ORIGINAL ARTICLE Year : 2021  |  Volume : 70  |  Issue : 1  |  Page : 118-123

Incidence of respiratory complications in obese adult patients after cardiac surgeries

Mohamed A El Assal1, Tarek S Essawy2, Mohamed A El Gazar3, Moataz E Rezk3, Basma M Hani4, Hossiny E Ghabn5
1 Department of General Medicine, Benha University, Benha, Egypt
2 Department of Chest, Benha University, Benha, Egypt
3 Department of Cardiothoracic Surgery, Benha University, Benha, Egypt
4 Department of Community, Benha University, Benha, Egypt
5 Department of ICU and Emergency, Benha University, Benha, Egypt

Date of Submission22-Mar-2020Date of Decision05-May-2020Date of Acceptance08-Jul-2020Date of Web Publication26-Mar-2021

Correspondence Address:
MD Moataz E Rezk
Cardiothoracic Surgery Department, Benha Faculty of Medicine, Benha University, Qualyubia
Egypt

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ejcdt.ejcdt_42_20

Introduction Patients experience multiple alterations in respiratory function physiology and mechanics owing to intubation, mechanical ventilation, and cardiopulmonary bypass during cardiac surgery and during getting off cardiopulmonary bypass. Obesity is one of the growing epidemic problems, with increased cardiovascular disease risk and mortality in the USA. The WHO in 2010 assigned Egypt as one of African countries where obesity problem is prevalent, as 70% of its population are obese, the authors investigated the hypothesis that obese patients are more liable to respiratory complication after cardiac surgery.
Patients and methods This cohort observational study was done on 50 patients admitted to the postoperative critical care unit, who were classified according to BMI into two groups. Group 1 included nonobese patients with BMI 18–25, and group 2 included obese patients with BMI more than 30.
Results The authors found that there was a highly statistically significant difference between both groups regarding weight and BMI (P<0.001). There is a highly statistically significant difference between the two studied groups regarding pH, PCO2, total leukocyte count, and occurrence of chest infection (P<0.001). There were no significant statistical differences between both groups regarding PO2 parameter and occurrence of other pulmonary complications.
Conclusion The authors conclude that there is a highly statistically significant strong positive association between BMI and chest infection, where the risk of chest infection increases with increase in BMI.

Keywords: BMI, cardiac surgeries, chest infection, obesity, respiratory complications

How to cite this article:
El Assal MA, Essawy TS, El Gazar MA, Rezk ME, Hani BM, Ghabn HE. Incidence of respiratory complications in obese adult patients after cardiac surgeries. Egypt J Chest Dis Tuberc 2021;70:118-23
How to cite this URL:
El Assal MA, Essawy TS, El Gazar MA, Rezk ME, Hani BM, Ghabn HE. Incidence of respiratory complications in obese adult patients after cardiac surgeries. Egypt J Chest Dis Tuberc [serial online] 2021 [cited 2021 Dec 5];70:118-23. Available from: http://www.ejcdt.eg.net/text.asp?2021/70/1/118/312142   Introduction 

Obesity is a complex disease involving an excessive amount of body fat; it is the risk factor of hypertension, diabetes mellitus (DM), atherosclerosis, and coronary artery disease. So, it is highly related to preoperative morbidity and mortality with cardiac surgery [1],[2].

Obesity is defined in terms of BMI, as BMI greater than or equal to 30 kg/m2. BMI may further be subdivided into four groups besides obesity, which are normal BMI between 18.5 and 24.9, underweight with BMI less than or equal to 18.5, overweight with BMI between 25 and 29.9, and severe obesity with BMI greater than or equal to 40 [3].

Postoperative pulmonary dysfunction affects virtually most treated patients following cardiac surgery; both changes in lung mechanics and gas exchange highly affect postoperative respiratory functions, which clinically lead to high respiratory rate, shallow respiration, increase in work of breathing, ineffective cough, hypoxemia, and changes in chest radiographs [4].

Pathogenesis of these complication stems from the multifactorial effects of obesity and cardiovascular pathology. There is a link between cardiovascular disease and postoperative respiratory complications related to cardiovascular diseases itself and its surgical setting including general anesthesia, operative approach, cardiopulmonary bypass, surgical trauma, blood transfusion, operative pain, and cooling for myocardial protection [5].

On the contrary, obesity affects directly lung compliance/resistance, gas exchange, lung volume, and work of breathing [3],[6].

  Patients and methods 

This cohort observational study was done on 50 patients admitted at Postoperative Critical Care Unit of Benha University and National Heart Institute, who were classified into two groups based on BMI; each group consist of 25 patients. Ethical consideration: An approval from Research Ethics Committee in Benha Faculty of Medicine was obtained. An informed written consent was obtained from all participant before participation; it included data about aim of the work, study design, site, time, subject and measures, confidentiality. Group 1 included nonobese patients with BMI 18–25, and group 2 included obese patients with BMI more than 30. We included both sexes, with age between 20 and 65 years, nonobese patients with BMI 18–25, obese patients with BMI more than 30, and no documentation of preoperative respiratory complication.

We exclude patients with BMI less than 18, immunocompromised patients, and patients with documented preoperative respiratory complications.

Patients were asked about past history of DM, hypertension, age, weight, and height and were subjected to routine laboratory investigations such as complete blood count, arterial blood gas, sputum culture, and routine investigation, including chest radiography.

Data were collected about type and priority of surgery, ventilation time, reintubation, duration of ICU admission, readmission to ICU, need for chest tube, and pneumonia diagnosed clinically and confirmed by sputum cultures.

  Results 

There was no statistical significance difference between the two studied groups regarding mean age, smoking, and DM or hypertension distribution (P>0.05) ([Table 1]).

Table 1 Comparison between the studied groups regarding demographic characteristics and comorbidities

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[Table 2] shows that there was a highly statistically significant difference between the studied groups regarding weight and BMI (P<0.001). There is no statistically significant difference between the studied groups regarding height (P<0.05).

Table 2 Comparison between the studied groups regarding general examination

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[Table 3] shows that there was a highly statistically significant difference between patients of the two studied groups regarding pH, PCO2, and total leukocyte count (TLC) count (P<0.001). No significant difference was seen between both groups regarding PO2 parameter (P>0.05).

Table 3 Comparison between the studied groups as regarding laboratory examination (ABG, CBC, and sputum culture and sensitivity).

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[Table 4] shows that there was a highly statistically significant difference between both groups regarding occurrence of chest infection (P<0.001). There were no significant statistically differences between both groups regarding occurrence of other pulmonary complications (P>0.05).

Table 4 Comparison between the studied groups regarding occurrence of pulmonary complications

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[Table 5] shows there was a highly statistically significant difference between the patients of the two studied groups regarding hospitalization (ward) stay times (P <0.001).

Table 5 Comparison between the studied groups regarding MV time, ICU stay, and hospitalization (ward) stay

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[Table 6] shows the univariate analysis, which revealed a highly statistically significant strong positive association between BMI and chest infection, where the risk of chest infection increases with increase in BMI (P<0.001).

Table 6 Association between BMI and pulmonary complications (univariate analysis)

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[Table 7] shows multivariate analysis, which revealed that increased BMI was an independent predictor for chest infection (odds ratio: 220.7; 95% confidence interval: 15–312; P<0.010).

  Discussion 

Obesity and cardiac surgery outcome relationship is still controversial. Some authors suggest better survival with obesity than normal-weight patients. Others deny and show the negative effect of obesity on mortality after valvular surgery [7],[8],[9].

In cardiac surgery risk assessment, the EuroSCORE is used, which does not include patient weight, so it may be incomplete to mortality predication.

In our study, the mean±SD age in group A (patients with BMI 18–25) was 33.64±7.48, and it included 88% males and 12% females. Overall, 84% were smokers, 60% of them were hypertensive, and 76% were diabetics. The mean±SD age in Group B (patients with BMI >35) was 37.6±11.35 years, and it included 80% males and 20% females. Overall, 76% were smokers, 48% of patients were hypertensive, and 68% were diabetics.

There was no statistically significance difference between the two studied groups regarding mean age, smoking, and DM or hypertension distribution (P>0.05).

The obese patients were more likely to be diabetic and hypertensive [10],[11].

In our study, there was a statistically significant difference between the studied groups regarding weight and BMI (P<0.001). There is no statistically significant difference between the studied groups regarding height (P<0.05).

In our study, regarding laboratory examination, the mean pH, PCO2, PO2, and TLC count (×1000) in group A patients were 7.4 (min: 7.33; max: 7.45), 39.4 (min: 35; max: 45), 79.1 (min: 70; max: 87), and 25.28×1000 (min: 20×1000; max: 28×1000), respectively. On the contrary, the mean pH, PCO2, PO2, and TLC count (×1000) in group B patients were 7.35 (min: 7.30; max: 7.41), 42.6 (min: 35; max: 48), 77 (min: 71; max: 84), and 28. 8×1000 (min: 20×1000; max: 33×1000), respectively. There was a highly statistically significant difference between patient of the two studied groups regarding pH, PCO2, and TLC count (P<0.001). No significant difference between both groups regarding PO2 parameter P more than 0.05.

Major surgical procedures are usually followed by hypoxemia for a few days, which improve 15–21 days later [4],[12]. Others found that impaired postoperative oxygenation following coronary artery bypass grafting (CABG) was closely related to obesity [13].

In our study regarding pulmonary complication, there was a highly statistically significant difference between both groups regarding occurrence of chest infection (P<0.001). There were no SSD between both groups regarding occurrence of other pulmonary complications (P>0.05).

In our study, regarding MV time, ICU stay, and hospitalization (ward) stay, it was seen that the mean postsurgical MV durations (in hours), ICU (in days), and ward stay (in days) in group A patients were 12.16 h (min: 6; max: 35), 2.8 days (min: 2; max: 6), and 5.6 days (min: 4; max: 9), respectively. In group B patients, the mean postsurgical MV durations (in hours), ICU (in days), and ward stay (in days) were 12.4 h (min: 6; max: 35), 3.7 days (min: 2; max: 9), and 11.3 days (min: 7; max: 13), respectively. There was a highly statistically significant difference between patients of the two studied groups regarding hospitalization (ward) stay times (P<0.001).

Similar hospitalization and ICU periods between obese and normal-weight patient groups were reported by Yazdanian et al. [14] agreed with our findings. Obese patients had longer hospital stay [15],[16].

After CABG operations, prolonged hospitalization and adverse outcomes were predicted with obesity, which is considered as a significant independent factor [17],[18].

Others considered obesity was not a predictor for major perioperative complications, apart from increased ICU days. Moreover, major perioperative complications were closely related more to lower BMI [7],[11],[19],[20].

In our study, the occurrence of pulmonary complication and chest infection revealed that increases BMI was an independent predictor for chest infection (odds ratio: 220.7; 95% confidence interval: 15–312; P<0.010).

It is reported that in obese group, MVT was longer than in the normal-weight group [15],[16],[21].

Similar results were found with prolonged postoperative care and increased risk of morbidity in obese patients compared with nonobese patients [2].In other studies, they found that prolonged MVT is associated with obesity (BMI is ≥40 kgm2) [22].

Obesity can profoundly alter pulmonary function and diminish exercise capacity by its adverse effects on respiratory mechanics, resistance within the respiratory system, respiratory muscle function, lung volumes, work and energy cost of breathing, control of breathing, and gas exchange [23].

Similar findings were reported by others, who observed that obese patients had a greater risk of perioperative myocardial infarction, pulmonary infection, leg wound infection, and sternal dehiscence [21].

Different findings were reported by Koshal et al. [24], who showed no increase in pulmonary complications and a similar length of hospital stay which is clearly different from the results of the current study.

Prabhakar et al. [17] and Gadaleta et al. [18] found obesity was a significant independent predictor for adverse outcomes and prolonged hospitalization after CABG operations.

Further research needs to be done to study the effect of obesity on the intermediate and long-term outcomes of patients after cardiac operations.

Limitations

The following were the limitations of the study.

Relatively small sample size.BMI use a measure of obesity is not ideal.Assessment of in-hospital postoperative events only.   Conclusion 

We concluded that obesity was associated with increased rate of chest infection and increased ICU and in-ward stay times.

Recommendation

We recommend good care of endotracheal chest tubes to reduce the rate of chest infection. Obesity should be managed in patients who are candidates for cardiac surgery to reduce the occurrence of complications together with their high cost.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 

  References 
1.Reeves BC, Ascione R, Chamberlain MH. Effect of body mass index on early outcomes in patients undergoing coronary artery bypass surgery. J Am coll Cardiol 2003; 42:668–676.  
    2.Mathew B, Francis L, Kayalar A. Obesity: effects on cardiovascular disease and its diagnosis. J Am Board Fam Med 2008; 21:562–568.  
    3.Johnson AP, Parlow JL, Milne B. Economies of scale: body mass index and costs of cardiac surgery in Ontario, Canada. Eur J Health Econ 2017; 9:18–47.  
    4.Augoustides J, Weiss SJ, Pochettino A. Hemodynamic monitoring of the post-operative adult cardiac surgical patients. Semin Thorac Cardiovasc Surg 2000; 12:309–415.  
    5.Stamou SC, Nussbaum M, Stiegel RM. Effect of body mass index on outcomes after cardiac surgery: is there an obesity paradox?. Ann Thorac Surg 2011; 91:42–47.  
    6.Cheung W. Outcomes of the morbidly obese having cardiac surgery. Crit Care Resusc 2005; 7:172–190.  
    7.Rahmanian PB, Adams DH, Castillo JG. Impact of body mass index on early outcome and late survival in patients undergoing coronary artery bypass grafting or valve surgery or both. Am J Cardiol 2007; 100:1702–1708.  
    8.Taylor J. Thirty-year trends of physical activity in relation to age, calendar time and birth. Eur J Public Health 2011; 3:339–344.  
    9.Vaduganathan M, Lee R, Beckham AJ. Relation of body mass index to late survival after valvular heart surgery. Am J Cardiol 2012; 110:1667–1678.  
    10.Wigfield CH, Lindsey JD, Muñoz A. Is extreme obesity a risk factor for cardiac surgery? An analysis of patients with a BMI ≥40. Eur J Cardiothorac Surg; 2006; 29:434–440.  
    11.Rockx MA, Fox SA, Stitt LW. Is obesity a predictor of mortality, morbidity and readmission after cardiac surgery?. Can J Surg 2004; 47:34–38.  
    12.Vargas FS, Terra-Filho M, Hueb W, Teixeira LR, Cukier A, Light RW. Pulmonary function after coronary arterybypass surgery. Respir 1997; 91:629–633.  
    13.Yamagishi T, Ishikawa S, Ohtaki A, Takahashi T, Ohki S, Morishika Y. Obesity and post-operative oxygenation after coronary artery bypass grafting. Jpn J Thorac Cardiovasc 2000; 48:632–636.  
    14.Yazdanian F, Faritous SZ, Mollasadeghi G. Impact of body mass index on in-hospital mortality and morbidity after coronary artery bypass grafting surgery. J Tehran Univ Heart Center 2008; 3:252–259.  
    15.Potapov EV, Loebe M, Anker S. Impact of body mass index on outcome in patients after coronary artery bypass grafting with and without valve surgery. Eur Heart J 2003; 24:1933–1941.  
    16.Dehbozorgi P, Ghodsbin F, Janati M. The effects of body mass index category on early outcomes of coronary artery bypass graft. ARYA Atherosclerosis 2010; 3:82–89.  
    17.Prabhakar G, Haan CK, Peterson ED et al. The risks of moderate and extreme obesity for coronary artery bypass grafting outcomes: a study from the Society of Thoracic Surgeons’ database. Ann Thorac Surg 2002; 74:1125–1130.  
    18.Gadaleta D, Risucci DA, Nelson RL et al. Effects of morbid obesity and diabetes mellitus on risk of coronary artery bypass grafting. Am J Cardiol 1992; 70:1613–1614.  
    19.Leone N, Courbon D, Thomas F. Lung function impairment and metabolic syndrome. The critical role of abdominal obesity. Am J Respir Crit Care Med 179:509–516 2009.  
    20.William CR, Carey CR, Travis JV. Effect of body mass index on survival in patients having aortic valve replacement for aortic stenosis with or without concomitant coronary artery bypass grafting. Am J Cardiol 2011; 108:1767–1771.  
    21.Fasol Schindler RM, Schumacher B. The influence of obesity on perioperative morbidity: retrospective study of 502 aortocoronary bypass operations. J Thorac Cardiovasc 1992; 40:126–129.  
    22.Sakr Y, Madl C, Filipescu D. Obesity is associated with increased morbidity but not mortality in critically ill patients. Intensive Care Med; 34:1999–2009 2008.  
    23.Koenig SM. Pulmonary complications of obesity. Am J Med Sci 2001; 321:249–279.  
    24.Koshal A, Hendry P, Raman SV, Keon WJ. Should obese patients not undergo coronary artery surgery?. Can J Surg 1985; 28:331–334.  
    

 
 

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]