Predicted end-tidal sevoflurane concentration for insertion of a Laryngeal Mask Supreme: a prospective observational study.

CONTEXT: The single-use Laryngeal Mask Airway (LMA) Supreme is a new supraglottic airway device. It has been reported to be reliable and easy-to-use in clinical practice; however, the anaesthetic techniques for its insertion are not standardised. OBJECTIVES: The purpose of this study was to determine the ED50 of end-tidal sevoflurane concentration for successful LMA Supreme insertion without the use of neuromuscular blockade. DESIGN: A prospective observational study. SETTING: A single tertiary care surgical centre. PATIENTS: Thirty-one consecutive elective patients scheduled for minor elective surgery under general anaesthesia. INTERVENTION: Patients were preoxygenated with 100% oxygen and anaesthetised using normal tidal volume inhalation of sevoflurane. The target sevoflurane concentration was determined using a modified Dixon's 'up-and-down' method (starting at 2.5% with 0.5% as the step size). After the predetermined end-tidal concentration had been established and maintained for 10 min, LMA Supreme insertion was attempted. MAIN OUTCOME MEASURE: The main outcome measure was the patient's response to LMA Supreme insertion, classified as either 'movement' or 'no movement'. The mean of the concentrations of seven cross-overs from 'movement' to 'no movement' was used to estimate the ED50. RESULTS: The estimated sevoflurane concentration for successful LMA Supreme insertion in 50% of adults was 3.03 ± 0.75% (95% confidence interval 2.3 to 3.7%). The values of the ET50 and ET95 obtained by logistic regression were 2.83 and 5.30%, respectively. CONCLUSION: Sevoflurane alone can provide acceptable conditions for insertion of the LMA Supreme in adults, at an estimated minimum alveolar anaesthetic concentration of 3% with minimal adverse effects.

[Impact on the primary carer of an intervention carried out on dependent elderly people]. / Impacto sobre el cuidador principal de una intervención realizada a personas mayores dependientes.

OBJECTIVE: To evaluate the impact of joining a home care program on primary caregivers of dependent elderly people. DESIGN: Non-randomised "before-after" intervention study. SETTING: Primary Care. PARTICIPANTS: Primary carers of elderly dependent people included in a home care program (n=156; 7.8% loss to follow up). INTERVENTIONS: Inclusion in a home care program for chronically dependent elderly and the assessment of the primary carer in the same year. VARIABLES ASSESSED: perceived health, frequency of visits, questionnaires of quality of life (Nottingham questionnaire), psychological health (Goldberg questionnaire), social support (Duke-UNC scale) and overburden of caregivers (Zarit questionnaire) and satisfaction with care received. RESULTS: There were no significant changes in perceived health. Improvement in the areas of energy, sleep, emotional and social relationship of the quality of life. Decreased attendance (8.4 vs. 7.5, p<0.05) and the percentage of overusers (30.1 vs 6.9%, P<.01). A reduced percentage of caregivers expressed low social support (8.3 vs 2.8%, P<.05) and caregiver overburden (56.4 vs 44.4%, P<.05). 90.3% of caregivers believed that care had improved at the end of intervention, with a significant improvement of satisfaction of overall medical and nursing care received (7.6 vs 8, 4, 7.9 vs 8.5 and 7 vs 8.5; P<.05). CONCLUSIONS: Joining a home care program for dependents has a positive impact on their primary caregiver and improves their perception of care received, reducing their use of health services, reducing the level of overburden and their perceived lack of social support.

[Anesthesia for cesarean section in a patient with recessive dystrophic epidermolysis bullosa]. / Tratamiento anestésico para cesárea en una paciente con epidermolisis bullosa distrófica recesiva.

Recessive dystrophic epidermolysis bullosa is inherited as a rare autosomal disorder which causes blisters to form in the skin. We describe the treatment of a 39-year-old parturient with this condition. She was scheduled for elective cesarean section at 37 weeks' gestation. The patient had widespread skin lesions, had lost fingers, and had esophageal stenosis. The cesarean was performed under spinal anesthesia without complications. Recessive dystrophic epidermolysis bullosa requires adaptation of anesthetic technique that includes control over posture and careful handling of the skin. Material for attaching monitoring devices and inserting venous lines must be adapted to the particular deformities and skin lesions present.

Air-Q® versus LMA Fastrach™ for fiberoptic-guided intubation: A randomized cross-over manikin trial. / Estudio aleatorizado cruzado para evaluar la intubación guiada con fibrobroncoscopio a través del dispositivo Air-Q® versus la mascarilla laríngea Fastrach™ en maniquís.

INTRODUCTION: Airway management is still a major cause of anesthesia-associated morbidity and mortality. Supraglottic devices are recommended in difficult airway management guidelines. The aim of this study was to compare the performance of the Air-Q® and the LMA Fastrach™ for fiberoptic guided tracheal intubation. METHODS: Thirty-three anesthesia trainees participated in this randomized crossover study. Time to insert the dedicated airways (insertion of the airway into the manikin and delivery of two breaths), time to tracheal intubation (fiberoptic-guided tracheal intubation), time to remove the dedicated airway (removal of the Air-Q®/LMA Fastrach™ over the tracheal tube) and the opinion of the ease of use of the anesthesia trainees were measured. RESULTS: There was 100% success rate for tracheal intubation with both devices on the first attempt. Time to insert the dedicated device and deliver two breaths was 10±3s for the Air-Q® and 11±3s for the LMA Fastrach™, P=.07. Time taken to intubate the trachea was shorter with the air-Q®, 38±15 s, than with the LMA Fastrach™, 47±19s, P=.017. Overall procedure time was significantly shorter with the Air-Q® as compared with the LMA Fastrach™, with a mean time of 74±21s and 87±28s respectively, P=.002. Air-Q® removal was considered easier than LMA Fastrach™ removal, P=.005. There were no tube dislodgements during the removal of the dedicated airways. CONCLUSIONS: Inexperienced anesthesia residents can perform fiberoptic-guided intubation through Air-Q® and LMA Fastrach™ in a clinically acceptable time with high success.

[Two cases of congenital airway obstruction managed with ex utero intrapartum treatment procedures: anesthetic implications]. / Dos casos de obstrucción congénita de la vía aérea sometidos a E.X.I.T. ("ex-utero intrapartum treatment"): implicaciones anestésicas.

An ex utero intrapartum treatment (EXIT) procedure provides sufficient time to gain control of the potentially obstructed fetal upper airway while uterine placental circulation is maintained during cesarean section. We report 2 cases in which fetal congenital upper airway obstruction was managed without complications during EXIT procedures. We also discuss general considerations concerning the obstetric patient and the performance of intramuscular fetal anesthesia. Before the hysterotomy, sevoflurane at 1.5 minimum alveolar concentration was administered to assure sufficient uterine relaxation during EXIT. The 2 parturients remained hemodynamically stable during the procedure and uterine and placental perfusion was adequate. Nasotracheal intubation was possible in 1 fetus after a cervical mass was dissected. In the other, a tracheostomy was created. After the umbilical cord was clamped, the concentration of sevoflurane anesthetic gas was reduced and oxytocin and methylergometrine were administered to induce adequate uterine contractions within a few minutes. Both neonates survived the EXIT procedure with no complications.

Bundle-branch reentry and the postpacing interval after entrainment by right ventricular apex stimulation: a new approach to elucidate the mechanism of wide-QRS-complex tachycardia with atrioventricular dissociation.

BACKGROUND: Diagnosis of bundle-branch reentry ventricular tachycardia (BBR-VT) by the standard approach is challenging, and this may lead to nonrecognition of this tachycardia mechanism. Because the postpacing interval (PPI) after entrainment has been correlated with the distance from the pacing site to the reentrant circuit, BBR-VT entrainment by pacing from the right ventricular apex (RVA) should result in a PPI similar to the tachycardia cycle length (TCL). This factor may differentiate BBR-VT from other mechanisms of wide-QRS-complex tachycardia with AV dissociation, such as myocardial reentrant VT (MR-VT) or AV nodal reentrant tachycardia (AVNRT), in which the circuit is usually located away from the RVA. METHODS AND RESULTS: Transient entrainment by RVA pacing was attempted in 18 consecutive BBR-VTs and finally achieved in 13. Results were compared with those found in 59 consecutive MR-VTs and 50 consecutive AVNRTs. The mean PPI-TCL difference was significantly (P:<0.0001) shorter in the BBR-VT group (9+/-11 ms) than in the MR-VT (109+/-48 ms) and the AVNRT (150+/-29 ms) groups. No BBR-VT showed a PPI-TCL >30 ms (range -12 to 24 ms). Except for 2 MR-VTs, no MR-VT (range 21 to 211 ms) or AVNRT (range 100 to 215 ms) showed a PPI-TCL <30 ms. CONCLUSIONS: A PPI-TCL >30 ms, after entrainment by RVA stimulation, makes BBR-VT unlikely. Conversely, a PPI-TCL <30 ms is suggestive of BBR-VT but should lead to further investigation by use of conventional criteria.

Radiofrequency ablation of the inferior vena cava-tricuspid valve isthmus in common atrial flutter.

Endocardial mapping has suggested that common atrial flutter (AF) is based on right atrial reentry surrounding the inferior vena cava (IVC). The isthmus between the IVC and the tricuspid valve (TV) appears essential to close the circuit. To test this hypothesis, radiofrequency was applied to the IVC-TV isthmus, with catheter electrodes, in 9 patients with AF. Mapping confirmed a right atrial circuit surrounding the IVC in all. In 4 patients another type of AF was induced that followed the circuit in the opposite direction. Radiofrequency interrupted AF in all patients. Multiple endocardial recordings showed that interruption was due to activation block at the point of application. Radiofrequency produced very brief or sustained, atrial fibrillation in 2 patients, which resulted in sinus rhythm. AF recurred in 4 patients with the same activation pattern and was interrupted again with radiofrequency in the IVC-TV isthmus in 3. AF was noninducible in 7 patients after 1 to 4 sessions. AF-free periods of 2 to 18 months without drugs were observed after radiofrequency, but 2 patients had paroxysmal atrial fibrillation. These results confirm that the IVC-TV isthmus is an essential part of the AF circuit. Ablation of this area may be of therapeutic value, but technical improvements are needed. Long-term efficacy of the procedure is uncertain.

Fragmented electrograms and continuous electrical activity in atrial flutter.

Multiple endocardial bipolar electrograms were recorded in 13 patients with atrial flutter (AF) to locate areas of fragmented electrical activity. Stable fragmentation patterns were found in each case, covering between 36% and 100% of the flutter cycle. Double or triple spike patterns were common. The direction of atrial activation was approximately defined in 11 patients, and in all of them at least part of the areas showing fragmentation was included in the circuit. In 1 patient an area of continuous electrical activity was found. AF circuits appeared to be included in the right atrium in 12 patients and in the left atrium in 1 patient. During atrial stimulation changes in fragmented electrograms coincided with changes in AF pattern before its interruption, while restoration of stable AF after stimulation was accompanied by reappearance of previous stable fragmented electrograms. In 6 patients electrograms were recorded after sinus rhythm was reestablished, and all showed marked decreases or disappearance of fragmentation. It is concluded that fragmented electrograms are often found in AF and may be related to abnormal local conduction in relation to the reentrant activation circuits.

Atrial endocardial mapping in the rare form of atrial flutter.

Endocardial atrial activation mapping was performed in 7 patients with rare atrial flutter (AF), inscribing predominantly positive deflections on leads II, III and aVF. In 2 cases both a rare and a common AF were mapped on different occasions. Every case displayed circular right atrial activation. In 5 of the 7 cases rare AF direction was clockwise (craniocaudal in the septum and posterior wall and caudocranial on the lateral and anterior walls). In 2 cases rare AF direction was counterclockwise (caudocranial in the septum and posterior wall and craniocaudal in the lateral and anterior walls). Both common AF rotated counterclockwise. A "line" of conduction delay or block was present in both clockwise and counterclockwise circuits between the posterior and lateral walls, in the probable location of the crista terminalis. This line of block extended the central obstacle made by the inferior vena cava toward, but perhaps not all the way to, the superior vena cava, making activation rotate roughly around the tricuspid ring. The ridge between the inferior vena cava and the tricuspid ring was a critical anatomic "closing" point in all clockwise and counterclockwise circuits. Right atrial macroreentry underlies rare AF. Direction of activation tends to be opposite to that in common AF. The cause of the positive deflection is unclear.

Electrophysiologic studies in atrial flutter.

The clinical electrophysiologic approaches to atrial flutter (F) have been activation mapping and the observation of changes induced by programmed stimulation. Sequential endocardial activation mapping has recently yielded information indicating that common F is produced by a large right atrial (RA) reentry circuit, with counterclockwise rotation in the frontal plane, including the inferior vena cava in its center. Functional block in the crista terminalis and conduction slowing in the approaches to the atrioventricular node seem to be important to support reentry. F inscribing positive deflections in the inferior leads usually follows the same path, but in a clockwise direction. Atypical F may be produced by left atrial circuits. Atrial stimulation during F entrains the circuit, resetting it with each stimulus. Collision between antidromic and orthodromic activation during entrainment produces fusion that can be identified in the surface electrocardiogram. The last paced activation restarts F, unless circuit penetration has been enough to modify it by block or disorganization. Entrainment may result in F acceleration, with changes in activation sequence, suggesting a different type of reentry, possibly based on functional factors.

[Catheter ablation of atrial flutter and fibrillation]. / Ablación con catéter del flutter y la fibrilación auricular.

The knowledge of the anatomic and functional bases of common flutter circuits has allowed the definition of an anatomic isthmus, between the inferior vena cava and the tricuspid valve, where radiofrequency application can interrupt the circuit. Some atypical flutter circuits are identical to common flutter circuits, but for an inverted rotation (clockwise), and these can be also ablated in the same isthmus. In cases of flutter (or reentrant tachycardia) due to surgical scars in the atrium, mapping supported with programmed stimulation, can define anatomic isthmuses, where ablation can also interrupt the circuit. There is still no definition of left atrial flutter circuits, that may guide ablation in these cases. Atrial fibrillation ablation is still in its infancy. Some initial experiences have tried to reproduce the division of atrial myocardium as in the maze procedure, and fibrillation was interrupted in a number of patients, submitted to very long procedures. There is still no clear definition of the muscular anatomy of the left atrium, in relation with the fibrillatory process, to guide the design of effective ablation lines. There are also technical problems to produce continuous, transmural ablation lines, that are not arrhythmogenic by themselves. The wide clinical application of ablation to treat atrial fibrillation is still in the distant future.

[Hypertensive cardiopathy and arrhythmias]. / Cardiopatía hipertensiva y arritmias.

The anatomical and tissue changes caused by hypertension are responsible of the higher incidence of atrial and ventricular arrhythmias as compared to normal population. Hypertension, when associated with atrial fibrillation, becomes an important risk factor for systemic embolism. Atrial dilatation and/or fibrosis because of haemodynamic overload due to left ventricular hypertrophy are the arrhythmic substrate. The higher incidence of ventricular arrhythmias is related to left ventricular hypertrophy. Ventricular premature beats, frequent and/or polymorphic in most of the cases, and short runs are the usual picture. Sustained ventricular tachycardia is seldom documented. The substrate is created by hypertrophy itself, resulting in conduction disturbances favoring reentry. Associated myocardial ischemia plays an important role in the genesis of ventricular arrhythmias. Left ventricular hypertrophy is associated with an increased incidence of total cardiac death and sudden death. Ventricular arrhythmias are suggested to be a poor prognostic factor. The aim of this article is to offer a simplified review of the meaning of cardiac arrhythmias in the hypertensive patient, and to give some clues to the practical approach in the clinical setting.

[Chronotropic competence in patients with the sick sinus syndrome wearing AAI or DDD pacemakers]. / Capacidad de taquicardización en pacientes con enfermedad del nódulo sinusal portadores de marcapasos AAI o DDD.

The prevalence of chronotropic incompetence in patients with sinus node disease (SND) is not well defined. To assess this, we evaluated 18 patients (7 men, 11 women; mean age: 64 +/- 11) with SND and permanent pacemakers (AAI/DDD) with Holter monitoring and treadmill stress test. Only 2 patients received active cardiac drugs (1, L-dopa an 1 propafenone). The treadmill tests results were compared with a control group of 15 men and 18 women (mean age: 66 +/- 5, p = NS) without organic heart disease. During ambulatory activity all pacemaker patients increased their own cardiac rate to a value higher than the programmed basic pacemaker rate. In 8 patients the maximal rate attained was over 100/min (mean 95 +/- 19/min). The maximal rate during treadmill test in pacemaker patients was 131 +/- 25 (control group 138 +/- 14, p = NS). Exercise tolerance in METs was similar in pacemaker patients (5.2 +/- 2.6) and in controls (5.8 +/- 1.2) (p = NS). Two pacemaker patients (12%) didn't reach 100/min during stress test. Most patients with SND and permanent pacemakers (AAI/DDD) are able to increase cardiac rate during exercise. Rate responsive pacing (AAIR/DDDR) should be limited to a minority of patients with true chronotropic incompetence.

[The ablation of atrial flutter. The long-term results after 8 years of experience]. / Ablación de flúter auricular. Resultados a largo plazo tras 8 años de experiencia.

OBJECTIVE: Since the 1990's radiofrequency ablation radiofrequency ablation of atrial flutter has evolved in its methods and results. We have reviewed the long term outcome in 62 patients with typical (common) or reversed (clockwise) flutter undergoing radiofrequency ablation between 1990 and 1997. PATIENTS AND METHODS: Fifty men and 12 women, aged 22-78 years (57 +/- 12) with flutter recurring after cardioversion and antiarrhythmic drugs make this series. Flutter was typical in 59 cases and reversed in 3. There was no heart disease in 14, bronchopulmonary disease in 10, coronary disease in 9, cardiomyopathies in 6 and other processes in the remainder. In 5 cases with previous surgery for atrial or ventricular septal defect, Ebstein's anomaly or myxoma, we treated also a macro-reentry tachycardia around the atriotomy in the right atrium. Radiofrequency ablation was directed to the inferior vena cava-tricuspid isthmus in typical and reversed flutter, and to the isthmus between the inferior end of the atriotomy and the inferior vena cava, in the lateral right atrium, in the atriotomy tachycardias. We subdivided our patients in Group 1 (24 patients), treated until the end of 1994, and Group 2 (38 patients) treated since 1995 using specially designed catheters and trying to produce isthmus block as the endpoint of the procedure. RESULTS: Radiofrequency ablation interrupted flutter in 61 of 62 cases (98.4%), and the atriotomy tachycardia in all 5. The number of application in Group 1 was 18.6 +/- 10.1 vs 12 +/- 10 in Group 2 (p < 0.05). Follow-up was 40 +/- 24 months in Group 1 vs 16 +/- 9.5 in Group 2. Flutter recurred in 58% of Group 1 and 13% of Group 2 patients (p < 0.001), usually 1-3 months after radiofrequency ablation and they were successfully treated by new radiofrequency ablation with a small number of applications. There was no recurrence of atriotomy tachycardia. Atrial fibrillation occurred in 14 patients (23%) (11 paroxysmal, 3 persistent), with equal incidence in both groups. At the end of follow-up 85% of the patients were in sinus rhythm, although 6 needed pacemakers for sinus node dysfunction (3) or AV ablation (3). Antiarrhythmic drugs were used by 46% of patients in Group 1 and 26% in Group 2 (p = NS) for atrial arrhythmias or recurrent flutter. CONCLUSIONS: Radiofrequency ablation is an effective treatment for flutter and macro-reentry atriotomy tachycardia. Progress in methods have improved results significantly. Atrial fibrillation can still be a problem in 20-25% of the patients after flutter control.

[Exercise-induced atrioventricular block]. / Bloqueo auriculoventricular inducido por el ejercicio.

Exercise-induced atrioventricular block in patients with normal atrioventricular conduction at rest is uncommon. Electrophysiologic studies have documented block distal to the atrioventricular node in these patients. Implantation of a permanent pacemaker is recommended because of a high incidence of subsequent symptomatic block. We report three symptomatic patients with exercise-induced atrioventricular block. Two patients showed a bundle branch block in the baseline electrocardiogram, suggesting a distal location of the block. In the remainder, with a normal QRS, the electrophysiologic study revealed AV block within the His bundle in response to atrial pacing.

[Pharmacologic maintenance of sinusal rhythm and/or control of the ventricular response in patients with atrial fibrillation or flutter]. / Mantenimiento farmacológico del ritmo sinusal y/o control de la respuesta ventricular en pacientes con fibrilación o flutter auricular.

Atrial fibrillation is the most common cardiac arrhythmia and is usually responsible for symptoms requiring some treatment. Antiarrhythmic drugs are the first choice therapy, but their potential risks are significant. This together with their limited efficacy restricts their use. Antiarrhythmic drug use should be tailored; mainly according to the underlying heart disease. When reversion to sinus rhythm is not eligible, the adequate control of ventricular rate and the reduction of embolic risk are the therapeutic goals. Atrial flutter shows different behaviour regarding the very limited efficacy of antiarrhythmic drugs for reversion to and maintenance in sinus rhythm.

[The efficacy of propafenone in preventing recurrent auricular fibrillation and flutter]. / Eficacia de la propafenona en la prevención de fibrilación y flúter auricular recurrente.

In order to investigate the efficacy of propafenone in the prevention of paroxysmal flutter or fibrillation, we treated 21 patients without left ventricular disfunction. Age was 60 +/- 14 (mean +/- sd) years, left atrial diameter by echocardiography 37 +/- 7 mm, cardiothoracic index 0.48 +/- 0.05 (0.41-0.57) and P wave duration 100 +/- 17 ms. The frequency of recurrences before treatment was: daily in five (23%), weekly or more in eight (38%), monthly-weekly in seven (33%) and quarterly-monthly in one (5%). Propafenone (671 +/- 187 mg/24 h) was given after recurrences were demonstrated under treatment with 1-3 antiarrhythmic drugs per patient. During 8.9 +/- 3.5 months of follow-up (range 6-19) 5 patients (23%) were completely free of recurrences; in seven (33%) the incidence decreased by greater than 50% with a marked decrease in duration. Side effects appeared in 12 cases (57%), leading to its discontinuation in four (19%). Arrhythmogenic effects were observed in 2 cases (9%). Propafenone is effective in greater than 50% of patients with paroxysmal atrial flutter or fibrillation, resistant to other antiarrhythmic agents. The incidence of side effects is high, but they are usually not severe and reversible.

[Severe hypoxemia due to a right-left shunt at the level of the foramen ovale. A complication of right ventricular infarct]. / Hipoxemia grave por cortocircuito derecha-izquierda a nivel del foramen oval. Una complicación del infarto de ventrículo derecho.

A 76-year-old woman with an inferior wall myocardial infarction, with right ventricular involvement, developed severe arterial hypoxemia with neurological involvement. Pulmonary edema or embolism and chronic obstructive pulmonary disease were ruled-out, and a right-to-left shunt was demonstrated by contrast echocardiography at the level of the foramen ovale. After inotropic support and oxygen supplementation, the patient recovered, although with significant neurological sequelae. No focal lesions were detected in the central nervous system by computerized tomography. Hypoxemia improved, coinciding with the disappearance of right-to-left shunt by contrast echocardiography.