Home About us Contact
|
Home About us Contact | ||
|
|
||
Inspiratory Pressure (inspiratory + pressure)
Kinds of Inspiratory Pressure Selected AbstractsRespiratory muscle performance with stretch-shortening cycle manoeuvres: maximal inspiratory pressure,flow curvesACTA PHYSIOLOGICA, Issue 3 2005G. E. Tzelepis Abstract Aim:, To test the hypothesis that the maximal inspiratory muscle (IM) performance, as assessed by the maximal IM pressure,flow relationship, is enhanced with the stretch-shortening cycle (SSC). Methods:, Maximal inspiratory flow,pressure curves were measured in 12 healthy volunteers (35 ± 6 years) during maximal single efforts through a range of graded resistors (4-, 6-, and 8-mm diameter orifices), against an occluded airway, and with a minimal load (wide-open resistor). Maximal inspiratory efforts were initiated at a volume near residual lung volume (RV). The subjects exhaled to RV using slow (S) or fast (F) manoeuvres. With the S manoeuvre, they exhaled slowly to RV and held the breath at RV for about 4 s prior to maximal inspiration. With the F manoeuvre, they exhaled rapidly to RV and immediately inhaled maximally without a post-expiratory hold; a strategy designed to enhance inspiratory pressure via the SSC. Results:, The maximal inspiratory pressure,flow relationship was linear with the S and F manoeuvres (r2 = 0.88 for S and r2 = 0.88 for F manoeuvre, P < 0.0005 in all subjects). With the F manoeuvre, the pressure,flow relationship shifted to the right in a parallel fashion and the calculated maximal power increased by approximately 10% (P < 0.05) over that calculated with the S manoeuvre. Conclusion:, The maximal inspiratory pressure,flow capacity can be enhanced with SSC manoeuvres in a manner analogous to increases in the force,velocity relationship with SSC reported for skeletal muscles. [source] Prethymectomy plasmapheresis in myasthenia gravisJOURNAL OF CLINICAL APHERESIS, Issue 4 2005Jiann-Horng Yeh Abstract Plasma exchange before thymectomy may decrease the time on mechanical ventilation (MV) and shorten the stay in the intensive care unit (ICU) for patients with myasthenia gravis (MG). This study evaluated the effects of prethymectomy plasmapheresis. A total of 29 myasthenic patients, 18 women and 11 men aged 20,73 years, were treated with double filtration plasmapheresis (DFP) for two to five consecutive sessions over a period between 2 and 21 days (mean 8.1 days) before transsternal thymectomy. Acetylcholine receptor antibody (AchRAb) titers, vital capacity (VC), maximal inspiratory pressure (Pimax), and MG score were measured before and after the course of DFP. Three outcome measures including duration of postoperative hospital stay, duration of ICU stay, and duration of MV were analyzed for correlation with clinical variables. The duration of MV ranged from 6 to 93 h, with a median of 21 h. The median ICU stay was one day and the median postoperative hospital stay was 10 days. A higher removal rate of AchRAb was associated with a shorter duration of ICU and postoperative hospital stay (P = 0.001 and 0.019, respectively). Postoperative hospital stay was strongly correlated with post-DFP Pimax (P = 0.010), and marginally correlated with pre-DFP VC (P = 0.047) and to a lesser extent with pre-DFP Pimax (P = 0.063). Univariate analysis using the log rank test revealed that removal rate of AchRAb <30% (P = 0.043) and pre-DFP Pimax <,60 cmH2O (P = 0.024) were significantly associated with prolonged ICU stay. Risk factors for prolonged postoperative stay included post-DFP Pimax <,60 cmH2O (P = 0.017), pre-DFP Pimax <,60 cmH2O (P = 0.031), and post-DFP VC < 1.0 L (P = 0.046). Our results confirmed the efficacy and safety of DFP in prethymectomy preparation for myasthenic patients. J. Clin. Apheresis, 2005 © 2005 Wiley-Liss, Inc. [source] A Scandinavian survey of drug administration through inhalation, suctioning and recruitment maneuvers in mechanically ventilated patientsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2009C. GRIVANS Background: The aim was to describe current practices for drug administration through inhalation, endotracheal suctioning and lung recruitment maneuvers in mechanically ventilated patients in Scandinavian intensive care units (ICUs). Methods: We invited 161 ICUs to participate in a web-based survey regarding (1) their routine standards and (2) current treatment of ventilated patients during the past 24 h. In order to characterize the patients, the lowest PaO2 with the corresponding highest FiO2, and the highest PaO2 with the corresponding lowest FiO2 during the 24-h study period were recorded. Results: Eighty-seven ICUs answered and reported 186 patients. Positive end-expiratory pressure (PEEP) levels (cmH2O) were 5,9 in 65% and >10 in 31% of the patients. Forty percent of the patients had heated humidification and 50% received inhalation of drugs. Endotracheal suctioning was performed >7 times during the study period in 40% of the patients, of which 23% had closed suction systems. Twenty percent of the patients underwent recruitment maneuvers. The most common recruitment maneuver was to increase PEEP and gradually increase the inspiratory pressure. Twenty-six percent of the calculated PaO2/FiO2 ratios varied >13 kPa for the same patient. Conclusion: Frequent use of drug administration through inhalation and endotracheal suctioning predispose to derecruitment of the lungs, possibly resulting in the large variations in PaO2/FiO2 ratios observed during the 24-h study period. Recruitment maneuvers were performed only in one-fifth of the patients during the day of the survey. [source] Ventilator treatment in the Nordic countries.ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2002A multicenter survey Background: A 1-day point prevalence study was performed in the Nordic countries to identify ventilator-treatment strategies in the region. Material and methods: On 30 May 30 2001 all mechanically ventilated patients in 27 intensive care units (ICUs) were registered via the internet. The results are shown as medians (25th, 75th percentile). Results: ,One hundred and eight patients were included (69% male) with new simplified acute physiology score (SAPS) 48 (37,57) and 4.5 d (2,11) of ventilator treatment. The most frequent indication for ventilator treatment was acute respiratory failure (73%). Airway management was by endotracheal tube (64%), tracheostomy (32%) and facial mask (4%). Pressure regulated ventilator modes were used in 86% of the patients and spontaneous triggering was allowed in 75%. The tidal volume was 7 ml/kg (6,9), peak inspiratory pressure 22 cmH2O (18,26) and positive end-expiratory pressure (PEEP) 6 cmH2O (6,9). FiO2 was 40% (35,50), SaO2 97% (95,98), PaO2 11 kPa (10,13), PaCO2 5.4 kPa (4.7,6.3), pH 7.43 (7.38,7.47) and BE 2.0 mmol/l (, 0.5,5). The PaO2/FiO2 ratio was 220 mmHg (166,283). The peak inspiratory pressure (r=0.37), mean airway pressure (r=0.36), PEEP (r=0.33), tidal volume (r=0.22) and SAPS score (r=0.19) were identified as independent variables in relation to the PaO2/FiO2 ratio. Conclusion: The vast majority of patients were ventilated with pressure-regulated modes. Tidal volume was well below what has been considered conventional in recent large trials. Correlations between the parameters of gas exchange, respiratory mechanics, ventilator settings and physiological status of the patients was poor. It appears that blood gas values are the main tool used to steer ventilator treatment. These results may help to design future interventional studies of ventilator treatment. [source] Airway closure in anesthetized infants and children: influence of inspiratory pressures and volumesACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2002A. Thorsteinsson Background: Cyclic opening and closing of lung units during tidal breathing may be an important cause of iatrogenic lung injury. We hypothesized that airway closure is uncommon in children with healthy lungs when inspiratory pressures are kept low, but paradoxically may occur when inspiratory pressures are increased. Methods: Elastic equilibrium volume (EEV) and closing capacity (CC) were measured with a tracer gas (SF6) technique in 11 anesthetized, muscle-relaxed, endotracheally intubated and artificially ventilated healthy children, aged 0.6,13 years. Airway closing was studied in a randomized order at two inflation pressures, +20 or +30 cmH2O, and CC and CC/EEV were calculated from the plots obtained when the lungs were exsufflated to ,20 cmH2O. (CC/EEV >1 indicates that airway closure might occur during tidal breathing). Furthermore, a measure of uneven ventilation, multiple breath alveolar mixing efficiency (MBAME), was obtained. Results: Airway closure within the tidal volume (CC/EEV >1) was observed in four and eight children (not significant, NS) after 20 and 30 cmH2O inflation, respectively. However, CC30/EEV was >CC20/EEV in all children (P,0.001). The MBAME was 75±7% (normal) and did not correlate with CC/EEV. Conclusion: Airway closure within tidal volumes may occur in artificially ventilated healthy children during ventilation with low inspiratory pressure. However, the risk of airway closure and thus opening within the tidal volume increases when the inspiratory pressures are increased. [source] Insertion characteristics, sealing pressure and fiberoptic positioning of CobraPLA in childrenPEDIATRIC ANESTHESIA, Issue 10 2007MAURIZIO PASSARIELLO MD Summary Background:, The CobraPLATM is a new supraglottic airway device designed for the use in spontaneously breathing and mechanically ventilated patients. In adults it has been found as effective as the LMA, but with better sealing qualities. The aim of the present study was to evaluate fit and sealing characteristics of CobraPLA size 1.5 and 2 in mechanically ventilated children. Methods:, Forty children, ASA I/II, aged 1,10 years, weighing 10,35 kg were scheduled for minor surgical procedures. The number of attempts for insertion and fiberoptic positioning of the CobraPLA was assessed. After muscle relaxation had been achieved, airway sealing pressure was measured by gradually increasing maximum inspiratory pressure to a maximum of 30 cmH2O. Results:, Insertion of CobraPLA was successful at the first attempt in 90% of patients. The vocal cords were visualized in 90% of patients (grade 0: 2.5%, grade 1: 7.5%, grade 2: 30%, grade 3: 15%, grade 4: 45%). Median sealing pressure was 20.0 ± 6.0 cmH2O. In 21% of patients gastric insufflation was observed at a peak inspiratory pressure of 20 cmH2O or below. Conclusions:, The CobraPLA was found to have easy insertion characteristics and good anatomical fitting in children between 10 and 35 kg. If positive pressure ventilation with CobraPLA size 1.5 and 2.0 is required, peak inspiratory pressure should be kept below the leak pressure and the abdomen closely monitored for signs of gastric insufflation. [source] Volume targeted ventilation (volume guarantee) in the weaning phase of premature newborn infantsPEDIATRIC PULMONOLOGY, Issue 10 2007F. Scopesi MD Abstract Objective Several options are currently available in neonatal mechanical ventilation: complete breathing synchronization (patient triggered ventilation, synchronized intermittent positive pressure ventilation,SIPPV); positive pressure flow-cycled ventilation (pressure support ventilation, PSV); and volume targeted positive pressure ventilation (volume guarantee, VG). The software algorithm for the guarantee volume attempts to deliver a tidal volume (Vt) as close as possible to what has been selected by the clinician as the target volume. Main objectives of the present study were to compare patient,ventilator interactions and Vt variability in premature infants recovering from respiratory distress syndrome (RDS) who were weaned by various ventilator modes (SIMV/PSV,+,VG/SIPPV,+,VG and SIMV,+,VG). Methods This was a short-term crossover trial in which each infant served as his/her own control. Ten premature infants born before the 32nd week of gestation in the recovery phase of RDS were enrolled in the study. All recruited infants started ventilation with SIPPV and in the weaning phase were switched to synchronized intermittent mandatory ventilation (SIMV). Baseline data were collected during an initial 20-min period of monitoring with the infant receiving SIMV alone, then they were switched to SIPPV,+,VG for a 20-min period and then switched back to SIMV for 15 min. Next, they were switched to PSV,+,VG for the study period and switched back to SIMV for a further 15 min. Finally, they were switched to SIMV,+,VG and, at the end of monitoring, they were again switched back to SIMV alone. Results Each mode combined with VG discharged comparable Vts, which were very close to the target volume. Among the VG-combined modes, mean variability of Vt from preset Vt was significantly different. Variability from the target value was significantly lower in SIPPV and PSV modes than in SIMV (P,<,0.0001 and P,<,0.04 respectively). SIPPV,+,VG showed greater stability of Vt, fewer large breaths, lower respiratory rate, and allowed for lower peak inspiratory pressure than what was delivered by the ventilator during other modes. No significant changes in blood gases were observed after each of the study periods. Conclusions With regards to the weaning phase, among combined modes, both of the ones in which every breath is supported (SIPPV/PSV) are likely to be the most effective in the delivery of stable Vt using a low working pressure, thus, at least in the short term, likely more gentle for the neonatal lung. In summary, we can suggest that the VG option, when combined with traditional, patient triggered ventilation, adheres very closely to the proposed theoretical algorithm, achieving highly effective ventilation. Pediatr Pulmonol. 2007; 42:864,870. © 2007 Wiley-Liss, Inc. [source] Which pulmonary volume should be used in physiotherapy to obtain higher maximal inspiratory pressure in COPD patients?PHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 4 2005Patricia EM Marinho Abstract Background and Purpose Patients with chronic obstructive pulmonary disease (COPD) present pulmonary hyperinflation as the main cause of mechanical disadvantage in respiratory muscles. Measurement of the force generated by those muscles is converted into pressure changes. The aim of the present study was to evaluate the maximal inspiratory pressure (MIP) from the residual volume (RV) and from the functional residual capacity (FRC), in patients with COPD, and to determine which pulmonary volume should be used in physiotherapy so as to obtain higher MIP results. Method An investigation of 18 male patients with stable COPD. Patients were examined using a manual vacuometer to measur the MIP of 20 daily manoeuvres. Ten measurements were taken from the RV and 10 from the FRC, taken alternately with an interval of 1 minute between each measurement, for five consecutive days. Results Increases in MIP were obtained from the RV measurements (mean ± SE) from 59.7 (±5.2) to 66.6 (±5.3) cm H2O (F (4,64) = 3.34; p < 0.015) and from the FRC measurements, from 55.4 (±4.9) to 64.4 (±4,8) cm H2O (F (4,64) = 6.72; p < 0.001). Post hoc analysis showed an increase, over consecutive days, in both RV and FRC. For FRC, an increase was revealed on the second and third days, a fall was found on the fourth day and a new increase was found on the last day. MIP reached different levels, between RV and FRC, on the first (t = 2.888; p = 0.010) and fourth ( t = 2.165; p = 0.045) days. Conclusion In the present study, MIP reached higher levels at FRC during the five days of evaluation, and a learning effect occurred in the patients. Motor units from the respiratory muscles may have been recruited in order to performe the manoeuvres during the days of evaluation. The study suggests that there is good evidence for the use of the FRC as a parameter to find the major MIP value. Copyright © 2005 John Wiley & Sons, Ltd. [source] Inspiratory muscle performance in endurance athletes and sedentary subjectsRESPIROLOGY, Issue 2 2001Peter R. Eastwood Objective: The aim of this study was to determine whether whole-body endurance training is associated with increased respiratory muscle strength and endurance. Methodology: Respiratory muscle strength (maximum inspiratory pressure (PImax)) and endurance (progressive threshold loading of the inspiratory muscles) were measured in six marathon runners and six sedentary subjects. Results: PImax was similar between the two groups of subjects but the maximum threshold pressure achieved was greater in marathon runners (90 ± 8 vs 78 ± 10% of PImax, respectively, mean ± SD, P < 0.05). During progressive threshold loading, marathon runners breathed with lower frequency, higher tidal volume, and longer inspiratory and expiratory time. At maximum threshold pressure, marathon runners had lower arterial O2 saturation, but perceived effort (Borg scale) was maximal in both groups. Efficiency of the respiratory muscles was similar in both groups being 2.0 ± 1.7% and 2.3 ± 1.8% for marathon runners and sedentary subjects, respectively. Conclusions: The apparent increase in respiratory muscle endurance of athletes was a consequence of a difference in the breathing pattern adopted during loaded breathing rather than respiratory muscle strength or efficiency. This implies that sensory rather than respiratory muscle conditioning may be an important mechanism by which whole-body endurance is increased. [source] Mechanical ventilatory constraints during incremental cycle exercise in human pregnancy: implications for respiratory sensationTHE JOURNAL OF PHYSIOLOGY, Issue 19 2008Dennis Jensen The aim of this study was to identify the physiological mechanisms of exertional respiratory discomfort (breathlessness) in pregnancy by comparing ventilatory (breathing pattern, airway function, operating lung volumes, oesophageal pressure (Poes)-derived indices of respiratory mechanics) and perceptual (breathlessness intensity) responses to incremental cycle exercise in 15 young, healthy women in the third trimester (TM3; between 34 and 38 weeks gestation) and again 4,5 months postpartum (PP). During pregnancy, resting inspiratory capacity (IC) increased (P < 0.01) and end-expiratory lung volume decreased (P < 0.001), with no associated change in total lung capacity (TLC) or static respiratory muscle strength. This permitted greater tidal volume (VT) expansion throughout exercise in TM3, while preserving the relationship between contractile respiratory muscle effort (tidal Poes swing expressed as a percentage of maximum inspiratory pressure (PImax)) and thoracic volume displacement (VT expressed as a percentage of vital capacity) and between breathlessness and ventilation . At the highest equivalent work rate (HEWR = 128 ± 5 W) in TM3 compared with PP: , tidal Poes/PImax and breathlessness intensity ratings increased by 10.2 l min,1 (P < 0.001), 8.8%PImax (P < 0.05) and 0.9 Borg units (P < 0.05), respectively. Pulmonary resistance was not increased at rest or during exercise at the HEWR in TM3, despite marked increases in mean tidal inspiratory and expiratory flow rates, suggesting increased bronchodilatation. Dynamic mechanical constraints on VT expansion (P < 0.05) with associated increased breathlessness intensity ratings (P < 0.05) were observed near peak exercise in TM3 compared with PP. In conclusion: (1) pregnancy-induced increases in exertional breathlessness reflected the normal awareness of increased and contractile respiratory muscle effort; (2) mechanical adaptations of the respiratory system, including recruitment of resting IC and increased bronchodilatation, accommodated the increased VT while preserving effort,displacement and breathlessness, relationships; and (3) dynamic mechanical ventilatory constraints contributed to respiratory discomfort near the limits of tolerance in late gestation. [source] A Pressure-controlled Rat Ventilator With Electronically Preset RespirationsARTIFICIAL ORGANS, Issue 12 2006Valentin L. Ordodi Abstract:, Major experimental surgery on laboratory animals requires adequate anesthesia and ventilation to keep the animal alive throughout the procedure. A ventilator is a machine that helps the anesthesized animal breathe through an endotracheal tube by pumping a volume of gas (oxygen, air, or other gaseous mixtures), comparable with the normal tidal volume, into the animal's lungs. There are two main categories of ventilators for small laboratory rodents: volume-controlled and pressure-controlled ones. The volume-controlled ventilator injects a preset volume into the animal's lungs, no matter the airways' resistance (with the peak inspiratory pressure allowed to vary), while the pressure ventilator controls the inspiratory pressure and allows the inspiratory volume to vary. Here we show a rat pressure ventilator with a simple expiratory valve that allows gas delivery through electronic expiration control and offers easy pressure monitoring and frequency change during ventilation. [source] Neopuff T-piece mask resuscitator: is mask leak related to watching the pressure dial?ACTA PAEDIATRICA, Issue 9 2010MB Tracy Abstract Aim:, The aim of the study is to compare mask leak and delivered ventilation during Neopuff (NP) mask ventilation in two modes: (i) with NP pressure dial hidden and resuscitator watching chest wall (CW) rise with, (ii) CW movement hidden and resuscitator watching NP pressure dial. Methods:, Thirty-six participants gave mask ventilation to a modified manikin designed to measure mask leak and delivered ventilation for two minutes in each mode randomly assigned. Paired t -tests were used to analyse differences in mean values. Linear regression was used to determine the association of mask leak with delivered ventilation. Results:, Of 7277 inflations analysed, 3621 were observing chest wall mode (CWM) and 3656 observing NP mode (NPM). Mask leak was similar between the groups; 31.6% for CWM and 31.5% (p = 0.56) for NPM. There were no significant differences in airways pressures and expired tidal volumes (TVe) between modes. Mask leak was strongly associated with TVe (R = ,0.86 p < 0.0001) and with peak inspiratory pressure (PIP) (R = ,0.51 p < 0.0001). TVe was associated with PIP (R = 0.51 p < 0.0001). Conclusion:, This study provides reassurance that NP mask leak is not greater when resuscitators watch the NP pressure dial. Mask leak is related to TVe. Mask ventilation training with manikins should include tidal volume measurements. [source] Airway closure in anesthetized infants and children: influence of inspiratory pressures and volumesACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2002A. Thorsteinsson Background: Cyclic opening and closing of lung units during tidal breathing may be an important cause of iatrogenic lung injury. We hypothesized that airway closure is uncommon in children with healthy lungs when inspiratory pressures are kept low, but paradoxically may occur when inspiratory pressures are increased. Methods: Elastic equilibrium volume (EEV) and closing capacity (CC) were measured with a tracer gas (SF6) technique in 11 anesthetized, muscle-relaxed, endotracheally intubated and artificially ventilated healthy children, aged 0.6,13 years. Airway closing was studied in a randomized order at two inflation pressures, +20 or +30 cmH2O, and CC and CC/EEV were calculated from the plots obtained when the lungs were exsufflated to ,20 cmH2O. (CC/EEV >1 indicates that airway closure might occur during tidal breathing). Furthermore, a measure of uneven ventilation, multiple breath alveolar mixing efficiency (MBAME), was obtained. Results: Airway closure within the tidal volume (CC/EEV >1) was observed in four and eight children (not significant, NS) after 20 and 30 cmH2O inflation, respectively. However, CC30/EEV was >CC20/EEV in all children (P,0.001). The MBAME was 75±7% (normal) and did not correlate with CC/EEV. Conclusion: Airway closure within tidal volumes may occur in artificially ventilated healthy children during ventilation with low inspiratory pressure. However, the risk of airway closure and thus opening within the tidal volume increases when the inspiratory pressures are increased. [source] | |||||||||||||||||||||||||