Epidural distribution of dye administered via an epidural catheter in a porcine model.

BACKGROUND: Local anaesthetics are commonly delivered to the epidural space by either intermittent bolus or continuous infusion. While these methods have been investigated in terms of analgesia and total dose administered, they have not been compared in terms of their effect on the spread of injectate within the epidural space. This animal study compared the spread of dye delivered to the epidural space in a porcine model by either bolus or infusion. METHODS: After ethical approval, epidural catheters were placed at three vertebral levels in seven anaesthetized pigs. Aqueous dye (1 ml) was injected into the catheter as a bolus, or as an infusion over 30 min. Animals were euthanized at the end of the study and necropsy performed immediately to quantify the extent of dye spread. RESULTS: In seven animals, 20 catheters were successfully placed in the epidural space. The mean (sd) extent of dye spread was 8.9 (2.6) cm in the infusion group compared with 15.2 (2.7) cm in the bolus group (P<0.001). Segmental spread was significantly greater in the bolus group compared with the infusion group (P<0.01). CONCLUSION: In the porcine epidural model, spread of one ml of epidural dye solution is more extensive after a single bolus compared with short term infusion.

Flexion-rotation manoeuvre increases dimension of the acoustic target window for paramedian thoracic epidural access.

BACKGROUND: The posterior longitudinal ligament (PLL) has been found to be a reliable measure of the acoustic target window for lumbar spinal anaesthesia and a predictive tool for difficult spinals. Currently, there is limited information on the PLL in the thoracic spine and its potential use for optimizing the acoustic target window during thoracic epidural placement. This study examined the effects of changes in body position on the length of the PLL as a measure of the acoustic target window for paramedian thoracic epidural access. METHODS: We performed thoracic ultrasonography on 30 adult volunteers to measure the length of the PLL at the T9/10 interspace, in five different positions: P1, neutral; P2, thoracic and lumbar flexion; P3, as in position 2 with dorsal table tilt to 10°; P4, as in position 2 with 45° rightward shoulder rotation; and P5, as in position 2 with 45° leftward shoulder rotation. RESULTS: The mean (sd) PLL length increased significantly from 9.9 (3.9) mm in P1 to 11.7 (3.4) mm in P2, 12.9 (3.1) mm in P3, and 13.8 (4.0) mm in P4 (P<0.01, <0.01, and <0.01, respectively). The mean PLL length in P3 and P4 was also significantly longer compared with P2 (P<0.01 and 0.01, respectively). CONCLUSIONS: In volunteers, flexion with 10° dorsal table tilt and flexion with right rotation significantly increased the length of the ipsilateral PLL, compared with the standard flexed sitting position, as visualized by paramedian ultrasonography at the level of T9/10.

Selective spinal anesthesia for outpatient transurethral prostatectomy (TURP): randomized controlled comparison of chloroprocaine with lidocaine.

BACKGROUND: This is a study comparing two short-acting local anesthetics lidocaine and 2-chloroprocaine in combination with fentanyl, to provide selective spinal anesthesia for outpatient transurethral resection of the prostate (TURP). METHODS: In this prospective, randomized double-blind study, selective spinal anesthesia was performed in 40 American Society of Anesthesiologists I-III outpatients undergoing TURP using either 40 mg of chloroprocaine mixed with 12.5 µg of fentanyl (n = 20) or 35 mg of lidocaine mixed with 12.5 µg of fentanyl (n = 20). The primary outcome was duration of spinal block. Secondary outcomes were time to reach T10 (onset), time to maximal level, duration above T10 and lidocaine 3, maximal level of block, and adverse effects. RESULTS: The median (minimum, maximum) onset time was 4 (1, 16) and 3 (2, 10) min for chloroprocaine and lidocaine, respectively. Time to maximal level was 20 (17, 29) and 22 (16, 26) min for chloroprocaine and lidocaine, respectively. Mean maximal level was T7-T8 for both agents. Duration of block above T10 was 54 (28, 88) and 63 (31, 87) min for chloroprocaine and lidocaine, respectively. Duration of block above lidocaine 3 was 93 (56, 218) and 98 (58, 151) min for chloroprocaine and lidocaine, respectively. There was no statistical difference between the two groups with respect to these clinical end points. Four patients in the lidocaine group developed transient neurological symptoms. One patient in the chloroprocaine group developed a cauda equina-like syndrome but recovered fully after several weeks. CONCLUSIONS: Selective spinal anesthesia with chloroprocaine and lidocaine for TURP yielded comparable results for clinical characteristics. Further research on transient neurological symptom and cauda equina risk with chloroprocaine is warranted.

Surgical placement of rectus sheath catheters in a cadaveric cystectomy model.

Introduction Surgically inserted rectus sheath catheters (RSCs) are used increasingly for analgesia after cystectomy and other abdominal surgery. Currently, there is little information on the optimal positioning of RSCs to allow maximal spread of local anaesthetic. This study sought to assess the spread of dye injected via RSCs and to highlight the extent of its coverage in a fresh unembalmed cadaveric cystectomy model in order to confirm the nerve endings that are likely to be anaesthetised with RSCs. Methods Four cadavers underwent lower midline incision with limited bladder mobilisation. A RSC was inserted into the eight hemiabdomens. The RSCs were positioned either anterior (n=5) or posterior to the rectus muscle (n=3). Dye was injected down the RSCs to evaluate spread. The eight hemiabdomens were dissected anatomically to determine the surface area of dye spread and nerve root involvement. Results The mean surface area of dye spread with anteriorly placed RSCs was 30.6cm2 anterior and 25.9cm2 posterior to the rectus muscle. The mean surface area of dye spread with posteriorly placed RSCs was 11.3cm2 anterior and 37.3cm2 posterior to the rectus muscle. The mean number of nerve roots stained with anteriorly and posteriorly placed RSCs was 3.8 and 2.7 respectively. Subcutaneous spread of dye was seen with one anterior RSC insertion. Peritoneal spread was seen with one anteriorly positioned RSC. Conclusions This study has demonstrated efficient nerve root infiltration with anteriorly and posteriorly positioned RSCs. It appears that dye spreads between the fibres of the rectus muscle rather than out laterally to the nerve roots when spreading from its initial compartment.

Airway resuscitation packs for nurses: a recommendation for their withdrawal.

Approximately one third of our hospitals appear to issue airway resuscitation packs (ARPs) to nurses responsible for the care of postanaesthetic and comatose patients. These packs contain instruments intended for use in overcoming airway obstruction. One hundred and eight nurses replied to a questionnaire designed to identify their knowledge of the instruments. The results indicate that nurses entrusted with ARPs were almost totally unfamiliar with the instruments and their application. The authors recommend the universal withdrawal of ARPs and suggest that nurses and doctors are taught to recognise airway obstruction and to manage it with simple manoeuvres not involving instrumentation.

Anaesthetic implications of the trismus pseudocamptodactyly (Dutch-Kentucky or Hecht Beals) syndrome.

The trismus pseudocamptodactyly syndrome is a relatively rare, autosomal dominant condition first described in 1969. Affected patients classically present with two main features: limited excursion of the mandible and flexion deformity of the fingers that occurs with wrist extension (pseudocamptodactyly). Foot deformities and a shorter-than-normal stature may also be present. The underlying abnormality is short muscle tendon units, which prevent normal growth and development. We reviewed the anaesthetic experience in three paediatric patients with the trismus pseudocamptodactyly syndrome and the pertinent clinical findings in three other members of the same family, spanning three generations. Limited mandible excursion was present in all six cases, but was not obvious preoperatively in the patients because of its subtle presentation. All three cases were successfully managed using mask anaesthesia with spontaneous ventilation, avoiding muscle relaxants. Attempts to visualize the larynx under anaesthesia were unsuccessful in two cases. Blind nasotracheal intubation was successful in one patient. Postoperatively, there were no problems with the airway.

Refractory dystonia during propofol anaesthesia in a patient with torticollis-dystonia disorder.

PURPOSE: To report a case of refractory dystonia under propofol anaesthesia in a patient with Torticollis-Dystonia disorder. CLINICAL FEATURES: A 38-yr-old man presented for an MRI scan for investigation of a Torticollis-Dystonia disorder. There was a biphasic response to propofol with complete amelioration of the torticollis and limb dystonia initially with subsequent recurrence under deep propofol anaesthesia. Coadministration of midazolam, diazepam, and thiopentone were not successful in abolishing the recurrent dystonia. CONCLUSIONS: Propofol should preferably be avoided in patients with torticollis and dystonias. Where complete control of movements is required, it may be necessary to consider general endotracheal anaesthesia with muscle relaxants.

Can nurses screen all outpatients? Performance of a nurse based model.

PURPOSE: This paper outlines and evaluates a nurse based model for screening outpatients that is utilized in our free standing Surgical Day Care Centre (SDCC). METHODS: For 668 outpatients presenting at our SDCC, the attending anesthesiologist completed a study survey that was designed to identify: completeness of history; important concerns as judged by the pre-admission nurse; whether the patient was seen in the anesthesia preadmission clinic (PAC) for a consultation; if there was a delay in SDCC, the duration and reasons for the delay; whether in the opinion of the attending anesthesiologist the patient should have had an anesthetic consultation; whether the patient was canceled and the reason for cancellation. RESULTS: A nurse based model for screening all outpatients in a university affiliated tertiary hospital day care unit had an accuracy of 81%, specificity of 86%, sensitivity of 46% and a negative predictive value of 92%. The cancellation rate with this model was 1.4%(8/551) and the case delay rate was 3.4%(19/551). The referral rate to anesthesiology staff was 17.5%(117/668) and the referral rate to the PAC for anesthetic consultation was 5.1%(34/668). CONCLUSIONS: The use of the nurse based model allowed for the efficient use of anesthesia and surgical day care centre resources. The model was better at 'ruling out' patients who do not need to be seen by anesthesiology ahead of the day of surgery rather than 'ruling in' patients who need to be seen by anesthesiology.

Use of a Doppler ultrasound stethoscope for intercostal nerve block.

Two cases with rib injuries are reported where intercostal nerve block without rib palpation was safely and successfully performed on six separate occasions using a Doppler blood-flow detector ultrasound stethoscope. A third case studied by a radiologist using a pulsed Doppler flowmeter, determined the source of the Doppler signals as originating from the intercostal artery. The significance of these findings is discussed.

Ankylosing spondylitis and neuraxial anaesthesia--a 10 year review.

PURPOSE: Ankylosing Spondylitis (AS) patients present specific challenges to the anaesthetist. Both airway management and neuraxial access may prove to be difficult. The trend has been to deal with the airway challenge, and avoid neuraxial anaesthesia. In many cases this may lead to unnecessarily denying the patient neuraxial anesthesia (NA). We retrospectively reviewed the operative anaesthetic management of 51 consecutive AS patients who underwent 82 perineal or lower limb procedures and concurrent anaesthetic management at the Vancouver Hospital and Health Sciences Center from 1984 through 1994 (inclusive). SOURCE: Anaesthetic records were used to document the type of anaesthetic used, i.e., general or regional, and the degree of difficulty experienced with each. PRINCIPAL FINDINGS: Of the 82 procedures performed on AS patients 16 (19.5%) were planned as NA. General anaesthesia (GA) was planned for 65 (79.3%) of the procedures. One procedure involved monitored anaesthetic care (MAC). Neuraxial access consisted of 13 spinal and three epidural attempts. Spinal anaesthesia was possible in 10 (76.2%) of cases and failed in 3 (23.8%). Epidural anaesthesia was unsuccessful in each attempt. There was no difference in demographics or duration of disease between the successes and failures. CONCLUSIONS: These data suggest that spinal anaesthesia can be used as an alternative to general anaesthesia in AS patients undergoing perineal or lower limb surgery. There were no factors identified in this review that were predictive of success or failure in gaining neuraxial access.

Tracheal intubation of outpatients with and without muscle relaxants.

PURPOSE: To compare intubating conditions and postoperative myalgias in outpatients after intubation with propofol/alfentanil compared with propofol/alfentanil/succinylcholine with and without precurarisation with d-tubocurarine. METHODS: 144 ASA I-II ambulatory patients for dental extraction under anesthesia were studied. Subjects received either 3 mg d-tubocurarine (Group II) or saline (Groups I, III) i.v. prior to induction of anesthesia with 20 microg x kg(-1) alfentanil and 2.5 mg x kg(-1) propofol followed by 1.5 mg x kg(-1) succinylcholine (II and III) or saline 0.9% (I) for muscle relaxation. The ease of airway management and the postoperative incidence, severity and distribution of muscle pains were examined. RESULTS: Intubation was successful in all patients and there were no differences in jaw mobility, ease of bag-mask ventilation, visualization of the vocal cords or cord position. Limb movement was more common during intubation in Group I (37.5%) than in Group III (8.3%) or Group II (2%), P < 0.05. At home, VAS scores for myalgia were higher in Group III than in Group I and II. Neck myalgia was more common in Group II (72%) than in Groups II (44%) and I (41%), P < 0.05. Myalgias were also more common in Group III patients (P < 0.05). CONCLUSION: Acceptable intubating conditions were achieved with propofol and alfentanil alone. Succinylcholine reduced limb movement during intubation but was associated with postoperative myalgias for up to five days. Precurarisation with tubocurarine reduced the severity of succinylcholine myalgia.