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Volume 12 No. 11
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Letters to the Editor

Obstructive Sleep Apnea: A Risk Factor of Cardiac Valve Replacement Surgery

Ning Ding1; Bu-Qing Ni2; Hong Wang1; Shi-Jiang Zhang, PhD, MD2; Xi-Long Zhang, PhD, MD1
1Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China; 2Department of Cardiovascular Surgery, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China

We thank Dr. Antonio Maria Esquinas and Luca Salvatore De Santo1 for their interest and commentary regarding our manuscript detailing obstructive sleep apnea (OSA) increases the perioperative risk of cardiac valve replacement surgery. We also are thankful for the opportunity to clarify some limitations in our study.

This article2 is one of our series of studies on “sleep apnea and valvular heart disease.” In our previous publication,3 we gave a detailed description about the difference among patients with various kinds of valvular lesions. Since in this study we focused on the correlation between sleep apnea and postoperative complications, special attention was not paid to the difference in types of cardiac valvular surgery. Here, we listed the types of cardiac valvular surgery in Table 1 and compared the clinical parameters between single valve replacement and multiple valve replacement patients in Table 2. In addition, the correlations were analyzed about types of cardiac valve replacement and postoperative adverse events, in which we found that when comparing with single valve replacement, multiple valve replacement did not increase ICU length of stay and duration of mechanical ventilation. In some previous studies,4,5 the preoperative baseline diseases of their study patients such as hypertension, diabetes mellitus, stroke, coronary artery disease (CAD) and chronic obstructive pulmonary disease (COPD) were described. In our study population, there are 10 (3.4%) patients combined with hypertension, 5 (1.7%) combined with diabetes, 5 (1.7%) combined with stroke, 15 (5.2%) combined with left atrial thrombi, 24 (8.3%) combined with CAD, and 2 (0.7%) combined with COPD.

Types of heart valve replacement.

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Table 1

Types of heart valve replacement.

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Comparisons of clinical parameters between single valve replacement and multiple valve replacement patients.

jcsm.12.11.1573.t02.jpg

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Table 2

Comparisons of clinical parameters between single valve replacement and multiple valve replacement patients.

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Excuse us for our carelessness, when we designed the study, we failed to take intraoperative blood management into consideration. Therefore, the data about blooding volume/ transfusion blood volume were devoid in this study. This is a limitation of our study. Our selection of postoperative adverse outcomes was based on some studies.6,7 We set up six adverse outcomes at beginning of the study: ICU length of stay ≥ 25 h, mechanical ventilation ≥ 20 h, pacemaker use, cardiopulmonary bypass ≥ 110 min, first dose of dopamine in ICU ≥ 3 μg/kg·min and first dose of dobutamine in ICU ≥ 3 μg/kg·min. However, because of the suggestions from reviewers and editors as well as the following reasons: 1) cardiopulmonary bypass ≥ 110 min was more associated with the complex of cardiac surgery itself rather than perioperative risks; 2) both first dose of dopamine in ICU ≥ 3 μg/kg·min and first dose of dobutamine in ICU ≥ 3 μg/kg·min were more closely related to preoperative cardiac function and bleeding amount during surgery rather than perioperative risks, the adverse events of cardiopulmonary bypass ≥ 110 min, first dose of dopamine in ICU ≥ 3 μg/ kg·min and first dose of dobutamine in ICU ≥ 3 μg/kg·min were deleted. Finally, only the following three outcomes were kept: ICU length of stay ≥ 25 h (reflect overall worsening of postoperative recovery), mechanical ventilation ≥ 20 h (reflect postoperative respiratory insufficiency) and pacemaker use (reflect severe cardiac arrhythmia).

Other postoperative adverse events such as reintubation, infection, pneumonia, myocardial infarction,4,6,810 were not included in our original protocol and failed to be recorded in our study as well. This limitation will push us to pursue more proper observation in our further study in the future. In spite of this, we have, to say the least, detected the phenomenon that preoperative OSA could increase the perioperative risk of cardiac valve replacement surgery. This finding might remind surgeons to consider sleep apnea in preoperative evaluation and postoperative management.

Apart from the limitations mentioned above, there are another two important limitations mentioned in this article, lack of long-term follow-up and no continuous positive airway pressure (CPAP) treatment. Our further studies are going to be performed under the following topics: (1) Sleep apnea and long-time outcomes in patients undergoing cardiac valve replacement surgery, (2) Association between preoperative CPAP treatment and postoperative complications in patients undergoing cardiac valve replacement surgery. The valuable comments and suggestions from Dr. Antonio Maria Esquinas and Luca Salvatore De Santo will be taken into consideration in our further studies.

DISCLOSURE STATEMENT

The authors have indicated no financial conflicts of interest.

ABBREVIATIONS

6MWT

six-minute walk test

AF

atrial fibrillation

AVR

aortic valve replacement

CAD

coronary artery disease

COPD

chronic obstructive pulmonary disease

CPAP

continuous positive airway pressure

CSA

central sleep apnea

LVEF

left ventricular ejection fraction

MVR

mitral valve replacement

NYHA

New York Heart Association

OSA

obstructive sleep apnea

PAH

pulmonary hypertension

TVR

tricuspid valve replacement

CITATION

Ding N, Ni BQ, Wang H, Zhang SJ, Zhang XL. Obstructive sleep apnea: a risk factor of cardiac valve replacement surgery. J Clin Sleep Med 2016;12(11):1573–1575.

REFERENCES

1 

Esquinas AM, De Santo LS, authors. Impact of sleep-disordered breathing on postoperative outcomes: another brick in the wall. J Clin Sleep Med. 2016;12:1571.

2 

Ding N, Ni BQ, Wang H, et al., authors. Obstructive sleep apnea increases the perioperative risk of cardiac valve replacement surgery: a prospective single-center study. J Clin Sleep Med. 2016;12:1331–7. [PubMed]

3 

Ding N, Ni BQ, Zhang XL, et al., authors. Prevalence and risk factors of sleep disordered breathing in patients with rheumatic valvular heart disease. J Clin Sleep Med. 2013;9:781–7. [PubMed Central][PubMed]

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Foldvary-Schaefer N, Kaw R, Collop N, et al., authors. Prevalence of undetected sleep apnea in patients undergoing cardiovascular surgery and impact on postoperative outcomes. J Clin Sleep Med. 2015;11:1083–9. [PubMed Central][PubMed]

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Melby SJ, Moon MR, Lindman BR, Bailey MS, Hill LL, Damiano RJ Jr, authors. Impact of pulmonary hypertension on outcomes after aortic valve replacement for aortic valve stenosis. J Thorac Cardiovasc Surg. 2011;141:1424–30. [PubMed Central][PubMed]

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Uchôa CH, Danzi-Soares Nde J, Nunes FS, et al., authors. Impact of OSA on cardiovascular events after coronary artery bypass surgery. Chest. 2015;5:1352–60.

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Kaw R, Golish J, Ghamande S, Burgess R, Foldvary N, Walker E, authors. Incremental risk of obstructive sleep apnea on cardiac surgical outcomes. J Cardiovasc Surg (Torino). 2006;6:683–9.

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Fortis S, Colling KP, Statz CL, Glover JJ, Radosevich DM, Beilman GJ, authors. Obstructive sleep apnea: a risk factor for surgical site infection following colectomy. Surg Infect (Larchmt). 2015;5:611–7.