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| Journal of the New Zealand Medical Association,
29-April-2011, Vol 124 No 1333
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|
Increased incidence of empyema in Polynesian
children
Naomi Wright, Philip Hammond, Philip Morreau, James
Hamill
Empyema in childhood causes significant morbidity and may be
increasing in frequency.1,2 Empyema is
classified into three stages:
The majority of cases
present in the exudative stage and can be effectively managed with tube
thoracostomy. Stage 3 empyema often requires open debridement of infective
loculations to prevent lung restriction.
The optimal management of fibrinopurulent empyema remains
under debate. Two recent randomised controlled trials comparing fibrinolysis
with video-assisted thoracoscopic surgery (VATS) in children have shown no
significant difference in clinical outcome or length of postoperative hospital
stay, but reduced treatment costs with
fibrinolysis.3,4 Several series demonstrate
that surgery can be safely avoided in approximately 80–90% of paediatric
empyema patients with the use of
fibrinolytics.1,3
The British Thoracic Society recommends fibrinolysis as
first line therapy for empyema.1 However,
Bishay et al recently suggested that the failure rates for VATS can be
considerably lower than for fibrinolysis if undertaken at a centre with high
levels of thoracoscopic surgical experience.5
VATS is minimally invasive and can be undertaken whilst the
child is under general anaesthesia for the chest drain, thus allowing early and
effective drainage.6–8
Starship Children's Hospital (SSH) in Auckland, New Zealand,
is a tertiary-referral centre for paediatric surgery. VATS was introduced in
2003 for the primary treatment of fibrinopurulent empyema. The aim of this study
is to review the epidemiology, treatment and outcome of surgically-managed
empyema in our first 5 years of VATS.
MethodsStudy design—A retrospective
case-note review was undertaken of all surgically-managed empyemas at SSH over
the 5 year period between 1 July 2003 and 30 June 2008. All children (<15
years) who had a diagnosis of empyema on hospital discharge coding data and had
undergone surgical management were included in the study.
Surgical intervention (VATS or thoracotomy) was
determined from examination of the medical records. Patient demographics, mode
of presentation, investigations, timing of illness onset to presentation,
surgical intervention, and discharge, duration of chest drainage and
complications were recorded. No cases were excluded.
Statistical analysis—Differences
between the ethnic distribution in our study and the New Zealand paediatric
population were assessed using a goodness of fit test. Differences in surgical
timing and chest drainage between those treated by VATS and thoracotomy were
assessed using a Wilcoxon 2 sample test.
Surgical technique—Surgery was
undertaken by three surgeons at SSH. The precise technique for VATS varied
according to surgeon preference. Single lung ventilation with a bronchial
blocker or double lumen tube was employed in a minority of cases but with
increasing frequency later in the series.
With the patient in the lateral position and the
affected hemithorax uppermost, two or three 5 mm ports are placed and carbon
dioxide pneumothorax established at 3–5 mmHg. Loculations are lysed,
fibrinous peel removed and the thoracic cavity irrigated. One or two chest tubes
are left in situ and removed on the ward when drainage minimal.
ResultsOf 93 children with empyema 62, comprising the study
population, were managed surgically (55 VATS, 7 thoracotomy) and 31 with tube
thoracostomy alone. No children were managed with fibrinolysis. Of those treated
by VATS, 45 (82%) underwent primary VATS and 10 (18%) underwent VATS following
prior chest drain insertion. Demographics are listed in Table 1.
Table 1. Patient characteristics
*Video-assisted thoracoscopic surgery; †Mostly of
Samoan, Tongan, Niuean, or Cook Islands origin.
Children of Pacific and Māori ethnic origin were
over-represented compared to their proportion of the New Zealand paediatric
population, p<0.0001 (Figure 1). 9
Figure 1. Ethnic distribution of the study
population and New Zealand paediatric
population9
 The Auckland 2006 Census showed a similar ethnic
distribution: 14% Pacific Peoples, 11% Māori, 56% European, 19% Asian, 1%
other. 10
Radiological investigations—54 (87%)
were investigated with ultrasonography (US) and 37 (60%) underwent chest
computed tomography (CT). All children had either US or CT.
Microbiology (Table 2)—53 (85%) had a
blood culture performed. Of these, 19 (36%) had a positive result. All 62
children had a pleural aspirate performed for culture. Of these 25 (40%)
resulted in positive culture.
Table 2. Microbiological
isolates
MRSA: methicillin-resistant Staphylococcus
aureus.
Clinical presentation (Table 3)—24
(39%) of patients presented directly to SSH. 38 patients (61%) were transferred
to SSH from another hospital; 36 patients from 13 hospitals across the North
Island, 1 from the South Island and 1 from a Polynesian Island.
Patients requiring a thoracotomy (43% of which were
converted from VATS) had a significantly longer time from presentation at
primary hospital to surgery than those treated with VATS (median 17 and 6 days
respectively, p=0.007). 10 patients (16%) had intrapulmonary abscesses (7 were
Polynesian) and 7 patients (11%) had multi-organ sepsis (5 were Polynesian).
Table 3. Clinical presentation (expressed in
median, range)
* p<0.01 †For
transferred patients.
Outcome (Table 4)—None of the
patients who underwent VATS required a repeat procedure. 3 of those treated by
thoracotomy initially underwent VATS but required conversion to an open
procedure to allow adequate debridement of infective loculations (5% conversion
to thoracotomy). Of those treated by VATS the chest drains remained in situ
postoperatively for a median of 3 days.
The total length of hospital stay was significantly longer
in those who underwent thoracotomy (34 days) compared to VATS (19 days)
(p=0.007). 10 children required PICU admission postoperatively and 1
preoperatively (8 of these were Polynesian).
Table 4. Outcome (expressed in median,
range)
PICU, Paediatric Intensive Care Unit; * p<0.01;
† Two cases not documented. ‡ One case not documented.
Complications (Table 5)—Complications
occurred in 16%. One intraoperative complication occurred. A 14-year-old
Māori boy with pre-existing severe bronchiectasis presented with empyema
and an intrapulmonary abscess on the right side (figure 2). Whilst on the
operating table immediately following an uneventful VATS drainage (without
single lung ventilation) he developed cardiorespiratory arrest. Copious pus was
suctioned from the endotracheal tube suggesting rupture of the intrapulmonary
abscess into the bronchial tree. Septic shock ensued requiring 10 days of
ventilatory support in PICU and 33 days inpatient treatment postoperatively.
Table 5. Complications
* In these cases there was no clinical or radiological
evidence of contralateral empyema prior to VATS. It may be that infective
secretions can be aspirated into the healthy lung by postural drainage
intraoperatively when a bronchial blocker is not employed. However, we recognise
these cases could reflect extent of disease rather than a complication.
Figure 2. Radiograph and CT scan of empyema
with intrapulmonary abscess in a patient with bronchiectasis.
    DiscussionIncidence—Empyema is a significant
source of childhood morbidity and accounts for approximately 1/1000 paediatric
admissions to SSH. This is consistent with previous reports of empyema
incidence, ranging from 0.4–6/1000 paediatric admissions, and highlights
the importance of an optimal management strategy for this patient
population.11
Susceptibility to infection—Children
of Māori or Pacific ethnicity represented 71% of children with empyema
despite making up just 30% of the NZ paediatric population
(p<0.0001).9 There is evidence to suggest
that children of Māori and Pacific ethnicity have an increased
susceptibility to and severity of certain infections with increased
hospitalisation rates for pneumonia compared to children of European descent and
more severe pneumonia within hospitalised populations with higher respiratory
rates, heart rates, oxygen and intravenous antibiotic requirements and an
elevated relative risk for invasive disease and Staphylococcus aureus
bacteraemia.12-15
Possible reasons include genetic factors, for which specific
genes have been identified, and lower socioeconomic status associated with
increased smoking rates, overcrowding, micronutrient deficiency (with associated
immunodeficiency), delayed presentation and reduced access to medical
services.12,16,17
Investigators elsewhere have shown that indigenous people
worldwide have increased rates of pneumococcal disease compared to others within
the same geographical region, including North American Indians, Alaskan and
Greenland natives and Australian
Aborigines.18-21
Severity of disease—Despite equal or
shorter durations of symptom onset to presentation, time to surgical
intervention and chest drainage, Bishay et al, Sonnappa et al and St.Peter et al
document considerably shorter median postoperative hospital stays following VATS
of 6–7 days compared to 14 days in this
study.4-6
Chen et al document a similar median time from diagnosis to
VATS as this study, but also a similar postoperative length of hospital stay of
13 days.22 In the latter study there was a high
severity of infection indicated by 36.5% of patients having necrotising
pneumonia, which they showed through multivariate analyses to be associated with
a significantly higher complication rate and postoperative length of stay.
In our study 16% had intrapulmonary abscesses, 11%
multi-organ sepsis and 18% required PICU care. There was a high complication
rate of 16%, including one life-threatening complication and others requiring
further tube thoracostomy. Together these factors resulted in prolonged
inpatient treatment. This may have been related to an increased severity of
infection within the Polynesian population. Hence, we highlight that severity of
empyema and treatment outcome may in part be influenced by ethnicity within a
population.
Limitations—The present study is a
retrospective series presenting our early experience with VATS for paediatric
empyema. Choice of intervention was at the surgeons’ discretion, surgical
technique was not standardised and evolved throughout the study period.
The majority of patients were referred or presented from the
North Island of New Zealand, for which specific paediatric ethnic distribution
statistics were not available. However, the Auckland specific population data is
highly similar to that of the New Zealand paediatric population data.
We have not drawn conclusions on outcome according to
treatment modality in view of the retrospective nature of the study and the
numerous prospective studies which have already been published on this
subject.
Conclusion—The incidence of
paediatric empyema is significantly higher in the Māori and Pacific
population than in the other ethnic groups in our region. Severity of empyema
may be higher within the Polynesian population affecting treatment outcome;
prospective studies using severity scoring systems are required to investigate
this.Further research is required to look at the immunological and environmental
factors relating to infections and responses in this population. A high level of
suspicion for empyema and intrapulmonary abscesses amongst Polynesian children
with pneumonia is required to allow swift referral and institution of treatment.
The hope is that this will prevent some of the complications related to the
disease process and more invasive therapeutic measures.
Competing interests: None.
Author information: Naomi J Wright, Senior
House Officer; Philip Hammond, Clinical Fellow; Philip Morreau, Consultant;
James Hamill, Consultant; Department of Paediatric Surgery, Starship
Children´s Hospital, Auckland
Acknowledgements: Thanks to Alistair
Stewart for statistical advice, and the paediatric surgeons and respiratory
paediatricians at SSH for facilitating this study.
Correspondence: Miss Naomi J. Wright,
Department of Surgery, University College Hospital, London, NW1 2PG, United
Kingdom. Email: naomiwright@doctors.org.uk
References:
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