Catheter technique in axillary plexus block. Presentation of a new method

A flexible, disposable intravenous catheter can be introduced into the neuro-vascular sheath in the axilla and used for injection of local anesthetic solution to block the axillary brachial plexus. The technique is described and the results of the first 137 consecutive catheter blocks are reported and compared to a similarly evaluated series of conventional axillary blocks. The catheter method constitutes an interesting alternative to needle techniques and offers the possibility of a continuous axillary block.     

Anesthesia for neonatal surgical emergencies

In this review of the anesthetic considerations for the neonate who requires anesthesia for emergency surgery, the authors discuss preoperative, intraoperative, and postoperative management from an anesthetic perspective. Monitoring the cardiorespiratory and metabolic status of neonates during anesthesia is usually difficult because the neonate is not physically accessible. Specific monitoring techniques that provide accurate measurements are discussed. General anesthesia is usually required for the surgery, the airway must be secured and anesthesia managed with a combination of inhalational and intravenous agents. Regional anesthesia and opioids may be included to decrease the intraoperative anesthetic requirements and prevent pain in the postoperative period. The pharmacology of specific anesthetic and adjuvant agents are discussed.     

Anesthetic efficacy of the supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in irreversible pulpitis

The purpose of this study was to determine the anesthetic efficacy of a supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in teeth diagnosed with irreversible pulpitis. Fifty-one patients with symptomatic, vital maxillary, and mandibular posterior teeth diagnosed with irreversible pulpitis received conventional infiltrations or inferior alveolar nerve blocks. Pulp testing was used to determine pulpal anesthesia after "clinically successful" injections. Patients who were positive to the pulp tests, or were negative to the pulp tests but felt pain during endodontic access, received an intraosseous injection using 1.8 ml of 2% lidocaine with 1:100,000 epinephrine. The results demonstrated that 42% of the patients who tested negative to the pulp tests reported pain during treatment and required supplemental anesthesia. Eighty-one percent of the mandibular teeth and 12% of maxillary teeth required an intraosseous injection due to failure to gain pulpal anesthesia. Overall, the Stabident intraosseous injection was found to be 88% successful in gaining total pulpal anesthesia for endodontic therapy. We concluded that, for posterior teeth diagnosed with irreversible pulpitis, the supplemental intraosseous injection of 2% lidocaine (1:100,000 epinephrine) was successful when conventional techniques failed.     

Electrocardiographic changes in cardiac patients having dental extractions under a local anesthetic containing a vasopressor

PURPOSE: This study attempted to identify which group of cardiac patients is most at risk when dental extractions are performed under a local anesthetic with a vasopressor. PATIENTS AND METHODS: Forty cardiac patients who had dental extractions under local anesthesia were connected to a Holter monitor for 24 hours, starting an hour before the procedure. The electrocardiogram was analyzed for the number of premature beats, ST depression, and cardiac rhythm. A mean rate was calculated for the first 2 hours after injection of the local anesthetic and for the subsequent 22 hours. The preoperative electrocardiogram was compared with the electrocardiogram performed 1 week before treatment. RESULTS: Electrocardiographic changes were observed in 15 patients (37.5%), and all occurred during the first 2 hours after injection of the local anesthetic. Of the 15 patients, eight were being treated with digoxin. CONCLUSIONS: Cardiac patients being treated with digoxin had more electrocardiographic changes after administration of a local anesthetic than other cardiac patients. When the local anesthetic contained a vasopressor, there was a greater incidence of tachycardia but less arrhythmia or ST depression.     

Arterial-phase three-dimensional gadolinium magnetic resonance angiography of the renal arteries. Strategies for timing and contrast media injection: original investigation

RATIONALE AND OBJECTIVES: The authors review different imaging and contrast-media infusion strategies for arterial-phase three-dimensional (3D) gadolinium-enhanced magnetic resonance angiography (Gd-MRA). METHODS: The influence of physicochemical factors on the infusion of contrast media, including viscosity, flow rate, inline pressure, and cannula size, is assessed. The combination of manual or automated contrast-media administration with timing-dependent or -independent 3D Gd-MRA techniques is reviewed regarding the aspects of effectiveness, robustness, image quality, and costs. RESULTS: For effective bolus delivery with high flow rates, the type and temperature of the contrast media, the size of the cannula, and an immediate saline flush must be considered. Timing-dependent techniques based on a test bolus and using automated contrast-media infusion as well as timing independent techniques such as MR SmartPrep or multiphase 3D Gd-MRA by using a manual injection with a SmartSet tubing set, are all effective procedures for arterial phase 3D Gd-MRA. CONCLUSIONS: Manual contrast-media injection with a tubing set can be used for timing-independent MRA techniques. The multiphase 3D Gd-MRA approach seems to be favorable for different MR systems, robustness, and speed.     

Euthanasia and palliative care--an uneasy partnership

PURPOSE: To compare the effectiveness of the intraligamentary technique of anesthetic administration (ILA) with the inferior alveolar nerve block (IANB) in extraction of mandibular teeth. MATERIALS AND METHODS: ILA and IANB injections using Citanest with Octapressin were administered on 16 patients requiring bilateral mandibular dental extractions. Discomfort during needle placement, profoundness of anesthesia obtained, and patient preference were evaluated for both techniques. RESULTS: A total of 45 teeth were extracted. Ten patients (62.5%) reported discomfort during needle placement with ILA injection compared to three patients (18.75%) with IANB (P = 0.031). Fifty percent (12/24) of teeth extracted with ILA injection were removed without discomfort to the patient compared to 85.7% (18/21) using IANB (P = 0.027). No difference in patient preference between the two techniques was noted.     

Variations in the composition of spinal anesthetic solutions: the effects of drug addition order and preparation methods

Adjuvants such as opioids or epinephrine are commonly added in small volumes to multicomponent spinal anesthetic solutions. In this study, we tested the hypothesis that final adjuvant concentrations vary depending on the devices and techniques used to prepare the anesthetic solution. We compared two aspiration devices, the filter needle and the filter straw, in a laboratory study. Two techniques for drawing up and estimating adjuvant volumes were assessed, as was variation in the composition of a model spinal anesthetic solution resulting from intra- and interindividual variability. A model hyperbaric anesthetic solution consisting of tetracaine, dextrose, and methylene blue (MB) as a small-volume tracer solution was studied. The components were drawn up into a syringe through one of two commercially supplied aspiration devices, a filter straw or a filter needle. The effect of the order of aspiration of the components into the syringe was measured by determining the MB concentration in the final solution by optical absorbance. Ten experienced anesthesiologists then prepared samples of the test solution using one of two different techniques to estimate tracer volume in the aspiration syringe. In comparison studies, the MB tracer was added to the hyperbaric solution with a tuberculin syringe. The order of aspiration of the solution components had a large effect on the final concentration of the MB tracer in the ultimate mixture. Variation in the MB concentration was on the order of four- to fivefold. Effects were larger for the filter straw compared with the filter needle. A comparison of 10 anesthesiologists revealed large intra- and interindividual variations in the final composition of the model anesthetic solution. The concentration of tracer added to the mixture with a tuberculin syringe approximated the planned yield. We conclude that the devices and techniques used to prepare mixtures of drugs for delivery to the cerebrospinal fluid may influence the concentrations of drugs in the anesthetic and, thus, the dose supplied to the patient receiving spinal anesthesia. Variation in clinical effects of spinal anesthetics may be attributable, in part, to variation in the composition of the anesthetic. IMPLICATIONS: This laboratory study demonstrates the potential for large variation in the composition of spinal anesthetic mixtures.     

A 21st century computerized injection system for local pain control

This article describes a new computerized local anesthetic injection system for pain control. The core technology of this system is the microprocessor-controlled delivery of anesthetic solution at a constant pressure and controlled volume, regardless of encountered variations in tissue resistance. This fine-tuned, high suffusion flow rate of anesthetic provides a rapid onset of anesthesia for most patients. Traditional block injections and infiltrations as well as palatal injections and periodontal ligament injections are administered with precision, ease, and patient comfort.     

Factors affecting discharge time in adult outpatients

Discharge time (total recovery time) is one determinant of the overall cost of outpatient surgery. We performed this study to determine what factors affect discharge time. Details regarding patients, anesthesia, surgery, and recovery were recorded prospectively for 1088 adult patients undergoing ambulatory surgery over an 8-mo period. The contribution of factors to variability in the discharge time was assessed by using multivariate linear regression analysis. In the last 4 mo of the study, nurses indicated the causes of discharge delays > or =50 min in Phase 1 or > or =70 min in Phase 2 recovery. When all anesthetic techniques were included, anesthetic technique was the most important determinant of discharge time (R2 = 0.10-0.15; P = 0.001), followed by the Phase 2 nurse. After general anesthesia, the Phase 2 nurse was the most important factor (R2 = 0.13; P = 0.01-0.001). In women, the choice of general anesthetic drugs was significant (R2 = 0.04; P = 0.002). The three most common medical causes of delay were pain, drowsiness, and nausea/vomiting. System factors were the foremost cause of Phase 2 delays (41%), with lack of immediate availability of an escort accounting for 53% of system-related delays. We conclude that efforts to shorten discharge time would best be directed at improving nursing efficiency; ensuring availability of an escort for the patient; and preventing postoperative pain, drowsiness, and emetic symptoms. The selection of anesthetic technique and anesthetic drug seems to be of selective importance in determining discharge time depending on patient gender and type of surgery. IMPLICATIONS: The relative importance of anesthetic and nonanesthetic factors were evaluated as determinants of discharge time after ambulatory surgery. Postoperative nursing care was the single most important factor after general anesthesia; anesthetic drugs, anesthetic technique, and prevention of pain and emetic symptoms were of selective importance depending on patient gender and type of surgery.     

The effects of general versus epidural anesthesia for outpatient extracorporeal shock wave lithotripsy

Although many anesthetic techniques are described for immersion extracorporeal shock wave lithotripsy (ESWL), regional and i.v. techniques are the most commonly reported. This randomized, prospective study compared general anesthesia (GA) and epidural anesthesia (EPID) with regard to effectiveness, side effects, induction time, and recovery in patients undergoing ESWL using an unmodified Dornier HM-3 lithotriptor. Twenty-six healthy outpatients were randomized to GA (propofol, N2O, laryngeal mask airway) or EPID (lidocaine 1.5% with epinephrine). Intraoperative and postoperative supplemental medications, side effects, and complications were noted. Induction times and times required to meet standard recovery criteria were compared between groups. Patients were surveyed regarding their satisfaction with anesthesia. All patients in the EPID group had effective blocks with a single catheter insertion and local anesthetic injection. In the GA group, the LMA was inserted successfully in all patients. Time from room entry to procedure start was significantly less in the GA group (23 +/- 11 vs 34 +/- 9 min; P < 0.05). Patients in the GA group were ready for discharge home earlier (127 +/- 59 vs 178 +/- 49 min; P < 0.05). Only three patients experienced nausea (one in the GA group, two in the EPID group). There were no differences in patient or urologist satisfaction with anesthesia. We conclude that GA is associated with a rapid recovery compared with EPID. Implications: General anesthesia with propofol, nitrous oxide, and a laryngeal mask airway is comparable to epidural anesthesia with lidocaine for outpatient extracorporeal shock wave lithotripsy procedures. However, early recovery is more rapid after general anesthesia compared with epidural anesthesia.     

Testing an implantable intraspinal drug delivery device in the ewe

OBJECTIVE: The authors report the use of multiple implanted intraspinal port and catheter systems per test animal to study the in vivo functional characteristics and reliability of a new implantable spinal drug delivery port system. METHODS: Four ewes were each implanted with two epidural and one subarachnoid silicone elastomer catheters at the lumbar level. Each catheter was connected in series to one of three Therex filtered spinal delivery ports implanted subcutaneously in a similar grid pattern in each ewe to facilitate percutaneous identification. Saline (2 ml) was injected 3 times weekly in each port. The ease of injection and behavioral responses were recorded for 207-213 days of implantation until sacrifice/necropsy. RESULTS: All ports functioned reliably during the study. However, injection through two of the four subarachnoid catheters resulted in behavioral withdrawal responses intermittently. This behavioral pattern was much less common after epidural port injections. All four subarachnoid and four of eight epidural port and catheter systems were tested with local anesthetic just before sacrifice. Motor block was observed in three of four subarachnoid and three of four epidural port and catheter systems tested. Integrity of the other four epidural ports was tested by injection of methylene blue at sacrifice. This dye did not distribute in the epidural space in one of the latter four epidural ports (not local anesthetic tested) because of a concentric fibrotic reaction about the catheter. Similar fibrotic reactions surrounded the catheters that failed a functional test with local anesthetic. CONCLUSIONS: The implantable intraspinal port system tested functions reliably under repetitive percutaneous access. However, filtering such ports, though desirable to prevent entry of debris into the spinal canal, did not eliminate pericatheter chronic subarachnoid and epidural reaction. The number of test animals required to test 12 ports chronically was reduced by two-thirds without undue trauma to the individual test subject. Chronic percutaneous injection of an implanted subarachnoid system is feasible but may be associated with behavioral effects similar to that seen with chronic epidural systems. Fibrosis around chronic silicone catheters limited functional utility in one-fourth of the implanted test systems. Further study of the potential reactivity of chronic epidural and subarachnoid catheters is indicated.     

The effect of intraarticular anesthesia and elastic bandage on elbow proprioception

Twenty uninjured male volunteers were studied to characterize normal elbow proprioception and to investigate the effect of applying an elastic bandage to the extremity and injection of an intraarticular anesthetic. A modified Biodex dynamometer was used to study position sense and detection of motion. In part 1 of the study position sense was tested by flexing the elbow to a predetermined angle, returning to the starting position, and then asking the subject to identify that angle. In part 2 detection of motion was tested by asking the subject to disengage the apparatus by pressing a stop button when movement was detected. The testing conditions in part 1 and part 2 were repeated after the elbow was wrapped with an elastic bandage and again after an intraarticular injection of 3 cc 1% lidocaine with the bandage removed. Ten additional subjects underwent testing of both elbows to examine the effect of arm dominance. Mean position sense was within 3.3 degrees+/-1.3 degrees of the actual angle in trials without an elastic bandage or an anesthetic. A significant improvement in position sense was observed (2.2 degrees+/-1.2 degrees) after an elastic bandage was applied (P < .004). No significant difference was seen in position sense after lidocaine was injected. The mean threshold for detection of motion in trials without an elastic bandage or an anesthetic was 4.21 degrees+/-1.56 degrees. No significant differences were seen in detection of motion observed with the elastic bandage or intraarticular anesthetic. No significant differences were seen between dominant and nondominant extremities for both position sense and detection of motion. The application of an elastic bandage improved position sense, suggesting that tactile cues from cutaneous or other extraarticular receptors may play a role in elbow proprioception. Intraarticular anesthesia, however, had little effect, suggesting that intracapsular receptors play a lesser role in elbow proprioception. The determination of proprioceptive qualities for the normal elbow can aid in the understanding of elbow function and provide a basis for defining its role in elbow dysfunction.     

Incremental bolus versus a continuous infusion of propofol for deep sedation/general anesthesia during dentoalveolar surgery

PURPOSE: This article compared the use of the traditional incremental bolus technique with the continuous infusion technique for the administration of propofol for deep sedation/general anesthesia. PATIENTS AND METHODS: Patients were sedated with midazolam and fentanyl and then had maintenance of an anesthetic state achieved with propofol administered by either of the two techniques. Data were collected to evaluate the overall surgical/anesthetic procedure, movement of the patient, and his or her hemodynamic status. RESULTS: Both groups received a mean maintenance dose of propofol exceeding 6 mg/kg/hr. However, the patients in the continuous infusion group received a statistically greater maintenance dose (continuous infusion + supplemental vs incremental bolus). All patients were maintained in a deep sedation/general anesthetic state. Respiratory and blood pressure values were comparable in both groups. However, the continuous infusion group showed improved hemodynamic stability manifested as fewer fluctuations in heart rate. Visual analog scale (VAS) questionnaires completed by the surgeon and surgical assistant reported less patient movement and improved surgical/anesthetic conditions with the continuous infusion technique. Recovery of the two groups was comparable. CONCLUSION: This study, although finding advantages in the continuous infusion technique, showed satisfactory conditions associated with both techniques.     

A retrospective cost-effectiveness analysis of interferon as adjuvant therapy in high-risk resected cutaneous melanoma

PURPOSE: To determine the relative corneal endothelial toxicities of the following topical anesthetic agents: bupivacaine HCl 0.75%, unpreserved lidocaine HCl 4%, proparacaine HCl 0.5%, and tetracaine HCl 0.5%. METHODS: The experiment was conducted using pigmented rabbits. Approximately nine animals each were randomly assigned to eight groups. Right eyes received injections of 0.2 ml of one of the four anesthetic agents at one of two concentrations and left eyes received injections of 0.2 ml of balanced salt solution. Corneal thickness and clarity were measured before surgery and on postoperative days 1, 3, and 7. RESULTS: A statistically significant increase (P < 0.05) in corneal thickness and opacification over preoperative measurements was noted with injections of bupivacaine, lidocaine, and proparacaine, controlling for changes occurring in control eyes from surgery alone. Proparacaine was statistically more toxic than were the others. The toxicity of tetracaine was statistically indistinguishable from balanced salt solution, although mild toxicity was evident clinically. Injection of 1:10 dilutions of the same anesthetic agents failed to produce a statistically significant increase in corneal thickness or opacification on any postoperative examination. CONCLUSIONS: Anterior chamber injection of bupivacaine HCl 0.75%, unpreserved lidocaine HCl 4%, and proparacaine HCl 0.5% produces corneal thickening and opacification that is clinically and statistically significant. Tetracaine HCl 0.5% injection produces corneal thickening and opacification that is clinically apparent in some eyes but statistically insignificant. Ophthalmic surgeons should be aware of the potential for endothelial cell injury if anesthetic agents enter or are injected into the eye during cataract surgery in the concentrations supplied commercially.     

Needle entrance into the maxillary sinus during retrobulbar anesthesia

Three patients are presented to whom an accidental needle entrance into the maxillary sinus occurred during retrobulbar anesthesia. In all cases air was aspirated during the aspiration check at the end of needle advancement, and the patients reported a bitter taste after the injection of a small quantity of anesthetic. After withdrawal and careful reinsertion of the needle, maxillary sinus entrance was avoided and a successful retrobulbar block was achieved. Two of the patients had no history of previous facial trauma or surgery, whereas the third had suffered a recent blowout fracture of the orbital floor. The authors suggest that air aspiration or anesthetic passage into the pharynx during retrobulbar anesthesia should raise the suspicion of maxillary sinus entrance, even in patients without any history of facial trauma or surgery. The early recognition of sinus entrance can prevent retrobulbar block failure and reinjection of a second anesthetic dose.     

Aiding reduction of smoking with nicotine replacement medications: hope for the recalcitrant smoker?

A 28-year-old female had a severe depressed deformity of the left cheek due to false local injection of ZnCl2 into her buccal mucosa instead of an anesthetic. After several attempts at plastic surgery in another hospital with unsatisfactory results, she was treated surgically in our clinic using cheek skin expanded by a tissue expander. The outcome was satisfactory.     

An echocardiographic study of interactions between pindolol and epinephrine contained in a local anesthetic solution

An increasing number of dental patients are taking beta-adrenergic blockers for the treatment of hypertension or angina pectoris. If epinephrine-containing local anesthetics are administered to such patients, interactions between epinephrine and the beta-blocking agent may induce cardiovascular complications. We assessed in volunteers the effects of intraoral injection with 2% lidocaine containing 1:80,000 epinephrine (L-E) on cardiac function after pretreatment with the beta-blocking agent pindolol. M-Mode echocardiography was used for the assessment. The injection of L-E after administration of pindolol did not alter cardiac preload, whereas it reduced the stroke volume, due to an increase in afterload and a decrease in myocardial contractility. Reductions in stroke volume and heart rate led to a decrease in cardiac output. Because total peripheral vascular resistance increased markedly, blood pressure was elevated despite the reduced cardiac output. These results suggest that cardiac function of dental patients on beta-blocker therapy can be adversely affected by epinephrine-containing local anesthetics. Therefore, when such an anesthetic solution has to be used in patients on beta-blocker therapy, careful systemic monitoring is needed.     

Arterial and pulmonary arterial concentrations of the enantiomers of bupivacaine after epidural injection in elderly patients

Bupivacaine HCl is a 50:50 racemic mixture of the levo [S(-)] and dex [R(+)] enantiomers. The R(+) enantiomer exhibits greater cardiac tissue binding and toxicity. To determine whether the lung exhibits selective uptake of one of the enantiomers of bupivacaine, we measured pulmonary artery and radial artery blood concentrations of the two enantiomers after a lumbar epidural injection of 20 mL of 0.75% bupivacaine in 10 elderly patients undergoing one-stage bilateral total knee arthroplasty. Significantly lower concentrations of R(+) than S(-) were noted in both pulmonary artery and arterial blood. Both enantiomers were absorbed by the lung to a similar extent within the first 5 min after epidural injection (extraction ratio approximately equal to 0.1 or 10%). Mean time of maximal concentration (Tmax) was 6 min. In 3 of the 10 patients, Tmax occurred in 1-3 min. We conclude that the lung absorbs both the R(+) and S(-) enantiomers of bupivacaine to a similar extent after epidural injection and that this is of doubtful clinical significance. This study also suggests that peak concentrations of bupivacaine may occur earlier after epidural injection in certain elderly patients than previously believed. Implications: In the first 5 min after epidural injection, approximately 10% of the local anesthetic bupivacaine was absorbed by the lung. Absorption of the two enantiomers (mirror images) of bupivacaine were similar. Lung absorption of bupivacaine is unlikely to influence local anesthetic toxicity.     

Letter: A caution about using photoillumination devices

The use of a jet injection instrument was particularly helpful in the anesthetic preparation of biopsy sites selected for tissue culturing of skin and did not lessen culturing success.     

Anesthetic management for a patient with pheochromocytoma using magnesium sulfate and epidural block

A 54-year-old woman with pheochromocytoma was anesthetized using magnesium sulfate infusion. Anesthesia was induced with thiopental and fentanyl, and maintained with 0.5% sevoflurane in nitrous oxide/oxygen and 60 mg.hr-1 of epidurally infused lidocaine. Muscle relaxation was achieved with intermittent administration of vecuronium under neuromuscular monitoring. Magnesium 2 g was infused prior to the tracheal intubation and followed by continuous infusion of 2 g.hr-1. These anesthetic techniques made hemodynamic state stable, and no additional vasoactive agents were needed. However, the infusion rate of magnesium was reduced to a half because of PQ interval prolongation. Magnesium is believed to be useful for anesthetic management for patients with pheochromocytoma, but the proper dose and the way of administration should be further investigated for their safe clinical use.