end-tidal O2
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Kolísavý průběh dechového objemu (VT), dechové frekvence (DF) a minutové ventilace (VE) při spiroergometrickém vyšetření rampovým protokolem se vyskytuje nejen u nemocných, ale relativně často i u zdravých osob. Může vysvětlit řadu nepravidelností průběhu křivek příjmu kyslíku (VO2), výdeje oxidu uhličitého (VCO2) a zejména křivek ventilačních ekvivalentů pro O2 a CO2 (EQO2, EQCO2) a též křivek parciálních tlaků O2 a CO2 na konci výdechu (PETO2, PETCO2), které se používají mimo jiné i ke stanovení ventilačních prahů. Přítomnost oscilujícího dýchání při zátěži (EOV) odráží závažnost srdečního selhání a je nezávislým prediktorem zvýšené morbidity, kardiální i celkové mortality a náhlé smrti z kardiálních příčin. V současné době ale není k dispozici všeobecně akceptovaná univerzální definice EOV, užívají se různá kritéria. Nenašli jsme porovnání, zda a jak se liší „síla“ prognostického kritéria pro EOV stanoveného dle různých metod. Je proto velmi důležité uvést, jakou metodou, respektive podle jakých kritérií byla EOV stanovena.
The fluctuating course of tidal volume (VT), breathing frequency (DF) and minute ventilation (VE) during the cardiopulmonary exercise test using a ramp incremental protocol occurs not only in patients, but relatively frequently also in healthy individuals. It can account for a number of irregularities in the course of the curves VO2, VCO2 and in particular of those of ventilatory equivalents for O2 and CO2 (EQO2, EQCO2) as well as curves of partial pressure of end-tidal oxygen and partial pressure of end-tidal carbon dioxide (PETO2, PETCO2), which are also used, inter alia, to establish ventilatory thresholds. The presence of exercise oscillatory ventilation (EOV) reflects the severity of heart failure and it is an independent predictor of the increased morbidity, cardiac and total mortality and sudden death caused by heart failure. However there is not a generally accepted universal definition of EOV available at present, as different criteria are used. We have not found a comparison which would indicate whether and how the “strength” of the prognostic criteria for EOV – established according to different methods – differs. Therefore it is very important to specify what method, or what criteria were used in the establishment of EOV.
The purpose of the present study was to examine whether excessive CO2 output (V . co2excess) is dominantly attributable to hyperventilation during the period of recovery from repeated cycling sprints. A series of four 10-sec cycling sprints with 30-sec passive recovery periods was performed two times. The first series and second series of cycle sprints (SCS) were followed by 360-sec passive recovery periods (first recovery and second recovery). Increases in blood lactate (?La) were 11.17±2.57 mM from rest to 5.5 min during first recovery and 2.07±1.23 mM from the start of the second SCS to 5.5 min during second recovery. CO2 output (V . co2) was significantly higher than O2 uptake (V . o2) during both recovery periods. This difference was defined as V . co2excess. V . co2excess was significantly higher during first recovery than during second recovery. V . co2excess was added from rest to the end of first recovery and from the start of the second SCS to the end of second recovery (CO2excess). ?La was significantly related to CO2excess (r=0.845). However, ventilation during first recovery was the same as that during second recovery. End-tidal CO2 pressure (PETco2) significantly decreased from the resting level during the recovery periods, indicating hyperventilation. PETco2 during first recovery was significantly higher than that during second recovery. It is concluded that V . co2excess is not simply determined by ventilation during recovery from repeated cycle sprints.
Noninvasive techniques are routinely used for assessment of tissue effects of lung ventilation. However, comprehensive studies of the response time of the methods are scarce. The aim of this study was to compare the response time of noninvasive methods for monitoring of gas exchange to sudden changes in the composition of the inspired gas. A prospective experimental study with 16 healthy volunteers was conducted. A ventilation circuit was designed that enabled a fast change in the composition of the inspiratory gas mixture while allowing spontaneous breathing. The volunteers inhaled a hypoxic mixture, then a hypercapnic mixture, a hyperoxic mixture and finally a 0.3% CO mixture. The parameters with the fastest response to the sudden change of O2 in inhaled gas were peripheral capillary oxygen saturation (SpO2) and regional tissue oxygenation (rSO2). Transcutaneous oxygen partial pressure (tcpO2) had almost the same time of reaction, but its time of relaxation was 2-3 times longer. End-tidal carbon dioxide (EtCO2) response time to change of CO2 concentration in inhaled gas was less than half in comparison with transcutaneous carbon dioxide partial pressure (tcpCO2). All the examined parameters and devices reacted adequately to changes in gas concentration in the inspiratory gas mixture.
- MeSH
- lidé MeSH
- oxid uhličitý chemie MeSH
- oxymetrie MeSH
- reakční čas MeSH
- transkutánní měření krevních plynů metody MeSH
- umělé dýchání metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Extremely preterm infants often develop chronic lung disease (CLD) characterized by heterogeneous aeration; poorly supported, floppy airways; and air trapping. High-frequency jet ventilation (HFJV) with high end-expiratory pressure (optimal lung volume strategy [OLVS]) may improve airway patency, lead to better gas distribution, improve gas exchange, and facilitate extubation. In a pilot trial, this study sought to explore the effect of HFJV on oxygenation, ventilation, and ease of extubation in preterm infants with evolving CLD and refractory respiratory failure (RRF). From September 2002 to October 2004, 12 episodes of RRF developed in 10 ventilated extremely immature infants with evolving CLD (10 on conventional and two on high-frequency oscillation). Chorioamnionitis was confirmed in all infants, patent ductus arteriosus was ligated in five patients, and UREAPLASMA UREALYTICUM was cultured from trachea in four patients. HFJV with OLVS was initiated when oxygenation index (OI) > 10 or exhaled tidal volume (V TE) >or= 7 mL/kg were required to maintain partial pressure of carbon dioxide, arterial (Pa CO2) < 60 mm Hg. Inspiratory time (0.02/s) and frequency (310 to 420/min) were set initially with adjustment of pressure amplitude to keep Pa CO2 between 45 and 55 mm Hg. Ventilatory stabilization and weaning from mechanical ventilation with extubation to nasal continuous positive airway pressure (CPAP) were the goals of this approach. Gas exchange data were analyzed by Analysis of variance for repeated measures. Ten patients on 11 occasions of RRF were extubated to nasal CPAP successfully in a median of 15.5 days. Nine of 10 patients survived (one died of pentalogy of Cantrell), all required supplemental O2 at 36 weeks. Pa CO2 decreased within 1 hour after the initiation of HFJV, and OI decreased by 24 hours. Both remained significantly lower until successful extubation ( P < 0.02). Compared with conventional ventilation or high-frequency oscillatory ventilation, HFJV used with OLVS appears to improve gas exchange and may facilitate weaning from mechanical ventilation (MV) in extremely immature infants with evolving CLD. These encouraging pilot data need to be confirmed in a larger clinical trial.
- MeSH
- chronická nemoc MeSH
- klinické křížové studie MeSH
- lidé MeSH
- nemoci nedonošenců * terapie MeSH
- novorozenec s extrémně nízkou porodní hmotností MeSH
- novorozenec MeSH
- pilotní projekty MeSH
- plicní nemoci * terapie MeSH
- plicní ventilace MeSH
- progrese nemoci MeSH
- spotřeba kyslíku MeSH
- vysokofrekvenční proudová ventilace * metody MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- klinické zkoušky MeSH
- práce podpořená grantem MeSH
