- Email: [email protected]
Body mass index is associated with inappropriate tidal volumes in adults intubated in the ED
Body Mass Index is Associated With Inappropriate Tidal Volumes in Adults Intubated in the Emergency Department Munish Goyal MD, Shannon K. Graf MD, MS, Anu Bhooshan MD, Eshetu Tefera MS, William J. Frohna MD PII: DOI: Reference:
S0735-6757(16)30102-4 doi: 10.1016/j.ajem.2016.04.052 YAJEM 55775
To appear in:
American Journal of Emergency Medicine
Received date: Revised date: Accepted date:
10 March 2016 28 April 2016 30 April 2016
Please cite this article as: Goyal Munish, Graf Shannon K., Bhooshan Anu, Tefera Eshetu, Frohna William J., Body Mass Index is Associated With Inappropriate Tidal Volumes in Adults Intubated in the Emergency Department, American Journal of Emergency Medicine (2016), doi: 10.1016/j.ajem.2016.04.052
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Body Mass Index is Associated With Inappropriate Tidal Volumes in Adults Intubated in the Emergency Department
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Munish Goyal, MDa,b, Rahul Bhat, MDa, Shannon K. Graf, MD, MSa, Jeffrey S. Dubin, MD, MBAa, Anu Bhooshan, MDa, Eshetu Tefera, MSe, William J. Frohna, MDa a
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Munish Goyal – [email protected] Rahul Bhat – [email protected] Shannon K. Graf – [email protected] Jeffrey S. Dubin – [email protected] Anu Bhooshan – [email protected] Eshetu Tefera – [email protected] William J. Frohna – [email protected]
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Department of Emergency Medicine, MedStar Washington Hospital Center, 110 Irving Street NW, NA1177, Washington DC 20010 b Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, MedStar Washington Hospital Center, 110 Irving Street NW, NA1177, Washington DC 20010 c Department of Biostatistics and Bioinformatics, MedStar Health Research Institute, 6525 Belcrest Road, Suite 700, Hyattsville, MD 20782
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Address for reprints: Department of Emergency Medicine, 110 Irving Street NW, Washington DC 20010. No reprints will be ordered.
CE
Financial Support: This work was supported by a Graduate Medical Education Grant from MedStar Washington Hospital Center for statistical support.
AC
Corresponding Author: Rahul Bhat MD, Department of Emergency Medicine, MedStar Washington Hospital Center, 110 Irving Street NW, NA1177, Washington DC 20010 phone 202-329-1376, email: [email protected]
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Introduction Emergency physicians (EPs) often care for mechanically ventilated patients[1]. Ventilator settings in the
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emergency department (ED), however, have not been adequately examined. Evidence-based, consensus guidelines for patients without acute lung injury (ALI) are lacking. Existing data suggest that using low
SC
TV ventilation in patients without ALI may decrease lung injury, inflammation, and mortality[2]. The impact of obesity on ventilator strategies is poorly defined, but is associated with increased morbidity[3].
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We sought to determine the frequency of inappropriate TV settings in adults intubated in the ED and if
MA
body mass index (BMI) is associated with inappropriate TV settings. Materials and methods
This was a retrospective study analyzing existing data collected by trained and monitored research
ED
assistants blinded to the hypotheses, using standardized forms, of all patients intubated in the 84,000
PT
annual visit ED of an urban, tertiary-care, teaching hospital from November 14, 2009 to June 1, 2011, and was approved by the local institutional review board.
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Patients identified by chart review from all ED visits with a current procedural terminology code for endotracheal intubation. Patients were included if ventilator management in the ED was confirmed and
AC
excluded if data were incomplete. Age, gender, weight, height, admitting diagnoses, and set TV were recorded. Ideal body weight (IBW) and BMI were calculated. Each patient’s BMI was categorized based on the World Health Organization classification. Patients were assigned a binomial value of “appropriate TV” (≤10cc/kg IBW) or “inappropriate” TV (>10cc/kg IBW).
For the continuous variables, the differences in means between the two groups were tested using a t-test. Pearson’s Chi-squared test was used to investigate the differences between categorical variables. Univariate logistic regression examined the relationship between the categorical outcome of inappropriate
2
ACCEPTED MANUSCRIPT TV and predictors BMI and IBW. A multivariate logistic regression analysis then controlled for confounders. Additionally, an ANOVA test was used to examine if there was a statistically significant
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difference between the mean TV (in cc/kg of IBW) in each BMI category.
Results
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Of 618 charts reviewed, 101 were excluded due to death prior to ventilator initiation or incomplete data. Of the 517 patients analyzed, 46% were female, mean age was 59 years, and mean BMI was 28.4 kg/m2.
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A total of 112 patients (21.7%) had inappropriately set TV. Overweight (n = 156) and obese (n= 165)
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patients accounted for 62% of the cohort, while underweight (n = 30) and normal BMI (n = 166) accounted for the remaining 38%. Patients in overweight and obese categories had higher unadjusted odds
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of receiving inappropriate TV, as did older and female patients. After adjusting for age and gender, patients in the overweight and all three obesity categories continued to have higher odds of receiving
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inappropriate TV compared with normal BMI (table 1). Additionally, as BMI rose from underweight to
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class III obesity, TV (in cc/kg of IBW) increased (figure 1).
Comparison
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Odds of receiving inappropriate tidal volume Odds Ratio (95% CI)
Underweight vs Normal
0.17 (0.02, 1.41)
Overweight vs Normal
2.54 (1.31, 4.91)
Class I Obesity vs Normal
2.30 (1.09, 4.84)
Class II Obesity vs Normal
3.98 (1.64, 9.63)
Class III Obesity vs Normal
7.68 (3.34, 17.66)
Table 1. Logistic regression of the categorical outcome variable “inappropriate tidal volume” on BMI categories, after adjusting for potential confounding factors age and gender.
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Discussion
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We demonstrated that higher BMI is associated with inappropriate TV settings in a heterogeneous patient population intubated in a single, adult ED. Increasing categories of BMI are associated with higher odds
SC
of inappropriate TV settings, suggesting a dose-response. Overall, 21.7% of patients had initial TV settings greater than 10 cc/kg IBW, across all BMI categories, suggesting a need to broadly examine ED
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ventilator strategies.
MA
After ensuring oxygenation, ventilation, and airway protection, lung protection is paramount; however, no evidence-based, national guidelines for ED ventilator management exist. It is reasonable to assume lung
ED
protective strategies with demonstrated benefit in ICU patients with ALI/ARDS should also benefit ED patients[4]. There are few data to guide ventilator strategies in patients without ALI/ARDS[5]. In a
PT
systematic review, Fuller, et al. noted that lower TVs reduce progression to ALI/ARDS; however, the
CE
data are too heterogeneous to make definitive recommendations[6]. The authors also noted that progression to ALI/ARDS occurs in as little as five hours in at-risk patients, further highlighting the
AC
importance of ventilator strategies in the ED.
It is our experience that ventilator settings are rarely changed while patients are in the ED, and often not until the attending intensivist sees the patient. This treatment momentum and the relevance of ED therapy as being continued in the ICU is likely not unique to our ED, and has been reported in other studies[3].
Limitations We defined the upper limit of appropriate TV as 10 cc/kg IBW. It is possible that the optimal TV is lower, in which case our data under-represent the actual number of patients with inappropriate TV. We were unable to evaluate the clinician’s reasoning for placing an individual patient on a particular ventilator
4
ACCEPTED MANUSCRIPT setting; although, we could not find any evidence-based guidelines to place any patients on TV greater than 10cc/kg IBW.
T
Conclusions
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Higher BMI is associated with increasing odds of receiving inappropriate TV in the ED. 21.7% of adults intubated in the ED have inappropriately set initial TV. Efforts to improve adherence with IBW-based TV
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are warranted.
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6.
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4.
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3.
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2.
Mullins PM, Goyal M, Pines JM: National growth in intensive care unit admissions from emergency departments in the United States from 2002 to 2009. Academic Emergency Medicine 2013, 20(5):479-486. Gajic O, Dara SI, Mendez JL, Adesanya AO, Festic E, Caples SM, Rana R, St Sauver JL, Lymp JF, Afessa B et al: Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation. Crit Care Med 2004, 32(9):1817-1824. Fuller BM, Mohr NM, Dettmer M, Kennedy S, Cullison K, Bavolek R, Rathert N, McCammon C: Mechanical ventilation and acute lung injury in emergency department patients with severe sepsis and septic shock: an observational study. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine 2013, 20(7):659-669. Investigators A: Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. The Acute Respiratory Distress Syndrome Network. New England Journal of Medicine 2000, 342(18):1301-1308. Serpa Neto A CS, Manetta JA, Pereira VG, Esposito DC, Pasqualucci Mde O, Damasceno MC, Schultz MJ: Association between use of lung-protective ventilation with lower tidal volumes and clinical outcomes among patients without acute respiratory distress syndrome: a meta-analysis. JAMA 2012, 308(16):1651-1659. Fuller BM, Mohr NM, Drewry AM, Carpenter CR: Lower tidal volume at initiation of mechanical ventilation may reduce progression to acute respiratory distress syndrome: a systematic review. Critical care (London, England) 2013, 17(1):R11.
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1.
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References:
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Figure 1
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ACCEPTED MANUSCRIPT
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S0735-6757(16)30102-4 doi: 10.1016/j.ajem.2016.04.052 YAJEM 55775
To appear in:
American Journal of Emergency Medicine
Received date: Revised date: Accepted date:
10 March 2016 28 April 2016 30 April 2016
Please cite this article as: Goyal Munish, Graf Shannon K., Bhooshan Anu, Tefera Eshetu, Frohna William J., Body Mass Index is Associated With Inappropriate Tidal Volumes in Adults Intubated in the Emergency Department, American Journal of Emergency Medicine (2016), doi: 10.1016/j.ajem.2016.04.052
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Body Mass Index is Associated With Inappropriate Tidal Volumes in Adults Intubated in the Emergency Department
T
Munish Goyal, MDa,b, Rahul Bhat, MDa, Shannon K. Graf, MD, MSa, Jeffrey S. Dubin, MD, MBAa, Anu Bhooshan, MDa, Eshetu Tefera, MSe, William J. Frohna, MDa a
ED
MA
NU
Munish Goyal – [email protected] Rahul Bhat – [email protected] Shannon K. Graf – [email protected] Jeffrey S. Dubin – [email protected] Anu Bhooshan – [email protected] Eshetu Tefera – [email protected] William J. Frohna – [email protected]
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Department of Emergency Medicine, MedStar Washington Hospital Center, 110 Irving Street NW, NA1177, Washington DC 20010 b Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, MedStar Washington Hospital Center, 110 Irving Street NW, NA1177, Washington DC 20010 c Department of Biostatistics and Bioinformatics, MedStar Health Research Institute, 6525 Belcrest Road, Suite 700, Hyattsville, MD 20782
PT
Address for reprints: Department of Emergency Medicine, 110 Irving Street NW, Washington DC 20010. No reprints will be ordered.
CE
Financial Support: This work was supported by a Graduate Medical Education Grant from MedStar Washington Hospital Center for statistical support.
AC
Corresponding Author: Rahul Bhat MD, Department of Emergency Medicine, MedStar Washington Hospital Center, 110 Irving Street NW, NA1177, Washington DC 20010 phone 202-329-1376, email: [email protected]
1
ACCEPTED MANUSCRIPT
Introduction Emergency physicians (EPs) often care for mechanically ventilated patients[1]. Ventilator settings in the
RI P
T
emergency department (ED), however, have not been adequately examined. Evidence-based, consensus guidelines for patients without acute lung injury (ALI) are lacking. Existing data suggest that using low
SC
TV ventilation in patients without ALI may decrease lung injury, inflammation, and mortality[2]. The impact of obesity on ventilator strategies is poorly defined, but is associated with increased morbidity[3].
NU
We sought to determine the frequency of inappropriate TV settings in adults intubated in the ED and if
MA
body mass index (BMI) is associated with inappropriate TV settings. Materials and methods
This was a retrospective study analyzing existing data collected by trained and monitored research
ED
assistants blinded to the hypotheses, using standardized forms, of all patients intubated in the 84,000
PT
annual visit ED of an urban, tertiary-care, teaching hospital from November 14, 2009 to June 1, 2011, and was approved by the local institutional review board.
CE
Patients identified by chart review from all ED visits with a current procedural terminology code for endotracheal intubation. Patients were included if ventilator management in the ED was confirmed and
AC
excluded if data were incomplete. Age, gender, weight, height, admitting diagnoses, and set TV were recorded. Ideal body weight (IBW) and BMI were calculated. Each patient’s BMI was categorized based on the World Health Organization classification. Patients were assigned a binomial value of “appropriate TV” (≤10cc/kg IBW) or “inappropriate” TV (>10cc/kg IBW).
For the continuous variables, the differences in means between the two groups were tested using a t-test. Pearson’s Chi-squared test was used to investigate the differences between categorical variables. Univariate logistic regression examined the relationship between the categorical outcome of inappropriate
2
ACCEPTED MANUSCRIPT TV and predictors BMI and IBW. A multivariate logistic regression analysis then controlled for confounders. Additionally, an ANOVA test was used to examine if there was a statistically significant
RI P
T
difference between the mean TV (in cc/kg of IBW) in each BMI category.
Results
SC
Of 618 charts reviewed, 101 were excluded due to death prior to ventilator initiation or incomplete data. Of the 517 patients analyzed, 46% were female, mean age was 59 years, and mean BMI was 28.4 kg/m2.
NU
A total of 112 patients (21.7%) had inappropriately set TV. Overweight (n = 156) and obese (n= 165)
MA
patients accounted for 62% of the cohort, while underweight (n = 30) and normal BMI (n = 166) accounted for the remaining 38%. Patients in overweight and obese categories had higher unadjusted odds
ED
of receiving inappropriate TV, as did older and female patients. After adjusting for age and gender, patients in the overweight and all three obesity categories continued to have higher odds of receiving
PT
inappropriate TV compared with normal BMI (table 1). Additionally, as BMI rose from underweight to
CE
class III obesity, TV (in cc/kg of IBW) increased (figure 1).
Comparison
AC
Odds of receiving inappropriate tidal volume Odds Ratio (95% CI)
Underweight vs Normal
0.17 (0.02, 1.41)
Overweight vs Normal
2.54 (1.31, 4.91)
Class I Obesity vs Normal
2.30 (1.09, 4.84)
Class II Obesity vs Normal
3.98 (1.64, 9.63)
Class III Obesity vs Normal
7.68 (3.34, 17.66)
Table 1. Logistic regression of the categorical outcome variable “inappropriate tidal volume” on BMI categories, after adjusting for potential confounding factors age and gender.
3
ACCEPTED MANUSCRIPT
Discussion
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T
We demonstrated that higher BMI is associated with inappropriate TV settings in a heterogeneous patient population intubated in a single, adult ED. Increasing categories of BMI are associated with higher odds
SC
of inappropriate TV settings, suggesting a dose-response. Overall, 21.7% of patients had initial TV settings greater than 10 cc/kg IBW, across all BMI categories, suggesting a need to broadly examine ED
NU
ventilator strategies.
MA
After ensuring oxygenation, ventilation, and airway protection, lung protection is paramount; however, no evidence-based, national guidelines for ED ventilator management exist. It is reasonable to assume lung
ED
protective strategies with demonstrated benefit in ICU patients with ALI/ARDS should also benefit ED patients[4]. There are few data to guide ventilator strategies in patients without ALI/ARDS[5]. In a
PT
systematic review, Fuller, et al. noted that lower TVs reduce progression to ALI/ARDS; however, the
CE
data are too heterogeneous to make definitive recommendations[6]. The authors also noted that progression to ALI/ARDS occurs in as little as five hours in at-risk patients, further highlighting the
AC
importance of ventilator strategies in the ED.
It is our experience that ventilator settings are rarely changed while patients are in the ED, and often not until the attending intensivist sees the patient. This treatment momentum and the relevance of ED therapy as being continued in the ICU is likely not unique to our ED, and has been reported in other studies[3].
Limitations We defined the upper limit of appropriate TV as 10 cc/kg IBW. It is possible that the optimal TV is lower, in which case our data under-represent the actual number of patients with inappropriate TV. We were unable to evaluate the clinician’s reasoning for placing an individual patient on a particular ventilator
4
ACCEPTED MANUSCRIPT setting; although, we could not find any evidence-based guidelines to place any patients on TV greater than 10cc/kg IBW.
T
Conclusions
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Higher BMI is associated with increasing odds of receiving inappropriate TV in the ED. 21.7% of adults intubated in the ED have inappropriately set initial TV. Efforts to improve adherence with IBW-based TV
SC
are warranted.
5.
6.
AC
4.
CE
PT
3.
MA
2.
Mullins PM, Goyal M, Pines JM: National growth in intensive care unit admissions from emergency departments in the United States from 2002 to 2009. Academic Emergency Medicine 2013, 20(5):479-486. Gajic O, Dara SI, Mendez JL, Adesanya AO, Festic E, Caples SM, Rana R, St Sauver JL, Lymp JF, Afessa B et al: Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation. Crit Care Med 2004, 32(9):1817-1824. Fuller BM, Mohr NM, Dettmer M, Kennedy S, Cullison K, Bavolek R, Rathert N, McCammon C: Mechanical ventilation and acute lung injury in emergency department patients with severe sepsis and septic shock: an observational study. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine 2013, 20(7):659-669. Investigators A: Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. The Acute Respiratory Distress Syndrome Network. New England Journal of Medicine 2000, 342(18):1301-1308. Serpa Neto A CS, Manetta JA, Pereira VG, Esposito DC, Pasqualucci Mde O, Damasceno MC, Schultz MJ: Association between use of lung-protective ventilation with lower tidal volumes and clinical outcomes among patients without acute respiratory distress syndrome: a meta-analysis. JAMA 2012, 308(16):1651-1659. Fuller BM, Mohr NM, Drewry AM, Carpenter CR: Lower tidal volume at initiation of mechanical ventilation may reduce progression to acute respiratory distress syndrome: a systematic review. Critical care (London, England) 2013, 17(1):R11.
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1.
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References:
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Figure 1
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ACCEPTED MANUSCRIPT
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