Nonsurgical collection and nonsurgical transfer of preimplantation embryos in the domestic rabbit (Oryctolagus cuniculus) and domestic ferret (Mustela putorius furo).
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The objective of this study was to develop nonsurgical methods of embryo collection and transfer in domestic rabbits (Oryctolagus cuniculus) and domestic ferrets (Mustela putorius furo) to serve as models for use in mammals in which surgical procedures are the usual means for applying embryo transfer technology. Specially designed transcervical catheters were used together with a fibre optic endoscope to visualize and then catheterize the rabbit and ferret cervices. Five consecutive transcervical uterine flushes in each of eight superovulated female rabbits 78-89 h after an ovulatory injection of LH resulted in the retrieval of 187 embryos, for an average of 23 embryos per rabbit. A total of 116 embryos were nonsurgically transferred to the uteri of ten recipients, and resulted in 23 young (20%). Eight rabbits (80%) produced young with an average litter size of 2.88 (range 1-7). Ten consecutive transcervical uterine flushes in each of 37 female ferrets 145-178 h after an ovulatory injection of hCG resulted in the retrieval of 324 embryos, an average of 8.76 embryos per ferret. A total of 251 embryos from 27 donors were nonsurgically transferred to the uteri of 31 recipients, and resulted in 65 young (26%). Twenty-eight of the recipients (90%) were initially pregnant, as indicated by postpartum necropsies, and twenty-two ferrets (71%) produced young. The average litter size was 2.95 (range 1-7). This is the first report of live births resulting from the nonsurgical collection of embryos from a donor followed by nonsurgical transfer of those same embryos to a synchronous recipient. The methods reported here can serve as models for use in other mammals in which direct visualization and manipulation of the cervix are not possible, and will be particularly useful in endangered species. (+info)
Relaxant effect of propofol on the airway in dogs.
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Propofol has been suggested to produce airway relaxant effects in vivo, although the mechanism is unclear. We have evaluated the bronchodilating effect of propofol using a direct visualization method with a superfine fibreoptic bronchoscope. We studied 21 mongrel dogs anaesthetized with pentobarbital 30 mg kg-1 i.v. and pancuronium 0.2 mg kg-1 h-1. The animals were allocated randomly to one of three groups (n = 7 in each): propofol group, atropine-propofol group and histamine-propofol group. The trachea was intubated using a tracheal tube that had a second lumen for insertion of the bronchoscope to monitor continuously bronchial cross-sectional area (BCA). BCA was measured using the NIH Image program. In the propofol group, dogs were given the following doses of propofol at 10-min intervals: 0 (saline), 0.2, 2.0 and 20 mg kg-1 i.v. In the atropine-propofol group, saline, atropine 0.2 mg kg-1 and propofol 20 mg kg-1 were given at 10-min intervals. In the histamine-propofol group, bronchoconstriction was elicited with histamine 10 micrograms kg-1 and 500 micrograms kg-1 h-1 until the end of the experiment. Thirty minutes after the start of infusion of histamine, propofol (0, 0.2, 2.0 and 20 mg kg-1) was administered. Changes in BCA were expressed as percentage of basal area. Histamine decreased BCA by 39.2 (SEM 5.4%). Propofol increased significantly basal and histamine-decreased BCA in a dose-dependent manner by 18.4 (4.5%) and 15.8 (4.9%), respectively after 20 mg kg-1 i.v. However, propofol following atropine i.v. did not increase BCA (129.9 (8.2)% after atropine vs 125.7 (8.9)% after propofol). Therefore, the relaxant effect of propofol may be a result of reduction in vagal tone. (+info)
Re-evaluation of appropriate size of the laryngeal mask airway.
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We have assessed 32 males and 31 females in a randomized, crossover study to see if there was any difference in the correct positioning of the laryngeal mask, optimal ventilation (defined as no gas leak around the mask at an airway pressure of 18 cm H2O) and cuff visibility between sizes 4 and 5 masks in males and sizes 3 and 4 in females. The position of the mask in relation to the glottis was assessed using a fibreoptic bronchoscope. There was no significant difference in correct positioning between the two sizes in either sex. Gas leak was significantly less frequent for a larger than a smaller mask (P < 0.01 for both sexes), whereas the cuff was more often seen in the mouth with larger masks (P < 0.02 for males and P < 0.01 for females). Therefore, larger masks (size 4 in females and size 5 in males) provided a better seal than smaller sizes without worsening the relative position of the mask to the glottis; however, the larger mask came up within the mouth more often, which could interfere with tonsillectomy and could increase the risk of sore throat or lingual nerve damage. (+info)
Fine structure of parvocellular receptive fields in the primate fovea revealed by laser interferometry.
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Optical blurring in the eye prevents conventional physiological techniques from revealing the fine structure of the small parvocellular receptive fields in the primate fovea in vivo. We explored the organization of receptive fields in macaque parvocellular lateral geniculate nucleus cells by using sinusoidal interference fringes formed directly on the retina to measure spatial frequency tuning at different orientations. Most parvocellular cells in and near the fovea respond reliably to spatial frequencies up to and beyond 100 cycles/ degrees of visual angle, implying center input arising mainly from a single cone. Temporal frequency and contrast response characteristics were also measured at spatial frequencies up to 130 cycles/degrees. We compared our spatial frequency data with the frequency responses of model receptive fields that estimate the number, configuration, and weights of cones that feed the center and surround. On the basis of these comparisons, we infer possible underlying circuits. Most cells had irregular spatial frequency-response curves that imply center input from more than one cone. The measured responses are consistent with a single cone center together with weak input from nearby cones. By exposing a fine structure that cannot be discerned by conventional techniques, interferometry allows functional measurements of the early neural mechanisms in spatial vision. (+info)
Serum concentrations of lignocaine before, during and after fiberoptic bronchoscopy.
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BACKGROUND: Lignocaine is commonly used for local anesthesia during fiberoptic bronchoscopy (FOB). Several studies have reported the peak serum concentration of lignocaine in relation to time, but most of them did not specify the administered dose of lignocaine gel and its possible correlation with peak serum concentration. OBJECTIVE: The aim of our study was to record the plasma concentrations of lignocaine before, during and after FOB and to evaluate whether the doses for nasal and tracheobronchial anesthesia have any correlation with the peak serum concentrations of the drug. METHODS: Twelve patients with no comorbid conditions undergoing FOB were studied. Lignocaine was administered as a 2% solution using a larynx syringe, 2% gel (mean dose 182.5 +/- 15 mg) and finally 2% solution through the bronchoscope (mean dose 339 +/- 12 mg). Total dose was 622 +/- 20 mg. Venous blood samples were taken before the beginning of local anesthesia and then at 5, 10, 20, 60, 90 and 120 min thereafter. RESULTS: Our results showed that peak plasma concentrations of lignocaine were observed in 8 patients 20 min after the beginning of local anesthesia, in 3 patients 30 min afterwards and in 1 patient 60 min afterwards (2.15 +/- 0.4 microg/ml, 1.9 +/- 0.3 microg/ml, 1. 81 microg/ml, respectively). None of our patients exceeded the critical level of toxicity (5 microg/ml). Both the total and tracheobronchial doses of lignocaine were significantly correlated with peak serum concentration (r = 0.63, p = 0.05 and r = 0.64, p = 0.02, respectively). No correlation was found between the dose for nasal anesthesia and peak serum concentration. No adverse reactions were observed. CONCLUSIONS: In conclusion our data show that although the amount of lignocaine used in this study exceeded the recommended highest dose (400 mg) in all patients, no toxic levels were observed. Peak plasma concentrations were found within 20-30 min from the beginning of local anesthesia. The dose for the anesthesia of nasal mucosa represented a significant percentage of the total dose, but did not correlate with the peak serum concentration of the drug. (+info)
Laryngeal mask airway and fibre-optic tracheal inspection in thyroid surgery: a method for timely identification of tracheomalacia requiring tracheostomy.
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Use of the laryngeal mask airway combined with fibre-optic laryngoscopy in thyroid surgery was first described in 1991. In this unit, it has been successfully used in over 130 cases. The advantages in identification and preservation of the recurrent laryngeal nerves using this technique have been demonstrated. However, to date, no report exists of a further advantage, namely the management of tracheomalacia. (+info)
Anaesthetic complications of acromegaly.
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The anaesthetic risks of acromegaly include difficulties in airway management, hypertension, and cardiac, gastrointestinal and renal problems. To estimate the incidence of major complications in this rare group of patients, we reviewed 28 patients with acromegaly who had pituitary tumour excision over a 10-yr period. Each patient was matched for age, weight and sex to a non-acromegalic patient undergoing transsphenoidal pituitary surgery. Acromegalic patients received significantly more fentanyl and midazolam and less thiopental and succinylcholine than controls (all P < 0.05). Mean arterial pressure (baseline, minimal and maximal values) was higher in acromegalic patients than in controls. There was no difference between groups in the use of vasoactive drugs. PaO2, FIO2 and PaCO2 were similar in both groups. Arterial pH was significantly lower (P = 0.015), blood glucose was higher (P < 0.001) and fluid intake minus output was higher (P = 0.04) in acromegalic patients than in controls. Airway difficulty and tongue enlargement were encountered more often in acromegalic patients (P = 0.002 and P = 0.001, respectively). Our data confirm that in acromegalic patients: airway difficulties occurred more frequently; severe haemodynamic instability did not typically occur during surgery for acromegaly; pulmonary gas exchange was not altered during operation; glucose intolerance may be an intraoperative problem; and fluid regulation may be altered. (+info)
Role of computed tomographic scanning of the thorax prior to bronchoscopy in the investigation of suspected lung cancer.
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BACKGROUND: Fibreoptic bronchoscopy (FOB) is the usual initial investigation of choice in patients with suspected endobronchial carcinoma, but it is often non-diagnostic. Once a positive diagnosis has been made, many patients undergo staging by computed tomographic (CT) scanning to assess the extent of the disease and its suitability for radical treatment. To determine whether initial CT scanning before FOB is a cost effective way of reducing subsequent unnecessary or unhelpful invasive diagnostic procedures, a study was undertaken in 171 patients with suspected endobronchial carcinoma. METHODS: A randomised two group study was performed with all patients undergoing an initial CT staging scan. In group A the CT scans were reviewed before FOB, allowing cancellation or a change to an alternative invasive procedure if considered appropriate. In group B all patients proceeded to FOB with the bronchoscopist blinded to the result of the CT scan until after the procedure. RESULTS: In group A six of 90 patients (7%) required no further investigations as the CT scan was either normal, consistent with benign disease, or consistent with widespread metastatic disease. Of the remainder, bronchoscopy was diagnostic in 50 of 68 (73%) in group A compared with 44 of 81 (54%) in group B (p = 0.015). Overall, a positive diagnosis was made after a single invasive investigation in 64 of 84 patients (76%) in group A compared with only 45 of 81 patients (55%) in group B (p = 0.005). Only seven of 90 patients (8%) in group A required more than one invasive investigation compared with 15 of 81 patients (18.5%) in group B. In patients with malignancy, bronchoscopy was more likely to be diagnostic in group A (50 of 56 patients (89%)) than in group B (44 of 62 (71%); p = 0. 012), and the diagnosis was more frequently made on the initial invasive investigation (group A, 63 of 70 (90%); group B, 44 of 62 (71%); p = 0.004). Because of the lower number of invasive procedures performed in group A than in group B, the cost of performing CT scans before FOB in all patients in group A would have equated to a projected cost of performing CT scans in 60% of patients after FOB in group B. CONCLUSIONS: Performing initial CT thoracic scans before bronchoscopy in patients with suspected endobronchial malignancy is a cost effective way of improving diagnostic yield from invasive diagnostic procedures and occasionally may obviate the need for any further investigation. (+info)