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Control of Cardiopulmonary Bypass Flow Rate Using Transfontanellar Ultrasonography and Cerebral Oximetry During Selective Antegrade Cerebral Perfusion
Author's Accepted Manuscript
Control of Cardiopulmonary Bypass Flow Rate using Transfontanellar Ultrasonography and Cerebral Oximetry during Selective Antegrade Cerebral Perfusion Ji-Hyun Lee MD, Se-Hee Min MD, In-Kyung Song MD, Ph.D., Hee-Soo Kim MD, Chong-Sung Kim MD, Ph.D., Jin-Tae Kim MD, Ph.D. www.elsevier.com/locate/buildenv
PII: DOI: Reference:
S1053-0770(15)00132-9 http://dx.doi.org/10.1053/j.jvca.2015.03.006 YJCAN3229
To appear in:
Journal of Cardiothoracic and Vascular Anesthesia
Cite this article as: Ji-Hyun Lee MD, Se-Hee Min MD, In-Kyung Song MD, Ph.D., HeeSoo Kim MD, Chong-Sung Kim MD, Ph.D., Jin-Tae Kim MD, Ph.D., Control of Cardiopulmonary Bypass Flow Rate using Transfontanellar Ultrasonography and Cerebral Oximetry during Selective Antegrade Cerebral Perfusion, Journal of Cardiothoracic and Vascular Anesthesia, http://dx.doi.org/10.1053/j.jvca.2015.03.006 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Title: Control of Cardiopulmonary Bypass Flow Rate using Transfontanellar Ultrasonography and Cerebral Oximetry during Selective Antegrade Cerebral Perfusion Ji-Hyun Lee, MD, Se-Hee Min, MD, In-Kyung Song, MD, Hee-Soo Kim, MD, PhD, Chong-Sung Kim, MD, PhD, Jin-Tae Kim, MD, PhD Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, # 101 Daehakno, Jongnogu, Seoul 110-744, Republic of Korea
E-mail address LJH: [email protected], MSH: [email protected], SIK: [email protected], KHS: [email protected], KCS: [email protected]
Corresponding author Jin-Tae Kim, MD, PhD Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, # 101 Daehakno, Jongnogu, Seoul 110-744, Republic of Korea Tel: 82-2-2072-3592, Fax: 82-2-745-5587 E-mail: [email protected], [email protected]
Key words: neonate, congenital heart defect, selective antegrade cerebral perfusion, transfontanellar ultrasonography, near infrared spectroscopy
Conflict of interest: none
Introduction Neonatal aortic arch reconstruction has been performed under deep hypothermic circulatory arrest (DHCA) because this affords a bloodless surgical field and a long cardiac arrest time 1
by reducing brain metabolism and oxygen demand.1 Despite these advantages, regional cerebral perfusion (RCP) including selective antegrade cerebral perfusion (SACP) is more widely performed than DHCA because this protects the brain from hypoxic ischemic injury by maintaining blood flow to the brain, avoids the complications of DHCA, and minimizes the risk of neurological injury.2, 3 The bypass flow rate during SACP varies among institutions, which was ranged from 20 to 108 ml/kg/min.4-7 However there is no established optimal SACP flow rate for neonates and infants yet. Pediatric patients with congenital heart diseases have impaired cerebral autoregulation and are prone to widespread neurological injury.8, 9 Therefore, delicate adjustment of the bypass flow rate is required during SACP via neurological monitoring. The authors report a case of bypass flow rate adjustment based on cerebral blood flow velocity (CBFV) as measured by transfontanellar ultrasonography (TFU) and regional cerebral oxygen saturation (rSO2) monitored using the near-infrared spectroscopy (NIRS) during SACP for neonatal aortic arch reconstruction. After commencement of SACP with bypass flow rate 50 mL/kg/min, NIRS values significantly increased and CBFV at anterior cerebral arteries were also three-fold higher than baseline values. Because of concern about cerebral hyperperfusion, the authors adjusted the bypass flow rate to 27 mL/kg/min to restore the baseline values of rSO2 and CBFV. As in this case, multimodal neurological monitoring may be useful during congenital heart surgery to prevent potential neurological complications.
2
Case Presentation A 1 month-old premature female infant (47 cm, 3.0 kg) was admitted for repair of coarctation of the aorta. Her gestational age was 35 weeks and the birth weight 1.6 kg. At admission, there was a difference in blood pressure between the upper and lower extremities (102/45 and 60/35 mmHg, respectively). Preoperative cardiac CT revealed a hypoplastic aortic arch with severe narrowing of the proximal descending thoracic aorta, but the brain sonographic findings were normal. Before induction of anesthesia, a pediatric SomaSensor™ probe of INVOS® (Somanetics Corporation, Troy, MI, USA) was attached to each side of the forehead to begin monitoring of bilateral regional cerebral oxygen saturation (rSO2). The baseline left and right rSO2 were 67% and 72%, respectively. After induction of anesthesia, arterial blood pressure monitoring was commenced at the right radial and dorsalis pedis arteries, and central venous catheterization was performed. There was significant difference systolic blood pressure between radial and dorsalis pedis arteries, which was 92 and 44 mmHg, respectively. A 3- to 8-MHz omniplane transesophageal echocardiography probe was inserted (S8-3t, Philips iE33 system; Philips Healthcare, Andover, MA, USA). TFU was performed using a sector probe (S12-3, Philips iE33 system; Philips Healthcare), which is used for transthoracic echocardiography, via the anterior fontanelle. Before surgery was commenced, baseline bilateral CBFVs at anterior cerebral artery (ACA) were measured (Fig. 1, Video 1). Systolic and diastolic CBFV was 58 cm/s and 8 cm/s respectively in both ACA. 3
After aortic and venous cannulae were inserted without any events, CPB was commenced. At the time of initiating CPB, nasopharyngeal and rectal temperature was 34.1℃ and 34.6℃ respectively. The bypass flow rate was maintained at 120-170 mL/kg/min. The rSO2 was maintained at 57-70% in the left frontal area and 62-75% in the right frontal area. Systolic CBFVs at the bilateral ACA were maintained as about 20 cm/s (Fig. 2). Nasopharyngeal and rectal temperature was gradually lowered to 23.5℃ and 25.0℃. After cross-clamping of the aorta, the aortic cannula was further advanced into the right innominate artery, and SACP was commenced at a bypass flow rate of 50 mL/kg/min. The mean blood pressure measured at the right radial artery was 28 mmHg after commencement of SACP. About 15 min later, we noticed that the right rSO2 was greater than 93% whereas the left rSO2 was maintained at about 70%. At that time, TFU revealed a CBFV of 60 cm/s at the proximal part of the both ACAs (Video 2) and the mean blood pressure had decreased to 12 mmHg. Suspecting that the tip of the aortic cannula might have moved toward the right common carotid artery (CCA), we performed a transesophageal echocardiographic examination; however, the flow distributions at the right CCA and subclavian artery were not clearly seen. After notification of possible cannula advancement into the right CCA, the surgeon tried to adjust the cannula position. However, he told that repositioning of the cannula is difficult because the length of innominate artery was only about 5 mm. Based on the patient’s history of preterm birth and because of our concern about cerebral hyperperfusion, we decided to adjust the bypass flow rate to restore the baseline values of rSO2 and CBFV. After careful monitoring of the rSO2 and CBFV, the bypass flow rate decreased to 27 mL/kg/min. As a result, the CBFV at the right ACA decreased to the baseline 4
level of 20 cm/s. The rSO2 became 61 and 78% on the left and right sides, respectively, and did not significantly changed during the remaining SACP time (Fig. 3, Table 1). pH-stat management was used during CPB including the period of SACP, and PaCO2 was maintained at 50-60 mmHg. The total SACP time was 42 min. After Extended end to end coartoplasty, the patient was successfully weaned from CPB with some inotropic support. Ten days after surgery, brain ultrasonography showed normal findings. The patient was discharged on postoperative day 12 without any complications.
Discussion
The incidence of neurological complications after congenital heart surgery in children is reported to be up to 25%.10 The causes of neurological complications are multifactorial. For example, patients with chromosomal abnormalities, such as deletion of chromosome 22, are at higher risk of central nervous system abnormalities with coarctation of aorta.11 Moreover, cerebral autoregulation has been suggested not to be fully developed in neonates12 and cerebral dysgenesis is not rare in neonates with congenital heart disease.13 The management techniques used for such patients, such as arterial blood gas management, the rate or extent of cooling and warming, and control of the bypass flow rate during CPB may affect their neurological outcomes.14, 15 Neonatal complex heart surgery, including aortic arch reconstruction, has been traditionally performed under DHCA. However, concerns about neurological morbidity and mortality16-19 5
has predisposed some clinicians to the use of RCP, which allows for perfusion of the brain and potential minimization of the deleterious effects of DHCA. Monitoring of rSO2 using NIRS technology has become routine during CPB, and its usefulness has been investigated for patients undergoing congenital heart surgery under DHCA and RCP. Kurth et al.20 analyzed the rSO2 values and neurological outcomes of 26 infants and children who had undergone congenital heart surgery with CPB and DHCA. The authors found that three patients with low rSO2 index suffered postoperative neurological complications. Pigula et al.21 found that the NIRS values in pediatric patients under DHCA were significantly lower than those under SACP, concluding that RCP with continuous monitoring of rSO2 could reduce the brain ischemic time. Additionally, the authors controlled the flow rate of SACP via NIRS in an attempt to maintain the baseline rSO2. Although NIRS technology can be a valuable method with which to guide bypass flow rate, rSO2 higher than 95% are not displayed, meaning that NIRS cannot detect the degree of hyperperfusion.22 Another neurological monitoring system, transcranial Doppler (TCD), provides additional information, avoiding cerebral overcirculation.4 TCD can noninvasively measure CBFV, which is a validated means of investigating cerebral blood flow (CBF).23 During moderate to deep hypothermic CPB, cerebral autoregulation is impaired,24 and, if the perfusion pressure is constant, the CBFV is proportional to the total CBF.25 The temporal window is the preferred site for TCD because of the reproducibility, and the middle cerebral artery is usually assessed by placing a Doppler probe at the temporal bone. During cardiac surgery for neonate and infant, however, continuous monitoring of CBFV via a transtemporal approach is sometimes clinically restricted. Instead, the anterior fontanelle 6
can be used as an alternative site for evaluation and monitoring of CBF. Especially in neonates and infants, transfontanellar access is known as the best ultrasonographic approach.26 Morphological data including cerebral ischemia/hemorrhage, hydrocephalus, tumors and the cerebral vasculature have usually been evaluated via TFU in neonates and infants.26 In addition, CBFV of the ICA and ACA can be easily obtained without angle correction because Doppler bean is parallel to the direction of CBF via transfontanellar access. Moreover, TFU enables prompt assessment and appropriate intervention for acute change in rSO2. In pediatric cardiac surgery, we usually perform TFU through the anterior fontanelle using transthoracic echocardiographic probe. As the echocardiographic machine is always placed right next to the patient throughout cardiac surgery, this can be an alternative to TCD in the operating room. In our patient, the CBFVs at the bilateral ACA were similar and maintained 20 cm/s, with constant NIRS values, during full-flow bypass period; however, they increased three-fold at the ACA with high rSO2 values during SACP. The left rSO2 was also higher than the baseline level because of a circulatory connection through the circle of Willis. Eventually, a bypass flow rate of 27 mL/kg/min was required to maintain the baseline levels of the bilateral rSO2 and CBFV. Although RCP has been widely used in congenital heart surgery, the flow rate during SACP has not yet been standardized and varies among patients.4 Concerns about cerebral hyperperfusion upon the use of SACP have been voiced21 because of the potential risk of cerebral edema and intracranial hemorrhage. According to the animal studies, a higher perfusion pressure resulted in complications such as upper torso edema, metabolic acidosis, an unstable recovery period27 and neurologic sequele after CPB28 when compared to a lower 7
perfusion pressure. Although there have been no reports of neurologic complications after neonatal cardiac surgery under RCP, excessive bypass flow rate during CPB may lead cerebral hyperperfusion and be associated with intracranial hemorrhage.29, 30 According to O'Brien et al.,29 about 22% pediatric patients suffered from intracranial hemorrhage (ICH) during ECMO support and all of their CBFV was significantly higher than patients without ICH. In one previous human study,21 authors gradually increased SACP flow rate from 5 mL/kg/min until the cerebral blood volume index was restored to baseline value, which obtained on full-flow bypass period in neonatal arch reconstruction. Consequently, a bypass flow rate of 20 mL/kg/min during SACP was adequate rSO2 were maintained at baseline level without any complication. In contrast, some clinicians prefer high-flow SACP because numerous collateral arteries exist in neonates with complex heart defects. Additionally, high-flow SACP is thought to facilitate somatic circulation via collateral arteries. Miyaji et al. 6 performed high-flow SACP at a flow rate of 43-108 mL/kg/min in 18 pediatric patients who underwent aortic arch reconstruction. It was concluded that the flow rate was optimal, affording adequate somatic oxygenation. Although the cerebral rSO2 during SACP was higher (up to 90%) than the baseline level, no neurologic complication occurred. The same authors compared low-flow (mean, 52 mL/kg/min) and high-flow (mean, 92 mL/kg/min) SACP in neonates undergoing Norwood operation.31 The high-flow SACP group showed better somatic oxygenation and lower lactate levels, without any neurological insult. However, neither of these two studies evaluated CBF which can be obtained via TCD and used chlorpromazine to reduce vascular resistance. It should be remembered that pediatric patients with congenital heart disease are more 8
vulnerable to neurological insults because of impaired cerebral autoregulation,22 potential neurodevelopmental abnormalities,8,
9
and increased intracranial pressure secondary to
damage from CPB.28 During CPB, the CBF may vary depending on whether a vasodilator is used, the number of collateral arteries present, the body temperature, and the blood gas management techniques employed, such as alpha-stat and pH-stat. Therefore, a decision on performance of optimal-flow-rate SACP, which can avoid both cerebral ischemia and hyperperfusion, must be made by monitoring of the CBF and cerebral oxygenation in tandem.4 The varying results of previous studies including our case indicate the importance and effectiveness of multimodal neurological monitoring.32
Conclusion TFU is reproducible and can be performed using echocardiography system during cardiac surgery when patient’s fontanel opens. We performed TFU with NIRS during SACP and controlled bypass flow rate to maintain baseline values of CBFV and rSO2. These combined monitoring may be useful to detect and prevent neurological complications induced by cerebral ischemia or hyperperfusion during congenital heart surgery.
References 1.
Svyatets M, Tolani K, Zhang M, et al.: Perioperative management of deep hypothermic circulatory arrest. J Cardiothorac Vasc Anesth. 24:644-655, 2010.
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Andropoulos DB, Easley RB, Brady K, et al.: Neurodevelopmental outcomes after regional cerebral perfusion with neuromonitoring for neonatal aortic arch 9
reconstruction. Ann Thorac Surg. 95:648-654; discussion 654-645, 2013. 3.
Fraser CD, Jr., Andropoulos DB: Principles of antegrade cerebral perfusion during arch reconstruction in newborns/infants. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu.61-68, 2008.
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Andropoulos DB, Stayer SA, McKenzie ED, et al.: Novel cerebral physiologic monitoring to guide low-flow cerebral perfusion during neonatal aortic arch reconstruction. J Thorac Cardiovasc Surg. 125:491-499, 2003.
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Goldberg CS, Bove EL, Devaney EJ, et al.: A randomized clinical trial of regional cerebral perfusion versus deep hypothermic circulatory arrest: outcomes for infants with functional single ventricle. J Thorac Cardiovasc Surg. 133:880-887, 2007.
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Miyaji K, Miyamoto T, Kohira S, et al.: Regional high-flow cerebral perfusion improves both cerebral and somatic tissue oxygenation in aortic arch repair. Ann Thorac Surg. 90:593-599, 2010.
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Visconti KJ, Rimmer D, Gauvreau K, et al.: Regional low-flow perfusion versus circulatory arrest in neonates: one-year neurodevelopmental outcome. Ann Thorac Surg. 82:2207-2211; discussion 2211-2203, 2006.
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Arduini M, Rosati P, Caforio L, et al.: Cerebral blood flow autoregulation and congenital heart disease: possible causes of abnormal prenatal neurologic development. J Matern Fetal Neonatal Med. 24:1208-1211, 2011.
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McQuillen PS, Miller SP: Congenital heart disease and brain development. Ann N Y Acad Sci. 1184:68-86, 2010.
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Khositseth A, Tocharoentanaphol C, Khowsathit P, et al.: Chromosome 22q11 10
deletions in patients with conotruncal heart defects. Pediatr Cardiol. 26:570-573, 2005. 12.
Verma PK, Panerai RB, Rennie JM, et al.: Grading of cerebral autoregulation in preterm and term neonates. Pediatr Neurol. 23:236-242, 2000.
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Newburger JW, Bellinger DC: Brain injury in congenital heart disease. Circulation. 113:183-185, 2006.
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Snookes SH, Gunn JK, Eldridge BJ, et al.: A systematic review of motor and cognitive outcomes after early surgery for congenital heart disease. Pediatrics. 125:e818-827, 2010.
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Wypij D, Newburger JW, Rappaport LA, et al.: The effect of duration of deep hypothermic circulatory arrest in infant heart surgery on late neurodevelopment: the Boston Circulatory Arrest Trial. J Thorac Cardiovasc Surg. 126:1397-1403, 2003.
16.
Newburger JW, Jonas RA, Wernovsky G, et al.: A comparison of the perioperative neurologic effects of hypothermic circulatory arrest versus low-flow cardiopulmonary bypass in infant heart surgery. N Engl J Med. 329:1057-1064, 1993.
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Hickey PR: Neurologic sequelae associated with deep hypothermic circulatory arrest. Ann Thorac Surg. 65:S65-69; discussion S69-70, S74-66, 1998.
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Clancy RR, McGaurn SA, Wernovsky G, et al.: Preoperative risk-of-death prediction model in heart surgery with deep hypothermic circulatory arrest in the neonate. J Thorac Cardiovasc Surg. 119:347-357, 2000.
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Guo Z, Hu RJ, Zhu DM, et al.: Usefulness of Deep Hypothermic Circulatory Arrest and Regional Cerebral Perfusion in Children. Ther Hypothermia Temp Manag. 3:126131, 2013.
20.
Kurth CD, Steven JM, Nicolson SC: Cerebral oxygenation during pediatric cardiac surgery using deep hypothermic circulatory arrest. Anesthesiology. 82:74-82, 1995. 11
21.
Pigula FA, Nemoto EM, Griffith BP, et al.: Regional low-flow perfusion provides cerebral circulatory support during neonatal aortic arch reconstruction. J Thorac Cardiovasc Surg. 119:331-339, 2000.
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Lee JK, Blaine Easley R, Brady KM: Neurocognitive monitoring and care during pediatric cardiopulmonary bypass-current and future directions. Curr Cardiol Rev. 4:123-139, 2008.
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Bishop CC, Powell S, Rutt D, et al.: Transcranial Doppler measurement of middle cerebral artery blood flow velocity: a validation study. Stroke. 17:913-915, 1986.
24.
Greeley WJ, Kern FH, Ungerleider RM, et al.: The effect of hypothermic cardiopulmonary bypass and total circulatory arrest on cerebral metabolism in neonates, infants, and children. J Thorac Cardiovasc Surg. 101:783-794, 1991.
25.
Polito A, Ricci Z, Di Chiara L, et al.: Cerebral blood flow during cardiopulmonary bypass in pediatric cardiac surgery: the role of transcranial Doppler--a systematic review of the literature. Cardiovasc Ultrasound. 4:47, 2006.
26.
Couture A, Veyrac C, Baud C, et al.: Advanced cranial ultrasound: transfontanellar Doppler imaging in neonates. Eur Radiol. 11:2399-2410, 2001.
27.
DeCampli WM, Schears G, Myung R, et al.: Tissue oxygen tension during regional low-flow perfusion in neonates. J Thorac Cardiovasc Surg. 125:472-480, 2003.
28.
Halstead JC, Meier M, Wurm M, et al.: Optimizing selective cerebral perfusion: deleterious effects of high perfusion pressures. J Thorac Cardiovasc Surg. 135:784791, 2008.
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O'Brien NF, Hall MW: Extracorporeal membrane oxygenation and cerebral blood flow velocity in children. Pediatr Crit Care Med. 14:e126-134, 2013.
30.
van de Bor M, Walther FJ, Gangitano ES, et al.: Extracorporeal membrane 12
oxygenation and cerebral blood flow velocity in newborn infants. Crit Care Med. 18:10-13, 1990. 31.
Miyaji K, Miyamoto T, Kohira S, et al.: The effectiveness of high-flow regional cerebral perfusion in Norwood stage I palliation. Eur J Cardiothorac Surg. 40:12151220, 2011.
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Austin EH, 3rd, Edmonds HL, Jr., Auden SM, et al.: Benefit of neurophysiologic monitoring for pediatric cardiac surgery. J Thorac Cardiovasc Surg. 114:707-715, 717; discussion 715-706, 1997.
Figure and Video Clip Legends
Figure 1. Cerebral blood flow velocity (CBFV) at the left (A) and right (B) anterior cerebral arteries (ACA). Baseline CBFV was determined via pulsed-wave Doppler using a transthoracic echocardiographic sector probe, before cardiopulmonary bypass. The peak CBFV at the left and right ACA were similar (about 55-60 cm/s).
Figure 2. Cerebral blood flow velocity (CBFV) at the left (A) and right (B) anterior cerebral arteries (ACA) after initiation of the cardiopulmonary bypass Bilateral peak CBFVs of ACA were maintained at 20 cm/s before regional cerebral perfusion.
Figure 3. Trend in regional cerebral oxygen saturation (rSO2) during surgery R: right, L: left, ACC: aorta cross-clamp 13
Video 1. Color Doppler image of the bilateral internal carotid arteries (ICAs) and anterior cerebral arteries (ACAs) in the coronal view The Doppler image was obtained via a transfontanellar approach.
Video 2. Cerebral blood flow velocity (CBFV) at the right anterior cerebral artery (ACA) 15 min after commencement of selective antegrade cerebral perfusion (SACP) The CBFV of the ACA was measured in the sagittal plane and attained almost 60cm/s, threefold higher than before SACP.
14
Table 1. Measured parameters at each epoch during surgery Bypass flow rate (mL/kg/mi n)
Blood pressur e* (s/d/m, mmHg)
CBF V at left ACA
CBF V at right ACA
(s/d, cm/s )
(s/d, cm/s )
Cerebral oximetry (left/right, %)
Hemoglobin/Hemat ocrit (g/dL, %)
Nasopharyng eal temperature
PaCO2 (mmH g)
(℃)
Before CPB
.
92/36/5 4
58/8
58/8
67/72
8.5/25
35.5
42
After initiati on of CPB
167
52/38/4 6
20/1 0
20/1 0
57/68
7.1/21
34.1
.
RCP (before control of flow rate)
50
./ ./12
60/1 0
60/1 0
70/93
.
23.5
.
RCP (after control of flow rate)
27
./ ./10
20/0
20/0
61/78
7.3/22
23.5
.
Full flow after RCP
127
32/28/3 0
20/2
20/2
74/72
10.2/30
27.6
61
After weanin g from CPB
.
82/38/5 6
52/0
52/0
62/67
13.3/39
35.1
52
* Blood pressure was measured at the radial artery. Therefore, the blood pressure was very low during RCP when most blood flow from the cannula was directed into the right common carotid artery. CPB: cardiopulmonary bypass, RCP: regional cerebral perfusion, CBFV: cerebral blood flow velocity, ACA: anterior cerebral artery
15
Fig 1
16
Fig 2
17
Fig 3
18
Control of Cardiopulmonary Bypass Flow Rate using Transfontanellar Ultrasonography and Cerebral Oximetry during Selective Antegrade Cerebral Perfusion Ji-Hyun Lee MD, Se-Hee Min MD, In-Kyung Song MD, Ph.D., Hee-Soo Kim MD, Chong-Sung Kim MD, Ph.D., Jin-Tae Kim MD, Ph.D. www.elsevier.com/locate/buildenv
PII: DOI: Reference:
S1053-0770(15)00132-9 http://dx.doi.org/10.1053/j.jvca.2015.03.006 YJCAN3229
To appear in:
Journal of Cardiothoracic and Vascular Anesthesia
Cite this article as: Ji-Hyun Lee MD, Se-Hee Min MD, In-Kyung Song MD, Ph.D., HeeSoo Kim MD, Chong-Sung Kim MD, Ph.D., Jin-Tae Kim MD, Ph.D., Control of Cardiopulmonary Bypass Flow Rate using Transfontanellar Ultrasonography and Cerebral Oximetry during Selective Antegrade Cerebral Perfusion, Journal of Cardiothoracic and Vascular Anesthesia, http://dx.doi.org/10.1053/j.jvca.2015.03.006 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Title: Control of Cardiopulmonary Bypass Flow Rate using Transfontanellar Ultrasonography and Cerebral Oximetry during Selective Antegrade Cerebral Perfusion Ji-Hyun Lee, MD, Se-Hee Min, MD, In-Kyung Song, MD, Hee-Soo Kim, MD, PhD, Chong-Sung Kim, MD, PhD, Jin-Tae Kim, MD, PhD Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, # 101 Daehakno, Jongnogu, Seoul 110-744, Republic of Korea
E-mail address LJH: [email protected], MSH: [email protected], SIK: [email protected], KHS: [email protected], KCS: [email protected]
Corresponding author Jin-Tae Kim, MD, PhD Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, # 101 Daehakno, Jongnogu, Seoul 110-744, Republic of Korea Tel: 82-2-2072-3592, Fax: 82-2-745-5587 E-mail: [email protected], [email protected]
Key words: neonate, congenital heart defect, selective antegrade cerebral perfusion, transfontanellar ultrasonography, near infrared spectroscopy
Conflict of interest: none
Introduction Neonatal aortic arch reconstruction has been performed under deep hypothermic circulatory arrest (DHCA) because this affords a bloodless surgical field and a long cardiac arrest time 1
by reducing brain metabolism and oxygen demand.1 Despite these advantages, regional cerebral perfusion (RCP) including selective antegrade cerebral perfusion (SACP) is more widely performed than DHCA because this protects the brain from hypoxic ischemic injury by maintaining blood flow to the brain, avoids the complications of DHCA, and minimizes the risk of neurological injury.2, 3 The bypass flow rate during SACP varies among institutions, which was ranged from 20 to 108 ml/kg/min.4-7 However there is no established optimal SACP flow rate for neonates and infants yet. Pediatric patients with congenital heart diseases have impaired cerebral autoregulation and are prone to widespread neurological injury.8, 9 Therefore, delicate adjustment of the bypass flow rate is required during SACP via neurological monitoring. The authors report a case of bypass flow rate adjustment based on cerebral blood flow velocity (CBFV) as measured by transfontanellar ultrasonography (TFU) and regional cerebral oxygen saturation (rSO2) monitored using the near-infrared spectroscopy (NIRS) during SACP for neonatal aortic arch reconstruction. After commencement of SACP with bypass flow rate 50 mL/kg/min, NIRS values significantly increased and CBFV at anterior cerebral arteries were also three-fold higher than baseline values. Because of concern about cerebral hyperperfusion, the authors adjusted the bypass flow rate to 27 mL/kg/min to restore the baseline values of rSO2 and CBFV. As in this case, multimodal neurological monitoring may be useful during congenital heart surgery to prevent potential neurological complications.
2
Case Presentation A 1 month-old premature female infant (47 cm, 3.0 kg) was admitted for repair of coarctation of the aorta. Her gestational age was 35 weeks and the birth weight 1.6 kg. At admission, there was a difference in blood pressure between the upper and lower extremities (102/45 and 60/35 mmHg, respectively). Preoperative cardiac CT revealed a hypoplastic aortic arch with severe narrowing of the proximal descending thoracic aorta, but the brain sonographic findings were normal. Before induction of anesthesia, a pediatric SomaSensor™ probe of INVOS® (Somanetics Corporation, Troy, MI, USA) was attached to each side of the forehead to begin monitoring of bilateral regional cerebral oxygen saturation (rSO2). The baseline left and right rSO2 were 67% and 72%, respectively. After induction of anesthesia, arterial blood pressure monitoring was commenced at the right radial and dorsalis pedis arteries, and central venous catheterization was performed. There was significant difference systolic blood pressure between radial and dorsalis pedis arteries, which was 92 and 44 mmHg, respectively. A 3- to 8-MHz omniplane transesophageal echocardiography probe was inserted (S8-3t, Philips iE33 system; Philips Healthcare, Andover, MA, USA). TFU was performed using a sector probe (S12-3, Philips iE33 system; Philips Healthcare), which is used for transthoracic echocardiography, via the anterior fontanelle. Before surgery was commenced, baseline bilateral CBFVs at anterior cerebral artery (ACA) were measured (Fig. 1, Video 1). Systolic and diastolic CBFV was 58 cm/s and 8 cm/s respectively in both ACA. 3
After aortic and venous cannulae were inserted without any events, CPB was commenced. At the time of initiating CPB, nasopharyngeal and rectal temperature was 34.1℃ and 34.6℃ respectively. The bypass flow rate was maintained at 120-170 mL/kg/min. The rSO2 was maintained at 57-70% in the left frontal area and 62-75% in the right frontal area. Systolic CBFVs at the bilateral ACA were maintained as about 20 cm/s (Fig. 2). Nasopharyngeal and rectal temperature was gradually lowered to 23.5℃ and 25.0℃. After cross-clamping of the aorta, the aortic cannula was further advanced into the right innominate artery, and SACP was commenced at a bypass flow rate of 50 mL/kg/min. The mean blood pressure measured at the right radial artery was 28 mmHg after commencement of SACP. About 15 min later, we noticed that the right rSO2 was greater than 93% whereas the left rSO2 was maintained at about 70%. At that time, TFU revealed a CBFV of 60 cm/s at the proximal part of the both ACAs (Video 2) and the mean blood pressure had decreased to 12 mmHg. Suspecting that the tip of the aortic cannula might have moved toward the right common carotid artery (CCA), we performed a transesophageal echocardiographic examination; however, the flow distributions at the right CCA and subclavian artery were not clearly seen. After notification of possible cannula advancement into the right CCA, the surgeon tried to adjust the cannula position. However, he told that repositioning of the cannula is difficult because the length of innominate artery was only about 5 mm. Based on the patient’s history of preterm birth and because of our concern about cerebral hyperperfusion, we decided to adjust the bypass flow rate to restore the baseline values of rSO2 and CBFV. After careful monitoring of the rSO2 and CBFV, the bypass flow rate decreased to 27 mL/kg/min. As a result, the CBFV at the right ACA decreased to the baseline 4
level of 20 cm/s. The rSO2 became 61 and 78% on the left and right sides, respectively, and did not significantly changed during the remaining SACP time (Fig. 3, Table 1). pH-stat management was used during CPB including the period of SACP, and PaCO2 was maintained at 50-60 mmHg. The total SACP time was 42 min. After Extended end to end coartoplasty, the patient was successfully weaned from CPB with some inotropic support. Ten days after surgery, brain ultrasonography showed normal findings. The patient was discharged on postoperative day 12 without any complications.
Discussion
The incidence of neurological complications after congenital heart surgery in children is reported to be up to 25%.10 The causes of neurological complications are multifactorial. For example, patients with chromosomal abnormalities, such as deletion of chromosome 22, are at higher risk of central nervous system abnormalities with coarctation of aorta.11 Moreover, cerebral autoregulation has been suggested not to be fully developed in neonates12 and cerebral dysgenesis is not rare in neonates with congenital heart disease.13 The management techniques used for such patients, such as arterial blood gas management, the rate or extent of cooling and warming, and control of the bypass flow rate during CPB may affect their neurological outcomes.14, 15 Neonatal complex heart surgery, including aortic arch reconstruction, has been traditionally performed under DHCA. However, concerns about neurological morbidity and mortality16-19 5
has predisposed some clinicians to the use of RCP, which allows for perfusion of the brain and potential minimization of the deleterious effects of DHCA. Monitoring of rSO2 using NIRS technology has become routine during CPB, and its usefulness has been investigated for patients undergoing congenital heart surgery under DHCA and RCP. Kurth et al.20 analyzed the rSO2 values and neurological outcomes of 26 infants and children who had undergone congenital heart surgery with CPB and DHCA. The authors found that three patients with low rSO2 index suffered postoperative neurological complications. Pigula et al.21 found that the NIRS values in pediatric patients under DHCA were significantly lower than those under SACP, concluding that RCP with continuous monitoring of rSO2 could reduce the brain ischemic time. Additionally, the authors controlled the flow rate of SACP via NIRS in an attempt to maintain the baseline rSO2. Although NIRS technology can be a valuable method with which to guide bypass flow rate, rSO2 higher than 95% are not displayed, meaning that NIRS cannot detect the degree of hyperperfusion.22 Another neurological monitoring system, transcranial Doppler (TCD), provides additional information, avoiding cerebral overcirculation.4 TCD can noninvasively measure CBFV, which is a validated means of investigating cerebral blood flow (CBF).23 During moderate to deep hypothermic CPB, cerebral autoregulation is impaired,24 and, if the perfusion pressure is constant, the CBFV is proportional to the total CBF.25 The temporal window is the preferred site for TCD because of the reproducibility, and the middle cerebral artery is usually assessed by placing a Doppler probe at the temporal bone. During cardiac surgery for neonate and infant, however, continuous monitoring of CBFV via a transtemporal approach is sometimes clinically restricted. Instead, the anterior fontanelle 6
can be used as an alternative site for evaluation and monitoring of CBF. Especially in neonates and infants, transfontanellar access is known as the best ultrasonographic approach.26 Morphological data including cerebral ischemia/hemorrhage, hydrocephalus, tumors and the cerebral vasculature have usually been evaluated via TFU in neonates and infants.26 In addition, CBFV of the ICA and ACA can be easily obtained without angle correction because Doppler bean is parallel to the direction of CBF via transfontanellar access. Moreover, TFU enables prompt assessment and appropriate intervention for acute change in rSO2. In pediatric cardiac surgery, we usually perform TFU through the anterior fontanelle using transthoracic echocardiographic probe. As the echocardiographic machine is always placed right next to the patient throughout cardiac surgery, this can be an alternative to TCD in the operating room. In our patient, the CBFVs at the bilateral ACA were similar and maintained 20 cm/s, with constant NIRS values, during full-flow bypass period; however, they increased three-fold at the ACA with high rSO2 values during SACP. The left rSO2 was also higher than the baseline level because of a circulatory connection through the circle of Willis. Eventually, a bypass flow rate of 27 mL/kg/min was required to maintain the baseline levels of the bilateral rSO2 and CBFV. Although RCP has been widely used in congenital heart surgery, the flow rate during SACP has not yet been standardized and varies among patients.4 Concerns about cerebral hyperperfusion upon the use of SACP have been voiced21 because of the potential risk of cerebral edema and intracranial hemorrhage. According to the animal studies, a higher perfusion pressure resulted in complications such as upper torso edema, metabolic acidosis, an unstable recovery period27 and neurologic sequele after CPB28 when compared to a lower 7
perfusion pressure. Although there have been no reports of neurologic complications after neonatal cardiac surgery under RCP, excessive bypass flow rate during CPB may lead cerebral hyperperfusion and be associated with intracranial hemorrhage.29, 30 According to O'Brien et al.,29 about 22% pediatric patients suffered from intracranial hemorrhage (ICH) during ECMO support and all of their CBFV was significantly higher than patients without ICH. In one previous human study,21 authors gradually increased SACP flow rate from 5 mL/kg/min until the cerebral blood volume index was restored to baseline value, which obtained on full-flow bypass period in neonatal arch reconstruction. Consequently, a bypass flow rate of 20 mL/kg/min during SACP was adequate rSO2 were maintained at baseline level without any complication. In contrast, some clinicians prefer high-flow SACP because numerous collateral arteries exist in neonates with complex heart defects. Additionally, high-flow SACP is thought to facilitate somatic circulation via collateral arteries. Miyaji et al. 6 performed high-flow SACP at a flow rate of 43-108 mL/kg/min in 18 pediatric patients who underwent aortic arch reconstruction. It was concluded that the flow rate was optimal, affording adequate somatic oxygenation. Although the cerebral rSO2 during SACP was higher (up to 90%) than the baseline level, no neurologic complication occurred. The same authors compared low-flow (mean, 52 mL/kg/min) and high-flow (mean, 92 mL/kg/min) SACP in neonates undergoing Norwood operation.31 The high-flow SACP group showed better somatic oxygenation and lower lactate levels, without any neurological insult. However, neither of these two studies evaluated CBF which can be obtained via TCD and used chlorpromazine to reduce vascular resistance. It should be remembered that pediatric patients with congenital heart disease are more 8
vulnerable to neurological insults because of impaired cerebral autoregulation,22 potential neurodevelopmental abnormalities,8,
9
and increased intracranial pressure secondary to
damage from CPB.28 During CPB, the CBF may vary depending on whether a vasodilator is used, the number of collateral arteries present, the body temperature, and the blood gas management techniques employed, such as alpha-stat and pH-stat. Therefore, a decision on performance of optimal-flow-rate SACP, which can avoid both cerebral ischemia and hyperperfusion, must be made by monitoring of the CBF and cerebral oxygenation in tandem.4 The varying results of previous studies including our case indicate the importance and effectiveness of multimodal neurological monitoring.32
Conclusion TFU is reproducible and can be performed using echocardiography system during cardiac surgery when patient’s fontanel opens. We performed TFU with NIRS during SACP and controlled bypass flow rate to maintain baseline values of CBFV and rSO2. These combined monitoring may be useful to detect and prevent neurological complications induced by cerebral ischemia or hyperperfusion during congenital heart surgery.
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Figure and Video Clip Legends
Figure 1. Cerebral blood flow velocity (CBFV) at the left (A) and right (B) anterior cerebral arteries (ACA). Baseline CBFV was determined via pulsed-wave Doppler using a transthoracic echocardiographic sector probe, before cardiopulmonary bypass. The peak CBFV at the left and right ACA were similar (about 55-60 cm/s).
Figure 2. Cerebral blood flow velocity (CBFV) at the left (A) and right (B) anterior cerebral arteries (ACA) after initiation of the cardiopulmonary bypass Bilateral peak CBFVs of ACA were maintained at 20 cm/s before regional cerebral perfusion.
Figure 3. Trend in regional cerebral oxygen saturation (rSO2) during surgery R: right, L: left, ACC: aorta cross-clamp 13
Video 1. Color Doppler image of the bilateral internal carotid arteries (ICAs) and anterior cerebral arteries (ACAs) in the coronal view The Doppler image was obtained via a transfontanellar approach.
Video 2. Cerebral blood flow velocity (CBFV) at the right anterior cerebral artery (ACA) 15 min after commencement of selective antegrade cerebral perfusion (SACP) The CBFV of the ACA was measured in the sagittal plane and attained almost 60cm/s, threefold higher than before SACP.
14
Table 1. Measured parameters at each epoch during surgery Bypass flow rate (mL/kg/mi n)
Blood pressur e* (s/d/m, mmHg)
CBF V at left ACA
CBF V at right ACA
(s/d, cm/s )
(s/d, cm/s )
Cerebral oximetry (left/right, %)
Hemoglobin/Hemat ocrit (g/dL, %)
Nasopharyng eal temperature
PaCO2 (mmH g)
(℃)
Before CPB
.
92/36/5 4
58/8
58/8
67/72
8.5/25
35.5
42
After initiati on of CPB
167
52/38/4 6
20/1 0
20/1 0
57/68
7.1/21
34.1
.
RCP (before control of flow rate)
50
./ ./12
60/1 0
60/1 0
70/93
.
23.5
.
RCP (after control of flow rate)
27
./ ./10
20/0
20/0
61/78
7.3/22
23.5
.
Full flow after RCP
127
32/28/3 0
20/2
20/2
74/72
10.2/30
27.6
61
After weanin g from CPB
.
82/38/5 6
52/0
52/0
62/67
13.3/39
35.1
52
* Blood pressure was measured at the radial artery. Therefore, the blood pressure was very low during RCP when most blood flow from the cannula was directed into the right common carotid artery. CPB: cardiopulmonary bypass, RCP: regional cerebral perfusion, CBFV: cerebral blood flow velocity, ACA: anterior cerebral artery
15
Fig 1
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Fig 2
17
Fig 3
18