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PubMed1996

A new tracheal tube for difficult intubation.

We have compared a new Portex tracheal tube with the Oxford tube in performing simulated grade 3 difficult intubations. The Portex tube was modified so that the bevel faced backwards, as in the Oxford tube. A gum elastic introducer was used with both tubes. The time taken and number of attempts needed were recorded, with changes in arterial pressure, heart rate and incidence of sore throat. Both tubes were successful in avoiding the problem of obstruction at the cords, which occurs when a standard Magill tube is used with an introducer. Thus the new tube has the merits of the Oxford tube without the disadvantages of rubber. It is suitable for both easy and difficult intubations with advantages in safety, cost and convenience. An unexpected but important finding was a clear learning effect, despite both investigators being familiar with the technique at the outset. Over the course of the study, intubation time decreased progressively (P < 0.001). This provides new evidence of the need for trainees to practise the art of intubation when the cords are not visible. Our estimate of the learning "half-life" was 15 intubations; we conclude that 30 simulated grade 3 intubations would be a reasonable objective for trainees before handling high-risk cases.

Adult↗

PubMed1997

Low-dose rocuronium improves conditions for tracheal intubation after induction of anaesthesia with propofol and alfentanil.

We studied 60 adult patients to assess if low doses of rocuronium improved conditions for tracheal intubation during induction of anaesthesia with propofol 2.5 mg kg-1 and alfentanil 10 micrograms kg-1. In a double-blind, randomized design, patients were allocated to one of three groups: group P = saline; group R1 = rocuronium 0.1 mg kg-1; and group R3 = rocuronium 0.3 mg kg-1. Intubation conditions were judged as optimal, suboptimal or failure, based on the scoring of ease of jaw opening and laryngoscopy, position of the vocal cords and degree of straining after tracheal intubation. Intubation conditions were judged as optimal in one patient in group P, in six patients in group R1 and in 18 patients in group R3. Conditions were judged as a failure in seven patients in group P, in one patient in group R1 and in none in group R3. No laryngospasm or other complications were observed in any patient. The addition of low doses of rocuronium significantly improved intubation conditions (P < < 0.001). Ventilation was controlled during surgery, and in no patient was any problem encountered with antagonism of neuromuscular block with neostigmine. Injection of rocuronium 0.3 mg kg-1 (ED95) with propofol and alfentanil provided a high proportion of optimal intubation conditions.

Adolescent↗

PubMed1998

Effects of lightwand (Trachlight) compared with direct laryngoscopy on circulatory responses to tracheal intubation.

We compared the effects of the lightwand technique on circulatory responses to tracheal intubation with those of direct-vision laryngoscopy. Forty adult patients received propofol and vecuronium, and their lungs were ventilated for 2 min via a mask with 5% sevoflurane in oxygen, after which the trachea was intubated orally using either the lightwand (Trachlight, n = 20) or the Macintosh laryngoscope (n = 20). Maximum mean arterial pressure changes did not differ between groups during (lightwand group, 25 (SD 21) mm Hg vs laryngoscopy group, 23 (19) mm Hg) and after (21 (24) mm Hg vs 21 (16) mm Hg) tracheal intubation. Maximum heart rate changes were similar for groups during (16 (14) beat min-1 vs 16 (15) beat min-1) and after (2 (11) beat min-1 vs 7 (19) beat min-1) tracheal intubation. There were no differences between the lightwand technique and direct-vision laryngoscopy in changes in mean arterial pressure and heart rate during and after tracheal intubation. We conclude that the effects of the lightwand technique on circulatory responses to tracheal intubation were similar to those of direct-vision laryngoscopy.

Adult↗

PubMed1999

Comparison of intubating conditions after rapacuronium (Org 9487) and succinylcholine following rapid sequence induction in adult patients.

We have assessed intubating conditions provided by rapacuronium (Org 9487) and succinylcholine after rapid sequence induction of anaesthesia in adult patients undergoing elective surgery. We studied 335 patients, ASA I and II, in five centres. Two hundred and thirty-four subjects with normal body weight and 101 obese subjects were allocated randomly to one of four treatment groups differing in the neuromuscular blocking drug administered (rapacuronium 1.5 mg kg-1 or succinylcholine 1 mg kg-1) and in the technique used for induction of anaesthesia (fentanyl 2-3 micrograms kg-1 with thiopental 3-6 mg kg-1 or alfentanil 20 micrograms kg-1 with propofol 1.5-2 mg kg-1). Intubation was started at 50 s by an anaesthetist blinded to the drugs used. Intubating conditions were clinically acceptable (excellent or good) in 89.4% of patients after rapacuronium and in 97.4% after succinylcholine (P = 0.004), the estimated difference being 8.1% (95% confidence interval (CI) 2.0-14.1%). Neither anaesthetic technique nor subject group had an influence on intubating conditions. After intubation, the maximum increase in heart rate averaged 23.1 (SD 25.4%) and 9.4 (26.1%) after rapacuronium and succinylcholine, respectively (P < 0.001). Pulmonary side effects (bronchospasm and increased airway pressure) were observed in 10.7% (95% CI 5.8-17%) and 4.1% (95% CI 1.3-8.8%) of patients given rapacuronium and succinylcholine, respectively (P = 0.021). We conclude that after rapid sequence induction of anaesthesia in adults, clinically acceptable intubating conditions were achieved less frequently after rapacuronium 1.5 mg kg-1 than after succinylcholine.

Adolescent↗

PubMed1999

Double-blind comparison of sevofluran vs propofol and succinylcholine for tracheal intubation in children.

We have studied intubating conditions in 64 healthy children, aged 3-10 yr, undergoing adenotonsillectomy, in a double-blind, randomized study. Intubation was performed 150 s after induction using either 8% sevoflurane in nitrous oxide and oxygen or propofol 3-4 mg kg-1 with succinylcholine 2 mg kg-1. An anaesthetist blinded to the technique performed intubation and scored intubating conditions using Krieg and Copenhagen Consensus Conference (CCC) scores. The trachea was intubated successfully at the first attempt in all patients under clinically acceptable conditions, although scores were significantly better with propofol and succinylcholine. The sevoflurane technique cost 3.62 +/- 0.55 Pounds to completion of tracheal intubation, significantly more (P < 0.001) than the cost of propofol-succinylcholine and isoflurane (2.04 +/- 0.54 Pounds) when based on actual amount of drug used. This cost increased to 4.38 +/- 0.05 Pounds when based on whole ampoules, which is significantly more than the cost of sevoflurane (P < 0.001).

Adenoidectomy↗

PubMed2001

Comparison of effects of remifentanil and alfentanil on cardiovascular response to tracheal intubation in hypertensive patients.

In a randomized double-blind study, we compared the effect of remifentanil and alfentanil on the cardiovascular response to laryngoscopy and tracheal intubation in patients on long-term treatment for hypertension. Forty ASA II-III patients were allocated to receive (i) remifentanil 0.5 microg kg(-1) followed by an infusion of 0.1 microg kg min(-1) or (ii) alfentanil 10 microg kg(-1) followed by an infusion of saline; all patients received glycopyrrolate 200 microg before the study drug. Anaesthesia was induced with propofol and rocuronium and maintained with 1% isoflurane and 66% nitrous oxide in oxygen. Laryngoscopy and tracheal intubation were performed after establishment of neuromuscular block. Arterial pressure and heart rate (HR) were measured non-invasively at 1 min intervals from 3 min before induction until 5 min after intubation. Systolic (SAP), diastolic and mean arterial pressure decreased significantly after induction in both groups (P<0.05). Maximum increases in mean SAP after laryngoscopy and intubation were 35 and 41 mm Hg in the remifentanil and alfentanil groups, respectively. After intubation, arterial pressure did not increase above baseline values in either group. HR remained stable after induction of anaesthesia, but increased above baseline values after intubation. Mean maximum HR was 87 beats min(-1) for the remifentanil group (12 beats min(-1) above baseline; P=0.065) and 89 beats min(-1) for the alfentanil group (15 beats min(-1) above baseline; P<0.05). There were no significant differences between groups in HR or arterial pressure at any time. There were no incidences of bradycardia. Seven patients in the remifentanil group and four in the alfentanil group received ephedrine for hypotension (i.e. SAP<100 mm Hg).

Adult↗

PubMed2003

Bispectral index changes following etomidate induction of general anaesthesia and orotracheal intubation.

BACKGROUND: Etomidate-associated hypnosis has only been studied using standard clinical criteria and raw EEG variables. We conducted a BIS-based investigation of etomidate induction of general anaesthesia. METHODS: Thirty hydroxyzine-premedicated ASA I patients were randomly allocated to receive etomidate 0.2, 0.3, or 0.4 mg kg(-1) intravenously over 30 s. The BIS was continuously recorded. A tourniquet was placed on a lower limb to record purposeful movements and myoclonia. Tracheal intubation was facilitated using rocuronium 0.6 mg kg(-1) when the BIS value was 50. The times to disappearance of the eyelash reflex, to a decrease in the BIS to 50, and to tracheal intubation were compared. The BIS values 30 s following tracheal intubation, and mean arterial pressure (MAP) and heart rate (HR) at all time points were also recorded. RESULTS: The BIS value decreased to 50 for tracheal intubation with no purposeful movement in all but one patient in the 0.2 mg kg(-1) group. There was no difference between the etomidate groups (0.2, 0.3, and 0.4 mg kg(-1)) in regards to time to loss of the eyelash reflex (103 (67), 65 (34), 116 (86) s, P=0.2), or to a decrease in BIS to 50 (135 (81), 82 (36), 150 (84) s, P=0.1). Also, the BIS value 30 s after intubation (41 (10), 37 (4), 37 (4), P=0.4), and plasma etomidate concentrations (161 [29-998], 308 [111-730], 310 [90-869] ng ml(-1), P=0.2) did not differ between groups. The time to loss of the eyelash reflex was 12-140 s shorter than the time to a decrease in BIS to 50 in three patients in each group who received etomidate 0.2 and 0.4 mg kg(-1), and in four patients who received 0.3 mg kg(-1). No awareness was recorded. MAP and HR increases following tracheal intubation were comparable between groups. CONCLUSIONS: Etomidate induction doses do not predict the time for BIS to decrease to 50 as this variable varies markedly following three etomidate dose regimen.

Adult↗

PubMed2005

Efficacy of A-line AEP Monitor as a tool for predicting acceptable tracheal intubation conditions during sevoflurane anaesthesia.

BACKGROUND: It is essential for the clinical anaesthetist to know whether patients are sufficiently anaesthetized to tolerate direct laryngoscopy and endotracheal intubation. Because of the lack of an accurate objective method to determine the level of general anaesthesia, under- or overdosing of anaesthetics may occur. Auditory evoked potential (AEP) is one of several physiological parameters under investigation. We aimed to determine the clinically required depth of anaesthesia, measured by the A-line AEP Monitor and expressed as A-Line ARX Index (AAI) for 90% probability of acceptable conditions for endotracheal intubation. METHODS: We studied 108 patients anaesthetized by mask with increasing concentration of sevoflurane in 30% oxygen and 70% nitrous oxide. Fentanyl 1.5 microg kg(-1) and glycopyrrolate 0.2 mg were administered intravenously immediately before starting induction of anaesthesia. The monitor was programmed to give an alarm at AAI 10, 15, 20, 25 or 30 according to randomization. When the alarm sounded, the end-expiratory sevoflurane concentration was registered and endotracheal intubation was attempted. Intubation conditions were assessed by an observer blinded to the AAI. RESULTS: At AAI 10 we found acceptable conditions in 91% (confidence interval [CI 72-99%]) of patients. The prediction probability value P(K) of AAI was 0.69 (CI 0.59-0.79) and the P(K) of end-expiratory sevoflurane concentration was 0.93 (CI 0.87-0.99). ED(90) (the AAI with a 90% probability of acceptable intubation conditions) was calculated as 8.5 (CI 0-17.5). CONCLUSIONS: AAI indicates the depth of anaesthesia necessary for acceptable endotracheal intubation conditions. Under the conditions of the present study, end-expiratory sevoflurane concentration was a better predictor and may turn out to be more useful in the clinical setting.

Adult↗

PubMed2005

Nasotracheal intubation: look before you leap.

Nasotracheal intubation is frequently used for airway management during maxillofacial surgery. Complications such as haemorrhage occur more frequently with this route of intubation than with the orotracheal route. This case report describes a male patient aged 51 yr who developed severe epistaxis after the tube had passed the nares. As an additional complication laryngoscopy and endotracheal intubation failed because of difficult airway (Cormack-Lehane grade 4). Attempts using an intubating laryngeal mask airway and a Bonfils intubating fibrescope did not succeed. The airway was finally managed by cricothyroidotomy. A modified sequence of nasotracheal intubation is proposed to avoid similar life-threatening complications.

Algorithms↗

PubMed2006

Gabapentin attenuates the pressor response to direct laryngoscopy and tracheal intubation.

BACKGROUND: Laryngoscopy and tracheal intubation increase blood pressure and heart rate (HR). The aim of the present study was to investigate the effect of gabapentin when given before operation on the haemodynamic responses to laryngoscopy and intubation. METHODS: Forty-six patients undergoing abdominal hysterectomy for benign disease were randomly allocated to receive gabapentin 1,600 mg or placebo capsules at 6 hourly intervals starting the day (noon) before surgery. Anaesthesia was induced with propofol and cis-atracurium. Systolic, diastolic arterial blood pressures (SAP, DAP) and heart rate (HR) were recorded before and after the anaesthetic and 0, 1, 3, 5 and 10 min after tracheal intubation. RESULTS: SAP was significantly lower in the gabapentin vs the control group 0, 1, 3, 5 and 10 min after intubation [128 (27) vs 165 (41), P=0.001, 121 (14) vs 148 (29), P=0.0001, 115 (13) vs 134 (24), P=0.002, 111 (12) vs 126 (19), P=0.004 and 108 (12) vs 124 (17), P=0.001 respectively]. DAP also was lower in the gabapentin group 0, 1, 3, and 10 min after intubation [81 (18) vs 104 (19), P=0.0001, 77 (9) vs 91 (16), P=0.001, 71 (10) vs 84 (13), P=0.001 and 67 (10) vs 79 (12), P=0.004]. HR did not differ between the two groups at any time [82 (11) vs 83 (15), 79 (10) vs 80 (12), 86 (17) vs 92 (10), 82 (11) vs 88 (10), 81 (12) vs 81 (11), 77 (13) vs 79 (13), and 75 (15) vs 78 (12)]. CONCLUSION: Gabapentin, under the present study design attenuates the pressor response but not the tachycardia associated with laryngoscopy and tracheal intubation.

Adult↗

PubMed1998

Difficult tracheal intubation in patients with retinoblastoma caused by 13q deficiency.

Anesthetic management of retinoblastoma patients is unremarkable in most cases. Patients are most often babies and laryngoscopic procedures for intubation are usually easy. However, we recently experienced two cases with retinoblastoma with whom tracheal intubation was accomplished with difficulty. We report the two cases with a review of all 5-year records of retinoblastoma (rbl) in our institution. The cases we experienced recently were all patients with rbl with deletion of the long arm of thirteenth chromosome (13q-). In the 5-year review, the incidence of the difficult intubation was significantly higher (P < 0.05) in rbl with 13q- (4/11) than in rbl without 13q- (0/147). In our experience macroglossia was noted for the difficulty in the intubation. We assume that some patients with rbl will be cases of difficult intubation even to cannot ventilate-cannot intubate level when the results of their chromosomal analysis show a deletion on the thirteenth chromosome.

Anesthesia↗

PubMed1997

Clinical trial of a new device for fiberoptic orotracheal intubation (Augustine Scope).

Blind oral intubation using the Augustine Guide is helpful for intubating the trachea of patients presenting with difficult airways. This device has been modified by adding a fiberoptic scope with a built-in battery-powered light. We studied this Augustine Scope in 104 patients (Group AS) and compared the results with 96 patients managed by direct laryngoscopy (Group DL). No significant differences in Mallampati class, thyromental distance, laryngoscopic view, and patients height or weight were observed between the two groups. The Augustine Scope provided conditions for successful intubation in 102 of 104 patients (98%), compared with a 97% success rate in the group where DL was used. The three patients who failed DL were successfully intubated with AS. The mean +/- SD time needed to perform intubation was 19 +/- 10 s in Group AS and 21 +/- 13 s in Group DL (P = not significant). No traumatizing effects were observed. We conclude that the Augustine Scope is an effective and safe device for orotracheal intubation in routine and difficult airways.

Adult↗

PubMed1997

The effect of goiter on endotracheal intubation.

The incidence of difficulty in tracheal intubation in the presence of goiter was investigated. Data were collected in a series of 4742 consecutive adult patients undergoing general anesthesia. The prevalence of goiter was 6.8%. Fifteen anesthesiologists performed the preoperative airway assessment using standardized guidelines. Seven individual risk factors were correlated with the potential for difficult tracheal intubation. Whenever evidence of goiter or airway pathology was observed, the evaluation was completed by indirect laryngoscopy and radiologic examination to establish the presence of any anatomical deviation. Difficult intubation was defined as inadequate exposure of the glottis by direct laryngoscopy. There was no difference in probability of difficulty in tracheal intubation between patients who presented for thyroidectomy and patients with goiter estimated as a random finding. Statistical analysis revealed an increased risk of difficult intubation amongst goiter patients compared with patients with no evidence of any risk factor (6.8% vs 0.9%, P < 10(-8), relative risk = 7.4). We conclude that goiter, when accompanied by airway deformity, constitutes an aggravating factor for difficult intubation.

Female↗

PubMed2000

Nitrous oxide prevents movement during orotracheal intubation without affecting BIS value.

UNLABELLED: We sought to determine whether the addition of nitrous oxide (N(2)O) to an anesthetic with propofol and remifentanil modifies the bispectral index (BIS) during the induction of anesthesia and orotracheal intubation. Thirty ASA physical status I or II patients were randomly allocated to receive either 50% air in oxygen (control group) or 60%-70% N(2)O in oxygen (N(2)O group) that was commenced via a mask simultaneously with the induction of anesthesia. Anesthesia was performed in all the patients with IV propofol at the target effect compartment site concentration of 4 microg/mL throughout the study. A target-controlled infusion (TCI) of remifentanil was initiated 3 min after the TCI of propofol and maintained at the effect-site concentration of 4 ng/mL until the end of the study. After loss of consciousness, and before the administration of vecuronium 0.1 mg/kg, a tourniquet was applied to one arm and inflated to a value more than the systolic blood pressure. An examiner, blinded to the presence of N(2)O, sought to detect any gross movement within the first minute after tracheal intubation, which was performed 10 min after remifentanil TCI began. Inspired and expired oxygen, N(2)O, and carbon dioxide were continuously monitored. A BIS value was generated every 10 s. Arterial blood pressure and heart rate (HR) were measured noninvasively every minute. Measures of mean arterial pressure (MAP), HR, and BIS were obtained before the induction, before the start of the remifentanil TCI, before laryngoscopy, and 5 min after intubation. No significant intergroup differences were seen in BIS, HR, and MAP throughout the study. Maximum changes in BIS, HR, and MAP with intubation were significant (P < 0.01) for both groups but comparable. Six patients in the control group and none in the N(2)O group moved after intubation (P < 0.05). IMPLICATIONS: We demonstrated that 0.6 minimal alveolar concentration of nitrous oxide combined with a potent anesthetic and an opioid prevents movement after orotracheal intubation without affecting the bispectral index. This demonstrates that the bispectral index is not a useful neurophysiologic variable to monitor the level of anesthesia when nitrous oxide is added to a general anesthetic regimen using propofol and remifentanil.

Adolescent↗

PubMed1985

Facilitation of rapid endotracheal intubations with divided doses of nondepolarizing neuromuscular blocking drugs.

The authors sought to determine whether prior administration of a small, subparalyzing dose of nondepolarizing muscle relaxant would shorten the onset time of an intubating dose of muscle relaxant. Initially, in 60 anesthetized patients, twitch response of adductor pollicis to ulnar nerve stimulation was studied after a small dose of pancuronium 0.015 mg . kg-1, metocurine 0.03 mg . kg-1, or d-tubocurarine 0.04 mg . kg-1, followed 3 min later by pancuronium 0.08 mg . kg-1 or atracurium 0.4 mg . kg-1 administered iv. After 60 s, the minimum neuromuscular block, in all patients was 79.0 +/- 5.0%. A 95% depression or twitch tension occurred between 59.1 +/- 5.3 and 86.1 +/- 5.9 s. In another 60 patients, intubating conditions under similar regimen were studied, except the small dose of muscle relaxant was given immediately prior to induction of anesthesia. At the end of 60 s, good to excellent intubating conditions were present in 100% of the patients following the second dose of pancuronium and in 83% of the patients following atracurium. In 17% of the patients, after atracurium intubating conditions were fair. When nondepolarizing neuromuscular blocking drugs are administered in divided doses, neuromuscular blockade adequate for endotracheal intubation is achieved in less than 90 s. This facilitates rapid endotracheal intubation in a time comparable to using succinylcholine, without undesirable effects of the depolarizing neuromuscular blocking drugs.

Adolescent↗

PubMed1996

Intramuscular rocuronium in infants and children. Dose-ranging and tracheal intubating conditions.

BACKGROUND: Rocuronium's rapid onset and intermediate duration of action with intravenous administration suggests that intramuscular administration might facilitate tracheal intubation without producing prolonged paralysis. Accordingly, in infants and children, the authors measured onset at the adductor pollicis and respiratory muscles to determine the optimal dose (phase I), then gave this optimal dose to determine the optimal time for tracheal intubation (phase II). METHODS: The authors studied 45 unpremedicated patients aged 3 months to 5 yr. In phase I, 25 patients were anesthetized with nitrous oxide and halothane and breathed spontaneously; twitch tension and minute ventilation were measured. Rocuronium (800-2,400 micrograms/kg) was injected into the quadriceps or deltoid muscle; doses varied, using an "up-down" technique, the goal being to bracket the dose depressing twitch 75-90% within 5 min. In phase II, deltoid injections of the optimal dose from phase I (infants: 1,000 micrograms/kg; children: 1,800 micrograms/kg) were given to 20 patients anesthetized with 0.82-1.0% halothane. Tracheal intubation was attempted 1.5-3.0 min later; time to tracheal intubation was varied, using an "up-down" technique. RESULTS: In phase I, 5 of 7 patients given quadriceps injections (1,200-2,200 micrograms/kg) had slow onset of twitch and ventilatory depression. With deltoid injections (800-2,400 micrograms/kg), all patients developed complete twitch depression; median time to 50% depression of minute ventilation was 3.2 min in infants and 2.8 min in children. In phase II, intubating conditions were consistently adequate or good-excellent at 2.5 min in infants and 3.0 min in children. Initial twitch recovery was at 57 +/- 13 min (mean +/- SD) in infants and 70 +/- 23 min in children. CONCLUSIONS: Deltoid injections of rocuronium, 1,000 micrograms/kg in infants and 1,800 micrograms/kg in children, rapidly permit tracheal intubation in infants and children, despite a light plane of anesthesia. Duration of action of these large doses might limit clinical utility.

Androstanols↗

PubMed1996

Induction of anesthesia and tracheal intubation with sevoflurane in adults.

BACKGROUND: The speed, quality, and cost of mask induction of anesthesia and laryngeal mask airway insertion or tracheal intubation were studied in young non-premedicated volunteers given high inspired concentrations of sevoflurane (6 to 7%). METHODS: Twenty healthy persons who were 19 to 32 years old participated three times, received 6 l/min fresh gas flow, and were randomized to receive 6 to 7% sevoflurane in 66% nitrous oxide/28% oxygen by face mask until tracheal intubation (treatment 1) or until laryngeal mask airway insertion (treatment 3), or 6 to 7% sevoflurane without nitrous oxide to tracheal intubation (treatment 2). Participants exhaled to residual volume and took three vital capacity breaths of the gas mixture; thereafter ventilation was manually assisted. The time of exposure to the inhaled gas was varied for consecutive participants. It was either increased or decreased by 30-sec increments based on the failure or success of the preceding volunteer's response to laryngoscopy and intubation after a preselected exposure time. Failure was defined as poor jaw relaxation, coughing or bucking, or inadequate vocal cord relaxation. RESULTS: Loss of the lid-lash reflex in unpremedicated young volunteers was achieved in 1 min and did not differ among groups. Average time (and 95% confidence interval) for acceptable conditions for LMA insertion was achieved in 1.7 (0.7 to 2.7) min, and all participants had an immediate return of spontaneous ventilation. The time for acceptable tracheal intubating conditions after manual hyperventilation by mask was 4.7 (3.7 to 5.7) min and 6.4 (5.1 to 7.7) min in treatments 1 and 2, respectively. There were no cases of increased secretions or laryngospasm. The incidence of breath holding and expiratory stridor ("crowing") was 7.5% and 25%, respectively, during treatment 1 and 15% and 40%, respectively, during treatment 2. CONCLUSIONS: The induction of anesthesia to loss of lid reflex in young non-premedicated adults approaches the speed of intravenous induction techniques. No untoward airway responses were noted during mask induction of anesthesia with a three-breath technique. In response to intubation, no adverse airway responses, including jaw tightness, laryngospasm, and excessive coughing or bucking, occurred in participants whose duration of mask administration of sevoflurane met the appropriate times (as determined in this study).

Adult↗

PubMed1997

Tracheal mucus velocity remains normal in healthy sheep intubated with a new endotracheal tube with a novel laryngeal seal.

BACKGROUND: Tracheal mucus velocity (TMV), an index of mucociliary clearance, is reduced markedly in patients intubated with standard endotracheal tubes (ETTs) with high-compliance low-pressure (hi-lo) cuffs. The authors developed a new ultra-thin walled ETT in which the inflatable cuff is replaced with a no-pressure seal, positioned at the level of the larynx. The seal consists of 12 to 20 toroidal layers of thin polyurethane film ("gills") at the level of the vocal cords and prevents both air leak and fluid aspiration. The authors hypothesized that ETTs with the new laryngeal seal may impair TMV less than ETTs with inflated hi-lo cuffs do. METHODS: The TMV was measured in seven healthy female sheep by radiographically tracking the motion of small discs of tantalum inserted into the trachea through a bronchoscope. The TMV was measured in spontaneously breathing sheep before intubation (baseline) and after intubation with either a hi-lo ETT (control group) or after intubation with a new ETT with gills (study group). Four to six weeks later, the studies were repeated, but the sheep that were previously in the control group served as the study group, and those in the study group served as controls. RESULTS: Baseline TMV did not differ in the two groups. In the control group, TMV decreased significantly (by 67%) from baseline. In the study group, TMV did not differ significantly from baseline and remained steady during 3 h of intubation. CONCLUSIONS: The TMV does not change in sheep intubated with new ETTs with gills. The new ETT's may help promote a normal mucociliary clearance in patients who require ventilation.

Animals↗