Ralf E. Gebhard

A randomized, double-blind comparison of the NK1 antagonist, aprepitant, versus ondansetron for the prevention of postoperative nausea and vomiting

BACKGROUND: Antiemetics currently in use are not totally effective. Neurokinin-1 receptor antagonists are a new class of antiemetic that have shown promise for chemotherapy-induced nausea and vomiting. This is the first study evaluating the efficacy and tolerability of the neurokinin-1 receptor antagonist, aprepitant, for the prevention of postoperative nausea and vomiting. METHODS: In this multicenter, double-blind trial, we randomly assigned 805 patients receiving general anesthesia for open abdominal surgery to a preoperative dose of aprepitant 40 mg orally, aprepitant 125 mg orally, or ondansetron 4 mg IV. Vomiting, nausea, and use of rescue therapy were assessed over 48 h after surgery. Treatments were compared using logistic regression. RESULTS: Incidence rates for the primary end point (complete response [no vomiting and no use of rescue] over 0–24 h after surgery, tested for superiority of aprepitant) were not different across groups (45% with aprepitant 40 mg, 43% with aprepitant 125 mg, and 42% with ondansetron). The incidence of no vomiting (0–24 h) was higher with aprepitant 40 mg (90%) and aprepitant 125 mg (95%) versus ondansetron (74%) (P < 0.001 for both comparisons), although between-treatment use of rescue and nausea control was not different. Both aprepitant doses also had higher incidences of no vomiting over 0–48 h (P < 0.001). No statistically significant differences were seen among the side effect profiles of the treatments. CONCLUSIONS: Aprepitant was superior to ondansetron for prevention of vomiting in the first 24 and 48 h, but no significant differences were observed between aprepitant and ondansetron for nausea control, use of rescue, or complete response.

The Accuracy of Electrocardiogram-Controlled Central Line Placement

BACKGROUND:Electrocardiogram (ECG) guidance to confirm accurate positioning of central venous catheters (CVC), placed before surgery in the operating room, is rarely used in the United States. We designed this randomized, controlled trial to investigate whether the use of this technique impacts the accuracy of CVC placement. METHODS:Patients in group ECG (n = 147) had a CVC placed using right-atrial ECG to guide catheter tip positioning. CVCs in group NO-ECG (n = 143) were positioned without this technique. RESULTS:Overall, guidewire-ECG control resulted in more correctly positioned CVCs (96% vs 76%, P ≤ 0.001) without increasing placement time. Significantly more CVCs were placed in the middle of the superior vena cava in group ECG (P ≤ 0.001), although placement into the right atrium or right ventricle and into other vessels occurred significantly more often in group NO-ECG (P ≤ 0.001). Twenty patients in group NO-ECG required repositioning of their CVC after surgery, whereas this maneuver was necessary only in three patients in group ECG (P ≤ 0.001). CONCLUSIONS:ECG guidance allows for more accurate CVC placement, and should be considered to increase patient safety and reduce costs associated with repositioning procedures.

Changes in onset time of rocuronium in patients pretreated with ephedrine and esmolol - The role of cardiac output

Background:  We investigated the hypothesis that manipulation of cardiac output (CO) with esmolol (Es) or ephedrine (E) affects the onset time of rocuronium.

Continuous posterior lumbar plexus block for acute postoperative pain control in young children.

A 60-yr-old man, 160 cm tall, weighing 75 kg, with American Society of Anesthesiologists physical status class II, was admitted for elective right shoulder surgery. His medical history was unremarkable except for recent mild diabetes with no related neuropathy, controlled by diet and glimepiride. Physical examination results were unremarkable, and the results of laboratory studies were all within normal limits, including preoperative glycemia and chest x-ray. He agreed to undergo a combination of regional and general anesthesia. Hydroxyzine, 100 mg, was administered 2 h preoperatively. After application of routine monitors, intravenous access was secured. He was positioned supine with the head turned to the contralateral side, and the right side of the neck was prepared as a sterile field. The elbow was flexed, with the forearm lying on the patient’s abdomen. Thereafter, interscalene brachial plexus block was performed as described by Winnie but using a nerve stimulator to ascertain that the needle’s tip was in the brachial plexus. The plexus was located with a nerve stimulator (Stimuplex HNS 11; B/Braun, Melsungen, Germany) and an insulated needle, 25 mm long with a short 30° bevel (Stimuplex, B/Braun). Three attempts at needle insertion were required to achieve an appropriate motor response: the brachial plexus was first located using a high current intensity (2 mA; 0.1 ms and 1 Hz), and then it was decreased to 0.5 mA to refine the approach. After obtaining a motor response of the deltoid muscle, a mixture of 30 ml ropivacaine, 0.75%, and 75 g clonidine was injected. No blood could be aspirated, and the patient reported neither pain nor paresthesia during the procedure, although phrenic nerve stimulation was transiently observed. After 20 min, profound surgical anesthesia was established on C5–C7 dermatomes. Then, general anesthesia was induced with 2 mg midazolam, 100 g fentanyl, 200 mg propofol, and 30 mg atracurium to facilitate tracheal intubation. General anesthesia was maintained with 1–2% sevoflurane and 50% nitrous oxide, and the patient underwent a right rotator cuff repair via a deltopectoral approach. He was placed in a “beach chair” position with his head turned the opposite direction. Vital signs and standard parameters remained stable throughout the 2-h procedure. At the end of surgery, the trachea was extubated, and the patient was observed for 1 h in the postanesthesia care unit. He did not report any pain. Vital signs and postoperative glycemia were normal. The interscalene brachial plexus blockade was still effective. Postoperative analgesia consisted of regular administration of a combination of propacetamol and nefopam intravenously. The patient was discharged to the ward. Postoperative follow-up was unremarkable. Ten days later, the patient was readmitted to the hospital because of increasing shortness of breath. A chest roentgenogram revealed marked elevation of the right hemidiaphragm when compared with the preoperative chest film. No signs of infection or other disorders were shown on the film. This pattern was suggestive of acquired phrenic nerve palsy. Because the moderate difficulty in breathing persisted despite physiotherapy, a complete checkup was made 3 months after the block. A new chest x-ray confirmed that the elevation of the right hemidiaphragm was unchanged and revealed atelectasis limited to the lower part of the right lung field, probably related to the right ventilatory deficit. No movement of the hemidiaphragm was observed during fluoroscopy, and paradoxical motion was shown by sniffing maneuver. Pulmonary function tests showed mild restrictive lung disease: vital capacity, forced expiratory volume in 1 s, forced vital capacity, and total lung capacity were respectively reduced to 89, 79, 88, and 76% of predicted values. By contrast, peak expiratory flow rate, arterial oxygen tension (PaO2), and arterial carbon dioxide tension (PaCO2) were in the normal range. Computed tomography and nuclear magnetic resonance scans of the neck and thorax were also normal. A definitive diagnosis of phrenic nerve dysfunction as the cause of hemidiaphragm paralysis was obtained by electromyography using phrenic nerve stimulation in the neck and the measurements of phrenic nerve latencies and conduction velocities. Stimulating electrodes were placed over the phrenic nerve in the supraclavicular fossa. The compound action potential of the hemidiaphragm was recorded using surface electrodes placed on the anterolateral aspect of the chest in the seventh intercostal space in the anterior axillary line. Results showed the absence of a right phrenic nerve compound action potential, whereas the left phrenic nerve conduction velocity was normal, suggesting that the right phrenic nerve was completely interrupted or significantly demyelinated. Although this examination failed to identify the mechanism or the precise location of the lesion, it was useful in confirming the lack of electromyographic pattern of diffuse neuropathy. One year after surgery, the patient still reported exertional dyspnea with no functional improvement.

Distal nerve blocks at the wrist for outpatient carpal tunnel surgery offer intraoperative cardiovascular stability and reduce discharge time.

UNLABELLED Carpal tunnel release is often performed as an outpatient procedure. We designed this retrospective study to assess the effect of different anesthesia techniques on intraoperative cardiovascular stability and discharge time. According to the anesthesia technique received, 62 consecutive patients were categorized in Group BIER (IV regional anesthesia), Group BLOCK (distal nerve blocks), and Group GENERAL (general anesthesia). Incidences of intraoperative periods of tachycardia or bradycardia and hyper- or hypotension were studied, as were tourniquet, surgical, operating room, and discharge times. Cardiovascular stability was better achieved in Group BLOCK, as indicated by a significantly smaller incidence of periods of hypertension compared with Group BIER (5% vs 25%) and a significantly less frequent incidence of periods of hypotension compared with Group GENERAL (14% vs 42%). Patients in Group BLOCK spent significantly less time in the hospital after surgery than patients in Group BIER (65 vs 88 min) or patients in Group GENERAL (65 vs 133 min). We conclude that distal nerve blocks for outpatient carpal tunnel surgery are associated with greater intraoperative cardiovascular stability than general anesthesia. After surgery, patients in Group BLOCK could be discharged earlier than patients who received IV regional anesthesia or general anesthesia; this could be related to the superior postoperative analgesia provided by this technique. IMPLICATIONS This retrospective analysis of three different anesthetic techniques for ambulatory carpal tunnel surgery shows that nerve blocks performed at the wrist provided excellent intraoperative cardiovascular stability and allowed for earlier discharge.

A 3-dimensional ultrasound study of local anesthetic spread during lateral popliteal nerve block: What is the ideal end point for needle tip position?

Background and Objectives Recent clinical trials suggest that subfascial (sometimes termed subepineural) injections result in faster block onset and success compared with conventional techniques. This prospective, randomized, observer-blinded study measured and compared the 3-dimensional spread pattern and volume of perineural local anesthetic (LA) in contact with the sciatic nerve after subfascial versus extrafascial lateral popliteal injections. Methods Sixty patients were randomly assigned to either the subfascial or the extrafascial injection group. All patients received a single-injection, US-guided lateral popliteal sciatic nerve block for postoperative pain. Depending on group assignment, the needle tip was placed outside or beneath the sciatic fascial sheath for a single injection of 30 mL of ropivacaine 0.5%. Using 3-dimensional ultrasound imaging, postblock scans were acquired to quantify the volume and spread pattern of perineural LA around the sciatic nerve in each group. Results The mean LA perineural volume for the extrafascial group was 1.48 (SD, 0.50) mL versus a mean of 5.57 (SD, 1.68) mL for the subfascial group, P < 0.05. The mean distance of longitudinal perineural LA spread (along the length of the nerve) for the subfascial group was 66% greater than that observed using the conventional technique (9.3 vs 5.6 cm, P < 0.01). Complete sensory block to pinprick for the extrafascial group was 63% versus 90% (P < 0.05) for the subfascial group. Conclusions Placement of the needle tip beneath the complex fascial sheath of the sciatic nerve resulted in significantly greater perineural local anesthetic volume following a single-injection lateral popliteal approach at the nerve bifurcation and was associated with greater sensory blockade and a characteristic laminar LA spread pattern.

An evaluation of the T‐Line® Tensymeter continuous noninvasive blood pressure device during induced hypotension*

A new continuous noninvasive blood pressure measurement device, the T‐Line® Tensymeter TL100 (Tensys Medical Inc., San Diego, CA, USA) which enables avoidance of arterial cannulation has been developed. We compared the values obtained using the T‐Line values to simultaneous arterial line measurements in patients undergoing general anaesthesia with induced hypotension. Twenty‐five patients, aged 18–70 years, were studied. The T‐Line and arterial line were positioned on the contralateral wrists. Intra‐operative, real‐time, blood pressure data were electronically captured and stored on a computer. Bland–Altman plots and 95% limits of agreement show that the majority of T‐Line data points were within 5 mmHg of the arterial line measurements (67%) and agreement was within 15 mmHg in 94.6% or more of all measurements. There was virtually no distinguishable error over the course of surgery using the device. In conclusion, the T‐Line measurements correlate with arterial measurements during anaesthesia in which there were periods of both normotensive and hypotensive anaesthesia. The T‐Line Tensymeter represents a noninvasive alternative to an arterial line in cases when arterial blood sampling is not required.

Surgery under extreme conditions in the aftermath of the 2010 haiti earthquake: The importance of regional anesthesia

The 12 January 2010 earthquake that struck Port-au-Prince, Haiti caused >200,000 deaths, thousands of injuries requiring immediate surgical interventions, and 1.5 million internally displaced survivors. The earthquake destroyed or disabled most medical facilities in the city, seriously hampering the ability to deliver immediate life- and limb-saving surgical care. A Project Medishare/University of Miami Miller School of Medicine trauma team deployed to Haiti from Miami within 24 hours of the earthquake. The team began work at a pre-existing tent facility in the United Nations (UN) compound based at the airport, where they encountered 225 critically injured patients. However, non-sterile conditions, no means to administer oxygen, the lack of surgical equipment and supplies, and no anesthetics precluded the immediate delivery of general anesthesia. Despite these limitations, resuscitative care was administered, and during the first 72 hours following the event, some amputations were performed with local anesthesia. Because of these austere conditions, an anesthesiologist, experienced and equipped to administer regional block anesthesia, was dispatched three days later to perform anesthesia for limb amputations, debridements, and wound care using single shot block anesthesia until a better equipped tent facility was established. After four weeks, the relief effort evolved into a 250-bed, multi-specialty trauma/intensive care center staffed with >200 medical, nursing, and administrative staff. Within that timeframe, the facility and its staff completed 1,000 surgeries, including spine and pediatric neurological procedures, without major complications. This experience suggests that when local emergency medical resources are completely destroyed or seriously disabled, a surgical team staffed and equipped to provide regional nerve block anesthesia and acute pain management can be dispatched rapidly to serve as a bridge to more advanced field surgical and intensive care, which takes longer to deploy and set up.

Ambulatory Continuous Perineural Infusion: Are We Ready?

1. Patients undergoing outpatient procedures deserve the same level of care as if they had remained in the hospital. In our practice, in which continuous perineural infusions are frequently used for total joint replacements (shoulder, ankle, hip, and knee), catheters are evaluated at least once a day to verify that they provide the expected sensory block and that the site is clear and there is no leaking, inflammation, or infection. We typically prefer approaches that allow a direct visual inspection of the site. For this reason, we favor the use of a lateral approach rather than the posterior approach chosen by Klein et al. for continuous infusions at the popliteal fossa. We also insist on removing these catheters ourselves. Transferring the responsibility for the care of these catheters to the patient seems to be inappropriate. After discharge, many patients undergoing same-day surgery are home alone for extended periods of time. Because confusion is one of the early symptoms of local anesthetic toxicity, one can question whether the patient or a significant other could qualify as a proper substitute to a trained healthcare professional. Several telephone calls from a trained healthcare professional and follow-up visits represent the minimum postoperative involvement. 2. Local anesthetics are intrinsically toxic; therefore, they should always be used at the minimum effective dose. The use of a device that allows an infusion at a rate of only 10 ml/h obviously does not allow any adjustment. In contrast, there are ambulatory pumps that offer variable basal rate combined with a patient-control analgesia (Sorenson Medical, West Jordon, UT). These patient-controlled analgesia pumps allow us to use smaller rates of infusion at which local anesthetics are administered and to adapt to any additional patient needs. 3. The technique described does not allow confirmation that the catheter was properly positioned in the first patient. By injecting 30 ml ropivacaine, 0.5%, before introduction of the catheter, the authors induced motor and sensory blocks that lasted long after the patient’s discharge. The second patient was more lucky; although the pump was connected 7 h after the initial bolus injection, she remained in the hospital long enough for verification that the infusion of 0.2% ropivacaine at a rate of 10 ml/h may have produced the desired sensory block. Given the potential local anesthetic toxicity and the possible complications of the perineural infusion techniques, it is important to confirm the intensity of the sensory block before discharge. The authors may want to consider using the technique described by Ayers and Enneking, which is based on an initial injection of 3 to 4 ml local anesthetic solutions using the introducing needle, followed by catheter placement and injection of the remaining volume of local anesthetic through the catheter. With this technique, it is possible to verify that the catheter is well-positioned before the patient’s discharge. 4. Like the authors, we also perform popliteal blocks for patients undergoing similar surgery. Although in the past we preferred the use of the single-injection techniques, we are evaluating continuous infusions for outpatient surgery. However, independent of the technique, our protocol includes calling the patient the day of and a week after surgery to verify the absence of complications and the quality of postoperative pain control. 5. It is of special interest to recognize that the sensory sapheneous nerve blocks (without continuous infusion) were effective for 24 and 23 h, respectively. Because 0.5% ropivacaine produced a block of similar duration in the sciatic and femoral territories, is it possible that the benefits were mostly a result of the initial bolus injection? Last, after confirmation from B. Braun Medical, Inc. (Bethlehem, PA), we would like to mention that this company did not manufacture 100-mm insulated needles, but rather 89-mm insulated needles.

Desmopressin before liver transplantation.

ante-room or inside patient’s room. The PAPR system consists of a belt-mounted powered air purifier (Figure, left) with a HEPA filter, connected via a tube to a light-weight head-piece (Figure, right). The HEPA filter removes particles of 0.3–15 mm with an efficiency of 98–100%.4 We have several years experience in using the PAPR system in the bronchoscopy suite and there are no documentation of disease transmission to health-care workers. The PAPR system has been suggested by the World Health Organization and the Center for Disease Control for SARS protection. It takes time to setup properly (steps 1–7). Therefore, it is crucial to have advance warning of patients requiring intubation. Furthermore, staff involved in intubation must be trained and familiar with the personal protection equipment so that it can be applied properly and expediently (steps 5–7); and removed properly to avoid contamination. As traditional respiratory and contact precautions have been shown to provide inadequate protection against SARS, we have developed this protocol which offers improved protection. The intubation protection protocol should be utilized whenever suspected SARS or infectious patients are encountered.