- Short Communication
- Open Access
Doppler images of intra-pulmonary shunt within atelectasis in anesthetized children
© The Author(s) 2016
- Received: 10 July 2016
- Accepted: 24 November 2016
- Published: 1 December 2016
Doppler images of pulmonary vessels in pulmonary diseases associated with subpleural consolidations have been described. Color Doppler easily identifies such vessels within consolidations while spectral Doppler analysis allows the differentiation between pulmonary and bronchial arteries. Thus, Doppler helps in diagnosing the nature of consolidations. To our knowledge, Doppler analysis of pulmonary vessels within anesthesia-induced atelectasis has never been described before. The aim of this case series is to demonstrate the ability of lung ultrasound to detect the shunting of blood within atelectatic lung areas in anesthetized children.
Three anesthetized and mechanically ventilated children were scanned in the supine position using a high-resolution linear probe of 6–12 MHz. Once subpleural consolidations were detected in the most dependent posterior lung regions, the probe was rotated such that its long axis followed the intercostal space. In this oblique position, color Doppler mapping was performed to detect blood flow within the consolidation. Thereafter, pulsed waved spectral Doppler was applied in the previously identified vessels during a short expiratory pause, which prevented interferences from respiratory motion. Different flow patterns were identified which corresponded to both, pulmonary and bronchial vessels. Finally, a lung recruitment maneuver was performed which leads to the complete resolution of the aforementioned consolidation thereby confirming the pathophysiological entity of anesthesia-induced atelectasis.
Lung ultrasound is a non-invasive imaging tool that not only enables the diagnosis of anesthesia-induced atelectasis in pediatric patients but also analysis of shunting blood within this consolidation.
- Intra-pulmonary shunt
- Lung ultrasound
- Recruitment maneuvers
Anesthesia-induced atelectasis is a well-known entity observed in approximately 68–100% of pediatric patients undergoing general anesthesia [1–4]. The collapse of dependent lung zones starts with anesthesia induction but can persist for hours after surgery. Anesthesia-related atelectasis have a number of negative clinical consequences such as the impairment of arterial blood oxygenation and lung mechanics [5–7] as well as the predisposition for ventilator-associated lung injury caused by tidal recruitment (i.e., the repetitive opening and closing of unstable lung units during mechanical ventilation) and tidal overdistension of the non-atelectatic regions [8–10].
Lung ultrasound (LUS) has demonstrated its high sensitivity and specificity for diagnosing the entity of anesthesia-induced atelectasis in mechanically ventilated patients [11, 12]. LUS can also reveal tidal recruitment occurring mainly at the boundary of atelectatic lung tissue and its complete resolution after an appropriate lung recruitment maneuver .
The use of Doppler for the study of pulmonary vessels within consolidated lung areas has already been reported by several authors [14–16]. Yuan et al.  described the role of Doppler in many pulmonary diseases such as infarction, pneumonia, pulmonary sequestration, abscesses and tumors. The same authors described different flow patterns in pulmonary vessels and proposed that such patterns may be helpful in differentiating malignant tumors from benign consolidations such as pneumonias, abscesses or obstructive atelectasis . Using Doppler, Görg et al.  described the dual arterial supply within different kinds of consolidations. They discriminated pulmonary from bronchial vessels by the pattern of the spectral flow signal.
Even though it has been known that intra-pulmonary shunting is the main reason for the deterioration of gas exchange in anesthesia-induced atelectasis, the visualization of shunting blood usually requires technologies such as PET, SPECT or arteriography. As opposed to these complex diagnostic tools, the examination of pulmonary vessels within consolidated lung areas by Doppler is simple, non-invasive, non-ionizing and perfectly suitable to assess shunt at the bedside [14, 15]. Furthermore, Doppler is capable of differentiating pulmonary from bronchial vessels within a lung consolidation . However, to our knowledge, Doppler has never before been used to visualize the intra-pulmonary shunting of blood within anesthesia-induced atelectasis. Therefore, the aim of this case series is to provide the first evidence of shunt in anesthetized mechanically ventilated children, in whom high-resolution images of atelectasis can easily be obtained using a linear high-frequency probe.
Sonographic diagnosis of anesthesia-induced atelectasis in the operating room and evidence of intra-pulmonary shunt
Three pediatric patients aged two months, one year and four years of age undergoing general anesthesia for abdominal laparoscopic surgery were analyzed. A protective ventilation strategy was applied using volume-controlled ventilation with a tidal volume of 6 ml/kg ideal body weight, a positive end-expiratory pressure (PEEP) of 5 cmH2O, an inspiration/expiration (I:E) ratio of 1:1 and FIO2 of 0.5. Respiratory rate was adjusted to keep end-tidal CO2 between 35 and 40 mm Hg.
Subpleural consolidations were identified as atelectasis when they were associated with the following signs : absence of lung sliding and A-lines, presence of multiple spaced B-lines or coalescent B-lines born in subpleural consolidation, static air bronchograms and the presence of a pulse sign. The finding of tidal recruitment within the consolidation reinforced the diagnosis of atelectasis. Finally, the reversal of the consolidation by the recruitment maneuver confirmed the entity of anesthesia-induced atelectasis .
Atelectasis should be distinguished from other types of consolidation like pneumonia and pulmonary embolism. Pneumonia appears as a consolidation with irregular and somewhat blurred margins, commonly associated with dynamic tree-shaped air bronchograms and pleural effusion. The sonographic signs of pulmonary embolism consist of generally two or more small pleural based, hypoechoic consolidations with sharp margins and without central vascularization. Importantly, these two kinds of consolidations cannot be reverted by a lung recruitment maneuver.
Color Doppler ultrasound detected pulmonary vessels within consolidated lung areas [14–16]. Most vessels showed a radial anatomical configuration (Fig. 2; Additional file 1: Video 1). Later on, pulsed wave spectral Doppler analysis was performed by positioning the sample volume into the center of the lumen of the detected vessel and by placing the ultrasound beam as parallel to the axial flow (≤60°) as possible . To avoid interferences from mechanical ventilation, spectral Doppler analysis was done during an expiratory hold and spectral waveforms of similar shape were sampled from at least five consecutive cardiac cycles.
Finally, we performed a lung recruitment maneuver as previously described [13, 20]. The maneuver consisted of a brief and controlled step-wise increase in airway pressure aiming at re-expanding the atelectasis. The maneuver started from 5 cmH2O of PEEP that was then increased in 5 cmH2O steps until airway opening pressure of 30 cmH20 was reached. At this point, LUS images confirmed the resolution of atelectasis, with the subsequent improvement in lung aeration. Thereafter, a step-wise decrease in PEEP allowed the detection of the minimum level that prevented the reappearance of atelectasis seen in the LUS images. The complete resolution of dependent lung atelectasis by the recruitment maneuver was confirmed 5 min after this maneuver by longitudinal and oblique LUS examination in three regions in each hemithorax, anterior, lateral y posterior; leading to the diagnosis of anesthesia-induced atelectasis  (Fig. 2; Additional file 1: Video 1). The normally aerated lung tissue now reflected the ultrasound beam such that intra-pulmonary vessels were no longer detectable.
Lung ultrasound can easily detect the presence of anesthesia-induced atelectasis and Doppler shunting within them in pediatric patients. Beyond the effects on gas exchange, the clinical impact of this shunting on pulmonary circulation must be analyzed in future studies.
CMA, MC, CE, and GT participated in the acquisition of data in the operating room. CMA, GT, SHB and FSS worked on the interpretation of the findings and in the final edition of the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
The institutional review board approved this publication and the corresponding written informed consent was obtained from the patient’s relatives.
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- Sargent MA, McEachen AM, Jamieson DH, Kahwaji R (1999) Atelectasis on pediatric chest CT: comparison of sedation techniques. Pediatr Radiol 29:509–513View ArticlePubMedGoogle Scholar
- Lutterbey G, Wattjes MP, Doerr D, Fischer NJ, Gieseke J, Schild HH (2007) Atelectasis in children undergoing either propofol infusion or positive pressure ventilation anesthesia for magnetic resonance imaging. Paediatr Anaesth 17:121–125View ArticlePubMedGoogle Scholar
- Serafini G, Cornara G, Cavalloro F, Mori A, Dore R, Marraro G, Braschi A (1999) Pulmonary atelectasis during paediatric anaesthesia: CT scan evaluation and effect of positive end expiratory pressure (PEEP). Paediatr Anaesth 9:225–228PubMedGoogle Scholar
- Tusman G, Böhm SH, Tempra A, Melkun F, Garcia E, Turchetto E, Mulder PG, Lachmann B (2003) Effects of recruitment maneuver on atelectasis in anesthetized children. Anesthesiology 98:14–22View ArticlePubMedGoogle Scholar
- Rothen HU, Sporre B, Engberg G, Wegenius G, Hedenstierna G (1998) Airway closure, atelectasis and gas exchange during general anaesthesia. Br J Anaesth 81:681–686View ArticlePubMedGoogle Scholar
- Gunnarsson L, Tokics L, Gustavsson H, Hedenstierna G (1991) Influence of age on atelectasis formation and gas exchange impairment during general anesthesia. Br J Anaesth 66:423–432View ArticlePubMedGoogle Scholar
- Xue FS, Huang YG, Tong SY, Liu QH, Liao X, An G, Luo LK, Deng XM (1996) A comparative study of early postoperative hypoxemia in infants, children, and adults undergoing elective plastic surgery. Anesth Analg 83:709–715View ArticlePubMedGoogle Scholar
- Steinberg JM, Schiller HJ, Halter JM, Gatto LA, Lee HM, Pavone LA, Nieman GF (2004) Alveolar instability causes early ventilator-induced lung injury independent of neutrophils. Am J Respir Crit Care Med 169:57–63View ArticlePubMedGoogle Scholar
- Pavone LA, Albert S, Carney D, Gatto LA, Halter JM, Nieman GF (2007) Injurious mechanical ventilation in the normal lung causes a progressive pathologic change in dynamic alveolar mechanics. Crit Care 11:R64View ArticlePubMedPubMed CentralGoogle Scholar
- Hauser GJ, Ben-Ari J, Covin MP, Dalton HJ, Hertzog JH, Bear M, Hopkins RA, Walker SM (1998) Interleukin-6 levels in serum and lung lavage fluid of children undergoing open heart surgery correlate with postoperative mortality. Intensive Care Med 24:481–486View ArticlePubMedGoogle Scholar
- Acosta CM, Maidana GA, Jacovitti D, Belaunzarán A, Cereceda S, Rae E, Ananda M, Gonorazky S, Bohm SH, Tusman G (2014) Accuracy of transthoracic lung ultrasound for diagnosing anesthesia-induced atelectasis in children. Anesthesiology 120:1370–1379View ArticlePubMedGoogle Scholar
- Yu X, Zhenping Z, Zhao Y, Zhu Z, Tong J, Yan J, Ouyang W (2016) Performance of lung ultrasound in detecting peri-operative atelectasis after general anesthesia. Ultrasound Med Biol. doi:10.1016/j.ultrasmedbio.2016.06.010 Google Scholar
- Tusman G, Acosta CM, Nicola M, Esperati M, Böhm SH, Suarez-Sipmann F (2015) Real-time images of tidal recruitment using lung ultrasound. Crit Ultrasound J 7:19View ArticlePubMedPubMed CentralGoogle Scholar
- Yuan A, Chang DB, Yu CJ, Kuo SH, Luh KT, Yang PC (1994) Color Doppler sonography of benign and malignant pulmonary masses. AJR 163:5545–5549View ArticleGoogle Scholar
- Yang PC (1996) Color Doppler ultrasound of pulmonary consolidation. Eur J Ultrasound 3:169–178View ArticleGoogle Scholar
- Görg C, Seifart U, Görg K, Zugmaier G (2003) Color Doppler sonographic mapping of pulmonary lesions: evidence of dual arterial supply by spectral analysis. J Ultrasound Med 22(10):1033–1039PubMedGoogle Scholar
- Volpicelli G, Elbarbary M, Blaivas M, Lichtenstein DA, Mathis G, Kirkpatric AW, Melniker L, Gargani L, Noble VE, Via G, Dean A, Tsung JW, Soldati G, Copetti R, Bouhemad B, Reissig A, Agricola E, Rouby JJ, Arbelot C, Liteplo A, Sargsyan A, Silva F, Hoppmann R, Breitkreutz R, Seibel A, Neri L, Storti E, Petrovic T (2012) Conference Reports and Expert Panel: international evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med 38:577–591View ArticlePubMedGoogle Scholar
- Cattarossi L (2013) Lung ultrasound: its role in neonatology and pediatrics. Early Hum Dev 89(Suppl 1):S17–S19View ArticlePubMedGoogle Scholar
- Yuan A, Yang PC, Lee L et al (2000) Reactive pulmonary artery vasoconstriction in pulmonary consolidation by color Doppler ultrasonography. Ultrasound Med Biol 26:49–56View ArticlePubMedGoogle Scholar
- Tusman G, Bohm SH (2010) Prevention and reversal of lung collapse during the intra-operative period. Best Pract Res Clin Anaesthesiol 24:183–197View ArticlePubMedGoogle Scholar
- Mongodi S, Bouhemad B, Iotti GA, Mojoli F (2015) An ultrasonographic sign of intrapulmonary shunt. Intensive Care Med. doi:10.1007/s00134-015-4169-3 PubMedGoogle Scholar
- Yekeler E, Ucar A, Yilmaz R, Cheikahmad I, Sharifov R, Somer A (2011) Predictive value of Doppler ultrasound in childhood pneumonia. J Inter Med Res 39:1536–1540View ArticleGoogle Scholar