthesia is required for kyphoplasty and lordoplasty. The anesthetic regimen follows the principles of anesthesia in the elderly population. SUMMARY: Vertebroplasty, kyphoplasty and lordoplasty are effective minimally invasive treatments for stable vertebral compression fractures without compression of the spinal canal. The anesthesiologist must be prepared to manage systemic cement or fat embolism.

Cardioverter-defibrillator implantation in the catheterization laboratory: initial experiences in 48 patients

The exponential increase in cardioverter-defibrillator implantations has resulted in a need for safe implantations that do not require long waiting periods. We report intraoperative and follow-up results in 48 patients with ventricular tachyarrhythmias who underwent cardioverter-defibrillator implantation in the catheterization laboratory. Twenty-six (54%) patients had their first cardioverter-defibrillator implant (group 1), and 22 (46%) patients underwent pulse-generator replacement (group 2). In all patients, cardioverter-defibrillator implant or pulse-generator replacement was performed with the patient under general anesthesia. In 25 (96%) of 26 patients in group 1, cardioverter-defibrillator implantation was possible with a mean defibrillation threshold of 13 +/- 8 J. One patient had a defibrillation threshold of > 25 J, and therefore cardioverter-defibrillator implant was not achieved. This patient underwent epicardial device implantation 1 day later. Another patient in group 1 had vessel rupture (vena subclavia) intraoperatively. During a mean follow-up of 2 +/- 1 months, two patients died from congestive heart failure 2 and 4 months after device implantation. An infection occurred in one patient in group 2, 3 months after generator replacement. In conclusion, these data show that in the majority of patients cardioverter-defibrillator implantation in the catheterization laboratory is safe and has a low complication rate and therefore can generally be recommended.

Late results after percutaneous closure of patent foramen ovale for secondary prevention of paradoxical embolism using the amplatzer PFO occluder without intraprocedural echocardiography: effect of device size

OBJECTIVES: We sought to assess the safety and clinical efficacy of patent foramen ovale (PFO) closure under fluoroscopic guidance only, without intraprocedural echocardiography. BACKGROUND: Percutaneous PFO closure has been shown to be safe and feasible using several devices. It is generally performed using simultaneously fluoroscopic and transesophageal or intracardiac echocardiographic guidance. Transesophageal echocardiography requires sedation or general anesthesia and intubation to avoid aspiration. Intracardiac echocardiography is costly and has inherent risks. Both lengthen the procedure. The Amplatzer PFO Occluder (AGA Medical Corporation, Golden Valley, Minnesota) can be safely implanted without echocardiographic guidance. METHODS: A total of 620 patients (51 +/- 12 years; 66% male) underwent PFO closure using the Amplatzer PFO Occluder for secondary prevention of presumed paradoxical embolism. Based on size and mobility of the PFO and the interatrial septum, an 18-mm device was used in 50 patients, a 25-mm device in 492, and a 35-mm device in 78. RESULTS: All procedures were successful, with 5 procedural complications (0.8%): 4 arteriovenous fistulae requiring elective surgical correction, and 1 transient ischemic attack. Contrast transesophageal echocardiography at 6 months showed complete closure in 91% of patients, whereas a minimal, moderate, or large residual shunt persisted in 6%, 2%, and 1%, respectively. During a mean follow-up period of 3.0 +/- 1.9 years (median: 2.6 years; total patient-years: 1,871), 5 ischemic strokes, 8 transient ischemic attacks, and no peripheral emboli were reported. Freedom from recurrent ischemic stroke, transient ischemic attack, or peripheral embolism was 99% at 1 year, 99% at 2 years, and 97% at 5 years. CONCLUSIONS: The Amplatzer PFO Occluder affords excellent safety and long-term clinical efficacy of percutaneous PFO closure without intraprocedural echocardiography.

Auditory event-related potentials, bispectral index, and entropy for the discrimination of different levels of sedation in intensive care unit patients

BACKGROUND: Sedation protocols, including the use of sedation scales and regular sedation stops, help to reduce the length of mechanical ventilation and intensive care unit stay. Because clinical assessment of depth of sedation is labor-intensive, performed only intermittently, and interferes with sedation and sleep, processed electrophysiological signals from the brain have gained interest as surrogates. We hypothesized that auditory event-related potentials (ERPs), Bispectral Index (BIS), and Entropy can discriminate among clinically relevant sedation levels. METHODS: We studied 10 patients after elective thoracic or abdominal surgery with general anesthesia. Electroencephalogram, BIS, state entropy (SE), response entropy (RE), and ERPs were recorded immediately after surgery in the intensive care unit at Richmond Agitation-Sedation Scale (RASS) scores of -5 (very deep sedation), -4 (deep sedation), -3 to -1 (moderate sedation), and 0 (awake) during decreasing target-controlled sedation with propofol and remifentanil. Reference measurements for baseline levels were performed before or several days after the operation. RESULTS: At baseline, RASS -5, RASS -4, RASS -3 to -1, and RASS 0, BIS was 94 [4] (median, IQR), 47 [15], 68 [9], 75 [10], and 88 [6]; SE was 87 [3], 46 [10], 60 [22], 74 [21], and 87 [5]; and RE was 97 [4], 48 [9], 71 [25], 81 [18], and 96 [3], respectively (all P < 0.05, Friedman Test). Both BIS and Entropy had high variabilities. When ERP N100 amplitudes were considered alone, ERPs did not differ significantly among sedation levels. Nevertheless, discriminant ERP analysis including two parameters of principal component analysis revealed a prediction probability PK value of 0.89 for differentiating deep sedation, moderate sedation, and awake state. The corresponding PK for RE, SE, and BIS was 0.88, 0.89, and 0.85, respectively. CONCLUSIONS: Neither ERPs nor BIS or Entropy can replace clinical sedation assessment with standard scoring systems. Discrimination among very deep, deep to moderate, and no sedation after general anesthesia can be provided by ERPs and processed electroencephalograms, with similar P(K)s. The high inter- and intraindividual variability of Entropy and BIS precludes defining a target range of values to predict the sedation level in critically ill patients using these parameters. The variability of ERPs is unknown.

Is carotid endarterectomy a trainee operation?

BACKGROUND: Recent dramatic changes in surgical training resulting from working-hour regulations may lead to lack of competence. Traditionally, carotid surgery has been the domain of specialists. This study was designed to compare the outcome of carotid endarterectomy performed by vascular surgical trainees versus vascular surgeon (VS). METHODS: A retrospective study of 1,379 consecutive patients who underwent carotid endarterectomy as the sole procedure under local or general anesthesia (from 1995-2004) was performed. All patients were admitted to the intensive care unit for 24 hours. Trainees performed 475 (34.5%) and vascular specialists performed 904 (65.5%) operations. RESULTS: Patient characteristics with regard to preoperative neurological status were similar. Trainees operated on 61.4% symptomatic patients and VS on 56.8% (P = 0.09). Shunt use did not differ (16% trainee vs. 17.8% VS). Clamping time and total operating time were longer among trainees (41.9 vs. 33.5 min, P < 0.001; and 121.2 vs. 101.8 min, P < 0.001, respectively). Postoperative stroke and death rates (3.2% vs. 3.1% and 0.4% vs. 0.9%, respectively) did not differ. Peripheral nerve complications were more common among trainees (12.2% vs. 6.5%; P < 0.0001); 99.6% of these nerve injuries had resolved at 3 months' follow-up. CONCLUSIONS: Carotid endarterectomy can be performed safely by a trainee vascular surgeon when assisted and supervised by a specialist vascular surgeon.

Preemptive carprofen for peri-operative analgesia in dogs undergoing Tibial Plateau Leveling Osteotomy (TPLO): a prospective, randomized, blinded, placebo controlled clinical trial

Eighteen client-owned dogs undergoing Tibial Plateau Leveling Osteotomy (TPLO) were included in this blinded clinical study and randomly assigned to one of two treatment groups. Group C (carprofen) received intravenous (IV) carprofen, 4 mg/kg, prior to anesthesia, whereas group P (placebo) received IV saline. General anesthesia was maintained with isoflurane in oxygen and a constant rate infusion (CRI) of sufentanyl IV. Intra-operatively, assessment of nociception was based on changes in physiological parameters and on the analgesics requirement, whereas in the post-operative period evaluation of pain was performed by using a Hellyer and Gaynor pain score and by comparing the doses of rescue buprenorphine required by the two treatment groups. Although no statistically significant differences in intra-operative sufentanyl doses were found between treatment groups, group C had superior cardiovascular stability, and lower post-operative pain scores and rescue buprenorphine doses than group P. Our results indicate that administration of carprofen prior to surgery was effective in improving peri-operative analgesia in dogs undergoing TPLO.

Successful treatment of an intrathoracic bronchogenic cyst in a Holstein-Friesian calf

A 5-½-month-old female Holstein-Friesian calf was presented with a history of recurring ruminal tympany and poor development. The absence of lung sounds on the right hemithorax suggested a right-sided intrathoracic pathology. Radiography and computed tomography revealed a large thin-walled cavernous lesion with a gas-fluid interface which almost completely filled the right thoracic cavity. Fluid aspirated from the lesion was clear, yellowish and odorless. These findings led to the diagnosis of a bronchogenic cyst. Thoracotomy was performed under general anesthesia. The cyst strongly adhered to the adjacent lung tissue. After removal of the free wall, the adjacent lung tissue was sealed using surgical stapling instruments, and the non-removable part of the wall was curetted and rinsed. The intensive postoperative management included antibiotic therapy, oxygen supplementation and regional lidocaine infusion. Anti-inflammatory drugs were administered for further pain control. The calf recovered well and was released from the clinic on postoperative day 11. Intra- or extrathoracic bronchogenic cysts result from abnormal budding during the embryonic development of the tracheobronchial system. Successful treatment of this calf despite the size of the lesion and the invasive character of the surgical intervention indicates that resection of bronchogenic cysts in cattle may be an option for valuable animals.

Anesthetic and Airways Management of a Dog with Severe Tracheal Collapse during Intraluminal Stent Placement

This case report describes the anesthetic and airways management of a dog affected by 4th degree tracheal collapse and undergoing endoscope-guided intraluminal stent placement. After premedication with acepromazine and butorphanol, general anesthesia was induced with propofol and maintained with intravenous propofol and butorphanol in constant rate infusion. During intraluminal stent placement, oxygen was supplemented by means of a simple and inexpensive handmade device, namely, a ureteral catheter inserted into the trachea and connected to an oxygen source, which allowed for the maintenance of airways’ patency and adequate patient’s oxygenation, without decreasing visibility in the surgical field or interfering with the procedure. The use of the technique described in the present paper was the main determinant of the successful anesthetic management and may be proposed for similar critical cases in which surgical manipulation of the tracheal lumen, which may potentially result in hypoxia by compromising airways patency, is required.

Comparison of Fluid Types for Resuscitation in Acute Hemorrhagic Shock and Evaluation of Gastric Luminal and Transcutaneous P co 2 in Leghorn Chickens

The objective of this study was to compare the effects of 3 different fluid types for resuscitation after experimentally induced hemorrhagic shock in anesthetized chickens and to evaluate partial pressures of carbon dioxide measured in arterial blood (Paco2), with a transcutaneous monitor (TcPco2), with a gastric intraluminal monitor (GiPco2), and by end tidal measurements (Etco2) under stable conditions and after induced hemorrhagic shock. Hemorrhagic shock was induced in 40 white leghorn chickens by removing 50% of blood volume by phlebotomy under general anesthesia. Birds were divided into 4 groups: untreated (control group) and treated with intravenous hetastarch (haes group), with a hemoglobin-based oxygen carrier (hemospan group), or by autotransfusion (blood group). Respiratory rates, heart rates, and systolic arterial blood pressure (SAP) were compared at 8 time points (baseline [T0]; at the loss of 10% [T10%], 20% [T20%], 30% [T30%], 40% [T40%], and 50% [T50%] of blood volume; at the end of resuscitation [RES]; and at the end of anesthesia [END]). Packed cell volume (PCV) and blood hemoglobin content were compared at 6 time points (T0, T50%, RES, and 1, 3, and 7 days after induced hemorrhagic shock). Measurements of Paco2, TcPco2, GiPco2, and Etco2 were evaluated at 2 time points (T0 and T50%), and venous lactic acid concentrations were evaluated at 3 time points (T0, T50%, and END). No significant differences were found in mortality, respiratory rate, heart rate, PCV, or hemoglobin values among the 4 groups. Birds given fluid resuscitation had significantly higher SAPs after fluid administration than did birds in the control group. In all groups, PCV and hemoglobin concentrations began to rise by day 3 after phlebotomy, and baseline values were reached 7 days after blood removal. At T0, TcPco2 did not differ significantly from Paco2, but GiPco2 and Etco2 differed significantly from Paco2. After hemorrhagic shock, GiPco2 and TcPco2 differed significantly from Paco2. The TcPco2 or GiPco2 values did not differ significantly at any time point in birds that survived or died in any of the groups and across all groups. These results showed no difference in mortality in leghorn chickens treated with fluid resuscitation after hemorrhagic shock and that the PCV and hemoglobin concentrations increased by 3 days after acute hemorrhage with or without treatment. The different CO2 measurements document changes in CO2-values consistent with poor perfusion and may prove useful for serial evaluation of responses to shock and shock treatment.

Epidural Analgesia during Open Radical Prostatectomy Does Not Improve Long-Term Cancer-Related Outcome: A Retrospective Study in Patients with Advanced Prostate Cancer

Background A beneficial effect of regional anesthesia on cancer related outcome in various solid tumors has been proposed. The data on prostate cancer is conflicting and reports on long-term cancer specific survival are lacking. Methods In a retrospective, single-center study, outcomes of 148 consecutive patients with locally advanced prostate cancer pT3/4 who underwent retropubic radical prostatectomy (RRP) with general anesthesia combined with intra- and postoperative epidural analgesia (n=67) or with postoperative ketorolac-morphine analgesia (n=81) were reviewed. The median observation time was 14.00 years (range 10.87-17.75 yrs). Biochemical recurrence (BCR)-free, local and distant recurrence-free, cancer-specific, and overall survival were estimated using the Kaplan-Meier technique. Multivariate Cox proportional-hazards regression models were used to analyze clinicopathologic variables associated with disease progression and death. Results The survival estimates for BCR-free, local and distant recurrence-free, cancer-specific survival and overall survival did not differ between the two groups (P=0.64, P=0.75, P=0.18, P=0.32 and P=0.07). For both groups, higher preoperative PSA (hazard ratio (HR) 1.02, 95% confidence interval (CI) 1.01-1.02, P<0.0001), increased specimen Gleason score (HR 1.24, 95% CI 1.06-1.46, P=0.007) and positive nodal status (HR 1.66, 95% CI 1.03-2.67, P=0.04) were associated with higher risk of BCR. Increased specimen Gleason score predicted death from prostate cancer (HR 2.46, 95% CI 1.65-3.68, P<0.0001). Conclusions General anaesthesia combined with epidural analgesia did not reduce the risk of cancer progression or improve survival after RRP for prostate cancer in this group of patients at high risk for disease progression with a median observation time of 14.00 yrs.

Effect of progressive mandibular advancement on pharyngeal airway size in anesthetized adults.

BACKGROUND: General anesthesia in adult humans is associated with narrowing or complete closure of the pharyngeal airway. The purpose of this study was to determine the effect of progressive mandibular advancement on pharyngeal airway size in normal adults during intravenous infusion of propofol for anesthesia. METHODS: Magnetic resonance imaging was performed in nine normal adults during wakefulness and during propofol anesthesia. A commercially available intraoral appliance was used to manually advance the mandible. Images were obtained during wakefulness without the appliance and during anesthesia with the participants wearing the appliance under three conditions: without mandibular advancement, advancement to 50% maximum voluntary advancement, and maximum advancement. Using computer software, airway area and maximum anteroposterior and lateral airway diameters were measured on the axial images at the level of the soft palate, uvula, tip of the epiglottis, and base of the epiglottis. RESULTS: Airway area across all four airway levels decreased during anesthesia without mandibular advancement compared with airway area during wakefulness (P < 0.007). Across all levels, airway area at 50% advancement during anesthesia was less than that at centric occlusion during wakefulness (P = 0.06), but airway area with maximum advancement during anesthesia was similar to that during wakefulness (P = 0.64). In general, anteroposterior and lateral airway diameters during anesthesia without mandibular advancement were decreased compared with wakefulness and were restored to their wakefulness values with 50% and/or maximal advancement. CONCLUSIONS: Maximum mandibular advancement during propofol anesthesia is required to restore the pharyngeal airway to its size during wakefulness in normal adults.

Optimal Workflow and Process-Based Performance Measures for Endovascular Therapy in Acute Ischemic Stroke: Analysis of the Solitaire FR Thrombectomy for Acute Revascularization Study.

BACKGROUND AND PURPOSE We report on workflow and process-based performance measures and their effect on clinical outcome in Solitaire FR Thrombectomy for Acute Revascularization (STAR), a multicenter, prospective, single-arm study of Solitaire FR thrombectomy in large vessel anterior circulation stroke patients. METHODS Two hundred two patients were enrolled across 14 centers in Europe, Canada, and Australia. The following time intervals were measured: stroke onset to hospital arrival, hospital arrival to baseline imaging, baseline imaging to groin puncture, groin puncture to first stent deployment, and first stent deployment to reperfusion. Effects of time of day, general anesthesia use, and multimodal imaging on workflow were evaluated. Patient characteristics and workflow processes associated with prolonged interval times and good clinical outcome (90-day modified Rankin score, 0-2) were analyzed. RESULTS Median times were onset of stroke to hospital arrival, 123 minutes (interquartile range, 163 minutes); hospital arrival to thrombolysis in cerebral infarction (TICI) 2b/3 or final digital subtraction angiography, 133 minutes (interquartile range, 99 minutes); and baseline imaging to groin puncture, 86 minutes (interquartile range, 24 minutes). Time from baseline imaging to puncture was prolonged in patients receiving intravenous tissue-type plasminogen activator (32-minute mean delay) and when magnetic resonance-based imaging at baseline was used (18-minute mean delay). Extracranial carotid disease delayed puncture to first stent deployment time on average by 25 minutes. For each 1-hour increase in stroke onset to final digital subtraction angiography (or TICI 2b/3) time, odds of good clinical outcome decreased by 38%. CONCLUSIONS Interval times in the STAR study reflect current intra-arterial therapy for patients with acute ischemic stroke. Improving workflow metrics can further improve clinical outcome. CLINICAL TRIAL REGISTRATION: URL http://www.clinicaltrials.gov. Unique identifier: NCT01327989.

Perioperative and Anesthetic Management of Complete Tracheal Rupture in One Dog and One Cat.

ABSTRACT The authors describe two animals (one dog and one cat) that were presented with severe respiratory distress after trauma. Computerized tomographic imaging under general anesthesia revealed, in both cases, complete tracheal transection. Hypoxic episodes during anesthesia were relieved by keeping the endotracheal tube (ETT) positioned in the cranial part of the transected trachea and by allowing spontaneous breathing. Surgical preparation was performed quickly, and patients were kept in a sternal position to improve ventilation and oxygenation, and were only turned into dorsal recumbency shortly before surgical incision. A sterile ETT was guided into the distal part of the transected trachea by the surgeon, at which point mechanical ventilation was started. Both animals were successfully discharged from hospital a few days after surgery. Rapid and well-coordinated teamwork seemed to contribute to the good outcome. Precise planning and communication between anesthetists, surgeons, and technicians, as well as a quick course of action prior to correct ETT positioning helped to overcome critical phases.