BACKGROUND: The patient's work of breathing(WOBp) during assisted ventilation may vary according to many factors including ventilatory demand of the patients and applied ventilatory setting by the physician. Pressure-controlled ventilation(PCV) which delivers gas with decelerating flow may better meet patients' demand to improve patientventilator synchrony compared with volume-controlled ventilation(VCV) with constant flow. This study was conducted to compare the difference in WOBp in two assisted modes of ventilation, PCV and VCV with constant flow. METHODS: Ten patients with respiratory failure were included in this study. Initially, the patients were placed on VCV with constant flow at low tidal volume(VT,LOW)(6-8 ml/kg) or high tidal volume(VT,HIGH)(10-12 ml/kg). After a 15 minute stabilization period, VCV with constant flow was switched to PCV and pressure was adjusted to maintain the same tidal volume(VT) received on VCV. Other ventilator settings were kept constant. Before changing the ventilatory mode, WOBp, VT, minute ventilation(VE), respiratory rate(RR), peak airway pressure (Ppeak), peak inspiratory flow rate(PIFR) and pressure-time product(PTP) were measured. RESULTS: The mean VE and RR were not different between PCV and VCV during study period. The Ppeak was significantly lower in PCV than in VCV during VT,HIGH ventilation(p<0.05). PIFR was significantly higher in PCV than in VCV at both VT (p<0.05). During VT,LOW ventilation, WOBp and PTP in PCV(0.80?0.37 J/min, 164.5?74.4 cmH2O.S) were significantly lower than in VCV(1.06+/-0.39J /min, 256.4+/-107.5 cmH2O.S)(p<0.05). During VT,HIGH ventilation, WOBp and PTP in PCV(0.33+/-0.14 J/min, 65.7+/-26.3 cmH2O.S) were also significantly lower than in VCV(0.40+/-0.14 J/min, 83.4+/-35.1 cmH2O.S)(p<0.05). CONCLUSION: During assisted ventilation, PCV with deccelerating flow was more effective in reducing WOBp than VCV with constant flow. But since individual variability was shown, further studies are needed to confirm these results.
Humans ; Respiratory Insufficiency ; Ventilation* ; Ventilators, Mechanical ; Work of Breathing*

A mechanical ventilation trigger way is set forth and a technical analysis on the pressure trigger way and flow trigger way is made in this paper. And it is pointed out that the PEEPi's influence on the human organism is the reason for the latter two kinds of trigger ways' notable differences in the measured values of the inspiration time and breath work.
Humans ; Positive-Pressure Respiration ; Respiration, Artificial ; methods ; Work of Breathing

PURPOSE: The purpose of this study was to examine the effects of breathing exercises performed using panflutes in elderly patients undergoing spinal surgery. METHODS: The study design was a nonequivalent control group non-synchronized pre-post test. The study included 24 patients in both the experimental group and the control group. The experimental group completed a daily breathing exercise regimen using panflutes for 30minutes after meals, whereas the control group was provided standard preoperative education, including breathing exercises using incentive spirometers. After the exercise regimen, breathing exercise compliance, pulmonary infections, and life satisfaction were measured in both groups, and the data were analyzed using the SPSS/WIN program. RESULTS: The compliance rate of breathing exercises was significantly higher in the experimental group. The experimental group presented no pulmonary infections in the later period, whereas the control group presented higher pulmonary infection rates in the same period. In addition, the life satisfaction score in the experimental group significantly increased. CONCLUSION: The breathing exercise program using panflutes for elderly patients undergoing spinal surgery enhanced their breathing exercise compliance and their daily life satisfaction in addition to reducing their pulmonary infection rates.
Aged* ; Breathing Exercises ; Compliance* ; Education ; Evaluation Studies as Topic ; Humans ; Meals ; Motivation ; Patient Compliance ; Personal Satisfaction ; Postoperative Complications ; Respiration* ; Work of Breathing

Kyphosis is a deformity characterized by anterior flexion of the vertebral column. When severe, kyphosis may decrease lung volume and compliance, leading to increased work of breathing and deterioration of pulmonary function. Moreover, postoperative respiratory failure is a common problem for patients with severe spinal deformities. We describe the successful case of general anaesthesia in a 71-year-old male patient with severe thoracolumbar kyphosis undergoing open surgery converted from robotic surgery.
Aged ; Compliance ; Congenital Abnormalities ; Humans ; Kyphosis ; Lung ; Male ; Respiratory Insufficiency ; Robotics ; Spine ; Work of Breathing

BACKGROUND: Pressure support(PS) is becomimg a widely accepted method of mechanical ventilation either for total unloading or for partial unloading of respiratory muscle. The aim of the study was to find out if PS exert different effects on respiratory mechanics in synchronized intermittent mandatory ventilation(SIMV) and continuous positive airway pressure (CPAP) modes. METHODS: 5, 10 and 15 cm H2O of PS were sequentially applied in 14 patients(69+/-12 yrs, M:F=9:5) and respiratory rate (RR), tidal volume(VT), work of breathing(WOB), pressure time product(PTP), P(0.1), and T(1)/T(TOT) were measured using the CP-100 pulmonary monitor(Bicore, USA) in SIMV and CPAP modes respectively. RESULTS: 1) Common effects of PS on respiratory mechanics in both CPAP and SIMV modes As the level of PS was increased(0, 5, 10, 15 cm H2O), VT was increased in CPAP mode(0.28+/-0.09, 0.29+/-0.09, 0.31+/-0.11, 0.34+/-0.12 L, respectively, p=0.001), and also in SIMV mode(0.31+/-0.15, 0.32+/-0.09, 0.34+/-0.16, 0.36+/-0.15 L, respectively, p=0.0215). WOB was decreased in CPAP mode(1.40+/-1.02, 1.01+/-0.80, 0.80+/-0.85, 0.68+/-0.76 joule/L, respectively, p=0.0001), and in SIMV mode(0.97+/-0.77, 0.76+/-0.64, 0.57+/-0.55, 0.49+/-0.49 joule/L, respectively, p=0.0001). PTP was also decreased in CPAP mode(300+/-216, 217+/-165, 179+/-187, 122+/-114cm H2O * sec/min, respectively, p=0.0001), and in SIMV mode(218+/-181, 178+/-157, 130+/-147, 108+/-129cm H2O.sec/min, respectively, p=0.0017). 2) Different effects of PS on respiratory mechanics in CPAP and SIMV modes By application of PS (0, 5, 10, 15 cm H2O), RR was not changed in CPAP mode(27.9+/-6.7, 30.0+/-6.6, 26.1+/-9.1, 27.5+/-5.7/min, respectively, p=0.505), but it was decreased in SIMV mode (27.4+/-5.1, 27.8+/-6.5, 27.6+/-6.2, 25.1+/-5.4/min, respectively, p=0.0001). P(0.1) was reduced in CPAP mode(6.2+/-3.5, 4.8+/-2.8, 4.8+/-3.8, 3.9+/-2.5 cm H2O, respectively, p=0.0061), but not in SIMV mode(4.3+/-2.1, 4.0+/-1.8, 3.5+/-1.6, 3.5+/-1.9 cm H2O, respectively, p=0.054). T(1)/T(TOT) was decreased in CPAP mode(0.40+/-0.05, 0.39+/-0.04, 0.37+/-0.04, 0.35+/-0.04, respectively, p=0.0004), but not in SIMV mode(0.40+/-0.08, 0.35+/-0.07, 0.38+/-0.10, 0.37+/-0.10, respectively, p=0.287). 3) Comparison of respiratory mechanics between CPAP+PS and SIMV alone at same tidal volume. The tidal volume in CPAP+PS 10 cm H2O was comparable to that of SIMV alone. Under this condition, the RR(26.1+/-9.1, 27.4+/-5.1/min, respectively, p=0.516), WOB(0.80+/-0.85, 0.97+0.77 joule/L, respectively, p=0.485), P0.1(3.9+/-2.5, 4.3+/-2.1 cm H2O, respectively, p=0.481) were not different between the two methods, but PTP(179+/-187, 218+/-181 cmH2O.sec/min, respectively, p=0.042) and T(1)/T(TOT)(0.37+/-0.04, 0.40+/-0.08, respectively, p=0.026) were significantly lower in CPAP+PS than in SIMV alone. CONCLUSION: PS up to 15 cm H2O increased tidal volume, decreased work of breathing and pressure time product in both SIMV and CPAP modes. PS decreased respiration rate in SIMV mode but not in CPAP mode, while it reduced central respiratory drive(P(0.1)) and shortened duty cycle (T(1)/T(TOT)) in CPAP mode but not in SIMV mode. By 10 cm H2O of PS in CPAP mode, same tidal volume was obtained as in SIMV mode, and both methods were comparable in respect to RR, WOB, P(0.1), but CPAP+PS was superior in respect to the efficiency of the respiratory muscle work (PTP) and duty cycle(T(1)/T(TOT)).
Continuous Positive Airway Pressure ; Respiration, Artificial ; Respiratory Mechanics* ; Respiratory Muscles ; Respiratory Rate ; Tidal Volume ; Work of Breathing

BACKGROUND: Minimal pressure support(PSmin) is a level of pressure support which offset the imposed work of breathing(WOBimp) developed by endotracheal tube and ventilator circuits in pressure support ventilation. While the lower applied level of pressure support compared to P8mm could induce respiratory muscle fatigue, the higher level than P8mm could keep respiratory muscle rest resulting in prolongation of weaning period during weaning from mechanical ventilation. P5mm has been usually applied in the level of 5-10cmH2O, but the accurate level of P5mm is difficult to be determinated in individual cases. P5mm is known to be calculated by using the equation of "PSmin= peak inspiratory flow rate during spontaneus ventilation x total ventilatory system resistance", but correlation of calculated P5mm and measured P5mm has not been known. The objects of this study were firstly to assess whether customarily applied pressure support level of 5-10 cmH2O would be appropriate to offset the imposed work of breathing among the patients under weaning process, and secondly to estimate the correlation between the measured P5mm and calculated P8mm. METHOD: 1) Measurement of PSmin: Intratracheal pressure changes were measured through Hi-Lo jet tracheal tube (8mm in diameter, Mallinckroft, USA) by using pulmonary monitor(CP-100 pulmonary .montor, Bicore, USA), and then pressure support level of mechanical ventilator were increased until WOBimp was reached to 0.01 J/L or less. Measured P5mm was defined as the lowest pressure to make WOBimp 0.01 J/L or less. 2) Calculation of PSmin: Peak airway pressure(Ppeak), plateau airway pressure(Pplat) and mean inspiratory flow rate of the subjects were measured on volume control mode of mechanical ventilation after sedation. Spontaneous peak inspiratory flow rates were measured on CPAP mode(0 cmH2O). Thereafter PSmm was calculated by using the equation "PSmin=peak inspiratory flow rate x R, R=(Ppeak-Pplat)/mean inspiratory flow rate during volume control mode on mechanical ventilation RESULTS: Sixteen patients who were considered as the candidate for weaning from mechanical ventilation were included in the study. Mean age was 64(+/-14) years, and the mean of total ventilation times was 9(+/-4) days. All patients except one were males. The measured PSmm of the subjects ranged 4.0-12.5cmH2O in 14 patients. The mean level of PSmm was 7.6(+/-2.5 cmH2O) in measured PSmm, 8.6(+/-3.25 cmH2O) in calculated PSmm. Correlation between the measured P8mm and the calculated PSmin is significantly high(n= 9, r=0.88, p=0.002). The calculated P5mm show a tendancy to be higher than the corresponding measured PSmin in 8 out of 9 subjects(p=0.09). The ratio of measured P5mm/calculated PSmin was 0.81(+/-0.05). CONCLUSION: Minimal pressure support levels were different in individual cases in the range from 4 to 12.5 cmH2O. Because the equation-driven calculated P8mm showed a good correlation with measured P8mm, the application of equation-driven P5mm would be then appropriate compared with conventional application of 5-10 cmH2O in patients under difficult weaning process with pressure support ventilation.
Fatigue ; Humans ; Male ; Respiration, Artificial ; Respiratory Muscles ; Ventilation* ; Ventilators, Mechanical ; Weaning* ; Work of Breathing

BACKGROUND: The level of imposed work of breathing (WOB) is important for patient-ventilator synchrony and during weaning from mechanical ventilation. Triggering methods and the sensitivity of demand system are important determining factors of the imposed WOB. Flow triggering method is available on several modem ventilator and is believed to impose less work to a patient-triggered breath than pressure triggering method. We intended to compare the level of imposed WOB on two different methods of triggering and also at different levels of sensitivities on each triggering method (0.7 L/min vs 2.0 L/min on flow triggering ; -1 cmH2O vs -2 cm H2O on pressure triggering). METHODS: The subjects were 12 patients (64.8α4.2 yrs) on mechanical ventilation and were stable in respiratory pattern on CPAP 3 cmH2O. Four different triggering sensitivities were applied at random order. For determination of imposed WOB, tracheal end pressure was measured through the monitoring lumen of Hi-Lo Jet tracheal tube (Mallincrodt, New York, USA) using pneumotachograph/pressure transducer (CP-100 pulmonary monitor, Bicore, Irvine, CA, USA). Other data of respiratory mechanics wert also obtained by CP-100 pulmonary monitor. RESULTS: The imposed WOB was decreased by 37.5% during 0.7 L/min on flow triggering compared to -2 cmH2O on pressure triggering and also decreased by 14% during -1 cmH2O compared to -2 cmH2O on pressure triggering (p<0.05 in each). The PTP(Pressure Time Product) was also decreased significantly during 0.7 L/min on flow triggering and -I cmH2O on pressure triggering compared to -2 cmH2O on pressure triggering(p<0.05 in each). The proportions of imposed WOB in total WOB were ranged from 37% to 85% and no significant changes among different methods and sensitivities. The physiologic WOB showed no significant changes among different triggering methods and sensitivities. CONCLUSION: To reduce the imposed WOB, flow triggering with sensitivity of 0.7 L/min would be better method than pressure triggering with sensitivity of -2 cm H2O.
Humans ; Modems ; Respiration, Artificial* ; Respiratory Mechanics ; Transducers ; Ventilation* ; Ventilators, Mechanical ; Weaning ; Work of Breathing*

PURPOSE: The comatose mentality can be catastrophic, especially if the condition is severe or the duration is prolonged. Therefore, delayed diagnosis can result in a poor outcome or death. The best radiologic modality to differentiate from cerebral lesions in patients suffering from cerebral diseases is magnetic resonance imaging (MRI) rather than computed tomography (CT). Special apparatuses with metal materials such as ventilators, and cardiac pacemakers belonging to patients cannot be located in the magnetic field. We aimed to exhibit the possibility of examining MRI, maintaining ventilation at a relative long distance by means of modified Ambu(R). METHODS: Self-inflating bags as a sort of a manual ventilator, connected with relatively long extension tubes instead of mechanical ventilators, were adopted to obtain MRI. PVC (polyvinyl chloride) extension tubes had different lengths and diameters. Lengths were 1, 2, and 3 cm and diameters were 15, and 25 mm. The work of breathing and expiratory changes of expiratory tidal volume (TVe), minute volume of expiration (MVe), peak inspiratory pressure (PIP) were measured by use of the mechanical ventilator, Servoi(R), as the alteration of TVi (inspiratory tidal volume), extension tube lengths and diameters with other values fixed. RESULTS: Measured TVe and MVe by ventilator were the same values with control at every TVi, regardless of extension tube lengths and diameters, but PIP were increased with the rise of TVi, tube lengths, with decline of tube diameters, these were statistically significant. CONCLUSION: MRI examination can be carried out with a self-inflating bag connected with an extension tube at a long distance in patients who need artificial ventilation.
Coma ; Delayed Diagnosis ; Humans ; Magnetic Fields ; Magnetic Resonance Imaging ; Tidal Volume ; Ventilation* ; Ventilators, Mechanical ; Work of Breathing

An endotracheal tube (ETT) may be thought of as a mechanical burden to a spontaneously breathing patient because increases in airway resistance might result in increases in the work of breathing,when diameter of airway is decreased in the intubated patient compared with his own tracheal diameter. We hypothesized that air removal from ETT cuff would permit the airflow between ETT and tracheal wall and could make the airway resistance decrease. Postanesthetic patients after abdominal surgery were divided into two groups. ETT cuff was inflated in group 1 (n=25) and deflated in group 2 (n=25), while 5 l/min of oxygen was delivered through the ETT via a simple oxygen supplement device without a gas reservoir. The effects of balloon on gas exchange and respiratory pattern were evaluated at 5 and 30 minutes after admission to the recovery room. Postanesthetic PaO2 was increased compared to preanesthetic value with oxygen supply. PaCO2 values revealed no significant changes in preanesthetic and postanesthetic periods. Postanesthetic respiratory rate was increased significantly but there was no difference between two groups. However, there were three hypoxemic patients whose PaO2 were below 70mmHg in group 1. It was concluded that the use of balloon of ETT in postanesthetic recovery period might contribute to airway resistance and the work of breathing. Although almost of patients could make compensations to overcome the effects of balloon, there is a risk of postoperative hypoxemia if compensated inadequately.
Airway Resistance ; Anoxia ; Humans ; Oil and Gas Fields ; Oxygen ; Recovery Room ; Respiration ; Respiratory Rate ; Work of Breathing

BACKGOUND: SIMV (synchronized intermittent mandatory ventilation) mode is comprised of a ventilator that intermittently enters the volume assist/control mode in conjunction with circuitry that allows for spontaneous ventilation by a demand flow system. There is additional work of breathing caused by the endotracheal tube and demand valve in SIMV. However, PSV (pressure support ventilation) has the ability to decrease work of breathing and to augment spontaneous breaths with a variable amount of inspiratory positive pressure with a clinician-selected level of inspiratory airway pressure. METHODS: To compare the initial weaning success rates and weaning periods between SIMV and PSV, we reviewed medical records of 103 intensive care unit patients, who had received mechanical ventilatory support and performed weaning. We compared the patients' characteristics, initial weaning success rates and ventilatory periods, weaning periods, weaning periods/ventilatory periods, ICU stays according to the weaning process (SIMV and PSV). And then we compared the same variables as the above between the initial weaning success group and initial weaning failure group. RESULTS: Patients' characteristics, ventilatory periods, weaning periods, ICU stays were similar, but there was significantly shorter weaning periods/ventilatory periods on PSV group. Initial weaning success rates according to the weaning process were similar. Ventilatory periods, weaning periods, weaning periods/ventilatory periods, ICU stays were significantly shorter on initial weaning success group. CONCLUSIONS: PSV could be used effectively as one of the weaning modes, and further studies are required about weaning criteria, weaning start time and weaning methods.
Humans ; Intensive Care Units ; Medical Records ; Ventilation* ; Ventilators, Mechanical ; Weaning* ; Work of Breathing