American Journal of Emergency Medicine (2011) 29, 1152-1157

Brief Report

A randomized controlled trial comparing minichest tube and Needle aspiration in outpatient management of primary Spontaneous pneumothorax^?

Khoy Kheng Ho MBBS^a,?, Marcus Eng Hock Ong MBBS, MPH^b, Mariko Siyue Koh MBBS^c,

Evelyn Wong MBBS^b, J. Raghuram MB BCh^d

^aDepartment of Emergency Medicine, Alexandra Hospital (Jurong Health Services), Singapore 159964, Singapore

^bDepartment of Emergency Medicine, Singapore General Hospital, Singapore 169608, Singapore

^cDepartment of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore 169608, Singapore

^dDepartment of Respiratory Medicine, Changi General Hospital, Singapore 529889, Singapore

Received 2 May 2010; revised 14 May 2010; accepted 15 May 2010

Abstract

Objectives: The aim of this study was to compare outcomes and complications associated with needle aspiration (NA) and minichest tube (MCT) insertion with Heimlich valve attachment in the treatment of Primary spontaneous pneumothorax at an emergency department (ED).

Methods: Patients presenting with primary spontaneous pneumothorax were randomized to NA or MCT. They had repeat chest X-rays immediately after the procedure and 6 hours later. Patients who underwent NA were discharged if repeat x-rays showed less than 10% pneumothorax. Those who had MCT were discharged if repeat x-rays did not show worsening of pneumothorax. They were reviewed at the outpatient clinic within 3 days.

The primary outcomes of interest were failure rate and admission rate. The secondary outcomes were complication rate, pain and Satisfaction scores, length of hospital stay, and rate of Full recovery during outpatient follow-up.

Results: There were 48 patients whose mean age was 25 years. We found no difference in failure rate between the groups, except that there were more MCT (24%) than NA patients (4%) with complete expansion at first review (difference, -0.20; 95% confidence interval, -0.38 to -0.01). Thirty-five percent of NA group and 20% of MCT group needed another procedure at the ED. Fifty- two percent of NA patients and 28% of MCT patients were admitted from the ED to the inpatient ward. Nine percent and 12%, respectively, of patients who had NA and MCT were admitted from the review clinic. Both groups of patients had equivalent pain scores, satisfaction scores, and complication rates.

Conclusion: Both MCT and NA allowed safe management of primary spontaneous pneumothorax in the Outpatient setting.

(C) 2011

^? Source of support: We acknowledge the support of the SingHealth Research Secretariat (CC032/2002) in providing the research grant.

* Corresponding author. Tel.: +65 63793167; fax: +65 64793102.

E-mail address: [email protected] (K.K. Ho).

0735-6757/$ – see front matter (C) 2011 doi:10.1016/j.ajem.2010.05.017

Introduction

Spontaneous pneumothorax is a relatively uncommon presenting problem at the emergency department (ED). The annual Incidence of pneumothorax (both primary and secondary combined) was found to be 24/100 000 for men and 9.8/100 000 for women in a study originating from England, resulting in annual incidence of hospital admission of 16.7/100 000 for men and 5.8/100 000 for women [1]. The management of primary spontaneous pneumothorax varies by location. Traditional preference has been for chest tube insertion and admission to the ward. British Thoracic Society recommends needle aspiration (NA) as the initial treatment of choice [2], but American College of Chest Physicians Consensus prefers insertion of small-bore catheters (<=14F) or Chest tubes (16-22F) [3].

Needle aspiration has been advocated as the First-line treatment for primary spontaneous pneumothorax because it has been found to be safe and less painful and leads to a shorter admission than chest tube insertion in randomized controlled trials [4,5]. However, aspiration followed by immediate catheter removal was only successful in approx- imately 60% of patients, and more than half of these patients needed to be hospitalized [6].

Outpatient management of primary spontaneous pneumo- thorax with minichest tubes (MCTs) attached to Heimlich valve was touted as the procedure to address the lack of invasiveness of aspiration while avoiding the discomfort and costs of chest tube insertion [7]. This was found to be safe in a pilot study [8] and a retrospective case series [9]. However, they were limited by the retrospective and nonrandomized nature of the studies.

The aim of this study is to compare failure rate and admission rate associated with the use of NA and MCT in the outpatient management of primary spontaneous pneumotho- rax. The secondary outcomes of interest are complication rate, length of hospital stay, patient acceptability, and rate of full recovery during outpatient follow-up.

Methods

Design

The design of this study is a randomized controlled trial comparing NA and MCT (12F) insertion with Heimlich valve attachment in the treatment of primary spontaneous pneu- mothorax. Patients were randomized (blocked randomization using sealed envelopes) into 2 study arms. The patients were not stratified according to the size of the pneumothorax.

Patients in the MCT arm had MCT inserted in the ED by the resident under supervision by the attending emergency physician. The tube was connected to a Heimlich valve, and a Chest x-ray was done to confirm tube placement and reexpansion. They were then monitored for 6 hours, and a CXR was repeated 6 hours later. They were discharged with

the Heimlich valve attachment if the repeat x-ray 6 hours later did not show any worsening of the pneumothorax. Otherwise, they would have chest tube insertion before being admitted to the inpatient ward.

Patients in the aspiration arm underwent manual aspira- tion in the ED by the resident under the supervision of the attending emergency physician. A 16G cannula was inserted in the second intercostal space at the midclavicular line. A CXR was then done to confirm reexpansion. Complete reexpansion is defined as up to 10% residual pneumothorax. These patients were observed for 6 hours followed by CXR to confirm sustained reexpansion and absence of recurrence. They were discharged if the repeat CXR 6 hours later showed less than 10% pneumothorax. If the pneumothorax was larger, they would have chest tube insertion before being admitted to the ward.

All patients were reviewed, and CXR was repeated at the outpatient clinic of the Department of Respiratory and Critical Care Medicine within 3 days. The subsequent management was at the discretion of the attending respiratory physicians depending on the patients’ clinical status.

The study protocol was approved by the hospital’s ethics committee before the commencement of the study.

Setting

Prospective patients presenting to the ED of the Singapore General Hospital were enrolled in this study. The study began in January 2004 and ended in December 2006. Singapore General Hospital is Singapore’s largest acute tertiary hospital and national referral centre. It accounts for approximately one third of total acute Hospital beds in the public sector and approximately a quarter of acute beds nationwide. More than 137 000 patients attend its ED annually.

Subjects

All consenting patients with primary spontaneous pneu- mothorax (defined as spontaneous pneumothorax in a patient with no previous lung disease) were included. The following patients were excluded: patients with Tension pneumothorax, pneumothorax secondary to trauma, minor pneumothorax (b3 cm from apex) not requiring any treatment, fluid level on CXR suggesting effusion or blood, unstable vital signs or respiratory distress or hypoxia, Bleeding disorders, underly- ing pulmonary disease (chronic obstructive airway disease, asthma); smokers older than 50 years; and patients with indication for chest tube (eg, recurrent pneumothorax; N2 episodes of pneumothorax on the same side).

Outcomes

The primary study outcomes were failure rate and admission rate. Procedure failure was defined as recurrence of pneumothorax, need for a second procedure, or need for

Whole group		NA	MCT
No. (%)	48 (100)	23 (47.9)	25 (52.1)
Age (y), mean (SD)	25 (7.4)	26 (8.6)	24.3 (6.1)
Sex: male (%)	92	91.3	92
Smoking
Smoker (%)	33.3	30.4	36
Nonsmoker (%)	60.4	69.6	52
Ex-smoker (%)	6.3	0	12
Type of pneumothorax
Primary first episode (%)	77.1	73.9	80
Primary recurrent episode (%)	22.9	26.1	20
Size of pneumothorax
b3 cm from apex (%)	4.2	4.3	4
3-5 cm from apex (%)	45.8	30.4	60
N5 cm from apex (%)	50	65.2	36
Side of pneumothorax: right (%)	64.6	60.9	68

surgical intervention (eg, video-assisted thoracoscopic surgery or thoracotomy). Recurrence was defined as either worsening of pneumothorax (for MCT group) or greater than

Table 1 Characteristics of patients

10% of pneumothorax (for NA group) after the observation period. The other outcomes of interest were length of hospital stay, complication rate (including bleeding,

Fig. 1 Outcome after initial procedure at ED.

Fig. 2 Patient flow diagram.

infection, death), pain and satisfaction scores (which were assessed using visual analog scale without blinding), and rate of full recovery (defined as complete reexpansion of pneumothorax) on outpatient follow-up.

Data analysis

Data entry was carried out using Microsoft Excel 2003 (Microsoft Corporation). All data analyses were performed using SPSS version 15.0 (SPSS, Chicago, Ill), presenting descriptive statistics and frequencies. We estimated that in order to detect a 25% difference in failure rate between NA and chest tube (35% versus 10%), with a 1-sided test size of 5% and a power of 90%, a sample size of 100 patients was required (50 patients in each arm).

Table 2 Key outcomes

NA MCT Difference

(n = 23) (n = 25) In proportion

95% CI

Lower limit

Upper limit

Results

During the period from January 2004 to December 2006, we recruited 48 consecutive patients with spontaneous pneumothorax (Table 1).

Twenty-three patients had NA. Three patients (13%) had complete reexpansion immediately after the procedure (Fig. 1). Eight patients (35%) required a second therapeutic procedure at the ED. Twelve patients (52%) were admitted from the ED (Fig. 2), of which 6 (26%) had thoracoscopic pleurodesis during admission. Both the mean and median number of days of admission were 4.5 days.

Twenty-five patients had MCT insertion. Three patients (12%) had complete reexpansion immediately after the procedure. Five patients (20%) required a second procedure at the ED. Seven patients (28%) were admitted, of which 3 (12%) had thoracoscopic pleurodesis during admission. The mean number of days of admission was 7.4 days (median, 7 days).

Although more patients from NA arm were admitted than those from MCT arm, the difference was not statistically significant (Table 2). We checked for association between the Treatment outcome (of being admitted or discharged from the ED) and covariates using Pearson ?2 test. There was no significant association between the treatment outcome and covariates like age, sex, smoking history, the side of pneumothorax, first or recurrent episode of pneumothorax, or the size of pneumothorax. The rates of second procedure in the 2 groups were also not significantly different.

Further analysis was performed on the whole group of patients, irrespective of the initial procedure. Among them, 19 (39.6%) were admitted from the ED. Thirteen (27%) patients had a second procedure, which by default should have been chest tube insertion. However, we found some violation of the study protocol, with some patients having NA instead.

Patients who were deemed to have failed (either no full reexpansion at ED, or had second procedure at ED, or were admitted from ED) were combined and analyzed. It was found that the rate of failure of NA patients (21, or 91.3%) was not significantly higher than that of the MCT patients (22, or 88%; P = .541).

Among patients who were successfully discharged from the ED after the initial procedure and observation, 6 (24%) of those who had MCT had full reexpansion at their first outpatient review compared with just 1 (4%) of those who had

No. of admission from ED	12 (0.52)	7 (0.28)	0.24	-0.028	0.511
No. of admission from clinic at first review	2 (0.09)	4 (0.16)	-0.07	-0.257	0.111
No. of second procedure at ED	8 (0.35)	5 (0.2)	0.15	-0.102	0.398
Complete reexpansion of pneumothorax at first clinic review	1 (0.04)	6 (0.24)	-0.20	-0.384	-0.010
CI indicates confidence interval.

Table 3 Complications
Type of complication	NA (n = 23)	MCT (n = 25)
subcutaneous emphysema	2	0
Tension pneumothorax	0	1
Total	2 (8.7%)	1 (4%)

NA, which was statistically significant (difference in proportion, -0.20; 95% confidence interval, -0.38 to

-0.01). The MCT was removed after an average of 3.5 days. Of the 23 patients from NA arm, 2 (8.7%) were found to have recurrence of pneumothorax at the first clinic review and were admitted to hospital. They were admitted for a mean of 6 days (median, 6 days), and 1 of them had thoracoscopic pleurodesis. Of the 25 patients who had MCT, 3 (12%) were found to have recurrence of pneumothorax at the clinic review and were admitted to hospital. They were admitted for an average of 5 days (median, 4.5 days). Two of them had thoracoscopic pleurodesis. Another patient was admitted from the clinic for

purely social reasons.

When the admissions from both the ED and the outpatient clinic were combined, a total of 14 patients (61%) from NA arm and 11 patients (44%) from MCT arm were admitted. The difference was not statistically significant.

Both groups of patients had similar rates of complication. Two patients (8.7%) who had NA developed subcutaneous emphysema (Table 3). One patient (4%) developed clinical signs of tension pneumothorax (which was subsequently confirmed radiologically) when the Heimlich valve was wrongly attached to the MCT. He was well after the immediate insertion of a chest tube. There were no other serious complications like death or massive hemothorax.

Both groups of patients had similar pain and satisfaction scores (Table 4).

More patients who had recurrent pneumothorax (27.3%) had pleurodesis compared with those who were having their first episode of pneumothorax (16.2%), but the difference was not statistically significant.

Discussion

Our results showed that most patients with primary spontaneous pneumothorax can be safely managed on an outpatient basis with either MCT or NA. In addition, there was a clinically important reduction of admissions from the

Table 4 Other outcomes

ED by 72% with MCT and 48% with NA, although the difference was not statistically significant.

Both these procedures allowed many patients who would have been admitted previously to be managed safely in the ambulatory setting. Compared with the hitherto practice of admitting all patients with primary spontaneous pneumothorax, there was significant savings of admission days. Patients who were previously treated with chest tube would have been admitted for an average of 7.4 days [10]. For patients treated with MCT insertion, there was 83% saving on admission days when both admissions from ED and the clinic were combined. For NA, there was 60% reduction in the number of admission days. This could possibly have implications for preserving inpatient beds in situations with Hospital overcrowding, which is surely a step in the right direction in this era of severe hospital bed shortage and escalating health care cost.

Our study is limited by the small number of patients in each arm. We were unable to achieve our targeted sample size of 100 due to low patient recruitment rate and inadequate funding to replace expired MCT. A possible study in future will be outpatient stepwise management of PSP, where NA and MCT attached to Heimlich valve are used in a stepwise manner.

Conclusion

Both MCT and NA allowed safe management of primary spontaneous pneumothorax in the outpatient setting. Both were equivalent in terms of failure rate, admission rate, pain score, satisfaction score, and complication rate. Among those who were successfully discharged from the ED, insertion of MCT attached to Heimlich valve was associated with a significantly higher rate of complete reexpansion of the pneumothorax at the first outpatient review.

Acknowledgments

The authors thank Dr Papia Sultana, Department of Clinical Research, Singapore General Hospital.

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NA (n = 23), median (IR) MCT (n = 25), median (IR) P a

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IR indicates interquartile range. a Mann-Whitney test.

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