Ultrasound measurement Of Inferior VenaC”>Correspondence

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American Journal of Emergency Medicine

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Ultrasound Measurement Of Inferior Vena

Cava Collapse Predicts Propofol Induced Hypotension?

Keywords:

Ultrasound Sedation Hypotension Propofol

We thank the writers for their interest in our study. We defined sig- nificant hypotension as a systolic blood pressure (SBP) of b 90 mmHg, as this is the most commonly used definition for absolute hypotension. Al- ternatively, if a patient’s blood pressure has decreased causing the pro- vider to give a vasopressor we felt that also represented the outcome of interest. We chose to combine both of these scenarios into our final pri- mary outcome. We agree that the addition of a 30% SBP drop may also be significant, however it was not what we used in our definitions. Re- analysis of our data using a 30% or greater drop in SBP results in the fol- lowing table (Table 1):

Of note many more people experienced a 30% SBP reduction (28) than our definition of either a SBP b 90 mmHg or administration of a va- sopressor (22). Given that a 30% SBP reduction occurred in 70% of cases it may not be a useful cut point for determining Significant hypotension after Propofol administration.

When setting the timing of our data collection, we took into account the mean duration of action of Propofol. However, we extended this time period because it is the experience of the authors (both EM and An- esthesia) that hypotension may occur later than the sedative effects of Propofol. Additionally, there are other variables in the operating room out of our control such as the speed at which the Anesthesiologists de- liver the medication, size of bolus and timing of a saline flush to ensure the entire dosage of medication was delivered. To ensure we did not miss any cases of hypotension we extended the time of observation to 21 min which is just over double the mean duration of action (approx- imately 3-10 min) [1,2]. Other studies have used similar time frames when studying the hypotensive effects of Propofol [3].

We appreciate the authors calling attention to the power calcula- tion as there is one slight error in the difference we were trying to detect as outlined below. We used a standard sample size determina- tion for detecting the difference between two proportions. With a significance level of 0.05 and power of 0.80 and assuming an equal ratio of hypotension if the true incidence of Propofol Induced Hypo- tension (PIH) in the IVC-CI b 50% was 45% or lower (the original man- uscript wrote 15% or lower which was a typo on the author’s part) and the Incidence of PIH in the IVC-CI >= 50% was 75% or higher, only

26 total patients would need to be enrolled (13 in each group). We enrolled a higher amount for the reasons stated in the paper. We apologize for this misprint and hope this explanation makes the power calculation more understandable.

In reporting our data, regrettably, our data in Table 2 was inaccurately transcribed. The data originally published in Table 2 reflects only cases in which SBP dropped below 90 mmHg but was not inclusive of the cases of vasopressor administration. We do not believe that this error effects the stated conclusion. Table 2 should have read as follows (Table 2):

In regards to your comment of mentioning a gold standard for PIH, the authors are unaware of any “gold standard” definition. Throughout the background articles that are cited in our original manuscript varying definitions are used. For our study we used the definition previously mentioned of any SBP b 90 mmHg or administration of vasopressors. We recognize that there may be a more optimal definition and this would require further study. The test characteristics we cite for IVC-CI

>= 50% are to predict PIH as we have defined it in this paper.

Again, we appreciate the interest in our study. As originally stated, this study was not without its limitations. Further research is needed to vali- date these findings and to determine its applicability to the ED setting.

Funding sources/disclosures

None.

Arthur K. Au?

J. Matthew Fields

Department of Emergency Medicine, Thomas Jefferson University

Philadelphia, PA, USA

*Corresponding author at: 1020 Sansom Street, Suite 239 Thompson

Building, Philadelphia, PA 19107, USA

E-mail address: arthur.au@jefferson.edu

http://dx.doi.org/10.1016/j.ajem.2016.11.060

References

1. Carmichael FJ, Haas DA. General anesthetics. In: Kalant H, Roschlau WH, editors. Prin- ciples of Medical Pharmacology. 6th ed. New York: Oxford University Press; 1998.

   p. 278-92.

   Vuyk J, Sitsen E, Reekers M. Intravenous Anesthetics. In: Miller R, editor. Miller’s Anesthesia. 8th edition. Philadelphia: Elsevier Saunders; 2015. p. 826 [[accessed 2016 Oct 20] http://www.r2library.com/Resource/Title/0702052833/ch0030s1302].

2. Verbeek T. The hypotensive effect of propofol: An observational study. [ClinicalTrials.gov [Internet]] Bethesda (MD): National Library of Medicine (US); 2000[[cited 2016 Oct 20]. Available from: https://clinicaltrials.gov/show/ NCT01508351 NLM Identifier: NCT01508351].

   Table 1

   Frequency of echocardiographic abnormalities in the patients underwent transthoracic echocardiogram

   No-risk group (n = 47)

   Risk group (n = 97)

   ? Prior presentations: nonereply.

   Normal, n (%) 46 (97.9) 70 (72.2)

   http://dx.doi.org/10.1016/j.ajem.2016.11.060

   0735-6757/(C) 2016

   Table 2

   2 x 2 table of IVC-CI >=50% and Propofol Induced Hypotension (PIH)

   + PIH – PIH

   IVC-CI >= 50% 13 4

   IVC-CI b50% 9 14

   Test characteristics of an IVC-CI of >=50% for Predicting PIH. Sensitivity 59.09% (95% CI, 36.68-78.52).

   Specificity 77.78% (95% CI, 51.92-92.63).

   Positive predictive value 76.47% (95% CI, 49.76-92.18).

   Negative predictive value 60.87% (95% CI, 38.78-79.53).

   Odds ratio 5.05 (95% CI, 1.25-20.48).

   Comments: Ultrasound measurement of inferior vena cava collapse predicts propofol- induced hypotension

   

   We read with great interest the recent published article by Arthur K. Au et al. [1] in which authors aimed to explore whether infe- rior vena cava (IVC) assessment by ultrasound can assist in predicting propofol induced hypotension (PIH). Although it is a well-designed study, there are some points that need further clarity for a proper un- derstanding of the subject.

   The authors defined significant hypotension as a systolic blood pres- sure (BP) below 90 mm Hg and/or administration of a vasopressor to in- crease BP within 21 min after the administration of propofol. Their results showed that patients who developed PIH had lower value of pre-induc- tion BP than the patients who didn’t developed hypotension (135 vs 146) (Table 1). It is obvious that lower value of pre-induction BP would reach to the level of hypotension more frequently than the higher pre-in- duction value. In our opinion, apart from defined criteria for hypotension in the article, addition of 30% fall in the systolic blood pressure from the pre-induction value could have been a better definition of hypotension. Also we failed to understand why they have chosen 21 min time for ob- servation while the mean duration of action of propofol is 3-8 min [2].

   The sample size was calculated by assuming an approximate 50% rate of PIH, and the authors hypothesized that patients with an IVC- CI <= 50% would have a low rate (<= 10%) of PIH whereas patients with an IVC-CI >= 50% would have a high (>= 75%) rate of PIH. It would be highly appreciated if reference of method of sample size calculation describing Power/Alpha Error/Precision/Effect size and statistical method can be mentioned.

   In the result section, it is mentioned that 55% of all patients had significant hypotension which is not in line with the Table 2 where only 18 patients (45%) are shown to develop hypotension out of 40 patients. Similarly, further clarity is required in results findings “76% of patients with a IVC-CI >= 50% had significant hypotension compared to 39% with a IVC-CI <= 50%, P = 0.02", as findings again are not as per the figures mentioned in the Table-2. In the result section, the sensitiv- ity as well as specificity is mentioned quoting "IVC-CI >= 50% has a specificity of 77.27% (95%CI, 64.29%-90.26%) and sensitivity of 66.67% (95%CI, 52.06%-81.28%) in predicting PIH”. For the better under- standing of Readers, the Gold Standard for predicting PIH is needed to be mentioned [3].

   Sadik Mohammed, MD Pradeep Kumar Bhatia, MD, FICCM, FICA Department of Anesthesiology and Critical Care, AIIMS, Jodhpur

   Rajasthan, India

   ?Corresponding author at: Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Basani Phase II, Jodhpur

   Rajasthan 342005, India

   E-mail addresses: drmsadik@gmail.com (S. Mohammed)

   bhatia_pk@yahoo.com (P.K. Bhatia)

   Pankaj Bhardwaj, MD, MA, MS, Associate Professor

   Department of Community Medicine and Family Medicine, AIIMS, Jodhpur

   Rajasthan, India E-mail address: pankajbhardwajdr@gmail.com

   Kamal Kishore, MD, Additional Professor

   Department of Anesthesiology and Critical Care, AIIMS, Jodhpur

   Rajasthan, India E-mail address: kamalkishore.sgpgi@gmail.com

   http://dx.doi.org/10.1016/j.ajem.2016.11.025

   References

   Au AK, Steinberg D, Thom C, Shirazi M, Papanagnou D, Ku SB, et al. Ultrasound measurement of inferior vena cava collapse predicts propofol induced hypotension. Am J Emerg Med 2016;34:1125-8.

3. J E Reeves, Peter SA Glass. Intravenous anesthetics: chapter 30; p. 880. Miller’s Anes- thesia 8th edition.
4. Parikh R, Mathai A, Parikh S, Chandra Sekhar G, Thomas R. Understanding and using sensitivity, specificity and predictive values. Indian J Ophthalmol 2008;56(1):45-50.

   Comparison of blind intubation through the I-gel and the Air-Q(TM) by novice physicians during cardiopulmonary resuscitation: A randomized, crossover, manikin trial

   

   Sir,

   Airway management is one of the key skills that health care profes- sionals should have [1,2]. Physicians and paramedics should be able to perform advanced airway management since they are often the first who witness or have to respond to a deteriorating patient. Airway man- agement is the integral part of resuscitation and in Poland endotracheal intubation using direct laryngoscopy is perceived as a routine approach. Tracheal intubation is still considered to be the “gold standard” in main- taining a Secure airway and providing effective ventilation [3]. However, during resuscitation, endotracheal intubation performed by rescuers in- experienced in intubation caused a prolonged period of chest compres- sion pause. Therefore, inexperienced in direct laryngoscopy personnel should seek alternative methods for airway control for example videolaryngoscopes [1,2] or supraglottic airway devices (SADs) [4]. As shown in several studies, it is possible to perform blind intubation using SAD, especially in case of unsuccessful intubation using direct lar- yngoscopy [5,6].

   The aim of the study was to determine the effectiveness of blind in- tubation using Supraglottic airway devices performed by novice physicians.

   Before the study, all participants took part in a 45-minute training including anatomy, physiology and pathophysiology of the respira- tory tract, as well as methods for airway control, including endotra- cheal intubation. Then the instructor demonstrated the correct endotracheal intubation using I-gel (size 4; Intersurgical Ltd., Berk- shire, UK; Fig. 1) and Air-Q (size 3.5; Cookgas LLC, Mercury Medical, Clearwater, FL, USA).

   Participants had the opportunity to practice the airway management using I-gel and the Air-Q and blindly perform endotracheal intubation using these devices as a guide for the endotracheal tube. The practical training took 5 min for each device. A standard 6.5 cuffed tracheal tube lubricated with silicon aerosol was used. Each participant preformed intubation on the Airway Assessment Training model (BT- CSIE, BT Inc., Republic of Korea).

   During the target study, both the order of participants and order of devices were randomly assigned using the Research Randomizer