INTUBACIÓN TRAQUEAL FALLIDA EN OBSTETRICIA:
NO MUY FRECUENTE PERO TODAVÍA
MANEJADO INADECUADAMENTE
DRA. Inés Escalona
Residente de I nivel
Anestesiología HCM
Durante el embarazo ocurren cambios anatómicos y fisiológicos en la mujer, que incluye mamas voluminosas que impiden la expansión torácica, edema en piel y mucosa, sobrepeso, hay un consumo metabólico de oxígeno aumentado, hiperventilación; y un volumen residual, capacidad funcional residual y volumen reserva espiratorio disminuido, que conllevan a un estado de hipercapnia e hipoxia. Esto hace que la incidencia de intubación fallida en la embarazada es 8 veces mayor que en las mujeres no gestantes, y es una causa de muertes en gestantes sometidas a anestesia general. Métodos: es un estudio realizado es la región de Tames, suroeste de Reino Unido, a partir de 1.999 a 2.003, tomando en cuenta 7 hospitales; es un estudio retrospectivo; los datos a tomar fueron demográficos, talla, peso, edad e índice de masa corporal y fueron recolectados anualmente en un expediente de papel o usando una base de datos de FileMaker; los resultados fueron sujetos a análisis estadístico estándar y definen la intubación fallida como aquella que no se puede realizar después de colocar la dosis de suxametonio. Resultados: el número de gestantes sometidas a anestesia general fueron 4768 de las cuales 20 presentaron intubación fallida, pero solo a 16 pacientes se le realizó la revisión, ya que eran las que tenían claramente en la historia la identificación y la conducta anestésica. De estas 16 pacientes ninguna cumplieron con el protocolo de intubación fallida a pesar que en 8 de ellas existía en el hospital, a 4 se les administró una segunda dosis de suxametonio, a 3 se les repitió 3 o más veces la intubación, un caso se le coloca una segunda dosis de tiopental antes de repetir la intubación y un caso presento regurgitación y vómito; en cuanto a los otros datos tomados el promedio fue el siguiente: 35 años, 85Kg, 1,67mts y un índice de masa corporal 31,9 Kg/mts2. Conclusión: la incidencia de intubación fallida en 5 años fue de 1:238, la mayoría de los casos son emergencia, fueron realizados fueron del horario de rutina y fueron hechas por aprendices; la exposición de los aprendices a la anestesia general obstétrica es baja y existe poca divulgación e información al respecto; la falta de cumplimiento del protocolo de intubación fallida es de un 50%; al presentarse estos casos tener en cuenta el uso de mascara laringea más uso de ventilación con presión positiva; la falta de evaluación preanestésica en las embarazadas aumenta la morbi-mortalidad del paciente y sobretodo que toda embarazada debe ser considerada siempre como una posible vía aérea difícil.
Failed tracheal intubation in obstetrics: no more frequent
but still managed badly
K. Rahman(1) and J. G. Jenkins (2)
1 Specialist Registrar and 2 Consultant, Department of Anaesthesia, Royal Surrey County Hospital, Egerton Road,
Guildford, GU2 7XX, UK
Anaesthesia, 2005, 60, pages 168–171
Summary
In the South-West Thames region of the United Kingdom, during a 5-year period from 1999 to 2003, there were 20 failed tracheal intubations occurring in 4768 obstetric general anaesthetics (incidence 1 : 238). In half of the 16 cases for which the patient’s notes could be examined there was a failure to follow an accepted protocol for failed tracheal intubation.
The incidence of failed tracheal intubation in the pregnant population is perhaps eight times higher than in the non-pregnant population [1] and cases are usually
unexpected. The Confidential Enquiries into Maternal Deaths in the United Kingdom [2–4] have highlighted the potentially disastrous outcome of difficulty in tracheal
intubation. There have been a few reports, from teaching hospitals, detailing experiences of failed intubation in obstetric anaesthesia [1, 5–7], and we have previously presented data on failed tracheal intubation in the South-West Thames region for the period 1993–98 [8]. Here we present data on the incidence and management of failed tracheal intubation for the subsequent 5-year period, 1999–2003. South-West Thames is a relatively affluent region of the United Kingdom, which stretches from south-west London to the south coast of England; it has a mainly urban population of over 3 million and there are approximately 37 000 deliveries each year.
Discussion
The results of this survey give an overall 5-year incidence of failed tracheal intubation in obstetrics of 1 : 238. This is not significantly different from the incidence of 1 : 249 in the preceding 6 years in the South-West Thames region [8], or from that in other previous reports, in which the incidence has ranged variously between 1 : 250 [7], 1 : 280 [1], 1 : 300 [5] and 1 : 750 [6]. There has been no significant change in the incidence of failed tracheal intubation over the 11 years of our survey. This steady incidence contrasts with that found by Hawthorne et al. [7], who reported an increased incidence, albeit not significant, from 1 : 300 in 1984 to 1 : 250 in 1994. Other data from this survey coincide with Hawthorne et al.’s observations: most of these cases are emergencies, occur outside normal working hours and involve anaesthetic trainees. However, the estimated relative risk for failed tracheal intubation at emergency caesarean section vs. elective caesarean section over the 11 years of our survey fails to reach statistical significance. Unfortunately, we do not have denominator data to estimate the relative risks of out of hours working or anaesthetic inexperience. Hawthorne et al. suggested that trainees’ exposure to obstetric general anaesthesia has decreased because there are more trainees, rather than fewer general anaesthetics administered. Our observations suggest that in this region, the majority of ‘first on’ obstetric anaesthetic cover is still provided by specialist registrars, with some provided by senior house officers or non-trainees. We have also observed that trainees’ exposure is reduced as a result of there being fewer general anaesthetics. Others have also reported reduced experience in general anaesthesia for caesarean section [9, 10]; however, this has not led to a higher incidence of failed tracheal intubation. With the exception of one case of regurgitation and aspiration, we have not noted any adverse maternal outcome over the 11 years of our survey. Tunstall first published a protocol for the management of failed tracheal intubation in obstetrics in 1976 [11]. Likemore recent protocols [12], all the protocols in use in hospitals in our study were derivatives of Tunstall’s original. Our study shows that, despite the widespread publication and teaching of protocols for the management of failed tracheal intubation, in the moment of crisis the anaesthetists concerned not uncommonly deviated from those protocols. The temporal arrangement of the cases inTable 1 suggests that there has been no lessening of this deviation with time. In fact, the situation appears to have worsened since our last report: between 1993 and 1998 there was a failure to follow an accepted protocol in 35% of cases, compared to 50% of cases between 1999 and 2003. We found the most common departure was the administration of further intravenous agents to allow repeated attempts at tracheal intubation. The Confidential Enquiries into Maternal Deaths [2] has suggested that protocols be regularly rehearsed and practised. However, Cook and McCrirrick [13] found that, whilst protocols were in place in most of the hospitals they surveyed, in few hospitals were they practised. The laryngeal mask airway has found a place in the management of failed tracheal intubation [14] and has been used for caesarean section following failure to intubate [15, 16]. If the operation proceeds, it has been recommended that further neuromuscular blocking drugs should not be given and that a spontaneous ventilation technique should be used [17, 18]. However, there are recent reports of the successful use of the ProSeal laryngeal mask airway (Intavent Orthofix Ltd., Maidenhead, UK) with intermittent positive pressure ventilation following failed intubation at caesarean section [19, 20]. Lack of pre-operative assessment is a contributory factor in anaesthesia-related mortality [21]. In our previous report, we were able to find evidence of preoperative airway assessment in fewer than half of the cases, compared to a documented assessment in 88% of cases in the current report. Assuming no other grade-3 or -4 laryngoscopy occurred in any of the other general anaesthetics administered, our data give an incidence of 1 : 530 for grade 3 and 1 : 1800 for grade 4. Theseare Table 2 Points common to failed intubation protocols in hospitals reporting a failed tracheal intubation 1999–2003. Initial management Do not give a second dose of Suxamethonium Give 100% oxygen Maintain cricoid pressure Call for help Ventilation possible and Turn patient to left lateral position Wake patient Ventilation possible and urgent need to continue Proceed using a spontaneous breathing technique e ventilation impossible Ease cricoid pressure If ventilation still impossible, Insert laryngeal mask airway If ventilation still impossible, Perform cricothyrotomy no urgent need to continue
