Sugantha Ganapathy

Beating heart surgery: why expect less central nervous system morbidity?

BACKGROUND The incidence and etiology of brain dysfunction after conventional coronary artery bypass surgery using cardiopulmonary bypass (CPB) are reviewed. METHODS Stroke rates and incidences of cognitive dysfunction from various studies are considered. Mechanisms of injury including cerebral embolization as detected by transcranial Doppler and retinal angiography, and imaging-based evidence for postoperative cerebral edema, are discussed. Preliminary results from a prospective clinical trial assessing cognitive dysfunction after beating heart versus conventional coronary artery bypass with CPB are discussed. RESULTS Initial evidence for lower overall postoperative morbidity, and for a lower incidence of cognitive dysfunction specifically, after nonpump coronary revascularization is presented. CONCLUSIONS Beating heart surgery results in less potential for generation of cerebral emboli and appears to produce a lower incidence of cognitive dysfunction in both short- and intermediate-term postoperative follow-up periods as compared with conventional coronary artery bypass surgery using CPB.

Anaesthesia for adenotonsillectomy: a comparison between tracheal intubation and the armoured laryngeal mask airway

A prototype armoured laryngeal mask airway (LMA) was compared with tracheal intubation (ETT) for anaesthesia for adenotonsillectomy. Fifty-five children were randomised into the LMA group and 54 into the ETT group. During insertion of the LMA, peripheral oxyhaemoglobin desaturation (SpO2) < 94% occurred in ten patients (18.2%) and in seven patients (13%) during tracheal intubation (NS). After opening the Boyle-Davis gag, airway obstruction occurred in ten patients (18.2%) in the LMA group and in three patients (6%) in the ETT group (P = 0.07). In five patients (9%) the LMA was abandoned in favour of tracheal intubation. In all others (91%), when the need for adequate depth of anaesthesia was realized, a satisfactory airway was achieved more rapidly than with tracheal intubation (P < 0.001), and maintained throughout surgery. Manually assisted ventilation was required in all patients in the ETT group, mean duration 373 ± 385 sec, and in 26 patients (52%) in the LMA group, mean duration 134 ± 110 sec, P < 0.001. Mean end-tidal CO2 (PetCO2) was 45.5 ± 6.21 mmHg in the ETT group and 46.6 ± 6.09 in the LMA group (NS). The LMA did not limit surgical access. Heart rate, MAP and blood loss in the LMA group were 110 ± 21, 74 ± 9 mmHg and 1.92 ± 1.22 ml · kg−1 respectively, compared with 143 ± 13 (P < 0.001), 85 ± 12 mmHg (P < 0.001) and 2.62 ± 1.36 ml · kg−1 (P < 0.05) with tracheal intubation. Fibreoptic laryngoscopy at the end of surgery in 19 patients in the LMA group revealed no blood in the larynx. In the LMA group postintubation stridor and laryngospasm occurred in five and three patients respectively, compared with 14 (P < 0.05) and six patients respectively (NS) with tracheal intubation. SpO2 on admission to the PACU in the LMA group was 95.9 ± 2.21, and 93.5 ± 4.53 (P < 0.05) after tracheal intubation. Our study demonstrated that the LMA is a safe alternative to tracheal intubation for adenotonsillectomy. Control of airway reflexes by ensuring sufficient depth of anaesthesia is essential for successful use of the LMA in children.RésuméUn prototype de masque larngyé armé (ML) est comparé à l’intubation trachéale (TE) pendant l’anesthésie pour adéno-amygdalectomie. Cinquante-cinq enfants sont assignés au hasard au groupe ML et 54 au groupe TE. Pendant l’insertion du ML, une désaturation périphérique inférieure à 94% survient chez dix patients (18,2%) et pendant l’intubation trachéale chez sept patients (13%) (NS). Après la mise en place de l’ouvre-bouche de Boyle-Davis, l’obstruction des voies aériennes supérieures survient chez dix patients (18,2%) dans la groupe ML et trois patients dans le groupe TE (P = 0.07). Chez cinq patients (9%), on abandonne le ML en faveur de l’intubation trachéale. Chez tous les autres (91%), après l’atteinte d’un niveau d’anesthésie adéquat, un airway satisfaisant est réalisé plus rapidement qu’avec l’intubation trachéale (P < 0,001) et maintenu pendant la chirurgie. Une ventilation assistée manuellement devient nécessaire pour tous les patients du groupe TE, avec une durée moyenne de 373 ± 385 sec, et chez 26 patients (52%) du groupe ML, avec une durée moyenne de 134 ± 110 sec (P < 0,001). Le CO2 télé-expiratoire (PetCO2) est de 45,5 ± 6,21 mmHg dans le groupe TE et de 46,6 ± 6,09 mmHg dans le groupe MLA (NS). Le MLA ne limite pas l’accès chirurgical. La fréquence cardiaque, la PAM et la perte sanguine est de 110 ± 21, 74 ± 9 mmHg et 1,92 ± 1,22 ml · kg−1 respectivement pour le groupe ML, comparativement à 143 ± 13 (P < 0,001), 85 ± 12 mmHg (P < 0,001) et 2,62 ± 1,36 ml · kg−1 (P < 0,05) pour le groupe TE. Chez 19 patients du groupe ML, la fibroscopie à la fin de la chirurgie n’a pas révélé la présence de sang dans le larynx. Dans le groupe ML après l’intubation, un stridor et un laryngospasme sont apparus chez cinq et trois patients respectivement, comparativement à 14 (P < 0,05) et six patients respectivement (NS) dans le groupe TE. Notre étude montre que le ML est une alternative sécuritaire à l’intubation trachéale pour l’adéno-amygdalectomie. Pour utiliser avec succès la LM, il est essentiel de contrôler les réflexes des voies aériennes par une anesthésie suffisamment profonde.

Elastomeric pumps for ambulatory patient controlled regional analgesia

Purpose: To report our experience with the use of the (Eclipse®) elastomeric pump for ambulatory Patient Controlled Regional Analgesia (PCRA)Method: After a pilot study using this device in patients admitted to the hospital, seven patients received PCRA at home using the elastomeric pump. Patients with a variety of continuous regional anesthetic blocks were sent home with written and verbal instructions regarding the use of this device, boluses, side effects of local anesthetics and removal of block catheters. Patients were contracted daily to collect data with regards to the efficacy of the block, problems associated with the use of this device and their satisfaction with the method of analgesia.Results: During the pilot study there were two catheter disconnections requiring rescue analgesics. Two patients had the entire contents of the bulb delivered over several minutes. Among the seven patients receiving PCRA at home, one patient had to be admitted to the hospital. One patient had block catheter slip out during transit. The volume delivered could not be measured. Patients found it difficult to know if the drug had been delivered. Three patients noted that the pumps were empty earlier than expected. One patient found it difficult to change the bulb. No patient had difficulty with catheter removal or with bolusing.Conclusion: PCRA offers excellent postoperative analgesia at home. Elastomeric pumps facilitate PCRA but are imprecise with drug delivery and may not be safe for epidural infusions. The safety of this device for peripheral nerve blocks should be evaluated further.RésuméObjectif: Décrire l’expérience de l’usage de la pompe en élastomère (Eclipse®) pour l’analgésie régionale contrôlée par le patient (ARCP) ambulatoire.Méthode: Après avoir utilisé l’appareil lors d’une étude pilote avec des patients admis à l’hôpital, sept patients ont reçu l’ARCP à domicile au moyen de la pompe en élastomère. Des patients ayant besoin de différents blocs anesthésiques régionaux ont quitté l’hôpital avec des directives écrites et verbales sur l’usage du dispositif, sur les bolus, les effets secondaires des anesthésiques locaux et le retrait de cathéters. À chaque jour, on prenait contact avec les patients pour recueillir les données au sujet de l’efficacité du bloc, des difficultés associées à l’usage de l’appareil et de leur appréciation de cette méthode d’analgésie.Résultats: Pendant l’étude pilote, il y a eu deux débranchements de cathéters qui ont nécessité des analgésiques de rattrapage. Deux patients ont vu le contenu entier du réservoir se vider en quelques minutes. Parmi les sept patients qui ont reçu l’ARCP à domicile, l’un d’eux a dû être admis à l’hôpital. Le cathéter d’un patient s’est retiré pendant le retour. Le volume de médicament administré n’a pu être mesuré. Les patients ne pouvaient savoir exactement si le médicament avait été administré. Trois patients ont noté que la pompe s’était vidée plus vite que prévu. Un patient a eu de la difficulté à changer le réservoir. Le retrait du cathéter ou l’administration des bolus n’a présenté de problème pour aucun patient.Conclusion: L’ARCP offre une excellente analgésie postopératoire à domicile. Les pompes en élastomère facilitent l’ARCP, mais sont imprécises sur la quantité de médicament administrè et ne sont peut-être pas sécuritaires pour les perfusions péridurales. La sécurité de ce dispositif pour le bloc des nerfs périphériques exige une évaluation supplémentaire.

Development and Validation of a New Technique for Ultrasound-guided Stellate Ganglion Block

Background and Objectives: Although the stellate ganglion is located anteriorly to the first rib, anesthetic block is routinely performed at the C6 level. Ultrasonography allegedly improves accuracy of needle placement and spread of injectate. The technique is relatively new, and the optimal approach has not been determined. Moreover, the location of the cervical sympathetic trunk relative to the prevertebral fascia is debatable. Methods: Three-dimensional sonography was performed on 10 healthy volunteers, and image reconstruction was completed. On the basis of analysis of pertinent anatomy, a lateral trajectory for needle placement was simulated. Accuracy was tested by injection of methylene blue in cadavers. A clinical validation study was then conducted. A block needle was inserted according to the predetermined lateral path, and 5 mL of a mixture of bupivacaine and iohexol was injected. Spread of the contrast agent was verified fluoroscopically. Results: Image reconstruction revealed that the cervical sympathetic trunk is located posterolaterally to the prevertebral fascia on the surface of the longus colli muscle. The mean anteroposterior width of the muscle at the C6 level was 11 mm. The lateral approach does not interfere with any visceral or nerve structures. Anatomic dissection in cadavers confirmed entirely subfascial spread of the dye and staining of the sympathetic trunk. The contrast agent spread was seen in all patients between the C4 and T1 levels in a typical prevertebral pattern. Conclusions: This study revealed that, at the C6 level, the cervical sympathetic trunk lies entirely subfascially. Subfascial injection via the lateral approach ensures reliable spread of a solution to the stellate ganglion.

Using perfusion MRI to measure the dynamic changes in neural activation associated with tonic muscular pain.

&NA; Knowledge regarding neural pain processing is primarily the result of studies involving models of brief cutaneous pain; however, clinical pain generally originates in deep tissue and is prolonged. This study measured the dynamic neural activation associated with a muscular pain model incorporating both acute and tonic states. Hypertonic saline (5% NaCl) was infused into the brachioradialis muscle of eleven healthy volunteers for 15 min after an initial bolus of 0.5 mL. Ten controls followed the same protocol with normal saline (0.9% NaCl). Magnetic resonance images of cerebral blood flow (CBF) were acquired using an arterial spin labelling method. The imaging volume extended from the thalamus to the primary somatosensory cortices, but did not include the brainstem and cerebellum. Using a numerical scale from 0 to 10, ratings of pain intensity peaked at 5.9 ± 0.6 and remained near 5 for the remainder of the trial. Controls experienced minimal pain, reporting a peak value of 1.8 ± 0.4. Significant CBF increases in rostral and caudal anterior insula bilaterally, anterior mid‐cingulate cortex (aMCC), bilateral thalamus, and contralateral posterior insula were observed. The time courses of CBF revealed significant differences in the activation pattern during tonic pain. In particular, a more rapid return to baseline in aMCC versus insula was interpreted as a preferential decrease in the affective component of pain. This conclusion was supported by the strong correlation between pain intensity ratings and CBF in the contralateral insula (R2 = 0.911, p < 0.01), which is a region believed to be responsible for pain intensity processing.

Randomized trial of 10 mL and 20 mL of 2% intraurethral lidocaine gel and placebo in men undergoing flexible cystoscopy.

PURPOSE To determine if 20 mL of 2% intraurethral lidocaine gel is superior to 10 mL of 2% lidocaine or sterile lubricant for flexible cystoscopy in men. PATIENTS AND METHODS A randomized, double-blind, placebo-controlled trial was conducted. Sixty men scheduled to undergo diagnostic flexible cystoscopy were randomized to receive either 20 mL of placebo gel (Group I), 10 mL, of 2% lidocaine gel (Group II) or 20 mL of 2% lidocaine gel (Group III). A penile clamp was applied for 15 minutes to ensure consistent indwelling time in all patients. Patients recorded their pain on a 10-cm non-graphical visual analog scale prior to cystoscopy as a baseline, during the procedure, and immediately after the procedure. Patients also recorded their pain and willingness to have the same anesthetic on a 4-point descriptive scale. Heart rate and mean arterial blood pressure (MAP) were recorded at specific intervals throughout the procedure, and increases in mean arterial pressure were considered objective evidence of patient pain. RESULTS Pain perception was not statistically different in the groups (Group I 4.65, Group II 3.93, Group III 3.57; P = 0.406). Pain assessment and willingness to have the same anesthetic also did not differ statistically among the groups. Similarly, differences in the increases in MAP were not statistically significant between groups. CONCLUSION Instillation of 20 mL or 10 mL of 2% lidocaine gel has no advantage over plain lubricant in providing anesthesia for flexible cystoscopy in men.

Comparative evaluation of ultrasound-guided continuous infraclavicular brachial plexus block with stimulating catheter and traditional technique: a prospective-randomized trial

Background: Secondary catheter failure has been reported in up to 40% of patients with continuous peripheral nerve blocks resulting in failure to provide pain relief after the initial block wears off. Introduction of stimulating catheters as well as ultrasound for regional anaesthesia has facilitated correct placement of catheter tip, closer to the plexus. This randomized study was conducted to compare the efficacy of continuous infraclavicular brachial plexus blocks using non‐stimulating catheter, stimulating catheter and ultrasound‐guided catheter placement with nerve stimulation assistance.

Prolonged Epidural Infusions of Ropivacaine (2 mg/ml) After Colonic Surgery: The Impact of Adding Fentanyl

We evaluated the safety and efficacy of a 72-h epidural infusion of ropivacaine and measured the impact of adding fentanyl 2 &mgr;g/mL to the required infusion rate, on the quality of postoperative pain relief and the incidence of side effects, after colonic surgery. One hundred fifty-five patients scheduled for elective colonic surgery were randomized in this trial. Epidural infusions of ropivacaine 2 mg/mL with fentanyl 2 &mgr;g/mL (R + F) and without fentanyl (R) were commenced during surgery and continued for 72 h postoperatively. This was a prospective, randomized, double-blinded, multi-center trial. The median infusion rate required was less in the R + F group (9.3 vs 11.5 mL/h, P < 0.001). Median pain scores at rest and on coughing were lower in the R + F group (P < 0.0001). The incidence of hypotension was more in the R + F group (P = 0.01). Time to readiness for discharge was delayed in the R + F group (median 6.6 vs 5.5 days, P = 0.012). The addition of fentanyl to ropivacaine resulted in decreased infusion rates and enhanced pain control; however, adverse effects were increased and readiness to discharge was delayed.

Postoperative cognitive impairment in the elderly : Choice of patient-controlled analgesia opioid

This study evaluated the safety and cognitive impact of patient‐controlled analgesia with fentanyl compared to patient‐controlled analgesia with morphine among elderly postoperative patients. In addition, two screening tests for cognitive impairment, the Mini Mental Status Exam and the Short Portable Mental Status Questionnaire, were compared. Ninety‐six elderly patients were randomly allocated to receive patient‐controlled analgesia with either fentanyl or morphine following hip or knee arthroplasty. Patients were evaluated postoperatively for clinical confusion, cognitive function test results, adequacy of analgesia, drug use and complications. Fentanyl produced less depression in postoperative cognitive function compared to morphine. The incidence of clinical confusion was not statistically different between groups (4.3% for fentanyl versus 14.3% for morphine). Fentanyl patients used more opioid based on a dose ratio of 100:1 suggesting that this dose ratio is inadequate. The incidence of urinary retention was lower in the fentanyl group. A poor agreement between the two tests of cognitive impairment mandates caution when peri‐operative cognitive function is compared using different tests.

Use of ultrasound guidance and contrast enhancement: a study of continuous infraclavicular brachial plexus approach*

Purpose: We describe our experience of combining the use of ultrasound (US) guidance with contrast enhancement and peripheral nerve stimulation for the insertion of infraclavicular brachial plexus catheters.