Cardiovascular and respiratory dysfunction in chronic obstructive pulmonary disease complicated by impaired peripheral oxygenation

Figures & data

Table 1 Variables related to impaired peripheral oxygenation and selected clinical characteristics and lung function test data in patients with COPD

	IPO	Non-IPO	P-value
	(n=14)	(n=43)
Age, years	62.9±5.9	65.2±6.1	NS
Height, cm	168.2±6.1	164.3±5.8	0.05
Body mass index, kg/m^2	21.3±3.2	22.9±3.6	0.01
Triceps skin thickness, mm	6±2.7	8.7±5.3	0.02
Cigarette, pack-years	38.5±17.6	42.9±18.4	NS
Hemoglobin, g/dL	14.3±2.1	15.2±1.3	NS
FVC (L)	2.58±0.65	2.63±0.73	NS
FEV1 (L)	1.21±0.64	1.3±0.48	NS
FEV1/FVC, %	48±18	50±12	NS
COPD stage I/II/III/IV, n	1/4/6/3	2/23/15/3	NS
TLC, L	6.99±1.07	6.26±0.87	0.04
RV, L	4.35±0.97	3.5±0.69	0.01
RV/TLC, %	62±9	56±9	0.05
FRC, L	5.34±1	4.51±0.79	0.02
DLCO/DLCOpred, %	57±21	79±19	0.003
IPO criteria
${\dot{\mathrm{V}}\mathrm{O}}_{2\text{peak}}/\text{pred}{\dot{\mathrm{V}}\mathrm{O}}_{2\max }$, % (≥ or <85%)	47±12	77±15
Anerobic threshold/pred ${\dot{\mathrm{V}}\mathrm{O}}_{2\max }(\ge \text{or}<40\%)$	24±6	37±10
${\dot{\mathrm{V}}\mathrm{O}}_2\text{-work}$ rate ratio, mL/watt (≥ or <8.6)	5.6±2.5	8±1.5
Oxygen pulsepeak, % pred maximum (≥ or <80%)	60±12	95±18
Ventilatory equivalent for O2nadir (≤ or >34)	40.4±5.4	34.2±6.5
Ventilatory equivalent for CO2nadir (≤ or >31)	41.8±4.9	32.5±5.7
Maximum exercise effort level, point (AU)	1.9±1.8	3.1±2.1	NS

Notes: Groups were compared using the unpaired-t-test. Between-group comparisons of RV were performed using the Mann–Whitney U-test.

Abbreviations: COPD, chronic obstructive pulmonary disease; IPO, impaired peripheral oxygenation; non-IPO, patients failing to fit IPO criteria; FVC, forced vital capacity; FEV₁, forced expired volume in one second; D_LCO, diffusing capacity for carbon monoxide; AU, arbitrary unit; TLC, total lung capacity; RV, residual volume; FRC, functional residual capacity; NS, not statistically significant; pred, predicted.

Table 2 Distribution of the six variables regarding IPO criteria for the non-IPO group (n=43*)

Subjects having	n
Any 5 abnormal of 6 criteria	9
Any 4 abnormal of 6 criteria	7
Any 3 abnormal of 6 criteria	9
Any 2 abnormal of 6 criteria	16
Any 1 abnormal of 6 criteria	1
${\dot{\mathrm{V}}\mathrm{O}}_{2\text{peak}}/\text{pred}{\dot{\mathrm{V}}\mathrm{O}}_{2\text{max}}<85\%$	29
Anerobic threshold/pred $\dot{V}{\text{O}}_{2\max }<40\%$	24
${\dot{\mathrm{V}}\mathrm{O}}_2\text{-work}$ rate ratio <8.6 mL/watt	25
Oxygen pulsepeak % pred maximum <80%	8
Ventilatory equivalent for O2nadir >31	24
Ventilatory equivalent for CO2nadir >34	12

Notes:

* Technical difficulty was encountered in one subject. IPO indicates impaired peripheral oxygenation or patients with six variables in the abnormal range; non-IPO indicates patients failing to fit IPO criteria and having from one criterion with an abnormal value to five criteria with abnormal values. The six criteria were ${\dot{\mathrm{V}}\mathrm{O}}_{2\text{peak}}/\text{pred}{\dot{\mathrm{V}}\mathrm{O}}_{2\max }<85\%$, anerobic threshold/pred ${\dot{\mathrm{V}}\mathrm{O}}_2-\text{work}<40\%$ rate ratio <8.6 mL/watt, oxygen pulse_peak % pred maximum <80%, ventilatory equivalent for O_2nadir >31, and ventilatory equivalent for CO2nadir >34

Abbreviations: IPO, impaired peripheral oxygenation; pred, predicted.

Table 3 Two-dimensional echocardiography results

Variable	IPO	Non-IPO	P-value
	(n=14‡)	(n=43‡)
Left ventricular ejection fraction, %	69±5	67±6	NS
Apical four-chamber view*, yes/no
EDRV >15 cm^2	3/9	15/23	NS
ESRV >10 cm^2	0/12	5/33	NS
Subcostal four-chamber view*, yes/no
EDRV >13 cm^2	6/6	28/10	NS
ESRV >8 cm^2	7/5	15/23	NS
Long and short axes view*, yes/no
Paradoxical motion of interventricular septum	0/12	2/36	NS
Right ventricular free wall thickness >4 mm	10/2	31/7	NS
Tricuspid regurgitation*, yes/no	8/4	30/8	NS
Pulmonary regurgitation*, yes/no	0/12	3/37	NS

Notes:

‡ Some missing data.

* The definitions of EDRV and ESRV were from Bertoli et al²⁰ and Danchin et al.²¹

Abbreviations: IPO, impaired peripheral oxygenation; ED, end-diastolic; RV, right ventricular; ES, end-systolic; NS, not statistically significant.

Figure 1 Findings in 14 patients with COPD complicated by IPO (solid line and solid circle symbol) and 43 patients with COPD complicated by non-IPO (dashed line and open circle symbol) performing incremental cardiopulmonary exercise testing.

Notes: (A) Minute ventilation (${\dot{\mathrm{V}}}_{\mathrm{E}}$) as a function of ${\dot{\mathrm{V}}\mathrm{O}}_2\%$ predicted maximum. (B) $\dot{\mathrm{V}}\mathrm{E}$ demand/capacity ratio as a function of ${\dot{\mathrm{V}}\mathrm{O}}_2\%$ predicted maximum. (C) Tidal volume/inspiratory time (V_T/T_i) indicating mean inspiratory flow rate as a function of ${\dot{\mathrm{V}}\mathrm{O}}_2\%$ predicted maximum. (D) Tidal volume (V_T) as a function of oxygen uptake $({\dot{\mathrm{V}}\mathrm{O}}_2)\%$ predicted maximum. (E) V_T/total lung capacity ratio (V_T/TLC) indicating lung expansion as a function of ${\dot{\mathrm{V}}\mathrm{O}}_2\%$ predicted maximum. (F) Dead space/tidal volume ratio (V_D/V_T) as a function of ${\dot{\mathrm{V}}\mathrm{O}}_2\%$ predicted maximum. (G) Respiratory frequency/tidal volume (RR/V_T) indicating the rapid shallow breathing index as a function of ${\dot{\mathrm{V}}\mathrm{O}}_2\%$ predicted maximum. (H) Borg scores at peak exercise normalized with peak ${\dot{\mathrm{V}}\mathrm{O}}_2$ indicating perception of dyspnea as a function of ${\dot{\mathrm{V}}\mathrm{O}}_2\%$ predicted maximum. All circles indicate the group mean at rest, anaerobic threshold, and peak exercise, respectively; bars indicate standard errors. Between-group comparisons: *P<0.05; **P<0.01; ***P ≤0.001.
Abbreviations: COPD, chronic obstructive pulmonary disease; IPO, impaired peripheral oxygenation; max, maximum; pred, predicted.

Figure 2 Flow chart showing the deductive mechanism of ventilatory dysfunction and perception of dyspnea at peak exercise in patients with chronic obstructive pulmonary disease complicated with impaired peripheral oxygenation.

Notes: ↑, increased; ↓, decreased. Increased or decreased means increase or decrease when compared to the non-IPO group.
Abbreviations: V_D/V_T, dead space to tidal volume ratio; ${\dot{\mathrm{V}}}_{\mathrm{E}}$, minute ventilation; V_T, tidal volume.

BertoliLManteroACiceroSLAlpagoRRizzatoGBelliCUsefulness of two-dimensional echocardiography in the assessment of right heart in chronic obstructive lung diseaseProgress in Respiratory Research19852091100

 Google Scholar

DanchinNCornetteAHenriquezATwo-dimensional echocardiographic assessment of the right ventricle in patients with chronic obstructive lung diseaseChest19879222292332956068

 PubMed Web of Science ®Google Scholar