| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
* From the Departments of Anesthesia, and
Pediatrics, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Address correspondence to: Dr. David C. Campbell, Department of Anesthesia, College of Medicine, University of Saskatchewan, Royal University Hospital, 103 Hospital Drive, Saskatoon, Saskatchewan S7N 0W8, Canada. Phone: 306-655-1183; Fax: 306-655-1279; E-mail: david.campbell{at}saskatoonhealthregion.ca
 |
Abstract |
|---|
 TOP Abstract IntroductionCase reportDiscussionReferences |
|---|
Clinical features: A 21-yr-old parturient with Noonan syndrome received patient-controlled epidural analgesia for labour at 39 weeks gestation. Meticulous attention to the anesthetic technique resulted in good analgesia, and a successful outcome for mother and child. The different approaches to labour analgesia in parturients, with particular attention to combined spinal epidural vs epidural analgesia in this setting are discussed.
Conclusion: Parturients with Noonan syndrome can present with an array of anomalies that may present difficulties to the anesthesiologist including a difficult airway, cardiopulmonary abnormalities, exaggerated lumbar lordosis and short stature. Careful preoperative consultation and determination of the degree of associated anomalies will help to prepare the anesthesiologist for potential problems.
|
Introduction |
|---|
|
TOPAbstractIntroductionCase reportDiscussionReferences |
|---|
|
Case report |
|---|
|
TOPAbstractIntroductionCase reportDiscussionReferences |
|---|
The patient had maternal serum screening in the first trimester which did not reveal increased risk for Down’s syndrome or an open neural tube defect. An obstetrical ultrasound at 18 weeks gestation detected mild edema of the anterior chest wall, and a fetal echo-cardiogram revealed some echogenic foci in the area of the ventricular septum, suggestive of aneuploidy or other genetic condition.
The parturient had an obstetric anesthesia consultation at 35 weeks gestation. Of importance, the airway examination revealed a tongue ring, high arched palate, and a modified Mallampati class III/IV airway, with normal neck range of motion, and three finger breadths thyromental distance suggestive of a potential difficult intubation. The patient also had a characteristic shield-shaped chest, but denied symptoms of respiratory compromise. She was 164.2 cm tall (55th percentile), with no evidence of kyphoscoliosis or exaggerated lumbar lordosis, and she had easily palpable spinous processes.
There was no clinical evidence of a bleeding diathesis. Laboratory investigations revealed hemoglobin (148 g·L–1), platelets (253 10–9·L–1), and the partial thromboplastin time (31) and international normalization ratio (1.0) were within normal limits.
A 12-lead electrocardiogram revealed normal sinus rhythm with evidence of left anterior fascicular block and increased voltages suggestive of left ventricular hypertrophy. Echocardiography undertaken when the patient was a child revealed asymptomatic subaortic stenosis. At approximately 20 weeks gestation, echocardiography identified hypertrophic cardiomyopathy, primarily involving the interventricular septum. This resulted in mild left ventricular outflow tract obstruction with a peak gradient of 56 mmHg at rest, and chordal systolic anterior motion during systole. The ejection fraction was normal (65–70%) with normal left ventricular systolic function and mild diastolic dysfunction, as well as trivial to mild mitral regurgitation. The mitral valve leaflets were thickened with restricted motion of the posterior leaflet, with all other valves reported as normal. A secundum atrial septal defect (ASD) was also identified with a shunt ratio of 1.4:1, although no right heart enlargement was noted. Importantly, the patient remained completely asymptomatic throughout her entire pregnancy.
At 35 weeks gestation, the obstetrical plan included a trial of labour with an intended vaginal delivery. The obstetrician had informed the patient, however, that an intrapartum Cesarean delivery was highly probable due to the potential cephalopelvic disproportion.
At 39 weeks gestation, an elective Cesarean delivery was planned due to a breech presentation. During the preoperative anesthetic assessment, a review of the options of neuraxial vs general anesthesia for the Cesarean delivery was discussed. Due to the likelihood of a difficult intubation, it was decided to avoid the induction of general anesthesia and proceed with neuraxial anesthesia. Of the neuraxial options, epidural surgical anesthesia was presented as the optimal anesthetic choice. Although the parturient remained asymptomatic in relation to the cardiac abnormalities, a brief discussion regarding invasive blood pressure monitoring and central venous line placement prior to the induction of surgical anesthesia ensued, should her clinical presentation change. It was intended that all iv lines were to be de-aired and saline used for the epidural loss-of-resistance technique to reduce the possibility of a venous air embolism, given the presence of the patient’s atrial septal defect.
Surprisingly, at the time of presentation for elective Cesarean delivery, ultrasound examination revealed a vertex rather than breech presentation, with a small for gestational age fetus. The obstetrical plan was revised, and it was decided to proceed with an iv induction of labour, using a completely de-aired iv access.
Epidural labour analgesia was requested at 4 cm cervical dilatation and established with the patient placed in the sitting position. Using an aseptic technique, the epidural space was located with a 17-G Tuohy needle and a loss-of-resistance to saline technique. The placement was uncomplicated with only one attempt required to locate the epidural space. A 20-G, saline flushed, multi-orifice epidural catheter threaded easily so that 4 cm remained within the epidural space. An analgesic solution of ropivacaine 0.08% + fentanyl 2 µg·mL–1 was administered slowly in 5 mL boluses to a total volume of 20 mL over a period of ten minutes to initiate ELA.6 The patient reported excellent pain relief with bilateral T8 cutaneous levels to ice within ten minutes. Epidural labour analgesia was maintained using ropivacaine 0.08% and fentanyl 2 µg·mL–1 administered as a patient controlled epidural regimen using 5 mL boluses with a ten-minute lockout and a 10-mL·hr–1 basal infusion.7,8 Heart rate (70–90 beat·min–1) and blood pressure (108–116/50–60 mmHg) remained stable as determined by continuous SpO2 and an automatic non-invasive blood pressure cuff. The fetal heart tracing revealed a reactive fetal heart rate with a baseline of 145 beat·min–1.
The parturient remained comfortable throughout her labour, and did not require any unscheduled anesthesiologist-administered "top ups" throughout the prolonged labour of almost 24 hr. Labour culminated 14 hr following the establishment of ELA, in an uncomplicated vaginal delivery of a male infant weighing 2,880 g, with APGAR scores of 7 at one minute and 9 at five minutes. The mother remained hemodynamically stable throughout labour and delivery, and was transferred to the postpartum ward within two hours of delivery. She was discharged home on postpartum day one and at six-week follow-up the patient and baby were doing very well. Six-month follow-up with the medical geneticist confirmed the newborn exhibited none of the characteristic features of Noonan syndrome.
|
Discussion |
|---|
|
TOPAbstractIntroductionCase reportDiscussionReferences |
|---|
The incidence of Noonan syndrome is between 1:1,000 to 1:2,500 live births.5 The inheritance pattern is autosomal dominant and has been mapped to mutations in the gene PTPN11 which resides on the long arm of chromosome 12.5 Sporadic cases with spontaneous mutations also occur. However, Noonan syndrome is known to be heterogeneous with more than one causal gene responsible for the condition.10
Patients with Noonan syndrome may present anesthetic challenges due to the potential for difficult intubation compounded by the possibility of multiple major organ system involvement. Importantly, patients may have a difficult airway due to a high arched palate, micrognathia, and short webbed neck. A previous report described a difficult awake fibreoptic intubation of a mentally challenged parturient with Noonan syndrome.3 Respiratory compromise may also occur due to the abnormality of the chest wall including a "shield-shaped" chest, kyphoscoliosis, as well as short stature,11 although some have normal stature.12
Various cardiac abnormalities can be identified in these patients, although pulmonary stenosis and hypertrophic cardiomyopathy are the most common abnormalities.13 Thus, the anesthesiologist must be aware of the hemodynamic consequences of these lesions and take necessary precautions including sub-acute bacterial endocarditis prophylaxis. Bleeding diatheses including coagulation factor deficiencies and abnormal platelet count have been described which may contraindicate regional anesthesia14 and lymphedema may lead to difficult iv access.15 Varying degrees of mental impairment may present the health-care team with challenges from consent to cooperation with procedures, although most individuals with Noonan syndrome are of normal intelligence. Finally, technical difficulties with neuraxial placement may be experienced due to exaggerated lumbar lordosis, short stature,11 and a narrow spinal canal.16
The parturient in this case displayed many of the aforementioned characteristics, leading to multiple anesthetic challenges. One of our primary concerns was the possibility of a difficult airway typical of Noonan syndrome.3 The physiologic changes of pregnancy, in addition to the anatomical airway abnormalities associated with Noonan syndrome, increase the risk of a difficult or failed endotracheal intubation.17 Consequently, our goal was to provide a labour analgesic technique that could be rapidly converted to regional anesthesia should an urgent Cesarean delivery be necessary.
Additional concerns relate to abnormalities of the cardiovascular system. Although the majority of patients with Noonan syndrome have pulmonary stenosis,13 this parturient presented with mild hypertrophic cardiomyopathy, subaortic stenosis and an ASD. Although historically it has been suggested that neuraxial techniques should be avoided in parturients with hypertrophic cardiomyopathies,18 more recent reports have demonstrated the safe use of ELA.19,20 It is suggested that the provision of effective ELA avoids the deleterious effect of elevated catecholamines on myocardial contractility that may adversely impact hypertrophic cardiomyopathy. In addition, epidural anesthesia has been safely utilized for Cesarean delivery in parturients with hypertrophic cardiomyopathy.21 As our parturient was asymptomatic and had tolerated the physiologic cardiovascular changes during pregnancy and early labour, invasive blood pressure and central venous pressure monitoring was not established. Importantly, the presence of the ASD required that all iv lines be de-aired and that the loss-of-resistance technique for epidural placement utilize saline and not air to avoid the consequences of venous air embolism.
To control labour pain and secondary catecholamine elevations, parenteral opioids and three neuraxial labour analgesia options (epidural, combined spinal epidural, and continuous spinal anesthesia) were considered for our parturient once labour was established. Ultimately, our goal was to afford an analgesic modality that could facilitate urgent surgical anesthesia without the need for general anesthesia should urgent Cesarean delivery become necessary. Consequently, we considered the three neuraxial techniques that utilize an indwelling catheter which had the capability to provide the conduit for neuraxial surgical anesthesia. As routine intrathecal catheters are currently not available in Canada, our analgesic options were restricted to a "traditional" ELA or a combined spinal epidural (CSE) technique.
The CSE technique has been reported to provide successful labour analgesia in a parturient with hypertrophic cardiomyopathy.22 Unfortunately, the CSE technique for labour analgesia has been associated with high analgesia levels related to the intrathecal component resulting in adverse effects including maternal respiratory depression and respiratory arrest.23–25 We were concerned about the potential for a high-intrathecal level spinal which might require emergent airway manipulation in a parturient with an identified potential difficult intubation. Rapid onset of intrathecal labour analgesia was also undesirable, as abrupt sympatholysis in a patient with hypertrophic cardiomyopathy and subaortic stenosis could lead to potentially catastrophic consequences. Importantly, the "single shot" intrathecal component of CSE technique leaves the parturient with an "unproven" epidural catheter should urgent Cesarean delivery be required. Pan et al.26 reported inadequate labour analgesia in 4.2% of parturients and 3.2% of epidural catheters requiring replacement when the "unproven" epidural component of the CSE technique was activated. Importantly, these results are likely an underestimation of the actual number of ineffective epidural catheter components of the CSE technique, as many parturients likely delivered prior to requiring the activation of the "unproven" epidural component of the CSE. Should the epidural component of the CSE prove "ineffective" during the conversion to epidural surgical anesthesia for an urgent Cesarean delivery, the parturient may require a general anesthetic necessitating airway instrumentation. Consequently, we believe that use of the CSE technique with a potentially "ineffective" epidural component in a parturient with a difficult airway, is undesirable, considering the potential need for an urgent Cesarean delivery.
We then considered the advantages of "traditional" ELA, using a loss-of-resistance to saline technique, with a slowly titrated initiation of the block. During the consultation process it was agreed that ELA should be initiated as soon as the parturient was in established labour or the obstetricians committed her to delivery to ensure the adverse hemodynamic effects of excessive labour pain would be minimized. The slow initiation of ELA did not produce any adverse hemodynamic effects in our patient with hypertrophic cardiomyopathy and subaortic stenosis. Secondly, the slow titration of ELA permitted avoidance of excessively high neuraxial block should the epidural catheter migrate intrathecally. Thirdly, establishing effective ELA resulted in a "proven" epidural catheter which had a high probability of successful conversion to epidural surgical anesthesia should an urgent Cesarean delivery be indicated. Avoidance of general anesthesia and airway manipulation was a priority in this parturient who had a potentially difficult airway.
For completeness, we considered the possibility of utilizing an intrathecal placement of the epidural catheter if epidural needle placement proved technically difficult, and an accidental dural puncture occurred. This approach would have allowed for either a slowly titrated intrathecal labour analgesic or surgical anesthetic. Finally, the benefits of "traditional" ELA far outweighed the risks associated with the CSE technique.
In summary, Noonan syndrome can present with an array of anomalies with challenges for the anesthesiologist. Difficulties may include problems with the airway, cardiac anomalies, musculoskeletal abnormalities, and bleeding diatheses. These anomalies may be further exacerbated by the normal physiologic changes of pregnancy. Careful preoperative assessment will help to prepare the anesthesiologist for potential problems during the anesthetic. This is the first report of successful epidural analgesia for labour culminating with vaginal delivery in a parturient with Noonan syndrome. A multidisciplinary approach involving medical genetics, obstetrics, cardiology, anesthesia and nursing, ensured optimal care and a positive outcome for the parturient and fetus.
|
Footnotes |
|---|
|
References |
|---|
|
TOPAbstractIntroductionCase reportDiscussionReferences |
|---|
2 Grange CS, Heid R, Lucas SB, Ross PL, Douglas MJ. Anaesthesia in a parturient with Noonan’s syndrome. Can J Anaesth 1998; 45: 332–6.
3 McLure HA, Yentis SM. General anaesthesia for cesarean section in a parturient with Noonan’s syndrome. Br J Anaesth 1996; 77: 665–8.
4 Dadabhoy ZP, Winnie AP. Regional anesthesia for cesarean section in a parturient with Noonan’s syndrome. Anesthesiology 1988; 68: 636–8.[Medline]
5 Tartaglia M, Kalidas K, Shaw A, et al. PTPN11 mutations in Noonan syndrome: molecular spectrum, genotype-phenotype correlation, and phenotypic heterogeneity. Am J Hum Genet 2002; 70: 1555–63.[Medline]
6 Campbell DC, Zwack RM, Crone LA, Yip RW. Ambulatory labor epidural analgesia: bupivacaine versus ropivacaine. Anesth Analg 2000; 90: 1384–9.
7 Campbell DC, Breen TW, Halpern S, Muir H, Nunn R. Determination of the efficacy of PCEA alone compared to PCEA + CIEA using ambulatory epidural labor analgesics. Anesthesiology 2004; 101: A1210.
8 Halpern SH, Muir H, Breen TW, et al. A multicenter randomized controlled trial comparing patient-controlled epidural with intravenous analgesia for pain relief in labor. Anesth Analg 2004; 99: 1532–8.
9 Noonan JA, Ehmke DA. Associated noncardiac mal-formations in children with congenital heart disease. J Pediatr 1963; 63: 468–70.
10 Jamieson CR, van der Burgt I, Brady AF, et al. Mapping a gene for Noonan syndrome to the long arm of chromosome 12. Nat Genet 1994; 8: 357–60.[Medline]
11 Noonan JA, Raaijmakers R, Hall BD. Adult height in Noonan syndrome. Am J Med Genet A 2003; 123: 68–71.[Medline]
12 Sharland M, Burch M, McKenna WM, Paton MA. A clinical study of Noonan syndrome. Arch Dis Child 1992; 67: 178–83.[Abstract]
13 Campbell AM, Bousfield JD. Anaesthesia in a patient with Noonan’s syndrome and cardiomyopathy. Anaesthesia 1992; 47: 131–3.[Medline]
14 Bertola DR, Carneiro JD, D’Amico EA, et al. Hematological findings in Noonan syndrome. Rev Hosp Clin Fac Med Sao Paulo 2003; 58: 5–8.[Medline]
15 Ho WL, Wang JK, Li YW. Radiological features of late-onset lymphoedema in Noonan’s syndrome. Pediatr Radiol 2003; 33: 200–2.[Medline]
16 Lee CK, Chang BS, Hong YM, Yang SW, Lee CS, Seo JB. Spinal deformities in Noonan syndrome: a clinical review of sixty cases. J Bone Joint Surg 2001; 83: 1495–502.
17 Campbell DC. Physiological changes of pregnancy. Semin Anesth 2000; 19: 149–56.
18 Loubser P, Kyoung S, Cohen S. Adverse effects of spinal anesthesia in a patient with idiopathic hypertrophic subaortic stenosis. Anesthesiology 1984; 60: 228–30.[Medline]
19 Minnich ME, Quirk JG, Clark RB. Epidural anesthesia for vaginal delivery in a patient with idiopathic hypertrophic subaortic stenosis. Anesthesiology 1987; 67: 590–2.[Medline]
20 Thaman R, Varnava A, Hamid MS, et al. Pregnancy related complications in women with hypertrophic cardiomyopathy. Heart 2003; 89: 752–6.
21 Autore C, Brauneis S, Apponi F, Commisso C, Pinto G, Fedele F. Epidural anesthesia for cesarean section in patients with hypertrophic cardiomyopathy: a report of three cases. Anesthesiology 1990; 90: 1205–7.
22 Ho KM, Ngan Kee WD, Poon MC. Combined spinal and epidural anesthesia in a parturient with idiopathic hypertrophic subaortic stenosis. Anesthesiology 1997; 87: 168–9.[Medline]
23 Katsiris S, Williams S, Leighton BL, Halpern S. Respiratory arrest following intrathecal injection of sufentanil and bupivacaine in a parturient. Can J Anaesth 1998; 45: 880–3.
24 Campbell DC. Combined spinal-epidural analgesia for labor. Reg Anesth Pain Med 1997; 1: 114–7.
25 Greenhalgh CA. Respiratory arrest in a parturient following intrathecal injection of sufentanil and bupivacaine. Anaesthesia 1996; 51: 173–5.[Medline]
26 Pan PH, Bogard TD, Owen MD. Incidence and characteristics of failures in obstetric neuraxial analgesia and anesthesia: a retrospective analysis of 19,259 deliveries. Int J Obstet Anesth 2004; 13: 227–33.[Medline]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
