title: Cardiorespiratory optimal point: a submaximal exercise variable to assess panic disorder patients.
abstract: Panic disorder (PD) patients often report respiratory symptoms and tend to perform poorly during maximal cardiopulmonary exercise testing (CPX), at least partially, due to phobic anxiety. Thus, we hypothesized that a submaximal exercise variable, minimum VE/VO2 - hereafter named cardiorespiratory optimal point (COP) -, may be useful in their clinical assessment. Data from 2,338 subjects were retrospectively analyzed and 52 (2.2%) patients diagnosed with PD (PDG) (70% women; aged 48±13 years). PD patients were compared with a healthy control group (CG) precisely matched to number of cases, age and gender profiles. PDG was further divided into two subgroups, based on having achieved a maximal or a submaximal CPX (unwilling to continue until exhaustion). We compared COP, VO2 max, maximum heart rate (HR max) between PDG and CG, and also COP between maximal and submaximal PD subgroups. COP was similar between PDG and CG (21.9±0.5 vs. 23.4±0.6; p = 0.07), as well as, for PD subgroups of maximal and submaximal CPX (22.0±0.5 vs. 21.6±1.3; p = 0.746). Additionally, PD patients completing a maximal CPX obtained VO2 max (mL x kg-1 x min-1) (32.9±1.57 vs 29.6±1.48; p = 0.145) and HR max (bpm) similar to controls (173±2.0 vs 168±2.7; p = 0.178). No adverse complications occurred during CPX. Although clinically safe, it is sometimes difficult to obtain a true maximal CPX in PD patients. Normalcy of cardiorespiratory interaction at submaximal effort as assessed by COP may contribute to reassure both patients and physicians that there is no physiological substrate for exercise-related respiratory symptoms often reported by PD patients.
authors.affiliation: Exercise Medicine Clinic - CLINIMEX, Rio de Janeiro, Rio de Janeiro, Brazil; Maternity Hospital Therezinha de Jesus, Faculty of Medical and Health Sciences - SUPREMA, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Plínio Santos
authors.initials: PS
authors.lastname: Ramos
authors.affiliation: Panic and Respiration Laboratory, Institute of Psychiatry, Federal University of Rio de Janeiro, National Institute for Translational Medicine (INCT-TM/CNPq), Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Aline
authors.initials: A
authors.lastname: Sardinha
authors.affiliation: Panic and Respiration Laboratory, Institute of Psychiatry, Federal University of Rio de Janeiro, National Institute for Translational Medicine (INCT-TM/CNPq), Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Antonio Egidio
authors.initials: AE
authors.lastname: Nardi
authors.affiliation: Exercise Medicine Clinic - CLINIMEX, Rio de Janeiro, Rio de Janeiro, Brazil; Heart Institute Edson Saad, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Claudio Gil Soares
authors.initials: CG
authors.lastname: de Araújo
mesh_terms: D000328:Adult; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D016584:Panic Disorder / Q000175:diagnosis*; D012189:Retrospective Studies