| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Guest Access | Sign In via User Name/Password
|
|
|
|||||||
Guest Access | Sign In via User Name/Password |
|||||||||
* From the Sections of Pediatric Pulmonology (Drs. Bandla, Beckerman, and Gozal) and Critical Care (Dr. Hopkins), Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA.
Correspondence to: David Gozal, MD, FCCP, Section of Pediatric Pulmonology, Department of Pediatrics, Tulane University School of Medicine, SL-37, 1430 Tulane Ave, New Orleans, LA 70112; e-mail: dgozal{at}tmcpop.tmc.tulane.edu
 |
Abstract |
|---|
 TOP Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
2 years)
undergoing surgical repair for congenital heart disease (CHD). Design: Retrospective case series analysis.
Setting: Tertiary-care facility.
Patients:
Clinical records of 134 consecutive patients aged 2 years
undergoing cardiac surgery for CHD were reviewed, and 37 were excluded
according to inclusion criteria. Thus, 97 patients were allocated to
two groups based on the duration of ICU stay: 7 days (group 1,
n = 57), and > 7 days (group 2, n = 40).
Results: Mean ICU duration for groups 1 and 2 was 3.0 ± 0.4 days and 28.1 ± 4.4 days, respectively (p < 0.001). In group 1, there were three extubation failures, whereas 41 extubation failures occurred in group 2 (p < 0.0001). A total of 22 patients (4 in group 1 and 18 in group 2) developed noninfectious pulmonary complications, such as airway problems, including extrinsic airway compression and tracheobronchomalacia (n = 6); pulmonary hypertension (n = 5); phrenic nerve palsy (n = 7); and pleural effusion (n = 8). These 22 patients (23%) contributed to the majority of total ventilator days (67%) as well as ICU stay (61%).
Conclusions: Pulmonary complications in general, and central airway problems in particular, are a frequent cause for delayed recovery following cardiac surgery in young children.
Key Words: cardiac surgery • congenital heart disease • flexible bronchoscopy • intensive care • mechanical ventilation • phrenic nerve palsy • respiratory morbidity • tracheobronchomalacia
|
Introduction |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
One of the major factors contributing to the high cost associated with surgical interventions in complex CHD is the duration of stay in the ICU. Indeed, studies examining the impact of ICU stay have shown that ICU utilization accounts for about 20% of total hospital costs.1 Thus, it is not surprising that with reforms in health care, early and more aggressive extubation after cardiac surgical procedures in children and neonates has been attempted and, in fact, shown to be both safe and feasible by several investigators.2 3 4 5 In an effort to identify risk factors associated with prolonged mechanical ventilation (MV), Kanter and colleagues6 retrospectively reviewed a cohort of 140 patients, aged < 2 years, who underwent surgical cardiac repair. The need for preoperative MV, longer cardiopulmonary bypass (CPB) and aortic cross-clamp durations, and additional surgical interventions were all identified as independent variables associated with prolonged MV and ICU stay. More recently, preoperative measurements of pulmonary vasculature physiologic variables, such as systemic and pulmonary resistance, were highly correlated with the duration of MV in patients undergoing repair of ventricular septal defects (VSDs).5 However, there is a paucity of information regarding the relative contribution of respiratory tract pathology to the need for prolonged MV and ICU stay in these patients. While postoperative diaphragmatic dysfunction is a well-recognized complication contributing to prolonged MV,7 acquired or congenital tracheobronchomalacia with significant airway obstruction complicating the postoperative period has only been reported in case report format in patients undergoing repair for CHD.8
We therefore undertook a critical 1-year retrospective review of all young patients undergoing cardiac surgery at our institution, and attempted to identify specific pulmonary risk factors that may underlie increases in the duration of MV and ICU length of stay in this patient population.
|
Materials and Methods |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
24
months, who underwent palliative or corrective surgery for CHD at
Tulane University Medical Center during the 1-year period from August
1995 to July 1996 were retrospectively reviewed. Premature infants and
infants with preexisting lung disease or with other major congenital
anomalies were excluded (n = 13). Twenty-four patients died within
48 h after surgery (immediate mortality) and were also excluded.
Therefore, the study population included a total of 97 infants. The
cardiac diagnoses were established by echocardiography, cardiac
catheterization, and/or cineangiography. The following variables were
recorded: demographics; cardiac diagnosis; surgical procedure;
intraoperative information, namely total duration of surgery, CPB time,
and aortic cross-clamp time; and duration of postoperative MV. Patients
were allocated to two groups based on the duration of ICU stay: 7
days (group 1), and > 7 days (group 2).
ICU Data
The clinical course during the ICU stay was critically reviewed
and complications were identified based on written reports and/or
laboratory and other ancillary data. Complications were subdivided into
four major groups: pulmonary, cardiac, infection, and others. However,
for the present study, a detailed analysis was done only for those
patients in whom noninfectious pulmonary complications were
identified. Furthermore, in those patients in whom complications
affected more than one system, attempts were made to identify the
dominant system most likely to contribute to the adverse clinical
course based on a consensus among the investigators. The group with
pulmonary complications was further subdivided by type of complication:
phrenic nerve dysfunction, airway problems, pulmonary vascular
hypertension, and pleural effusion. Criteria for the diagnosis of
phrenic nerve palsy included the presence of an elevated dome of the
diaphragm with paradoxical motion on fluoroscopy or ultrasound.
Tracheobronchomalacia was bronchoscopically identified from the
occurrence of a dynamic collapse of the trachea and/or mainstem bronchi
during spontaneous respiratory efforts. Atelectasis was defined as the
radiographic finding of a lobar infiltrate and volume loss in the
absence of clinical or laboratory signs of infection. Pulmonary
hypertension was identified from echocardiographic estimates and/or
catheterization measurements. Patients with pleural drainage > 5
mL/kg/d and patients requiring continued chest tube drainage
beyond the third postoperative day were considered to have pleural
effusion, and the nature of the pleural fluid (serous, bloody, or
chylous) was noted.
Patients were extubated based on ongoing ICU algorithm protocols and the decision of the attending primary physician. When a patient was reintubated and mechanically ventilated within the first 48 h after planned extubation, the extubation was considered to have failed. The number of failed extubations and the overall durations of the ICU stay and the hospital stay were also documented. Nonimmediate postoperative mortality (> 48 h) was assessed until discharge from the ICU.
Flexible Fiberoptic Bronchoscopic Airway Assessment
When clinically indicated, fiberoptic flexible bronchoscopy was
performed either in the operating room under general anesthesia or by
the bedside in the ICU under sedation and additional topical
anesthesia. Two pediatric bronchoscopes, one with a 2.2-mm external
diameter (Olympus BF 22; Olympus America, Inc; Melville, NY) and the
other with a 3.6-mm external diameter (Olympus BF 3C20), were used.
Cardiorespiratory stability was continuously monitored in all patients,
and supplemental oxygen was administered as necessary. To rule out the
possibility of upper airway obstruction in patients with failed
extubations, endotracheal tube removal was performed under
bronchoscopic guidance, the upper airway was evaluated, and patients
were reintubated if necessary with visual verification of appropriate
positioning of the endotracheal tube.
Data Analysis
Data are expressed as mean ± SEM. Comparisons between groups 1
and 2 were performed using one-way analysis of variance followed by
post hoc tests or unpaired t tests as
appropriate. Linear regression analysis with calculation of regression
coefficients was employed for assessment of potential relationships
between bypass time and duration of MV or ICU stay. A p value of
< 0.05 was considered to be statistically significant.
|
Results |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
|
|
|
Phrenic nerve dysfunction occurred primarily in neonates (n = 5), and in all seven patients, the surgical procedure was conducted in the vicinity of aortopulmonary trunk (arterial switch procedure, n = 3; coarctation of aorta, n = 1; truncus arteriosus, n = 1; tetralogy of Fallot repair, n = 1; and augmentation of pulmonary artery, n = 1). In three patients, surgical plication of the diaphragm was necessary to wean the patient from MV.
Pleural effusions were noted in eight patients (four in group 1 and four in group 2). One patient developed bilateral chylothoraces that ultimately required thoracic duct ligation. Bilateral serous pleural effusions complicated the postoperative course in two patients, while unilateral effusions occurred in the other patients.
Moderate to severe pulmonary hypertension was present in five patients. All the patients were managed with the standard protocol for postoperative pulmonary hypertension, which included sedation, neuromuscular paralysis, hyperoxygenation, and respiratory alkalosis. When conservative measures failed, inhaled nitric oxide was successfully employed in two patients.
Thus, a total of 22 patients (22.6%) developed pulmonary complications (4 in group 1 and 18 in group 2) and required 522 days of MV (61.7% of all ventilator days), 686 days in the ICU (52.8% of the cumulative days for this cohort), and a total of 970 hospital days (43.1% of the overall hospital stay).
Deaths
Three deaths occurred in group 2 and no deaths were recorded in
group 1. In the three patients from group 2, the primary cause of death
was not directly attributable to the pulmonary involvement. An
11-day-old neonate with the diagnosis of DiGeorge syndrome and an
interrupted aortic arch died of left ventricular dysfunction on the
11th postoperative day following a surgical repair attempt with
interposition of a Gore-Tex tube graft (W.L. Gore & Associates, Inc;
Flagstaff, AZ) from the ascending to the descending aorta. A 25-day-old
neonate with total anomalous pulmonary venous return of
infradiaphragmatic type underwent repair of the anomaly and developed
pulmonary venous obstruction, thus needing a second surgical procedure
for pulmonary vein augmentation. However, the postoperative course was
complicated by severe congestive cardiac failure and candidial
septicemia from which the infant did not recover. The third patient was
a 4-month-old infant with the diagnosis of pulmonary atresia and intact
ventricular septum who had undergone a modified Blalock-Taussig shunt
placement in the neonatal period. The patient underwent a bidirectional
Glenn procedure and atrial septostomy, after which he developed severe
cardiac failure further complicated by Serratia sepsis, subacute
bacterial endocarditis, and candidial septicemia; the infant died on
postoperative day 72. Of note, diffuse hemorrhagic tracheobronchitis
was noted in this particular patient during a flexible bronchoscopy
performed on day 60 for hemoptysis.
|
Discussion |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This is the first study to examine the role of pulmonary involvement in
postoperative morbidity in this population. Several studies estimate
that 18 to 41% of infants will require prolonged mechanical
ventilatory support following cardiac surgery.9
10
11
12
Analysis of risk factors for prolonged ventilatory support requirements
assign independent risk to the preoperative clinical status, to
intraoperative elements such as CPB and cross-clamp durations, to the
underlying cardiac defect, and to the nature of the surgical
procedure.5
6
12
In general, patients with simple shunt
lesions, such as atrial septal defect (ASD), VSD, and patent ductus
arteriosus (PDA), and patients undergoing extracardiac palliation are
frequently extubated in the operating room and therefore require
minimal ICU stays. The current study supports such a contention, as
evidenced by the low number of ventilator days and overall ICU days in
group 1. On the other hand, patients with more complicated
perioperative pathophysiology who undergo complex cardiac surgical
procedures will be expected to require longer postoperative respiratory
support, and it is the general consensus that in these patients,
cessation of mechanical ventilatory support is usually achievable
within the first 72 h postoperative.13
Inability to
extubate in 72 h is indicative of a more complicated postoperative
course that usually will involve dysfunction of several
systems. Our current study indicates that the respiratory system is a
major system contributing to this postoperative morbidity, and that
four major groups could be identified in this setting: central airway
obstruction, diaphragmatic dysfunction, pulmonary hypertension, and
pleural effusion.
Central Airway Compression
It has long been known that children with CHD may be at increased
risk for airway complications by virtue of the anatomical proximity of
the cardiac chambers and major vessels to the central
airways.14
Airway compression has been reported in
association with dilated pulmonary arteries, left atrial enlargement,
and massive cardiomegaly.14
The left lateral trachea, the
superior aspect of the left mainstem bronchus, and the junction of the
right intermediate bronchus with the right middle lobe bronchus are
particularly vulnerable sites.15
In the vast majority of
patients, the existing airway compression is usually relieved by
surgical repair of the primary cardiac defect, such that most patients
will be asymptomatic. However, residual compression and/or secondary
bronchomalacia can be severe enough to manifest as persistent lobar
atelectasis and recurrent pneumonia associated with poor mucociliary
clearance in that region. Additionally, with the advent of prosthetic
devices and conduits in the central vessels, extrinsic tracheobronchial
compression by such devices has been increasingly
recognized.16
17
18
Thus as evidenced by the current series,
airway compression can be an important and often unrecognized source of
pulmonary dysfunction in CHD patients during the postoperative period.
Persistent wheezing is generally misconstrued as bronchoconstriction,
leading to aggressive bronchodilator therapy with or without inhaled or
systemic steroids that essentially postpones the recognition of
extrinsic airway compression until the patient undergoes one or more
extubation failures, and chronic respiratory failure settles
in.19
Flexible bronchoscopic evaluation of the airways is
the obvious diagnostic tool for central airway involvement in the
postoperative CHD patient. The morbidity and overall medical care costs
of airway involvement in this population are quite impressive. Indeed,
the three patients with tracheobronchomalacia accounted for 12 of the
44 extubation failures, and all three required tracheostomy placement
and application of positive pressure ventilation.
Of interest, none of our patients developed subglottic stenosis after extubation, although such a complication has been reported in up to 2.3% of the patients.20
Diaphragmatic Dysfunction
Diaphragmatic dysfunction is primarily caused by phrenic nerve
injury after CHD repair, and conservative estimates assign a 0.3 to
2.1% risk to this complication.21
22
23
However, this
relative risk may be underestimated. When preoperative evaluation of
phrenic nerve conduction was conducted, the incidence of phrenic nerve
dysfunction rose to 10%.24
The mechanisms leading to
phrenic nerve dysfunction probably involve cold injury from iced
cardioplegic solution or result from surgical trauma to the phrenic
nerve as it courses around the great vessels in the thoracic cavity.
The clinical manifestations are variable, and may range from lower
lobar atelectasis on the affected side to ventilatory dysfunction
secondary to respiratory pump failure. Infants and children < 2 years
of age are at particular risk for development of respiratory failure
because of the high compliance of the thoracic cage, the relatively
weak intercostal musculature, and the mediastinal shifts induced by
paradoxical motion of the paralyzed diaphragm. Thus, these patients are
at high risk for extubation failure and for prolonged ventilatory
dependency. In this study, the seven patients with phrenic nerve
dysfunction accounted for a total of 14 extubation failures (31% of
all failures) leading to prolonged MV (mean, 29.8 days) and ICU stay
(mean, 43.4 days). Recognition of this complication is usually delayed
by the nonspecific nature of the symptoms (ie, respiratory
distress following extubation or during weaning protocols) and by the
absence of the characteristic radiologic findings in a mechanically
ventilated patient. Although the therapeutic approach to postoperative
diaphragmatic paresis in young children remains controversial, early
plication of the diaphragm may decrease the duration of MV and
associated respiratory morbidity in selected cases.7
25
Indeed, a favorable outcome was noted in our three patients who
underwent diaphragmatic plication, and extubation was successful within
48 h of the plication procedure.
Pleural Effusion
Ordinarily, the pleural drainage during the immediate
postoperative period is expected to be < 3 mL/kg/d, such that chest
tubes can be removed by the third postoperative day. Causes for
excessive pleural drainage include fluid overload, pulmonary edema,
serous fluid leakage from the extracardiac shunts, chylothorax
secondary to thoracic duct dysfunction,26
27
and increased
central venous pressure as seen in patients undergoing the Fontan
procedure. Effusions are generally small, transient, and self-limiting,
and pure hemorrhagic effusion is rare and usually manifests in the
first few hours after surgery. However, chylothorax leading to
respiratory distress and malnutrition may necessitate administration of
IV hyperalimentation and modified enteral diets, which, if
unsuccessful, may lead to surgical placement of pleuroperitoneal shunts
and ligation of the thoracic duct as seen in one of our
patients.28
Pulmonary Hypertension
Pulmonary hypertension can be a frequent complication in the
postoperative period, particularly in neonates and in infants with
preoperatively increased pulmonary blood flow such as those who have
large VSDs, AV canal defects, or truncus arteriosus.29
Elevated pulmonary arterial pressure and resistance increase the
perioperative morbidity and mortality by compromising right ventricular
function and oxygenation.30
Aggressive efforts to improve
oxygenation and alveolar ventilation and to achieve effective sedation
with adequate muscle relaxation may need to be coupled with
pharmacologic interventions such as inhaled nitric
oxide.31
Extubation Failure
In a critical care unit setting, figures for extubation failure
range from 17 to 19% in adults to 22 to 28% in premature
infants.32
33
In the only pediatric series addressing this
issue, extubation failure in the absence of upper airway obstruction
was observed in 16.3% of cases.34
However, we are unaware
of any data specifically examining the rate of extubation failure in
young patients undergoing cardiac surgery. In the present study, we
found that 24 of 97 patients (21 patients in group 2 and 3 patients in
group 1), or about 25% of patients, had at least one extubation
failure, suggesting that this particular population is at high risk for
such a complication. It has become quite clear that extubation failure
is associated with an increased number of medical complications and
with significantly higher mortality rates in the critical care
unit.35
36
Therefore, we recommend that young children
undergoing cardiac surgical repair be identified as a particular
high-risk group for extubation failure, and that clinicians actively
seek to identify specific pulmonary factors: Among the 21 patients in
group 2 who failed extubation, pulmonary dysfunction was the leading
etiologic factor in 13 patients (54%).
Intraoperative Variables
CPB duration has been associated with higher incidence of
prolonged MV in the postoperative period.5
6
Although the
exact mechanism(s) for such association are yet to be elucidated,
pulmonary function tests after CPB reveal reduced static dynamic
compliance, decreased functional residual capacity, increased
alveolar-arterial oxygen gradient, and atelectasis, all of which can
contribute to extended mechanical ventilatory needs.37
However, our study does not support such a correlation between CPB
duration and the duration of either MV or ICU stay. Our findings concur
with those of Heinle et al,4
who reported that the
duration of CPB or aortic cross-clamp time did not prevent extubation
at the conclusion of the operation in neonates and young infants after
surgical repair for CHD.
Some methodologic considerations regarding the present study deserve comment. First, allocation of patients to two groups on the basis of the duration of ICU stay was an arbitrary decision based on previous experience at our institution, and more specifically based on the fact that 7 days was the 95th percentile of the mean duration of ICU stay for all young patients undergoing cardiac surgical repair (data not shown). Thus, we believe that, although the decision was somewhat arbitrary, it clearly differentiates between low- and high-risk groups of patients. A second limitation of this study is inherent to the retrospective evaluation of clinical data; it is sometimes difficult to establish true comparisons among the groups because they were not prospectively evaluated with each variable controlled. This is particularly important for assignment of individual roles to specific postoperative courses in which comorbidity was present. Nevertheless, the high degree of pulmonary involvement in general, and particularly that of central airway compression, in those patients requiring prolonged ICU stay indicates that such factors are important contributors to less favorable postoperative outcomes, and should therefore be considered early rather than late in the event of extubation failure.
In summary, in young children undergoing surgical repair of complex cardiac lesions, increased postoperative morbidity is clearly associated with pulmonary involvement, and more specifically when central airway compression and/or phrenic nerve dysfunction are present. Thus, early evaluation for these pulmonary conditions should be considered in any postoperative patient who fails extubation. It is possible that prospective evaluation of clinical algorithms encompassing the information and considerations reported herein may lead to earlier identification and decreased morbidity in this high-risk population.
|
|
Footnotes |
|---|
This research was supported by National Institutes of Health grant HD-01072, Maternal and Child Health Bureau grant MCJ-229163, and an American Lung Association Career Development Award CI-002-N (Dr. Gozal).
Received for publication November 5, 1998. Accepted for publication April 16, 1999.
|
References |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  V. L. Vida, J. Leon-Wyss, M. Rojas, R. Mack, J. Barnoya, and A. R. Castaneda Pulmonary Artery Hypertension: Is It Really a Contraindicating Factor for Early Extubation in Children After Cardiac Surgery? Ann. Thorac. Surg., April 1, 2006; 81(4): 1460 - 1465. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Hoskote, G. Cohen, A. Goldman, and L. Shekerdemian Tracheostomy in infants and children after cardiothoracic surgery: Indications, associated risk factors, and timing J. Thorac. Cardiovasc. Surg., October 1, 2005; 130(4): 1086 - 1093. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Bhatt, S. J. Roth, R. K. Kumar, K. Gauvreau, S. G. Nair, S. Chengode, K. Shivaprakasha, and S. G. Rao Management of infants with large, unrepaired ventricular septal defects and respiratory infection requiring mechanical ventilation J. Thorac. Cardiovasc. Surg., May 1, 2004; 127(5): 1466 - 1473. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Kumar, A. P. Bush, G. P. Ladas, and P. Goldstraw Tracheobronchial obstruction in children: experience with endoscopic airway stenting Ann. Thorac. Surg., May 1, 2003; 75(5): 1579 - 1586. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Buchhorn, M. Hulpke-Wette, W. Ruschewski, R. Pregla, J. Fielitz, R. Hetzer, and V. Regitz-Zagrosek {beta}-Receptor downregulation in congenital heart disease: a risk factor for complications after surgical repair? Ann. Thorac. Surg., February 1, 2002; 73(2): 610 - 613. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
