Preoxygenation before laryngoscopy in children: how long is enough?

The ideal preoxygenation period prior to laryngoscopy in children is unclear. This study was performed to determine an appropriate duration of preoxygenation for infants and children prior to laryngoscopy using endtidal oxygen (Fe ′O₂) criteria. Healthy paediatric patients for elective day surgery procedures were studied. An inflatable mask connected to an oxygen-primed paediatric anaesthesia semiclosed circuit was placed on the face while patients breathed spontaneously during 6.min^?1 oxygen flow. An Fe ′O₂ of 0.9 was considered the endpoint, and if not achieved in two min the protocol was ended. Fifty-eight children were studied. Six patients never achieved an Fe ′O₂ of 0.9 and were not considered in the analysis. The times (in seconds with mean±sd and range) to achieve a minimum endtidal (Fe ′O₂) of 0.9 for under six months were 36±11.4(20–50), 7–12 months were 35.5±13.3(20–60),13–36 months were 42.6±18.7(20–90), 37–60 months were 50.8±18.5(30–90), >60 months were 68.4±24.1(30–100). Logistic regression curves were determined for each age group describing the probability of achieving an Fe ′O₂ of 0.9 against time of preoxygenation. All children with satisfactory mask fit were able to preoxygenate to an Fe ′O₂ of 0.9 within 100 s.     

HOLMIUM LASER VERSUS TRANSURETHRAL RESECTION OF THE PROSTATE: A RANDOMIZED PROSPECTIVE TRIAL WITH 1-YEAR FOLLOWUP

PURPOSE: The high-powered holmium:YAG laser can be used for incision, ablation and resection of the prostate. The technique of holmium laser resection of the prostate is compared to transurethral prostatic resection for surgical management of benign prostatic hyperplasia in this prospective randomized study. MATERIALS AND METHODS: A total of 120 urodynamically obstructed cases were randomized to holmium laser or transurethral prostatic resection. All eligible patients were assessed preoperatively and at 3 weeks, and 3, 6 and 12 months postoperatively with an American Urological Association symptom score, peak urinary flow rate, and questionnaires concerning sexual function and continence. Preoperative pressure flow study, ultrasound prostate volume assessment and post-void residual volume measurement were repeated at the 6-month visit. All complications were noted. RESULTS: Holmium laser and transurethral resections resulted in significant improvements in symptom score, quality of life score, peak urinary flow rate and post-void residual urine measurements. Operating time was significantly longer in the holmium group but nursing contact time, catheter time and hospital stay were significantly less compared to the transurethral prostatic resection group. Urodynamic results were equivalent at 6 months. There were fewer side effects in the holmium group. Effects on continence, potency and symptoms were similar with 1-year followup. CONCLUSIONS: Holmium and transurethral resections of the prostate appear to be equivalent in surgical management of bladder outflow obstruction due to benign prostate hyperplasia. Perioperative morbidity was less in the holmium group.     

APPLICATION OF PROGNOSTIC SCORING SYSTEMS IN DIFFERENTIATED THYROID CARCINOMA

Background : Total thyroidectomy is widely practised in Australasia for papillary and follicular thyroid carcinoma. Data from large overseas series have demonstrated that patients with these cancers may be separated into risk groups based on clinicopathological prognostic factors. Furthermore, evidence suggests that low-risk patients may be safely treated with less than total thyroidectomy. The aim of the present paper was to determine what proportion of our patients with papillary and follicular thyroid cancer were in the low-risk group in order to select candidates for less aggressive treatment. Methods : A prospectively documented series of 175 previously untreated patients with papillary and follicular thyroid carcinoma, treated principally by total thyroidectomy over a 10-year period, was divided into risk groups using the Mayo Clinic, Lahey Clinic and Memorial Hospital prognostic scoring systems. Complication rates for 103 patients treated by total thyroidectomy were also studied and reported. Results : Women outnumbered men by 2.3:1. There were 128 papillary carcinomas (73%) and 47 follicular cancers (27%). These tumours were < 4 cm in diameter in 81% of patients, and 41% of patients were 40 years of age or younger. Low-risk patients accounted for 75, 81 and 45% of the study group, respectively, when the three prognostic scoring systems were applied to our patient population. The rates for recurrent laryngeal nerve palsy and permanent hypoparathyroidism for patients having total thyroidectomy were 1 and 1.9%, respectively. In the low-risk group there were no permanent complications. Conclusion : Most patients treated at Royal Prince Alfred Hospital during the past 10 years were low-risk patients who may have been eligible for less aggressive surgical treatment.     

COLOR DOPPLER ULTRASOUND ASSESSMENT OF URETHRAL ARTERY LOCATION: POTENTIAL IMPLICATION FOR TECHNIQUE OF VISUAL INTERNAL URETHROTOMY

Purpose

We assessed the location of urethral arteries in patients with urethral stricture using color Doppler ultrasound.

Materials and Methods

We performed 41 color ultrasound studies of the urethra in 33 patients 17 to 76 years old. The linear array transducer was placed on the ventral surface of the penis and perineum to image the urethra and periurethral structures. In addition of evaluating the extent of stricture disease, color Doppler ultrasound determined the location of the urethral arteries at the segment with stricture.

Results

The number and site of the urethral arteries vary among individuals. Contrary to the common belief that these arteries are located at the 3 and 9 o'clock positions, we have found that in the bulbous urethra the arteries are at the 1 to 2 o'clock positions in 14% of cases, 3 to 4 in 22%, 5 to 6 in 17%, 7 to 8 in 18%, 9 to 10 in 18% and 11 to 12 in 11%. The arteries may be close to the surface of the urethral lumen, especially in patients who have undergone previous urethral procedures. Preoperative evaluation of urethral artery location may be helpful for preventing arterial bleeding at visual internal urethrotomy.

Conclusions

Color Doppler ultrasound can effectively assess the extent of stricture disease and urethral artery sites. Because the location of the urethral arteries varies among patients, individual preoperative assessment is advisable. Color Doppler ultrasound is currently our imaging method of choice for evaluating strictures of the pendulous and bulbous urethra.     

Effects of Electrocautery on Transvenous Lead Insulation Materials

Introduction: Insulation defects are a leading cause of transvenous lead failure. The purpose of this study was to determine the effects of electrocautery on transvenous lead insulation materials.
Methods: A preparation was done to simulate dissection of a transvenous lead from tissues. Radiofrequency energy was delivered using a standard cautery blade at outputs of 10, 20, and 30 W, for 3 and 6 seconds, using parallel and perpendicular blade orientations on leads with outermost insulations of silicone rubber, polyurethane, and silicone–polyurethane copolymer. Damage to each lead segment was classified after visual and microscopic analysis.
Results: Significant insulation damage occurred to almost all polyurethane leads. Full insulation breaches were observed with 30 W regardless of application duration with a parallel direction and with all power outputs with a perpendicular direction. Thermal insulation damage to copolymer insulation was similar to that of the polyurethane leads. In contrast, there was no thermal damage to silicone leads, regardless of the power output and duration of power delivery. However, mechanical insulation damage was observed to all silicone leads when at least 20 W was applied in a direction perpendicular to the lead.
Conclusions: Polyurethane (PU55D) and copolymer materials have low thermal stability and are highly susceptible to thermal damage during cautery. Implanting physicians should be aware of the lead insulation materials being used during implant procedures and their properties. The use of direct contact cautery on transvenous leads should be minimized to avoid damage to the lead, especially on leads with polyurethane or copolymer outer insulations.     

Acute Success of Cryoablation of Left-Sided Accessory Pathways: A Single Institution Study

Objective: To compare the acute success and recurrence rate of cryoablation for left-sided accessory pathways (AP) with controls who underwent radiofrequency ablation (RFA) at the same institution.
Background: Catheter cryoablation of supraventricular tachycardia (SVT) is considered to be a safer alternative a compared with RFA. At our institution, cryoablation has become the primary interventional modality for all APs. The reported success rates of cryoablation for AP-mediated tachycardia have generally been less favorable than for RFA. However, the location of AP may influence cryoablation outcome. Furthermore, there are little data available on cryoablation of left-sided pathways.
Methods: A chart review was performed for all patients undergoing cryoablation between August 2005 and August 2007. Twenty-nine patients (mean age 13 years, range 6–18 years) were identified with SVT secondary to left-sided AP. The data collected included patient age, height, weight, date of procedure, mapping, ablation and procedure time, pathway location, success, and recurrence. Cryoablation was performed via a transseptal approach. Procedural success and recurrence rate were compared with our most recent 28 patients undergoing RFA ablation.
Results: Procedural success was achieved in 97% of patients in the cryoablation group, compared with 100% in the RFA control group. Recurrence rate in the cryoablation group was 1 of 24 (4.2%) patients compared with 4 of 28 (14%) patients in the RFA group over 12 months.
Conclusion: Cryoablation can be safely and effectively used in the treatment of left-sided AP. Long-term outcomes remain to be seen.