Dear Dr. Natalie Pafitis,
In response to your letter dated May 17, 2011, I would like to submit the revised
version of our manuscript entitled: “Subcutaneous dissociative conscious sedation
(sDCS) an alternative method for airway regional blocks: A new approach”
I considered your comments and included all requested parts and highlighted them
in the manuscript.
I considered all comments of the reviewers point by point and marked them in the
manuscript.
Sincerely yours
Dr. Javid
Dear Dr. Ray,
Thank you for reviewing the manuscript and your comments.
Question 1: “The study lacks impact as only 30 patients were studied.”
Answer: Difficult airway is not a common problem but it is of significant importance.
Although the sample size should be bigger to confirm the effectiveness and safety of a
new method, regarding to the sample size in similar studies in the field of difficult
airway (references 5,7,9 10,11), as a preliminary study, the present study could be
suggestive of the future studies with a bigger sample size.
Question 2: “The technique was not compared with alternative sedation such as
midazolam.”
Answer: Keeping spontaneous ventilation in predicted difficult airway is of paramount
importance and using midazolam as mentioned in references (21, 22) causes an
unintended deep sedation, hypoxemia, desaturation and upper airway obstruction
which is irreversible with flumazenil. Usual methods of sedation in difficult airway
may be accompanied by the risk of respiratory depression or apnea and patients’
safety may be overshadowed by these complications.
Question 3:” In the introduction no rationale is given for why you studied the effects of
ketamine though you do cover this in the discussion.”
Answer: I agree with you. There was something missed in the introduction. I included
some statements to make it clear.
Question 4: “The methods lack some clarity and detail. For example why was 0.6-0.7
mg/kg”.
Answer: The dose of ketamine decreases about 0.1mg.kg in patient with poor physical
condition. We use the lower limit in poor condition patients and the upper limit in
patients with a good physical condition.
Question5: “The dose given? 3-4 mcg/kg fentanyl is quite a large dose
and would have been better given in a fixed dose ie either 3 or 4 mcg/kg. How
much lidocaine spray was used in each patient?”
Answer: Fentanyl is given 3mcg/Kg. As mentioned in the” Methods” additional
intravenous fentanyl (50-100ug) is administered if the level of sedation is not
appropriate to keep the patient moveless during direct laryngoscopy. The dose
4mcg/Kg is the upper limit. Lidocaine spray 4% was used 1-2ml regarding to the
patients’ need.
Question 6:” The final paragraph on page 6 is not correctly placed and the comments
are not backed up with supporting references.”
Answer: The final paragraph on page 6 is a part of method. I agree with you. As you
mentioned it is not correctly placed and makes misunderstanding. I changed the
statement in the manuscript..
Question 7:” In the discussion on page 9 you state that dissociative conscious sedation
is the same as dissociative conscious anesthesia - I would take issue with this
comment as sedation and anesthesia are not the same entity.”
Answer: In the discussion on page 9 I stated that: Dissociative conscious sedation or
in other words dissociative conscious anesthesia is defined as……
Regarding to medical terminology, anesthesia is defined as: “loss of feeling or
awareness”. (Medical dictionary)
Epidural and spinal anesthesia are kinds of anesthesia with loss of feeling without
affecting awareness. Dissociative conscious sedation is kind of anesthesia with
loss of feeling and loss of awareness.
Question 8:” You also state that anesthesiologists are not interested in using
ketamine as an anesthetic becauseof its adverse effects - this is certainly not
representative of European or Australian practice where ketamine is being used
increasingly, particlularly in the critically ill”.
Answer: I agree with you. I removed inappropriate sentence.
Question 9: You comment that side effects of ketamine can be avoided by
keeping the plasma concentration below 150 ng/ml - it would have been helpful if
you had measured the plasma concentration of ketamine in your study to support
your observations.
Answer: As a fact It has been mentioned in literature that complications of ketamine are
dose dependent and the renewed interest in ketamine is related to the use of
smaller doses (100 to 250 µg/kg) as an adjuvant during anesthesia because the
sub-anesthetic dose of ketamine is accompanied by low plasma concentration of 85160 mcg/ml and low complication rate (Clinical Anesthesia 2009 Chapter 18).
References 29,30 and 17 indicate the low concentration of ketamine and low
complication rate while using subcutaneously.
Question 10: Your conclusion that subcutaneous ketamine as part of sDCS is safe
needs tempered - it is not possible to be sure the technique is safe based on only 30
patients, one of whom developed hypertension.
Answer: This method has been used in 60 patients previously(reference 17) and
reported as a method of safety in maintaining spontaneous ventilation which is the
rational of the present study).
Thank you,
Dr. Javid
Dear Dr. Holger Herff,
Thank you for reviewing the manuscript and for your kind comments.
Comment 1: “Sections given in bold letters should be changed to normal letters”
The bold letters was changed to normal letters.
Comment 2: I see the last paragraph of the introduction ("Some points should be in
mind...")asa comment and suggest placement in the discussion. For example middle
paragraph on page 10 (After reference 29, 30). However, that decision is at the
authors (or editors) discretion.
As you mentioned I made some changes in that paragraph and highlighted it.
Sincerely Yours,
Dr.Javid