Vasectomy reversal with ultrasonography-guided spermatic cord block

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Vasectomy reversal is often performed in general or neuraxial anaesthesia. Even though the site of vasectomy reversal is easily amenable to regional/local anaesthesia, spermatic cord blocks are rarely applied because of their risk of vascular damage within the spermatic cord. Recently, we described the technique of ultrasonography (US)-guided spermatic cord block for scrotal surgery, which, thanks to the US guidance, at the same time avoids the risk of vascular damage of blindly performed injections and the risks of general and neuraxial anaesthesia. Vasectomy reversal can easily be done in regional anaesthesia with the newly described technique of US-guided spermatic cord block without the risks of vascular damage by a blindly performed injection and the risks of standard general and neuraxial anaesthesia. In addition, this technique grants long-lasting postoperative pain relief and patients recover more quickly. Microsurgical conditions are excellent and patient satisfaction is high. Thanks to these advantages, more patients undergoing vasectomy reversal might avoid general or neuraxial anaesthesia.

The location of paravertebral catheters placed using the landmark technique

The aim of this prospective clinical study was to evaluate the location of paravertebral catheters that were placed using the classical landmark puncture technique and to correlate the distribution of contrast dye injected through the catheters with the extent of somatic block. Paravertebral catheter placement was attempted in 31 patients after video-assisted thoracic surgery. In one patient, an ultrasound-guided approach was chosen after failed catheter placement using the landmark method. A fluoroscopic examination in two planes using contrast dye was followed by injection of local anaesthetic and subsequent clinical testing of the extent of the anaesthetised area. In nine patients (29%), spread of contrast dye was not seen within the paravertebral space as intended. Misplaced catheters were in the epidural space (three patients), in the erector spinae musculature (five patients), and in the pleural space (one patient). There was also a discrepancy between the radiological findings and the observed distribution of loss of sensation. We have demonstrated an unacceptably high misplacement rate of paravertebral catheters using the landmark method. Additional research is required to compare the efficacy and safety of continuous paravertebral block using ultrasound-guided techniques or surgical inserted catheters.

Ultrasound-guided retrobulbar nerve block in horses: a cadaveric study

Objective  To develop an ultrasound-guided technique for retrobulbar nerve block in horses, and to compare the distribution of three different volumes of injected contrast medium (CM) (4, 8 and 12 mL), with the hypothesis that successful placement of the needle within the retractor bulbi muscle cone would lead to the most effective dispersal of CM towards the nerves leaving the orbital fissure. Study design  Prospective experimental cadaver study. Animals  Twenty equine cadavers. Methods  Ultrasound-guided retrobulbar injections were performed in 40 cadaver orbits. Ultrasound visualization of needle placement within the retractor bulbi muscle cone and spread of injected CM towards the orbital fissure were scored. Needle position and destination of CM were then assessed using computerized tomography (CT), and comparisons performed between ultrasonographic visualization of orbital structures and success rate of injections (intraconal needle placement, CM reaching the orbital fissure). Results  Higher scores for ultrasound visualization resulted in a higher success rate for intraconal CM injection, as documented on the CT images. Successful intraconal placement of the needle (22/34 orbits) resulted in CM always reaching the orbital fissure. CM also reached the orbital fissure in six orbits where needle placement was extraconal. With 4, 8 and 12 mL CM, the orbital fissure was reached in 16/34, 23/34 and 28/34 injections, respectively. Conclusion and clinical relevance  The present study demonstrates the use of ultrasound for visualization of anatomical structures and needle placement during retrobulbar injections in equine orbits. However, this approach needs to be repeated in controlled clinical trials to assess practicability and effectiveness in clinical practice.

Evaluation of high-definition and conventional oscillometric blood pressure measurement in anaesthetised dogs using ACVIM guidelines

OBJECTIVES: To evaluate high-definition and conventional oscillometry in comparison with direct blood pressure measurements in anaesthetised dogs. METHODS: Eight simultaneous readings for systolic, diastolic and mean pressure were obtained directly and with each of two devices in nine anaesthetised dogs. Measurement procedure and validation were based on the 2007 ACVIM guidelines. RESULTS: Sixty-three simultaneous readings were evaluated for each device and direct measurements. The mean differences (bias) to direct values were within 10 mmHg for both devices although bias for systolic and diastolic blood pressures was higher for Memodiagnostic. The standard deviations of differences (precision) were within 15 mmHg for Dinamap but exceeded for Memodiagnostic. Correlation coefficients were higher for Dinamap than Memodiagnostic but both failed to reach a correlation of 0.9. Over 50% of values lay within 10 mmHg of direct measures for both devices, but this percentage was greater for Dinamap than Memodiagnostic. Over 80% of values lay within 20 mmHg of direct measures for Dinamap but not for Memodiagnostic. CLINICAL SIGNIFICANCE: Both devices failed to meet ACVIM guideline validation. However, Dinamap only failed with regards to correlation. Memodiagnostic failed on several requirements, and based on poor correlation, accuracy and precision, this device cannot be currently recommended for dogs under anaesthesia.

The effects of isoflurane minimum alveolar concentration on withdrawal reflex activity evoked by repeated transcutaneous electrical stimulation in ponies

The aim of this study was to quantify the effects of isoflurane at approximately the minimum alveolar concentration (peri-MAC) on the temporal summation (TS) of reflex activity in ponies. TS was evoked by repeated electrical stimulations applied at 5 Hz for 2 s on the digital nerve of the left forelimb of seven ponies. Surface electromyographic activity was recorded from the deltoid and common digital extensor muscles. TS thresholds and amplitude of response to stimulations of increasing intensities were assessed during anaesthesia at 0.85, 0.95 and 1.05 times the individual MAC, and after anaesthesia in standing animals. Under isoflurane anaesthesia, TS thresholds increased significantly in a concentration-dependent fashion and at each isoflurane MAC, the responses increased significantly for increasing stimulation intensities. A concentration-dependent depression of evoked reflexes with a reduction in the slopes of the stimulus-response function was observed for both muscles. The results demonstrated that with this model it is possible to describe and quantify the effects of anaesthetics on spinal sensory-motor processing in ponies.

Pancuronium dose refinement in experimental pigs used in cardiovascular research

To quantify the dose of pancuronium required to obtain moderate neuromuscular blockade as monitored by acceleromyography (NMB(mod) : train-of-four count of ≤2) as a part of a balanced anaesthetic protocol in pigs used in cardiovascular research.

Respiratory function during anesthesia: effects on gas exchange

Anaesthesia causes a respiratory impairment, whether the patient is breathing spontaneously or is ventilated mechanically. This impairment impedes the matching of alveolar ventilation and perfusion and thus the oxygenation of arterial blood. A triggering factor is loss of muscle tone that causes a fall in the resting lung volume, functional residual capacity. This fall promotes airway closure and gas adsorption, leading eventually to alveolar collapse, that is, atelectasis. The higher the oxygen concentration, the faster will the gas be adsorbed and the aleveoli collapse. Preoxygenation is a major cause of atelectasis and continuing use of high oxygen concentration maintains or increases the lung collapse, that typically is 10% or more of the lung tissue. It can exceed 25% to 40%. Perfusion of the atelectasis causes shunt and cyclic airway closure causes regions with low ventilation/perfusion ratios, that add to impaired oxygenation. Ventilation with positive end-expiratory pressure reduces the atelectasis but oxygenation need not improve, because of shift of blood flow down the lung to any remaining atelectatic tissue. Inflation of the lung to an airway pressure of 40 cmH2O recruits almost all collapsed lung and the lung remains open if ventilation is with moderate oxygen concentration (< 40%) but recollapses within a few minutes if ventilation is with 100% oxygen. Severe obesity increases the lung collapse and obstructive lung disease and one-lung anesthesia increase the mismatch of ventilation and perfusion. CO2 pneumoperitoneum increases atelectasis formation but not shunt, likely explained by enhanced hypoxic pulmonary vasoconstriction by CO2. Atelectasis may persist in the postoperative period and contribute to pneumonia.

[Castration of calves: a survey among Swiss suckler beef farmers]

In fall 2004, a survey of a representative sample of 1185 Swiss suckler beef farmers was carried out by questionnaire (return rate 51.9%). 32.7% of the respondents castrated their calves without the help of a veterinarian, 37.8% mandated a veterinarian to carry out the castrations and 29.4% did not castrate their bull calves at all. On average, 8 calves were castrated per farm and year at an average age of 7 days when the castration was carried out by a farmer or 34 days when the castration was carried out by a veterinarian. Almost all farmers castrated their calves with the rubber ring, and a majority considered no other method as feasible. 73.9% of the veterinarians used the Burdizzo technique, 14.9% applied rubber rings, and 11.2% performed a surgical procedure. 22.6% of the farmers and 85.4% of the veterinarians used sedation; local anaesthesia was performed in 32.1% of the castrations carried out by farmers and in 84.5% of the castrations carried out by veterinarians. 65.7% of the farmers were concerned by the change of the Swiss Animal Protection Ordinance (2001), when pain relief became mandatory. 47.6% of these farmers changed their castration routine: 53.1% now mandated a veterinarian, 33.0% used sedation or local anaesthesia and 8.9% abandoned castration of their calves. 59.8% of the farmers intended to participate in a future course for laymen, to study and train the technique of local anaesthesia for castration. Castration of their calves is for many suckler beef farmers an inevitable husbandry procedure. The political goal, that all calves shall be castrated with local anaesthesia can only be reached when livestock owners are informed about the distress caused by the castration and convinced of the benefit of the local anaesthesia.Veterinarians are important information carriers in this process. The implementation also produces work, be it the more complex castration procedure or the education of the farmers who want to carry out the local anaesthesia themselves.

Castration of lambs: a welfare comparison of different castration techniques in lambs over 10 weeks of age

Seventy male lambs over 10 weeks of age were castrated using Burdizzo, rubber rings, or surgery to assess the acute and long-term effects of castration. All castrations were performed under local anaesthesia. The surgically castrated lambs were additionally sedated with xylazine and the sedation reversed with tolazoline. The frequency of abnormal postures and immediate behavioural responses indicated that surgically castrated lambs were most distressed; the lambs castrated using Burdizzo and rubber rings were not dissimilar to those of the control group. Between 1.5 and 9h after castration, signs of pain and distress were at a lower level in lambs anaesthetised with bupivacaine compared with those treated with lidocaine. Due to the markedly faster wound healing, Burdizzo castration seemed to be preferable (fewer signs of long-term pain) when compared to the rubber ring technique. It was concluded that local anaesthesia with bupivacaine, followed by the Burdizzo method is the preferable technique for the castration of lambs older than 10 weeks of age.

Continuous extradural analgesia in a cow with complex regional pain syndrome

A chronic pain syndrome, similar to the complex regional pain syndrome (CRPS) described in human beings, was diagnosed in a cow with persisting severe pelvic limb lameness. Diagnosis was based on the disproportionate relationship between the severity and duration of pain and the lesion, the failure of conventional analgesic and surgical therapy and the presence of characteristic clinical features. Multimodal therapy, i.e. a mixture of methadone, ketamine and bupivacaine was administered continuously for 17 days via an extradural catheter to counteract nociceptive hypersensitization. Doses were adjusted daily after assessing the effect, using a composite pain score. Physiotherapy was also performed. The diagnosis of CRPS in cattle is unusual. In this case, treatment was successful and the cow was discharged mildly lame and in improving physical condition. Long-term extradural analgesia proved to be safe and effective in the treatment of this syndrome, which was nonresponsive to conventional therapy.

Comparison of rebound tonometry with Goldmann applanation tonometry and correlation with central corneal thickness

BACKGROUND/AIMS: Rebound tonometry (RT) is performed without anaesthesia with a hand held device. The primary aim was to compare RT with Goldmann applanation tonometry (GAT) and to correlate with central corneal thickness (CCT). The secondary aim was to prove tolerability and practicability of RT under "study conditions" and "routine practice conditions." METHODS: In group 1 (52 eyes/28 patients), all measurements were taken by the same physician, in the same room and order: non-contact optical pachymetry, RT, slit lamp inspection, GAT. Patients were questioned about discomfort or pain. In group 2 (49 eyes/27 patients), tonometry was performed by three other physicians during routine examinations. RESULTS: RT was well tolerated and safe. Intraocular pressure (IOP) ranged between 6 mm Hg and 48 mm Hg. No different trends were found between the groups. RT tended to give slightly higher readings: n = 101, mean difference 1.0 (SD 2.17) mm Hg; 84.1% of RT readings within plus or minus 3 mm Hg of GAT; 95% confidence interval in the Bland-Altman analysis -3.2 mm Hg to +5.2 mm Hg. Both RT and GAT showed a weak positive correlation with CCT (r2 0.028 and 0.025, respectively). CONCLUSIONS: RT can be considered a reliable alternative for clinical screening and in cases where positioning of the head at the slit lamp is impossible or topical preparations are to be avoided.

[Disorders of the origin of the suspensory ligament in the horse: a diagnostic challenge]

Lameness in horses due to pain originating from the proximal metacarpal/metatarsal region remains a diagnostic challenge. In cases of obvious lameness the pain can be localised to this region by diagnostic anaesthesia. Because a variety of disorders can cause lameness in this region different imaging modalities including radiography, ultrasonography and scintigraphy should be used to arrive at an accurate diagnosis. Even though a precise anatomic-pathologic diagnosis can still be an enigma, because not only bone and joints, but also soft tissue structures including the proximal suspensory ligament, its origin at the proximal metacarpus/ metatarsus, its fascia, the superficial fascia, as well as the intermetacarpal/metatarsal ligaments, the accessory ligament of the deep digital flexor tendon and both digital flexor tendons may be involved. Magnet resonance tomography (MRT) shows a high diagnostic sensitivity in imaging soft tissue structures and bone. In horses MRT is still at the beginning. The MRT appearance of the proximal metacarpal/metatarsal region has not yet been evaluated in detail and there are only few anatomic studies of the origin of the suspensory ligament in horses. The first experiences showed, that more gross and histologic examinations are necessary to fully interpret MRT-images and to differentiate pathologic alterations from clinically not relevant variations.

Ultrasound-guided blocks of the ilioinguinal and iliohypogastric nerve: accuracy of a selective new technique confirmed by anatomical dissection

BACKGROUND: Ilioinguinal and iliohypogastric nerve blocks may be used in the diagnosis of chronic groin pain or for analgesia for hernia repair. This study describes a new ultrasound-guided approach to these nerves and determines its accuracy using anatomical dissection control. METHODS: After having tested the new method in a pilot cadaver, 10 additional embalmed cadavers were used to perform 37 ultrasound-guided blocks of the ilioinguinal and iliohypogastric nerve. After injection of 0.1 ml of dye the cadavers were dissected to evaluate needle position and colouring of the nerves. RESULTS: Thirty-three of the thirty-seven needle tips were located at the exact target point, in or directly at the ilioinguinal or iliohypogastric nerve. In all these cases the targeted nerve was coloured entirely. In two of the remaining four cases parts of the nerves were coloured. This corresponds to a simulated block success rate of 95%. In contrast to the standard 'blind' techniques of inguinal nerve blocks we visualized and targeted the nerves 5 cm cranial and posterior to the anterior superior iliac spine. The median diameters of the nerves measured by ultrasound were: ilioinguinal 3.0x1.6 mm, and iliohypogastric 2.9x1.6 mm. The median distance of the ilioinguinal nerve to the iliac bone was 6.0 mm and the distance between the two nerves was 10.4 mm. CONCLUSIONS: The anatomical dissections confirmed that our new ultrasound-guided approach to the ilioinguinal and iliohypogastric nerve is accurate. Ultrasound could become an attractive alternative to the 'blind' standard techniques of ilioinguinal and iliohypogastric nerve block in pain medicine and anaesthetic practice.

Stimulation induced variability of pulse plethysmography does not discriminate responsiveness to intubation

BACKGROUND: Hypnotic depth but not haemodynamic response to painful stimulation can be measured with various EEG-based anaesthesia monitors. We evaluated the variation of pulse plethysmography amplitude induced by an electrical tetanic stimulus (PPG variation) as a potential measure for analgesia and predictor of haemodynamic responsiveness during general anaesthesia. METHODS: Ninety-five patients, ASA I or II, were randomly assigned to five groups [Group 1: bispectral index (BIS) (range) 40-50, effect site remifentanil concentration 1 ng ml(-1);Group 2: BIS 40-50, remifentanil 2 ng ml(-1); Group 3: BIS 40-50, remifentanil 4 ng ml(-1); Group 4: BIS 25-35, remifentanil 2 ng ml(-1); Group 5: BIS 55-65, remifentanil 2 ng ml(-1)]. A 60 mA tetanic stimulus was applied for 5 s on the ulnar nerve. From the digitized pulse oximeter wave recorded on a laptop computer, linear and non-linear parameters of PPG variation during the 60 s period after stimulation were computed. The haemodynamic response to subsequent orotracheal intubation was recorded. The PPG variation was compared between groups and between responders and non-responders to intubation (anova). Variables independently predicting the response were determined by logistic regression. RESULTS: The probability of a response to tracheal intubation was 0.77, 0.47, 0.05, 0.18 and 0.52 in Groups 1-5, respectively (P<0.03). The PPG variability was significantly higher in responders than in non-responders but it did not improve the prediction of the response to tracheal intubation based on BIS level and effect site remifentanil concentration. CONCLUSION: Tetanic stimulation induced PPG variation does not reflect the analgesic state in a wide clinical range of surgical anaesthesia.