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At least 1,261 records · Page 70Linked to original sources
PubMed2001

Midazolam reduces the dose of propofol required for induction of anaesthesia and laryngeal mask airway insertion.

BACKGROUND AND OBJECTIVE: Insertion of the laryngeal mask airway in the anaesthetized patient can sometimes be difficult and propofol has been advocated as the anaesthetic induction agent of choice because of its depressant effect on laryngeal reflexes compared with other intravenous anaesthetics. However, when used as the sole induction agent, relatively large doses of propofol are required to achieve successful laryngeal mask insertion. This has cost implications and may produce unwanted cardiorespiratory depression. METHODS: One hundred and forty-two patients were randomized to receive either: fentanyl 1 microg kg(-1) and lidocaine 1.5 mg kg(-1) (group 1), or fentanyl 1 microg kg(-1) and midazolam 0.04 mg kg(-1) (group 2), or fentanyl 1 microg kg(-1), midazolam 0.04 mg kg(-1) and lidocaine 1.5 mg kg(-1) (group 3) or fentanyl 1 microg kg(-1) (group 4) 2 min before induction of anaesthesia. Anaesthesia was established with propofol infused at 33.3 mg min(-1). RESULTS: Patients who were given midazolam required significantly less propofol to achieve satisfactory laryngeal mask insertion, median propofol doses: group 1, 1.63 mg kg(-1); group 2, 1.16 mg kg(-1); group 3, 1.01 mg kg(-1); group 4, 1.9 mg kg(-1), P < 0.0001 (analysis of variance). Patients given midazolam reported less pain on injection with propofol 13% and 3% groups (2 and 3) compared with 37.5% and 77% (groups 1 and 4) P = 0.002 (chi(2)). CONCLUSIONS: Midazolam reduces the dose of propofol required for induction of anaesthesia and successful insertion of the laryngeal mask airway. There was no clinical benefit to be gained from the addition of lidocaine.

Adjuvants, Anesthesia↗
PubMed1998

Gastro-oesophageal reflux during day case gynaecological laparoscopy under positive pressure ventilation: laryngeal mask vs. tracheal intubation.

This study aimed to evaluate whether or not the use of intermittent positive pressure ventilation via the laryngeal mask airway is associated with a higher risk of gastro-oesophageal reflux when compared with intermittent positive pressure ventilation via a tracheal tube in patients undergoing day case gynaecological laparoscopy in the head down position. Sixty healthy women were randomly allocated to receive either the laryngeal mask or cuffed tracheal tube for intra-operative airway maintenance. Using continuous oesophageal pH monitoring, four patients in the tracheal tube group and none in the laryngeal mask group had evidence of gastro-oesophageal reflux (as indicated by a decrease in oesophageal pH to below 4). The difference in the incidence of reflux did not achieve statistical significance (p = 0.11). In conclusion, we found no evidence to suggest that the use of intermittent positive pressure ventilation via the laryngeal mask increases the risk of gastro-oesophageal reflux in patients undergoing elective day case gynaecological laparoscopy.

Adult↗
PubMed1999

The cuffed oropharyngeal airway vs. the laryngeal mask airway: a randomised cross-over study of oropharyngeal leak pressure and fibreoptic view in paralysed patients.

We conducted a randomised cross-over study of 20 patients to test the hypothesis that oropharyngeal leak pressure and the fibreoptic view differ between the cuffed oropharyngeal airway and laryngeal mask airway in paralysed patients. We also tested the design premise that inflation of the cuffed oropharyngeal airway cuff elevates the epiglottis from the posterior pharyngeal wall. Both airways were inserted into each patient in random order. Oropharyngeal leak pressure and fibreoptic view were documented at zero volume and after each additional 10 ml up to the maximum recommended volume for each device. The laryngeal mask had a higher maximum (23 vs. 16 cmH2O, p = 0.03), minimum (9 vs. 2 cmH2O, p < 0.02) and overall (17 vs. 9 cmH2O, p < 0.001) oropharyngeal leak pressure compared with the cuffed oropharyngeal airway. The glottic inlet was visible more frequently with the laryngeal mask (96 vs. 39%, p < 0.0001). There was no elevation of the epiglottis from the posterior pharyngeal wall with the cuffed oropharyngeal airway. We conclude that the laryngeal mask forms a more effective seal and provides a better fibreoptic view of the glottic inlet than the cuffed oropharyngeal airway in paralysed patients. Inflation of the cuffed oropharyngeal airway cuff does not cause elevation of the epiglottis.

Adult↗
PubMed1999

The use of cricoid pressure with the intubating laryngeal mask.

Unexpected difficulty with tracheal intubation contributes to anaesthetic morbidity and mortality. The intubating laryngeal mask is effective in facilitating blind intubation. We have evaluated the effect of cricoid pressure on the ability to insert an intubating laryngeal mask, and to pass a tracheal tube through it. Insertion and intubation through the mask were attempted in 50 patients, Mallampati grade 1-3, randomly allocated to cricoid and noncricoid pressure groups. Tracheal intubation was successful in 21 (84%) of the noncricoid group and 13 (52%) of the cricoid group (p = 0.03). Cricoid pressure may have to be released to allow correct placement and intubation through the intubating laryngeal mask.

Adult↗
PubMed1999

Electroencephalographic arousal response during tracheal intubation and laryngeal mask airway insertion after induction of anaesthesia with propofol.

Laryngoscopy and tracheal intubation, or insertion of a laryngeal mask airway may lead to an arousal response on the electroencephalogram. We studied whether more intense stimulation (laryngoscopy and tracheal intubation) causes a greater arousal response than less intense stimulation (laryngeal mask airway insertion). Thirty-four patients (ASA I-II) were anaesthetised with propofol 3 mg.kg-1, followed by vecuronium 0.15 mg.kg-1 and a propofol infusion of 10 mg.kg-1.h-1. Three minutes after induction of anaesthesia, either laryngoscopy and tracheal intubation (n = 18), or laryngeal mask airway insertion (n = 16) was performed. Laryngoscopy and tracheal intubation caused a significantly greater increase in blood pressure (but not heart rate) than laryngeal mask airway insertion (p < 0.05). Electroencephalogram responses were not different. More intense stimulation does not cause a greater arousal response during propofol anaesthesia.

Adult↗
PubMed1999

Minimum alveolar sevoflurane concentrations required for insertion of the cuffed oropharyngeal airway and the laryngeal mask airway: a comparative study.

Both the cuffed oropharyngeal airway and the laryngeal mask airway share a similar property of being less stimulating to the upper airway than the tracheal tube. This study was conducted to compare sevoflurane concentrations required for insertion of the cuffed oropharyngeal airway and the laryngeal mask airway in elderly and young adult patients. Forty-one elderly (65-90 years) and 34 young adult (18-50 years) patients, scheduled for elective surgery during spontaneous breathing anaesthesia were randomly assigned to either the cuffed oropharyngeal airway or the laryngeal mask airway group. After a predetermined end-tidal concentration of sevoflurane had been established and maintained for at least 20 min, insertion of the device was attempted without neuromuscular relaxants or other adjuvants. Each concentration at which insertion of the device was attempted was predetermined by modification of Dixon's up-and-down method with 0.5% as the step size. Sevoflurane MACCOPA [mean 1.17 (SD 0.38)%, 0.77-1.56% (95% CI)] was significantly less than MACLMA [2.00 (0.52)%, 1.45-2.55%, p < 0.05] for elderly patients. Similarly, sevoflurane MACCOPA [1.33 (0.38)%, 0.94-1.73%] was significantly less than MACLMA [2.00 (0.42)%, 1.56-2.44%, p < 0.05] for young adult patients. There were no significant differences in either MACCOPA or MACLMA between the elderly and the young adult patients. We conclude that the insertion of the cuffed oropharyngeal airway can be accomplished at a lower sevoflurane concentration, and hence, is less stimulating to the upper airway than that of the laryngeal mask airway.

Adolescent↗
PubMed1999

Complications following the use of the Combitube, tracheal tube and laryngeal mask airway.

In a prospective, randomised trial, 75 patients scheduled for routine surgery were randomly allocated to one of three groups to evaluate trauma and postoperative complications after insertion of the Combitube, tracheal tube or laryngeal mask airway. Insertion of the Combitube was associated with a higher incidence of sore throat (48% vs. 16% vs. 12% [p < 0.01]) and dysphagia (68% vs. 12% vs. 8% [p < 0.01]) compared with tracheal intubation or insertion of the laryngeal mask airway, respectively. Hoarseness was significantly less common in both the Combitube and the laryngeal mask groups (both 12%) than in the tracheal tube group (44%; p < 0.01). Haematoma occurred in 36% of the Combitube group compared with 4% in both the laryngeal mask and the tracheal tube groups (p < 0.01). The higher incidence of complications should be considered when using the Combitube.

Adult↗
PubMed2000

Emergence characteristics and postoperative laryngopharyngeal morbidity with the laryngeal mask airway: a comparison of high versus low initial cuff volume.

In this study we tested the hypothesis that the initial cuff volume of the laryngeal mask airway influences emergence characteristics and postoperative laryngopharyngeal morbidity. One hundred and sixty adult patients undergoing minor surgery were randomly assigned for airway management with the laryngeal mask airway with either a fully inflated cuff (LMA-High) or a semi-inflated cuff (LMA-Low). Anaesthesia was with propofol, nitrous oxide, oxygen and isoflurane. Following insertion, the cuff was inflated with either 15 or 30 ml for the size 4 (females) and 20 or 40 ml for the size 5 (males). At the end of surgery, a blinded observer documented the presence or absence of adverse airway events (hypoxia, hypercapnea, coughing, retching, regurgitation/vomiting, airway obstruction, hypoventilation, hiccupping, biting, body movement or shivering) during every 1 min epoch and cardiorespiratory variables (heart rate, mean blood pressure, arterial oxygen saturation, end-tidal carbon dioxide and respiratory rate) every 5 min until the patient was awake and the laryngeal mask airway removed. Patients were interviewed about pharyngolaryngeal morbidity (sore throat, dysphonia and dysphagia) immediately before leaving the postanaesthesia care unit and 18-24 h following surgery. Analysis by epoch showed more partial airway obstruction in the LMA-High group, but analysis by patient numbers revealed no difference. Heart rate was slightly higher in the LMA-High group upon arrival in the postanaesthesia care unit, but otherwise there were no differences in cardiorespiratory responses. Sore throat and dysphagia were more common in the LMA-High group. We conclude that, in general, emergence characteristics with the laryngeal mask airway are not influenced by the volume of air used to inflate the cuff, but that postoperative sore throat and dysphagia are more likely at high initial cuff volumes.

Adolescent↗
PubMed2000

A comparison of blind and lightwand-guided tracheal intubation through the intubating laryngeal mask.

We have tested the hypothesis that intubation success rates, haemodynamic changes, airway complications and postoperative pharyngolaryngeal morbidity differ between blind and lightwand-guided intubation through the intubating laryngeal mask airway. One hundred and twenty paralysed anasthetised adult patients (ASA I-II, no known or predicted difficult airways) were assigned in a random manner to one of two equal-sized groups. In the blind group, patients were intubated blindly through the intubating laryngeal mask airway. In the lightwand group, patients were intubated through the intubating laryngeal mask airway assisted by transillumination of the neck with a lightwand. A standard sequence of adjusting manoeuvres was followed if resistance occurred during intubation or if transillumination was incorrect. The number of adjusting manoeuvres, time to intubation, intubation success rates, haemodynamic changes (pre-induction, pre-intubation, postintubation), oesophageal intubation, mucosal trauma (blood detected), hypoxia (oxygen saturation < 95%) and postoperative pharyngolaryngeal morbidity (double-blinded) were documented. Overall intubation success was similar (blind, 93%; lightwand, 100%), but time to successful intubation was significantly shorter (67 vs. 46 s, p = 0. 027) and the number of adjusting manoeuvres was significantly fewer (p = 0.024) in the lightwand group. There were no significant differences in blood pressure or heart rate between the groups at any time. Oesophageal intubation occurred more frequently in the blind group (18 vs. 0%, p = 0.002). The incidence and severity of mucosal injury, sore throat and hoarseness were similar between the groups. We conclude that lightwand-guided intubation through the intubating laryngeal mask is superior to the blind technique.

Adult↗
PubMed2001

Facilitation of laryngeal mask airway insertion: effects of remifentanil administered before induction with target-controlled propofol infusion.

Eighty-six adult day-case patients were recruited into a prospective, randomised study and allocated to one of two groups. Patients received either intravenous remifentanil 0.3 microg.kg(-1) or an equivalent volume of sodium chloride 0.9% followed by induction of anaesthesia with propofol target-controlled infusion until the effect (brain) site calculated concentration was 2 microg.ml(-1). Jaw opening and ease of laryngeal mask insertion were assessed immediately after mask insertion. A higher incidence of failure of induction of anaesthesia was observed in the control group compared with the remifentanil group [15 (35%) vs. 3 (7%); p < 0.01] and addition of remifentanil significantly increased the ease and success of laryngeal mask insertion, with grade 1 (no coughing/gagging) conditions observed in 29 (68%) of the remifentanil group and 21 (49%) of the control group (p < 0.01). The doses of remifentanil and propofol used were not associated with any significant cardiorespiratory instability. In conclusion, when combined with propofol target-controlled infusion, remifentanil 0.3 microg.kg(-1) facilitates laryngeal mask insertion with minimal adverse haemodynamic changes.

Adolescent↗
PubMed2003

The effect of neuromuscular blockade on the efficiency of mask ventilation of the lungs.

We conducted a two-part study to assess the practice of withholding neuromuscular blockade until the ability to ventilate the lungs using a bag and face mask (mask ventilation) has been established following induction of anaesthesia. The first part of the study consisted of a postal survey (71% response rate) of 188 anaesthetists in the Oxford region to assess their current practice. Thirty per cent of respondents always checked mask ventilation before administering a neuromuscular blocking drug, whereas 39% of respondents (all them consultants) never did this. A further 31% only did so in the case of known or anticipated difficulty with the airway. In the second part of the study, we measured inspired (V(TI)) and expired (V(TE)) tidal volumes before and after neuromuscular blockade in 30 patients undergoing general anaesthesia. The ratio V(TE)/V(TI) was used as a measure of the efficiency of ventilation. There was no difference in V(TE)/V(TI) before [mean (SD) 0.47 (0.13)] and after [0.45 (0.13)] neuromuscular blockade. We conclude that neuromuscular blockade does not affect the efficiency of mask ventilation in patients with normal airways.

Adolescent↗
PubMed1999

The laryngeal mask airway in tonsillectomy: the surgeon's perspective.

The laryngeal mask airway presents certain advantages in the management of the airway during general anaesthesia. However, from the surgeon's perspective, there have been reports of problems occurring when the laryngeal mask airway is used in tonsillectomy. This study of 90 patients undergoing tonsillectomy suggests that surgical access is inferior with a laryngeal mask airway and the weight of tonsillar tissue excised is less. In addition the laryngeal mask airway needs to be changed to an endotracheal tube during the procedure in 11.4% of patients.

Airway Obstruction↗
PubMed1999

The laryngeal mask airway in fresh cadavers versus paralysed anaesthetized patients: ease of insertion, airway sealing pressure, intracuff pressures and anatomic position.

We compared the performance of the size 5 laryngeal mask airway in 20 paralysed anaesthetized male patients and 20 male cadavers (6-24 h post-mortem). Groups were matched for height and weight. Airway sealing pressure, in vivo intracuff pressure and anatomical position (judged fibre-optically) were documented at zero volume and after each additional 10 mL up to 40 mL. All laryngeal mask airways were inserted at the first attempt and insertion times were similar. There were no differences in airway sealing pressure, in vivo intracuff pressure or fibre-optic position between the groups. We conclude that the performance of the laryngeal mask airway is similar for fresh cadavers and paralysed anaesthetized patients. This may have implications for laryngeal mask airway research and training.

Adult↗
PubMed1999

Difficult airway management in the neonate: a simple method of intubating through a laryngeal mask airway.

Tracheal intubation through a laryngeal mask airway is one option for securing an airway in the patient with a difficult airway. A variety of techniques and equipment have been used to stabilize the position of the tracheal tube while removing the laryngeal mask airway. We have shown that if a fibreoptic bronchoscope is used to place an tracheal tube through a laryngeal mask in neonates, additional equipment is not needed to remove the laryngeal mask airway without endangering tracheal tube placement. This is possible even in small neonates.

Bronchoscopy↗
PubMed1999

A new modification of anaesthesia mask for fibreoptic intubation in children.

We made a paediatric anaesthesia mask suitable for fibreoptic intubation by modifying a commercially available disposable mask with a ventilation port (Vent port) on a side. We added a large fibreoptic port (FO port, 22 mm in ID) in the middle of the mask to allow the passage of all sizes of paediatric tracheal tubes. This FO port was covered with an elastic rubber membrane to allow air-tight fibrescopic manipulation Fibreoptic intubation was performed safely through the FO port under continuous manual ventilation with anaesthetic gases via a Vent port connected to the breathing circuit. We succeeded in tracheal intubation in several infants and children with difficult airway in less than ten min, mainly via the nasotracheal route. This fibreoptic mask provides a safer technique for fibreoptic intubation in patients with difficult airways, especially in infants and small children.

Anesthesia, Inhalation↗
PubMed2004

Gastric insufflation pressure, air leakage and respiratory mechanics in the use of the laryngeal mask airway (LMA) in children.

BACKGROUND: The objective of the present study was to evaluate the prelaryngeal position of the laryngeal mask airway (LMA(TM)) in children, and to determine the influence of mask positioning on gastric insufflation and oropharyngeal air leakage. METHODS: A total of 100 children, 3-11 years old, scheduled for surgical procedures in the supine position under general anaesthesia were studied. After clinically satisfactory LMA placement, tidal volumes were increased stepwise until air entered the stomach, airway pressure exceeded 30 cmH(2)O, or air leakage from the mask seal prevented further increases in tidal volume. LMA position in relation to the laryngeal entrance was verified using a flexible bronchoscope. RESULTS: The insertion of the LMA with a clinically satisfactory position was achieved in all patients at the first attempt. Gastric air insufflation occurred in five of 49 patients with malpositioned LMA. No incident of gastric air insufflation was observed in 51 patients with correctly positioned LMA. The minimum inspiratory pressure leading to mask leakage was 17 cmH(2)O for incorrectly positioned LMA, and 25 cmH(2)O for correctly positioned LMA. Clinically unrecognized LMA malposition was associated with a significantly increased incidence of either oropharyngeal leakage (r = 0.59; P = 0.0001) or gastric insufflation (r = 0.25; P = 0.01). CONCLUSIONS: Clinically undetected LMA malpositioning is a significant risk factor for gastric air insufflation in children between 3 and 11 years, undergoing positive pressure ventilation, especially at inspiratory airway pressures above 17 cmH(2)O.

Air↗
PubMed2004

Stress response to tracheal intubation in patients undergoing coronary artery surgery: direct laryngoscopy versus an intubating laryngeal mask airway.

OBJECTIVE: Stress response caused by endotracheal intubation may be harmful for the coronary or cerebral circulation of high-risk patients. This study evaluated the hypothesis that tracheal intubation via an intubating laryngeal mask airway is associated with less cardiovascular and endocrine stress response than the conventional technique using direct laryngoscopy. DESIGN: Randomized, patient-blinded trial. SETTING: University department (single center). PARTICIPANTS: Eighty-six patients undergoing elective coronary artery surgery. INTERVENTION: Tracheal intubation was performed via an intubating laryngeal mask or by conventional direct laryngoscopy after standardized induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Electrocardiogram with automatic ST-segment analysis and invasive measured blood pressure were recorded continuously and blood samples to analyze norepinephrine plasma levels were taken at 4 times. Catecholamine concentrations and the pressure-rate product were analyzed by using an analysis of variance for repeated measures. In both groups, the pressure-rate product (p = 0.003) and norepinephrine concentrations (p < 0.0001) significantly decreased after induction of anesthesia. However, the fall was more marked in the patients intubated via the laryngeal mask (p = 0.031) than in patients receiving direct laryngoscopy. There were neither signs of cardiac ischemia nor major adverse events during induction of anesthesia. CONCLUSIONS: Reduction of cardiovascular and endocrine stress response associated with endotracheal intubation is more pronounced when performed via the intubating laryngeal mask. Thus, this technique can be helpful in high-risk cardiac patients.

Aged↗
PubMed2001

The usefulness of masks in preventing transient carriage of epidemic methicillin-resistant Staphylococcus aureus by healthcare workers.

We assessed the usefulness of wearing masks in preventing epidemic methicillin-resistant Staphylococcus aureus (EMRSA) carriage in nursing and physiotherapy staff on two dedicated EMRSA units. In the first phase of the study, members of staff were screened for EMRSA carriage immediately before and after periods of duty using nose, throat and hand swabs. During the second phase of the study, masks were worn by staff carrying out procedures associated with significant EMRSA exposure and examined for EMRSA as described for the first phase. Both phases were conducted over a period of two months. Forty-eight percent of nursing staff were colonized with EMRSA at some time during the first phase of the study. Wearing masks significantly reduced nasal, throat and hand carriage of EMRSA (P= 0.05). We conclude that the wearing of masks by healthcare workers performing certain activities for EMRSA positive patients may prevent transient colonization and hence may be a useful intervention in the control of EMRSA in the hospital environment.

Carrier State↗