Ventilation Management in a Patient with Ventilation–Perfusion Mismatch in the Early Phase of Lung Injury and during the Recovery

Round 1

Reviewer 1 Report

I have completed the evaluation of the article entitled ‘‘Electrical Injuries in Childrena 6-year retrospective Study’’ which you submitted to Frontiers. This retrospective study was conducted on 321 patients and ıt is a well-designed. However, minor revision is required. Especially, in discussion section and tables. The discussion section is too long and needs to be shortened. The number of table is large, 1-2 of the tables need to be removed. Although this study does not add new information to the current medical literature, I think it can contribute to the medical literature

Author Response

According to your suggestion, we added some statements so that conclusions are supported by the results. Thank you for suggestion. 

Your comments seems to be by mistake changed, and are not related to our manuscript. 

Reviewer 2 Report

Respiratory failure due to pulmonary trauma is sometimes difficult to manage. When complicated by infection, ICU stays are prolonged and prognosis is poor. This paper describes a case of S. maltophilia infection treated in addition to ventilatory management of chest trauma.

S. maltophilia is detected when broad-spectrum antimicrobial agents such as carbapenems are used, and the high level of resistance makes the choice of therapeutic agent difficult. In this case, the initial choice of antimicrobial agents is questionable. The patient was started on cefepime and levofloxacin and then changed to linezolid and meropenem. The reasons for choosing these agents are unclear. Is it the policy of the authors' institution ? Inappropriate antimicrobial use may have induced maltophilia infection.

There is nothing novel or special about the case course or discussion in this paper. No particular comments.

Author Response

Dear reviewer

Thank you for the review. Given that the microbiological samples taken at the time of admission were sterile and did not confirm causal agent, empiric antibiotics were introduced in view of the patient's severe general condition. Sometimes, during the treatment of patients, it happens that signs of pneumonia are described radiologically, but unfortunately not a single specimen can be isolated. Since his inflammatory parameters were very high, clinical presentation poor, and ventilation extremely difficult, antibiotics were chosen to cover Klebsiella and Pseudomonas strains. After no clinical response was obtained, within two days, these antibiotics were changed to cover both G+ and G- bacteria. After the detection of the causative agent, the antibiotic therapy was corrected.
We think that unventilated areas in our patient were infected by Stenotrophomonas at the beginning of his injury, but we were not able to obtain these samples until the bronchi were severely injured and obstructed and these lung areas were unventilated. 

Reviewer 3 Report

This is a case report of a 53 year old patient who presented with severe hypoxaemia 5 days after blunt trauma to the chest.  He was initially managed with broad-spectrum antibiotic therapy and weaned from ventilation after 10 days.  Five days later a resistant S maltophilia was identified and appropriate antimicrobial therapy commenced.  The authors use the discussion to highlight the prevalence of S maltophilia in patients receiving long-term broad spectrum antibiotics and also to highlight the physiological background of hypoxaemia in V/Q mismatch.

Major points:

11)      Given the hypoxaemia and need for mechanical ventilation was corrected prior to identification of S maltophilia, I would argue that the initial presentation was one of lung contusion and possible bacterial/viral infection which was successfully managed, followed by colonisation with S maltophilia.  This also fits with the inflammatory markers especially WBC and PLT which decline during the first week then increase again.  As such, the presentation is more of a “two-hit” insult.  I would be interested to know the author’s views here, and in particular whether there were any radiographic changes seen that would fit or refute this?

22)      During the prolonged phase of high inspired oxygen requirements and high inspiratory pressures, was any consideration given to:

a.       Continuous muscle relaxation?

b.       Prone positioning?

c.       ECMO?

33)      Please expand the section in the discussion regarding S maltophilia.  This is important for the general intensivist (I would argue the rest regarding ventilatory physiology is relatively well known).  In particular, please discuss prevalence, predisposing factors, typical progression and which antimicrobials it is usually resistant/sensitive to.

Minor points:

44)      Abstract: Line 23.  “… current blood bas values and oxygen saturation.  After S maltophilia …”.  The description here jumps forward by 15 days from initial management to identification of S maltophilia via bronchoscopy.  Please make this clearer to the reader.

55)      Introduction p2 line 44.  Please provide a reference for pulmonary embolism causing an increase in PaCO2.  Typically PaCO2 is insensitive to V/Q mismatch and reliably inversely proportional to minute alveolar ventilation due to the high solubility of CO2 (as opposed to O2 which is sensitive to V/Q mismatch).

66)      P2 line 45.  H2CO3 needs subscript for “2”.

77)      P2 line 46.  Duplication in “non – non-ventilated lung areas”

88)      P2 line 54.  “pO2” – please consistently use upper or lowercase for “P” here – “PaO2” was used earlier.

99)      Start of case report – “no comorbidities”.  It is later mentioned the patient stopped smoking.  Please provide smoking history – was there undiagnosed pre-existing lung disease?

110)   Fig 1B, Fig 2, Fig 3.  Thank you for providing the 3D reconstructions of lung CTs showing aerated regions.  Please could a representative axial slice with typical lung windows also be provided for each image so the reader can accurately see the progression in lung parenchymal disease.

111)   P3 line 81.  Please provide FiO2 at time of ABG analysis.

112)   P3 line 88.  “emergency thoracic CT” – is this figure 1B if so please mention this.

113)   P3 line 109.  I did not receive supplementary Video S1 so cannot comment on this.

114)   P3 line 149.  Table 1 legend – please add that these values were 6 months after the injury.

Author Response

Dar Reviewer 3 our answers are in the file attached 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Author Response

Thank you for your comment. 

Reviewer 3 Report

Thank you for the changes made to this manuscript.

If possible, please provide representative axial CT scans corresponding to Fig 1B, Fig 2 and Fig 3.  Whilst the 3D reconstructions and serial chest X-rays are good for highlighting regions of lung that are not aerated, they do not adequately identify the parenchyma of the non-ventilated lung which is much better demonstrated by the raw CT images.

My only other comment relates to p6 lines 221-222 "we could not prove it ... until the collapsed part of the lung was not ventilated".  Should this read "until the collapsed part of the was ventilated"?

Author Response

Dear Reviewer 3

as you suggested, we have attached representative axial CT scans corresponding to Fig 1B, Fig 2 and Fig 3. We have done this in Fig. 2A, B and C. This figure shows the dynamics of the pulmonary infiltrate.

Thank you for your comment