Congenital
Cystic Adenomatoid Malformation of the Lung in Combination a Pulmonary Sequestration B.S. Yogasakaran,
MBBS, FFARCS, and D.A. Sudhaman,
T
HE MOST COMMON presentation of congenital cystic adenomatoid malformation (CCAM) of the lungs is progressive respiratory distress in the newborn period. In its most severe form, perturbations of fetal growth can result in stillborn infants with massive fetal anasarca and polyhydramnios. In other individuals, the disease may not be recognized until later in life when pulmonary infection supervenes.’ The lesion is a developmental malformation of those parts of the lungs that are normally destined to become the terminal and respiratory bronchioles, and alveolar ducts.’ If the bronchial buds and alveolar mesenchyma fail to join at 16 to 20 weeks of gestation, uncontrolled overgrowth of the bronchioles, especially the terminal branches, occurs, and is characteristic of CCAM. The noncommunicating alveolar ducts and air sacs develop from the surrounding mesenchyma, and contribute to the alveolar component of this congenital anomaly. Because the amount of bronchiolar and alveolar components can vary within the mass, the tumors can range from solid masses without cysts to mixed solid and cystic masses within the lungs.3 An earlier impairment in pulmonary development may result in sequestration of the lung. In this condition, a portion of the primitive lung develops separately from the remainder of the lung and receives its blood supply from the aorta.4 There is a high incidence of associated congenital heart disease in these patients. Although both cardiac and pulmonary lesions may be severe, pulmonary hyperinflation or infection is generally the more disruptive situation.” There have been no previous case reports in the anesthesia literature of this rare condition that is of importance to the anesthesiologist and intensivist in the newborn period. Thus, a case is reported of CCAM in association with a sequestered lobe, a combination of two rare entities. CASE
REPORT
An S-week-old infant weighing 3.45 kg was admitted to the Grantham Hospital Paediatric Intensive Care Unit for surgical treatment of his lung condition. Antenatally at 28 weeks’ gestation, ultrasonography showed adenomatous malformation of the left lung. At term, the baby was delivered by cesarean section due to fetal distress. The baby was born with respiratory distress and was immediately managed by tracheal intubation and controlled mechanical ventilation (CMV) using a Bourns Infant Pressure ventilator (model 200D; Bourns, Riverside, CA) at a peak inflation pressure (PIP) of 25 cm HZO, a positive end-expiratory pressure (PEEP) of 5 cm H,O, a respiratory rate of 25 breaths/min, and an
From the Department of Anaesthesia, The Grantham Hospital, Aberdeen, Hong Kong. Address reprint requests to Dr B.S. Yogasakaran, MBBS, FFARCS, The Grantham Hospital, 125, Wong Chuk Hang Rd, Aberdeen, Hong Kong. Copyright 0 1991 by W.B. Saunders Company 1053-0770/91/0504-0012$03.00/0 368
With
MBBS, FFARCS
inspired oxygen fraction of 0.35, to yield the following blood results: pH 7.42, PaCOz 43 mm Hg, PaO, 147 mm Hg, BE 3.5.
gas
showed right ventricular hypertroOn day 26, echocardiography phy and mild pulmonary hypertension. Radiographically. the lesion showed up as an air-tilled mass on the left side displacing the mediastinum to the right causing contralateral atelectasis and “dextrocardia” (Figs 1 and 2). Cardiac catheterization showed a patent ductus arteriosus, and a sequestrated left lobe deriving its blood supply directly from the descending aorta (Fig 3). At 8 weeks, the decision to operate on the lung cyst was made, and the baby was transferred to the intensive care unit (ICU). The baby had been on CMV since birth. On the day of surgery, just prior to transfer to the operating room, the baby was given pancuronium, 0.1 mg/kg, and morphine, 0.1 mg/kg, intravenously (IV), in the ICU. CMV was continued using a Servo 900C ventilator (Siemens, Solna, Sweden) via a 3.5-mm nasotrdcheal tube at the settings mentioned earlier. The baby was positioned in the right lateral decubitus position for a left posterolateral thoracotomy. Anesthesia was maintained using 100% O2 at all times supplemented with 0.5% isoflurane. Fentanyl, 15 kg, and pancuronium, 0.5 mg, IV, were used to provide analgesia and myoneural block, respectively. Intraoperative monitoring included O2 and end-tidal CO, analysis, pulse
oximetry,
intraarterial
blood
pressure,
electrocardio-
gram, and rectal temperature. Blood gas analysis was performed prior to commencement of surgery and every 20 minutes thereafter. Once the chest was opened, high-frequency positive-pressure ventilation (HFPPV) was applied to both lungs to facilitate surgical access by not overdistending the alveoli. A respiratory rate of 60 breaths/min, inspiratoty time of 33%, an expired tidal volume of 20 mL, and PEEP of 5 cm HZ0 were used. At these settings there was a PIP of I6 cm H,O compared with the original PIP of 25 cm H,O. At this time end-tidal COZ measured While surgical resection proceeded,
between 37 and 44 mm Hg. the left lower bronchus was
clamped. Surgery consisted of resection of the left lower lobe due to CCAM and excision of a sequestered lobe lying on the left hemidiaphragm, with its own vascular pedicle. The left lower lobe measured 3 cm x 4 cm x 4 cm and its cut surface showed numerous small cysts 0.5 mm to 1 mm in diameter. The histological appearance consisted of cysts lined by ciliated columnar epithelium and a thin layer of smooth muscle was present in their walls. Mucous cells and striated muscle fibers were absent. The area in between the cysts was occupied by respiratory bronchioles or alveoli-like structures lined by nonciliated cuboidal epithelium. Many cystic spaces were filled with mucous and pus, depicting chronic inflammation and organization. The features were in keeping with a type II CCAM. The sequestrated lobe measured 3 cm x 6 cm x 7 cm in size and had a lobulated contour. The cut surface showed a multicystic appearance, with a rim of normal lung tissue, and its vascular pedicle was from the lower thoracic aorta. Attempts to further reduce the tidal volume failed as there was an immediate increase in end-tidal COZ. Hemodynamically, the baby was stable at a tidal volume of 20 mL and a PIP of I8 cm H,O (Table 1). After a period of 40 minutes on HFPPV with PaCO, measuring 79 mm Hg, HFPPV was abandoned. Manual hand ventilation was performed at an inflation pressure of 30 cm H,O and a respiratory rate of 40 breathsimin to lower the PaCO,. This lasted for about 20 minutes, at which time surgery was completed and CMV was resumed. The baby was returned to the ICU. where CMV was
Journal of Cardiothoracic and Vascular Anesthesia, Vol 5, No 4 (August), 1991: up 368-372
CCAM WITH PULMONARY
SEQUESTRATION
369
Fig 1. Preoperative chest radiograph showing the air-filled mass on the left displacing the mediastinum to the right. The opaque appearance on the right could easily be interpreted as the pathological side.
continued at a PJP of 25 cm H,O and respiratory rate of 40 breathsimin to maintain the PaCO, around 40 mm Hg. The chest x-ray taken postoperatively showed progressive expansion of the hypoplastic collapsed right lung and a shift of the mediastinum to a more central position (Fig 4). The weaning procedure was gradual and the endotracheal tube was removed on the 5th postoperative day. Thereafter, the course of events was
uneventful except for an upper respiratory tract infection. The baby was discharged home 3 weeks later. DISCUSSION
In 1949, Chin and Tang described CCAM of the lung. They described a stillborn infant who had a large cystic
Fig 2. Computad axial tomography scan of the chest showing the mufticystic nature of the left lung.
370
YOGASAKARAN
Fig 3. Lateral film during angiography lobe.
showing the sequestered
mass involving the lower lobe of the left lung.’ Since then there have been many reports of CCAM in the surgical and and radiological literature.‘.“’ The clinical presentation subsequent management of CCAM vary with the age at presentation. Prenatal detection and serial sonographic study of fetuses with CCAM now make it possible to define the natural history of this lesion, determine the pathophysiological features that affect clinical outcome, and formulate management based on prognosis.‘-’ In the neonatal period, the disease presents as respiratory distress and must be considered a relative emergency. Table 1. lntraoperative
AND SUDHAMAN
In its less severe form, it may present in an infant or older child with recurrent chest infections. CCAM occurs in both sexes, and the disease usually involves only a single lobar area. Both right and left lungs are equally involved.” Bilateral involvement of both lungs is very uncommon. No maternal or hereditary factors have been identified in the etiology of this malformation.“’ Although referred to at times as a cystic hamartoma,” the lesion is not composed of the intermixture of epithelium, cartillage, fat, and other tissues that is usually called a hamartoma of the lung. The infant born with CCAM usually shows signs of respiratory distress with tachypnea, subcostal retraction, and cyanosis. X-ray examination typically demonstrates multiple radiolucent areas that appear irregular in size and shape, and may displace the mediastinum to the opposite side with contralateral atelectasis as in this case. Differential diagnosis of this rare condition would include congenital lobar emphysema, diaphragmatic hernia, bronchogenic cyst, staphylococcal pneumonia with pneumatocele formation, tension pneumothorax, and a sequestered lobe. Congenital lobar emphysema is almost exclusively a disease of the upper lobes or the right middle lobe. It appears radiologically as a single radiolucent arca with compression of the lower lobe and a shift of the mediastinum to the opposite side. Respiratory distress is usually marked. The faint lung markings in the hyperlucent region and the histologically normal lung tissue help to differentiate it from CCAM. Pneumatoceles may be distinguished by a history of recent pneumonia and the presence on chest films of single or multiple thin-walled cysts; they are rarely associated with respiratory distress. Radiographically, the abnormality produced can be indistinguishable from a congenital diaphragmatic hernia. This difficult differential diagnosis can be resolved by means of a contrast enema or upper gastrointestinal study to demonstrate the location of the colon or stomach and small intestine in relation to the diaphragm. Tension pneumothorax can be differentiated by the absence of lung markings and the presence of a centrally collapsed lung. Intrapulmonary bronchogenic cyst is histologically similar to CCAM, but is a discrete mass and does not communicate with the tracheobronchial tree.
Monitoring of Pulmonary Gas Exchange Mode of Ventilation
IPPV
HFPPV
HFPPV’
ManualVentilation
IPPVt
100
100
100
100
50
0, saturation (%)
97
97
98
94
96
End-tidal CO, (mm Hgl
43
44
37*
35
38
PaCO, (mm Hg)
44
54
79*
33
45
107
151
207
577
282
40
F,O, W
PaO, (mm Hg) Respiratory rate (breaths/min)
30
60
60
Tidal volume (mL)
35
20
20
Inflation pressure (cm H,O)
25
16
18
30
Abbreviations: IPPV, intermittent positive-pressure ventilation; HFPPV, high-frequency positive-pressure ventilation. *Left lower bronchus clamped. tlPPV recommenced at the end of surgery. *During HFPPV there was an increase in PaCO,; end-tidal CO, was in the normal range.
40 40 25
CCAM WITH PULMONARY SEQUESTRATION
Fig 4I. Pos toperative chest radiiograph st lowing the pattirlly expanded collaosad hypopl and a shift of the mcrdiastl inum to a mcbre central In.
The association of CCAM with the systemic arterial blood supply has been reported previously.” CCAM is occasionally found within or in association with sequestration. There has also been a case with a left congenital diaphragmatic hernia and severely hypoplastic left lung, plus the entire right lung was affected by CCAM.’ A sequestered lobe lacks communication with the tracheobronchial tree and consists of a mass of nonfunctioning pulmonary tissue, receiving its own blood supply from the aorta.4 Two forms are described, intralobar and extralobar, depending on whether the accessory lung tissue is contained within the substance of a lobe or is located outside it.‘* Sequestration usually involves a lower lobe of the lung, with the left side involved more frequently than the right. In the case reported by Hutchin et al,” in spite of the systemic arterial blood supply and the absence of a clearly demonstrable bronchial communication with the intrapulmonary cyst, the diagnosis of intralobar sequestration was excluded on the basis of the clinical history and atypical location in the right lower lobe; a diagnosis of CCAM was made. However, in the present case there was a left lower lobe with definite CCAM changes plus a sequestered lobe, sitting on the left hemidiaphragm, with its own vascular pedicle from the descending aorta. Stocker et al” defined three types of CCAM (types I to III) based primarily on cyst size, whereas other authors have separated CCAM into two groups based on the predominant component of the lesion (cystic or solid).‘4 The cyst walls can have excessive elastic tissue and smooth muscle,” and are lined by full columnar mucous epithelium.
HFPPV was attempted intraoperatively to minimize the movement of the operative field.” The lower PIPS and tidal volumes to the nondependent lung give a relatively quiet operative field. HFPPV of the dependent lung could have also contributed to this effect by providing a still mediastinum. The feasibility of using HFPPV to facilitate thoracic operations has been well documented.“.” HFPPV with PEEP improved oxygenation in this case, but the increase in PaCO, was a result of hypoventilation, an increase in alveolar deadspace,17 or a consequence of clamping the left lower bronchus. The multicystic nature of the lung disease may have caused uneven distribution of inspired gas and delayed emptying of some units at a higher respiratory rate. Retraction of the left upper lobe during surgery created a right-to-left shunt and contributed to the increased alveolar deadspace. The hypoplastic left upper lobe would have been overventilated in the lateral position when the nondependent left lung received approximately 35% of total blood flow as opposed to 45% in the upright or supine positions. Another cause of decreased CO, elimination at higher frequencies of ventilation has been attributed to expiratory gas trapping, which increases physiological deadspace.” Manual ventilation helped to reduce the PaCO, by the increased inflation pressure and the PEEP applied during hand ventilation. In effect, this would have shifted the dependent lung units from the flat portion of the pressure volume curve to the vertical portion, providing better ventilation than during HFPPV. Therefore, HFPPV cannot
372
YOGASAKARANANDSUDHAMAN
recommended in preference to CMV or hand ventilation in this situation. The PaCOz did not correlate with end-tidal CO2 in this case, which emphasizes the fact that monitoring end-tidal CO, alone is not sufficient when ventilating pathologically diseased lungs.” When the diagnosis of CCAM is made, urgent lung resection is needed for the survival of the patient. Because be
as a rule the disease is limited to one lobe and the remainder of the lung is normal, lobcctomy should be performed in most cases. A lesser proccdurc is likely to result in recurrent symptoms and may necessitate reoperation.* The case reported here was successfully treated with left lower lobectomy and excision of a sequestered lobe while using either CMV or manual ventilation.
REFERENCES 1. Luck SR, Reynolds M, Raffensperger JG: Congenital bronchopulmonaly malformations. Curr Prob Surg 23:246-314, 1986 2. Kwittken J, Reiner L: Congenital cystic adenomatoid lung. Paediatrics 30:759, 1962 3. Benumof JL: Anesthesia for pediatric thoracic surgery, in Benumof JL: Anesthesia for Thoracic Surgery. Philadelphia, PA, Saunders, 1988, pp 421-424 4. Durnin RE, Lababidi Z, Butler C, et al: Bronchopulmonary sequestration. Chest 57:454-459, 1970 5. Martin JT: Case history number 93: Congenital lobar emphysema. Anesth Analg 55:869-873, 1976 6. Moncrieff MW, Carmeron AH, Astley R, et al: Congenital cystic adenomatoid malformation of the lung. Thorax 24:476-4X7, 1969 7. Golbus MS, Anderson RL: Fetal cystic adenomatoid malformation: Prenatal diagnosis and natural history. J Pediatr Surg 20:483-488, 1985 H. Nishibayashi SW, Andrassy RJ, Woolley MM: Congenital cystic adenomatoid malformation: A 30-year experience. J Pediatr Surg 16:704-706, 1981 9. Hartenberg MA, Brewer WH: Cystic adenomatoid malformation of the lung: Identification by sonography. Am J Radio1 140:693-694, 1983 IO. Hutchin P, Friedman PJ, Saltzstein SL: Congenital cystic
adenomatoid malformation with anomalous Cardiovasc Surg 62:220-225. 1971 1 I. Thomas MR: A cystic hamartoma infant. J Pathol Bact 61:599, 1949
blood supply. J Thorac of the lung in a newborn
12. Panedes CG, Pierce WS, Johnson DC, Waldhausen JA: Pulmonary sequestration in infants and children: 20-year experience and review of the literature. J Pediatr Surg 5:136-144, 1970 13. Stocker TJ, Madewell JE, Drake RM: Congenital cystic adenomatoid malformation of the lung: Classification and morphologic spectrum. Hum Pathol8:155-171, 1977 14. Bale PM: Congenital cystic adenomatoid the lung. Am J Clin Pathol71:411-420, 1979
malformation
of
15. Glenshi JA, Crawford M: High frequency, small volume ventilation during thoracic surgery. Anesthesiology 64:211-214, 1986 16. Seki S, Fukshima Y, Goto K, et al: Facilitation of intrathoracic operations by means of high frequency ventilation. J Thorac Cardiovasc Surg 86:388-392, 1983 17. Fletcher R: Arterial-end tidal CO, difference diothoracic surgery. J Cardiothorac Anesth 4:105-117,
during 1990
car-
1X. Chakrabarti MK, Sykes MK: Cardiorespiratory effects of high frequency intermittent positive pressure ventilation in the dog. Br J Anaesth 52:475-4X2, I980
Cystic Adenomatoid Malformation of the Lung in Combination a Pulmonary Sequestration B.S. Yogasakaran,
MBBS, FFARCS, and D.A. Sudhaman,
T
HE MOST COMMON presentation of congenital cystic adenomatoid malformation (CCAM) of the lungs is progressive respiratory distress in the newborn period. In its most severe form, perturbations of fetal growth can result in stillborn infants with massive fetal anasarca and polyhydramnios. In other individuals, the disease may not be recognized until later in life when pulmonary infection supervenes.’ The lesion is a developmental malformation of those parts of the lungs that are normally destined to become the terminal and respiratory bronchioles, and alveolar ducts.’ If the bronchial buds and alveolar mesenchyma fail to join at 16 to 20 weeks of gestation, uncontrolled overgrowth of the bronchioles, especially the terminal branches, occurs, and is characteristic of CCAM. The noncommunicating alveolar ducts and air sacs develop from the surrounding mesenchyma, and contribute to the alveolar component of this congenital anomaly. Because the amount of bronchiolar and alveolar components can vary within the mass, the tumors can range from solid masses without cysts to mixed solid and cystic masses within the lungs.3 An earlier impairment in pulmonary development may result in sequestration of the lung. In this condition, a portion of the primitive lung develops separately from the remainder of the lung and receives its blood supply from the aorta.4 There is a high incidence of associated congenital heart disease in these patients. Although both cardiac and pulmonary lesions may be severe, pulmonary hyperinflation or infection is generally the more disruptive situation.” There have been no previous case reports in the anesthesia literature of this rare condition that is of importance to the anesthesiologist and intensivist in the newborn period. Thus, a case is reported of CCAM in association with a sequestered lobe, a combination of two rare entities. CASE
REPORT
An S-week-old infant weighing 3.45 kg was admitted to the Grantham Hospital Paediatric Intensive Care Unit for surgical treatment of his lung condition. Antenatally at 28 weeks’ gestation, ultrasonography showed adenomatous malformation of the left lung. At term, the baby was delivered by cesarean section due to fetal distress. The baby was born with respiratory distress and was immediately managed by tracheal intubation and controlled mechanical ventilation (CMV) using a Bourns Infant Pressure ventilator (model 200D; Bourns, Riverside, CA) at a peak inflation pressure (PIP) of 25 cm HZO, a positive end-expiratory pressure (PEEP) of 5 cm H,O, a respiratory rate of 25 breaths/min, and an
From the Department of Anaesthesia, The Grantham Hospital, Aberdeen, Hong Kong. Address reprint requests to Dr B.S. Yogasakaran, MBBS, FFARCS, The Grantham Hospital, 125, Wong Chuk Hang Rd, Aberdeen, Hong Kong. Copyright 0 1991 by W.B. Saunders Company 1053-0770/91/0504-0012$03.00/0 368
With
MBBS, FFARCS
inspired oxygen fraction of 0.35, to yield the following blood results: pH 7.42, PaCOz 43 mm Hg, PaO, 147 mm Hg, BE 3.5.
gas
showed right ventricular hypertroOn day 26, echocardiography phy and mild pulmonary hypertension. Radiographically. the lesion showed up as an air-tilled mass on the left side displacing the mediastinum to the right causing contralateral atelectasis and “dextrocardia” (Figs 1 and 2). Cardiac catheterization showed a patent ductus arteriosus, and a sequestrated left lobe deriving its blood supply directly from the descending aorta (Fig 3). At 8 weeks, the decision to operate on the lung cyst was made, and the baby was transferred to the intensive care unit (ICU). The baby had been on CMV since birth. On the day of surgery, just prior to transfer to the operating room, the baby was given pancuronium, 0.1 mg/kg, and morphine, 0.1 mg/kg, intravenously (IV), in the ICU. CMV was continued using a Servo 900C ventilator (Siemens, Solna, Sweden) via a 3.5-mm nasotrdcheal tube at the settings mentioned earlier. The baby was positioned in the right lateral decubitus position for a left posterolateral thoracotomy. Anesthesia was maintained using 100% O2 at all times supplemented with 0.5% isoflurane. Fentanyl, 15 kg, and pancuronium, 0.5 mg, IV, were used to provide analgesia and myoneural block, respectively. Intraoperative monitoring included O2 and end-tidal CO, analysis, pulse
oximetry,
intraarterial
blood
pressure,
electrocardio-
gram, and rectal temperature. Blood gas analysis was performed prior to commencement of surgery and every 20 minutes thereafter. Once the chest was opened, high-frequency positive-pressure ventilation (HFPPV) was applied to both lungs to facilitate surgical access by not overdistending the alveoli. A respiratory rate of 60 breaths/min, inspiratoty time of 33%, an expired tidal volume of 20 mL, and PEEP of 5 cm HZ0 were used. At these settings there was a PIP of I6 cm H,O compared with the original PIP of 25 cm H,O. At this time end-tidal COZ measured While surgical resection proceeded,
between 37 and 44 mm Hg. the left lower bronchus was
clamped. Surgery consisted of resection of the left lower lobe due to CCAM and excision of a sequestered lobe lying on the left hemidiaphragm, with its own vascular pedicle. The left lower lobe measured 3 cm x 4 cm x 4 cm and its cut surface showed numerous small cysts 0.5 mm to 1 mm in diameter. The histological appearance consisted of cysts lined by ciliated columnar epithelium and a thin layer of smooth muscle was present in their walls. Mucous cells and striated muscle fibers were absent. The area in between the cysts was occupied by respiratory bronchioles or alveoli-like structures lined by nonciliated cuboidal epithelium. Many cystic spaces were filled with mucous and pus, depicting chronic inflammation and organization. The features were in keeping with a type II CCAM. The sequestrated lobe measured 3 cm x 6 cm x 7 cm in size and had a lobulated contour. The cut surface showed a multicystic appearance, with a rim of normal lung tissue, and its vascular pedicle was from the lower thoracic aorta. Attempts to further reduce the tidal volume failed as there was an immediate increase in end-tidal COZ. Hemodynamically, the baby was stable at a tidal volume of 20 mL and a PIP of I8 cm H,O (Table 1). After a period of 40 minutes on HFPPV with PaCO, measuring 79 mm Hg, HFPPV was abandoned. Manual hand ventilation was performed at an inflation pressure of 30 cm H,O and a respiratory rate of 40 breathsimin to lower the PaCO,. This lasted for about 20 minutes, at which time surgery was completed and CMV was resumed. The baby was returned to the ICU. where CMV was
Journal of Cardiothoracic and Vascular Anesthesia, Vol 5, No 4 (August), 1991: up 368-372
CCAM WITH PULMONARY
SEQUESTRATION
369
Fig 1. Preoperative chest radiograph showing the air-filled mass on the left displacing the mediastinum to the right. The opaque appearance on the right could easily be interpreted as the pathological side.
continued at a PJP of 25 cm H,O and respiratory rate of 40 breathsimin to maintain the PaCO, around 40 mm Hg. The chest x-ray taken postoperatively showed progressive expansion of the hypoplastic collapsed right lung and a shift of the mediastinum to a more central position (Fig 4). The weaning procedure was gradual and the endotracheal tube was removed on the 5th postoperative day. Thereafter, the course of events was
uneventful except for an upper respiratory tract infection. The baby was discharged home 3 weeks later. DISCUSSION
In 1949, Chin and Tang described CCAM of the lung. They described a stillborn infant who had a large cystic
Fig 2. Computad axial tomography scan of the chest showing the mufticystic nature of the left lung.
370
YOGASAKARAN
Fig 3. Lateral film during angiography lobe.
showing the sequestered
mass involving the lower lobe of the left lung.’ Since then there have been many reports of CCAM in the surgical and and radiological literature.‘.“’ The clinical presentation subsequent management of CCAM vary with the age at presentation. Prenatal detection and serial sonographic study of fetuses with CCAM now make it possible to define the natural history of this lesion, determine the pathophysiological features that affect clinical outcome, and formulate management based on prognosis.‘-’ In the neonatal period, the disease presents as respiratory distress and must be considered a relative emergency. Table 1. lntraoperative
AND SUDHAMAN
In its less severe form, it may present in an infant or older child with recurrent chest infections. CCAM occurs in both sexes, and the disease usually involves only a single lobar area. Both right and left lungs are equally involved.” Bilateral involvement of both lungs is very uncommon. No maternal or hereditary factors have been identified in the etiology of this malformation.“’ Although referred to at times as a cystic hamartoma,” the lesion is not composed of the intermixture of epithelium, cartillage, fat, and other tissues that is usually called a hamartoma of the lung. The infant born with CCAM usually shows signs of respiratory distress with tachypnea, subcostal retraction, and cyanosis. X-ray examination typically demonstrates multiple radiolucent areas that appear irregular in size and shape, and may displace the mediastinum to the opposite side with contralateral atelectasis as in this case. Differential diagnosis of this rare condition would include congenital lobar emphysema, diaphragmatic hernia, bronchogenic cyst, staphylococcal pneumonia with pneumatocele formation, tension pneumothorax, and a sequestered lobe. Congenital lobar emphysema is almost exclusively a disease of the upper lobes or the right middle lobe. It appears radiologically as a single radiolucent arca with compression of the lower lobe and a shift of the mediastinum to the opposite side. Respiratory distress is usually marked. The faint lung markings in the hyperlucent region and the histologically normal lung tissue help to differentiate it from CCAM. Pneumatoceles may be distinguished by a history of recent pneumonia and the presence on chest films of single or multiple thin-walled cysts; they are rarely associated with respiratory distress. Radiographically, the abnormality produced can be indistinguishable from a congenital diaphragmatic hernia. This difficult differential diagnosis can be resolved by means of a contrast enema or upper gastrointestinal study to demonstrate the location of the colon or stomach and small intestine in relation to the diaphragm. Tension pneumothorax can be differentiated by the absence of lung markings and the presence of a centrally collapsed lung. Intrapulmonary bronchogenic cyst is histologically similar to CCAM, but is a discrete mass and does not communicate with the tracheobronchial tree.
Monitoring of Pulmonary Gas Exchange Mode of Ventilation
IPPV
HFPPV
HFPPV’
ManualVentilation
IPPVt
100
100
100
100
50
0, saturation (%)
97
97
98
94
96
End-tidal CO, (mm Hgl
43
44
37*
35
38
PaCO, (mm Hg)
44
54
79*
33
45
107
151
207
577
282
40
F,O, W
PaO, (mm Hg) Respiratory rate (breaths/min)
30
60
60
Tidal volume (mL)
35
20
20
Inflation pressure (cm H,O)
25
16
18
30
Abbreviations: IPPV, intermittent positive-pressure ventilation; HFPPV, high-frequency positive-pressure ventilation. *Left lower bronchus clamped. tlPPV recommenced at the end of surgery. *During HFPPV there was an increase in PaCO,; end-tidal CO, was in the normal range.
40 40 25
CCAM WITH PULMONARY SEQUESTRATION
Fig 4I. Pos toperative chest radiiograph st lowing the pattirlly expanded collaosad hypopl and a shift of the mcrdiastl inum to a mcbre central In.
The association of CCAM with the systemic arterial blood supply has been reported previously.” CCAM is occasionally found within or in association with sequestration. There has also been a case with a left congenital diaphragmatic hernia and severely hypoplastic left lung, plus the entire right lung was affected by CCAM.’ A sequestered lobe lacks communication with the tracheobronchial tree and consists of a mass of nonfunctioning pulmonary tissue, receiving its own blood supply from the aorta.4 Two forms are described, intralobar and extralobar, depending on whether the accessory lung tissue is contained within the substance of a lobe or is located outside it.‘* Sequestration usually involves a lower lobe of the lung, with the left side involved more frequently than the right. In the case reported by Hutchin et al,” in spite of the systemic arterial blood supply and the absence of a clearly demonstrable bronchial communication with the intrapulmonary cyst, the diagnosis of intralobar sequestration was excluded on the basis of the clinical history and atypical location in the right lower lobe; a diagnosis of CCAM was made. However, in the present case there was a left lower lobe with definite CCAM changes plus a sequestered lobe, sitting on the left hemidiaphragm, with its own vascular pedicle from the descending aorta. Stocker et al” defined three types of CCAM (types I to III) based primarily on cyst size, whereas other authors have separated CCAM into two groups based on the predominant component of the lesion (cystic or solid).‘4 The cyst walls can have excessive elastic tissue and smooth muscle,” and are lined by full columnar mucous epithelium.
HFPPV was attempted intraoperatively to minimize the movement of the operative field.” The lower PIPS and tidal volumes to the nondependent lung give a relatively quiet operative field. HFPPV of the dependent lung could have also contributed to this effect by providing a still mediastinum. The feasibility of using HFPPV to facilitate thoracic operations has been well documented.“.” HFPPV with PEEP improved oxygenation in this case, but the increase in PaCO, was a result of hypoventilation, an increase in alveolar deadspace,17 or a consequence of clamping the left lower bronchus. The multicystic nature of the lung disease may have caused uneven distribution of inspired gas and delayed emptying of some units at a higher respiratory rate. Retraction of the left upper lobe during surgery created a right-to-left shunt and contributed to the increased alveolar deadspace. The hypoplastic left upper lobe would have been overventilated in the lateral position when the nondependent left lung received approximately 35% of total blood flow as opposed to 45% in the upright or supine positions. Another cause of decreased CO, elimination at higher frequencies of ventilation has been attributed to expiratory gas trapping, which increases physiological deadspace.” Manual ventilation helped to reduce the PaCO, by the increased inflation pressure and the PEEP applied during hand ventilation. In effect, this would have shifted the dependent lung units from the flat portion of the pressure volume curve to the vertical portion, providing better ventilation than during HFPPV. Therefore, HFPPV cannot
372
YOGASAKARANANDSUDHAMAN
recommended in preference to CMV or hand ventilation in this situation. The PaCOz did not correlate with end-tidal CO2 in this case, which emphasizes the fact that monitoring end-tidal CO, alone is not sufficient when ventilating pathologically diseased lungs.” When the diagnosis of CCAM is made, urgent lung resection is needed for the survival of the patient. Because be
as a rule the disease is limited to one lobe and the remainder of the lung is normal, lobcctomy should be performed in most cases. A lesser proccdurc is likely to result in recurrent symptoms and may necessitate reoperation.* The case reported here was successfully treated with left lower lobectomy and excision of a sequestered lobe while using either CMV or manual ventilation.
REFERENCES 1. Luck SR, Reynolds M, Raffensperger JG: Congenital bronchopulmonaly malformations. Curr Prob Surg 23:246-314, 1986 2. Kwittken J, Reiner L: Congenital cystic adenomatoid lung. Paediatrics 30:759, 1962 3. Benumof JL: Anesthesia for pediatric thoracic surgery, in Benumof JL: Anesthesia for Thoracic Surgery. Philadelphia, PA, Saunders, 1988, pp 421-424 4. Durnin RE, Lababidi Z, Butler C, et al: Bronchopulmonary sequestration. Chest 57:454-459, 1970 5. Martin JT: Case history number 93: Congenital lobar emphysema. Anesth Analg 55:869-873, 1976 6. Moncrieff MW, Carmeron AH, Astley R, et al: Congenital cystic adenomatoid malformation of the lung. Thorax 24:476-4X7, 1969 7. Golbus MS, Anderson RL: Fetal cystic adenomatoid malformation: Prenatal diagnosis and natural history. J Pediatr Surg 20:483-488, 1985 H. Nishibayashi SW, Andrassy RJ, Woolley MM: Congenital cystic adenomatoid malformation: A 30-year experience. J Pediatr Surg 16:704-706, 1981 9. Hartenberg MA, Brewer WH: Cystic adenomatoid malformation of the lung: Identification by sonography. Am J Radio1 140:693-694, 1983 IO. Hutchin P, Friedman PJ, Saltzstein SL: Congenital cystic
adenomatoid malformation with anomalous Cardiovasc Surg 62:220-225. 1971 1 I. Thomas MR: A cystic hamartoma infant. J Pathol Bact 61:599, 1949
blood supply. J Thorac of the lung in a newborn
12. Panedes CG, Pierce WS, Johnson DC, Waldhausen JA: Pulmonary sequestration in infants and children: 20-year experience and review of the literature. J Pediatr Surg 5:136-144, 1970 13. Stocker TJ, Madewell JE, Drake RM: Congenital cystic adenomatoid malformation of the lung: Classification and morphologic spectrum. Hum Pathol8:155-171, 1977 14. Bale PM: Congenital cystic adenomatoid the lung. Am J Clin Pathol71:411-420, 1979
malformation
of
15. Glenshi JA, Crawford M: High frequency, small volume ventilation during thoracic surgery. Anesthesiology 64:211-214, 1986 16. Seki S, Fukshima Y, Goto K, et al: Facilitation of intrathoracic operations by means of high frequency ventilation. J Thorac Cardiovasc Surg 86:388-392, 1983 17. Fletcher R: Arterial-end tidal CO, difference diothoracic surgery. J Cardiothorac Anesth 4:105-117,
during 1990
car-
1X. Chakrabarti MK, Sykes MK: Cardiorespiratory effects of high frequency intermittent positive pressure ventilation in the dog. Br J Anaesth 52:475-4X2, I980
