Best Evidence Topics
  • Send this BET as an Email
  • Make a Comment on this BET

In traumatic haemothoraces and haemopneumothoraces, are small bore seldinger chest drains non-inferior to large bore open drains?

Three Part Question

In [adult patients with traumatic heamothoraces or haemopneumothoraces requiring drainage] are [small bore (16Fr or less) seldinger drains non-inferior to open large bore (20Fr or more) thoracostomy tubes] at [reducing rates of retained haemothorax]?

Clinical Scenario

An 82 year old lady is brought in by ambulance after falling down a flight of stairs. He vital signs are unremarkable and she undergoes a whole body CT after the primary survey. This reveals a moderate right sided haemothorax. The trauma team are in agreement that drainage is indicted. Should a 28-38Fr open thoracostomy tube or a smaller (16Fr or less) seldinger drain be inserted?

Search Strategy

In 2020, the Eastern Association for the Surgery of Trauma (EAST) published guidelines which included a systematic review and meta-analysis on this topic. It was deemed reasonable to repeat a search limited to dates subsequent to their paper (24th March 2019). An update to the literature search was performed limited from 2019 to the 15th of June 2022. The databases searched were Medline (via Ovid), EMBASE (via Ovid) and CENTRAL (via Wiley).
1) wounds and injuries).mp. [mp=title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]

2) (trauma or traumas or traumatic or polytrauma or polytraumas or injury or injuries or injured or injure or injuring or blunt or crush or crushed or penetrate or penetrates or penetrating or penetrated or penetration or non-penetrating or fracture or fractures or fractured or lacerate or lacerates or lacerated or laceration or lacerations or perforation or perforations or perforate or perforates or perforated or rupture or ruptures or ruptured or falls or falling or abrasion or abrasions or contusion or contusions or wound or wounds or wounded or wounding or motor vehicle collision or motor vehicle collisions or motor vehicle accident or motor vehicle accidents or motor vehicle crash or motor vehicle crashes or car accident or car accidents or car crash or car crashes or vehicular accident or vehicular accidents or vehicular collision or vehicular collisions or vehicular crash or vehicular crashes or traffic accident or traffic accidents or MVC or traffic crash or automobile crash or automobile crashes or automobile collision or automobile collisions or automobile accident or road traffic accident or road traffic accidents or road traffic collision or road traffic collisions or Hematoma or hematomas or hematoma or haematomas or gunshot or gunshot or firearm or firearms or stab or stabbed or stabbing or burn or burns or burned or hemorrhage or hemorrhages or hemorrhaged or hemorrhaging or haemorrhage or haemorrhages or haemorrhaged or hemorrhaging or bleeding or bleed or bleeds or bled).mp.

3) hemopneumothorax/ or hemothorax/

4) "wounds and injuries"/ or accidental injuries/ or burns/ or crush injuries/ or lacerations/ or multiple trauma/ or rupture/ or shock, traumatic/ or thoracic injuries/ or flail chest/ or lung injury/ or rib fractures/ or war-related injuries/ or wounds, nonpenetrating/ or wounds, penetrating/ or wounds, gunshot/ or wounds, stab/

5) hemothorax or haemothorax or hematothorax or haematothorax or hemothoraces or haemothoraces or hematothoraces or haematothoraces or HTX or hemopneumothorax or haemopneumothorax or hemopneumothoraces or haemopneumothoraces or hematopneumothorax or haematopneumothorax or hematopneumothoraces or haematopneumothoraces).mp.

6) Chest Tubes/

7) Drainage/

8) Catheterization/

9) Catheters/

10) (catheterization or catheterisation or catheter or catheters or drain or drains or drainage or chest drain or chest drains or chest tube or chest tubes or intercostal drain or intercostal drains or intercostal tube or intercostal tubes or Seldinger or Seldinger drain or Seldinger drains or Seldinger catheter or Seldinger catheters or pigtail or pigtails or pig tail or pig tails or tube or tubes or large bore or small bore).mp. [mp=title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]

11) 1 or 2 or 4

12) 3 or 5

13) 6 or 7 or 8 or 9 or 10

14) 11 and 12 and 13

15) limit 14 to (adaptive clinical trial or classical article or clinical conference or clinical study or clinical trial, all or clinical trial, phase i or clinical trial, phase ii or clinical trial, phase iii or clinical trial, phase iv or clinical trial or comparative study or controlled clinical trial or "corrected and republished article" or dataset or equivalence trial or evaluation study or guideline or journal article or meta analysis or multicenter study or observational study or practice guideline or pragmatic clinical trial or preprint or randomized controlled trial or "systematic review")

16) limit 15 to humans

17) limit 16 to english language

18) limit 17 to yr="2019 -Current"

Search Outcome

The literature search yielded a total of 249 publications, 36 of which were duplicates leaving 213 papers for screening. 197 papers were excluded because they were not related to the study question. The remaining 16 papers were included for full text review. Of these, 11 papers were excluded because they were the wrong study design. One paper was excluded because it was an unfinished clinical trial. One paper was excluded because it was the EAST systematic review already included as mentioned above. This left 3 papers for full text review.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Patel NJ et al
A combined total of 1191 patients with traumatic HTX (with or without PTX) were included.Systematic review and meta-analysis. The systematic review identified 4 relevant papers which included 1 RCT, 2 prospective observational studies and 1 retrospective study. They compared small bore seldinger drains (14Fr or less) with open tube thoracostomy (20 or more). Meta-analysis could only be performed for the first two outcomes listed due to study heterogeneity.Primary outcome: risk of retained HTX (reported by 4/4 studies)Pigtail catheter group (n=475) failure rate = 18.3% vs thoracoscopy tube group (n= 716) failure rate = 22.3%. RR 0.87, [0.56-1.3]. No statistically significant difference.he included studies were of generally low quality with only one RCT. The studies are at risk of bias (particularly selection bias and observer bias) and are heterogeneous with regards to outcomes measured, intervention and study population. The confidence interval around the primary outcome are broad, meaning that clinically significant harm (or benefit) associated with the small-bore group cannot be excluded with a high degree of certainty. Most of the papers were non-randomised in design increasing risk of confounding and bias. It also limits the ability to identify causal associations.
Need for additional procedure specified as operative intervention or additional catheter/tube insertion (reported by 3/4 studies).Pigtail catheter group (n=439) additional procedure rate = 3.9% vs thoracoscopy tube group (n= 691) additional procedure rate = 13%. RR 0.45 [0.21-0.99]. Statistically significant difference.
Rate of empyema (1 study)Pigtail catheter group = 3.8%. Thoracostomy group 1.4%. No statistically significant difference.
Bauman ZM et al
43 adult patients with traumatic HTX/HPTX requiring drainage randomised to 14Fr seldinger pigtail catheters or to 28-32Fr open thoracostomy tubes. Patients requiring emergency tube placement were excluded.RCTPrimary outcome: Failure rate, defined as retained HTX requiring a second intervention or recurrent PTX requiring additional intervention.Pigtail catheter group (n=20 ) failure rate = 10% vs thoracoscopy tube group (n= 23) failure rate = 17%. P=0.49. No statistically significant difference.This was a small study which failed to meet its planned sample size, limiting the precision of its results and its ability to exclude a modest harm (or benefit) in one of the groups. The RCT was stopped early after an unplanned interim analysis due to slow recruitment and limited resources. This increases risk of overestimating treatment effects. Furthermore, there was no blinding of groups for assessment of outcomes or for statistical analysis. These factors all increase the risk of bias. The study was performed at a single centre study, limiting generalisability and potentially introducing further bias. There was a trend towards pigtail catheters being placed later than thoracostomy tubes with a median and IQ range of 2.5 (1,5) and 1 (1,2) respectively. Although this difference was not statistically significant, due to small numbers it may be a clinically significant suggesting differences between the two groups that were not accounted for. 60 patients were excluded from the analysis, 22 because of emergency placement and 11 because the “clinician forgot.” This increases risk of selection bias and limits generalisability. In this trial all drains were left on continuous suction, which is not routine practice in the UK, again limiting generalisability.
Drain output, tube days, ventilator days, ICU days, hospital length of stayo statistically significant difference.
Insertion perception score (1 best, 5 worst) medianPigtail catheter group = 1. Chest tube group = 3 (p=0.001). Statistically significant difference.
Kulvatunyou N et al
This RCT included 119 adult patients with traumatic HTX/HTPX requiring drainage. Exclusion criteria included haemodynamic instability. 56 patients were randomised to 14Fr Pigtail seldinger catheters, 63 patients to 28-32Fr open thoracostomy tubes.RCTFailure rate, defined as retained HTX requiring a second intervention.Pigtail catheter group = 11%. Chest tube group = 13% (p=0.74). No statistically significant differenceThe RCT was stopped early after an unplanned interim analysis due to slow recruitment and the COVID-19 pandemic. This increases risk of bias and overestimation of treatment effects. The study failed to meet the planned sample size and may be underpowered to detect clinically significant differences between the two groups. The degree of statistical imprecision means that we cannot conclude with a high degree of confidence that pigtail catheters are non-inferior to thoracotomy tubes. We cannot exclude that pigtail catheters are associated with clinically significant harm (or benefit). There was a non-statistically significant trend towards the pigtail group having their drains inserted later compared to the thoracostomy tube group, increasing the possibility of cofounding. 102 patients were excluded from the trial; 43 due to ‘emergency placement’ and 27 because of ‘MD preference.’ This raises concern of selection bias and reduces the generalisability of the results. In this trial all drains were left on continuous suction, which is not routine practice in the UK, which may limit external validity. It is unclear whether some of the patients included were also part of the Bauman et al trial above, as their enrolment dates overlap and it was conducted by the same group. The trial was partly industry funded, although the authors report that industry had no involvement in study design, delivery, data interpretation or reporting of results which should limit risk of bias. Non-permuted block of four randomisation was used, which could potentially had led to unblinding in some cases. IPE score is not a validated tool, but is intuitive and the findings believable so the findings are likely to be valid.
Initial drain output, (median, ml)Pigtail catheter group = 600ml. Chest tube group = 400ml (p=0.005). Statistically significant difference.
Output at 24h (median)Pigtail catheter group = 930ml. Chest tube group = 685ml (p=0.05). Not statistically significant.
Output at 48h (median)Pigtail catheter group = 150ml. Chest tube group = 180ml (p=0.77). Not statistically significant.
Output at 72h (median)Pigtail catheter group = 45ml. Chest tube group = 130ml (p=0.28). Not statistically significant.
Insertion perception score (1 best, 5 worst) medianPigtail catheter group = 1. Chest tube group = 3 (p<0.001). Statistically significant.
Ventilator day median (IQR)Pigtail catheter group = 0 (0-2). Chest tube group = 0 (0-0) (p=0.13). Statistically non-significant.


Our systematic search identified three papers relevant to the question published since the EAST literature search. These included two RCTs and one retrospective observational cohort study. The studies are limited by their size, precision, heterogeneity and design. They are at significant risk of several types of bias. Despite this, their findings are generally consistent in that they found no significant difference in rates of retained HTX in patient managed with 14Fr seldinger chest drains when compared to 28-32Fr thoracostomy tubes. However, there is significant impression in the results, as illustrated by the wide confidence intervals around the EAST meta-analysis outcome on retained haemothoraces. The trials published since have similar limitations due to their relatively small size. This means that modest but clinically significant harm (or benefit) associated with 14Fr seldinger drains cannot be confidently excluded. Further meta-analysis at this point may improve the precision, but would be unlikely to be sufficient. The groups appeared to perform similarly with respect to most secondary outcomes, with the exception of pain scores on insertion which were consistently found to be lower in the 14Fr seldinger group. Whilst the EAST meta-analysis reported a significantly reduced need for additional interventions in the small bore seldinger drain group, the studies published since observed a trend in this direction rather than a statistically significant difference. The secondary outcomes on drain output indicate that the 14Fr or less group had comparable drain outputs at most time points and indeed higher outputs in one of the secondary outcomes. This suggests the commonly held belief that smaller drains inserted for HTX will be ineffective due to obstruction from clotted blood is unfounded. As the trial results are generally consistent with each other as well as with the findings of the EAST meta-analysis we can have reasonable confidence that there is proof-of-concept that small bore seldinger chest drains may be non-inferior or even confer certain benefits over large bore thoracostomy tubes. Important limitations in the current literature were found, which lead to limited generalisability and translation to immediate changes to clinical practice: 1. Patients with haemodynamic instability were generally excluded, limiting generalisability to the whole trauma population/ED setting. 2. All studies were at significant risk of selection bias and as discussed above, low precision. 3. The use of ultrasound for small bore drain insertion may limit applicability to current UK EM practice. 4. None of the trials were designed to test non-inferiority (which is likely to need far higher recruitment numbers), however based on the findings of this review alternative trial designs such as superiority could be considered depending on the primary outcome selected. 5. Patient and public involvement was lacking in all studies to inform the optimal primary outcome and understand other potential benefits to patients of small-bore chest drains.

Clinical Bottom Line

This updated literature search provides proof-of-concept that small bore (16Fr or smaller) seldinger chest drains may be of benefit in selected, haemodynamically stable patients with traumatic haemothoraces and haemopneumothoraces. We conclude that, given ongoing concern around limitations described, there is insufficient evidence to inform widespread change in current practice or consensus guidelines generalisable to the UK trauma population and further evidence is needed.


  1. Patel NJ et al Management of simple and retained hemothorax: A practice management guideline from the Eastern Association for the Surgery of Trauma The American Journal of Surgery 2021;221(5):873-884.
  2. Bauman ZM et al Randomized Clinical Trial of 14-French (14F) Pigtail Catheters versus 28-32F Chest Tubes in the Management of Patients with Traumatic Hemothorax and Hemopneumothorax. World Journal of Surgery 2021;45(3):880-886
  3. Orlando A et al Comparing complications of small-bore chest tubes to large-bore chest tubes in the setting of delayed hemothorax: a retrospective multicenter cohort study. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine 2020 Jun 22;28(1):56.
  4. Kulvatunyou N et al The small (14 Fr) percutaneous catheter (P-CAT) versus large (28-32 Fr) open chest tube for traumatic hemothorax: A multicenter randomized clinical trial. Journal of Trauma and Acute Care Surgery 2021;91(5):809-813.