Biomedical subjects
R Marjot
Publications and source records attributed to R Marjot.
Nasal fibreoptic tracheal intubation in anaesthetised patients breathing via a modified laryngeal mask airway.
A modified laryngeal mask airway was used to facilitate nasotracheal intubation with a fibreoptic laryngoscope. A size 4 laryngeal mask airway was modified by creating a defect at the base of the stem and removing the bars to allow passage of the fibreoptic laryngoscope from the nasopharynx to the larynx. The laryngeal mask airway cuff was split and the cut edges were sealed with silicone. This design allowed the cuff to function normally and allowed removal of the split laryngeal mask airway after the tracheal tube had been 'railroaded' into place. Thirty-four patients were studied. The split laryngeal mask airway was easily inserted with satisfactory airway maintenance in 32 patients. Nasal airway endoscopy and laryngoscopy were successfully achieved with the split laryngeal mask airway in place in 31 of 32 patients. Railroading the tracheal tube over the fibreoptic laryngoscope with the split laryngeal mask airway in place was successful in all 31 of these patients. This prototype split laryngeal mask airway allows good airway maintenance while fibreoptic nasotracheal intubation is performed.
Prophylaxis of venous thromboembolism. Regional anaesthesia reduces thromboembolic morbidity.
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Laryngeal mask airway performance: effect of cuff deflation during anaesthesia.
We studied the effect of deflating the laryngeal mask airway (LMA) cuff in situ on recorded respiratory tidal ventilation in 30 spontaneously breathing anaesthetized patients. Another 26 patients were studied in whom the LMA cuff was undisturbed. Deflation of the cuff to a pressure of 22 mm Hg (below an estimated arteriolar perfusion pressure of the pharyngeal mucosa), by removing approximately 50% of the recommended cuff injection volume, had a minimal effect on tidal ventilation (P = 0.9). This manoeuvre may have a role in minimizing transmitted cuff pressure on the adjacent pharyngeal mucosa. Complete cuff deflation, however, resulted in a 17% decrease in mean tidal ventilation (P < 0.05), with two patients (6%) demonstrating a substantial leak around the cuff and airway obstruction. The practice of complete cuff deflation during the recovery period from anaesthesia cannot be recommended.
The optimal distance that a multiorifice epidural catheter should be threaded into the epidural space.
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Teaching fibreoptic nasotracheal intubation via the laryngeal mask airway.
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PCE: patient-controlled emesis.
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Give a hand to PCA.
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Pressure exerted by the laryngeal mask airway cuff upon the pharyngeal mucosa.
Ten patients were studied for each of the sizes 2, 3 and 4 laryngeal mask airways (LMA) in order to calculate the pressure exerted by the cuff upon the pharyngeal mucosa. Using a non-invasive method of comparing intracuff pressures recorded both in vitro and in vivo, the transmitted pharyngeal mucosal pressures were calculated over the clinical range of injection volumes. Cuff inflation with the "normal" injection volumes recommended resulted in the residual volumes of the cuffs being exceeded. The intracuff pressures recorded with the mask in situ at these normal injection volumes were in the range 103-251 mm Hg. The calculated transmitted mucosal pressures were substantial for all three sizes of cuff and potentially exceeded the capillary perfusion pressure of the adjacent pharyngeal mucosa, despite apparent pharyngeal accommodation to the mask.
Trauma to the posterior pharyngeal wall caused by a laryngeal mask airway.
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Arterial oxygen saturation following premedication for cardiac surgery.
We studied patients scheduled for coronary artery bypass surgery following premedication with lorazepam, morphine and droperidol, using pulse oximetry and serial electrocardiographic (ECG) recordings. Arterial oxygen saturation (SaO2) values were compared with those obtained during two control periods when the patients were awake and asleep. All patients demonstrated progressive arterial oxygen desaturation during the premedication period, statistically significant from both controls (P less than 0.001). Twelve of the 15 patients developed hypoxaemia or severe hypoxaemia which was corrected immediately by administration of oxygen. New ECG changes developed during the premedication period in 33% of patients. It is concluded that additional oxygen should be administered to patients receiving this and similar premedication regimens.
Preoxygenation in the elderly: a comparison of the four-maximal-breath and three-minute techniques.
To compare the effectiveness of two routinely used methods of preoxygenation in protecting against hypoxia in the elderly, the arterial O2 saturation was measured using an oximeter. Twenty-four elderly patients (greater than or equal to 65 yr) presenting for elective orthopedic surgery were randomly allocated to receive either 3-min or four-maximal-breaths of 100% O2 via a Bain circuit. After preoxygenation, anesthesia was induced, tracheal intubation performed with patients kept apneic, and the endotracheal tube left open to air. The arterial O2 saturation was measured before preoxygenation and continually recorded during desaturation. Although attaining similar arterial O2 saturation values after preoxygenation, patients in the four-maximal-breath group had significantly shorter times (P less than 0.0001) to all levels of desaturation. We suggest that preoxygenation with 3-min breathing of 100% O2 offers more protection against hypoxia due to prolonged apnea after induction of anesthesia in the elderly than does four maximal breaths of 100% O2.
The relevance of volatile substance abuse to anaesthetics.
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Chronic non-neurological toxicity from volatile substance abuse.
1. Most of the evidence for chronic non-neurological toxicity from volatile substance abuse is derived from case reports. 2. Factors important in assessing these reports are the marked variations in exposure conditions and in the composition of the products abused. 3. In a young and otherwise healthy population, any chronic organ toxicity arising from VSA has to be gross in order to become clinically apparent. This may partially explain the relatively low incidence of reporting. 4. Toluene and the chlorinated hydrocarbons 1,1,1-trichloroethane and trichloroethylene can cause permanent damage to the kidney, liver, heart and lung, in certain volatile substance abusers.
Chronic cardiac toxicity after inhalation of 1,1,1-trichloroethane.
Two patients showed evidence of chronic cardiac toxicity after repeated exposure to 1,1,1-trichloroethane. In both cases there was circumstantial evidence of a deterioration after routine anaesthetic use of the related compound halothane. An adolescent boy who sniffed trichloroethane presented with multiple ventricular arrhythmias during tonsillectomy. Follow up showed mild chronic left ventricular impairment. A 54 year old man had repeated industrial exposure to trichloroethane and deteriorated from mild stable cardiac failure to end stage cardiac failure after halothane anaesthesia for herniorrhaphy. Chronic cardiac toxicity is a previously unreported feature of this type of solvent exposure. Related compounds such as halothane may have a toxic interaction after exposure to trichloroethane.