CFD Analysis of CO_2 Concentration and Temperature Distribution in an Office Room Using Two Mechanical Ventilation Modes

Modern mechanical ventilators are more complex than those first developed in the 1950s. Newer ventilation modes can be difficult to understand and implement clinically, although they provide more treatment options than traditional modes. These newer modes, which can be considered alternative or nontraditional, generally are classified as either volume controlled or pressure controlled. Dual-control modes incorporate qualities of pressure-controlled and volume-controlled modes. Some ventilation modes provide variable ventilatory support depending on patient effort and may be classified as closed-loop ventilation modes. Alternative modes of ventilation are tools for lung protection, alveolar recruitment, and ventilator liberation. Understanding the function and application of these alternative modes prior to implementation is essential and is most beneficial for the patient.

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A CFD analysis of room aspect ratio on the effect of buoyancy and room air flow

Thermal Science ◽

10.2298/tsci0704079t ◽

2007 ◽

Vol 11 (4) ◽

pp. 79-94 ◽

Cited By ~ 2

Author(s):

Brajesh Tripathi ◽

Moulic Sandipan ◽

Late Arora

Keyword(s):

Temperature Distribution ◽

Distribution System ◽

Air Distribution ◽

Cooling Load ◽

Cfd Analysis ◽

Uniform Temperature ◽

Air Volume ◽

Recent Developments ◽

Careful Design ◽

Occupied Zone

Comfort conditions in air-conditioned rooms require that temperature in the occupied zone should not vary by more than 1?C and velocity, every where in the room, should be less than 0.15 m/s so that occupants do not feel draft. Recent developments in providing effective insulation and making leak tight buildings are considerably reduced the cooling load requirements and the supply airflow rates. Obtaining uniform temperature distribution with reduced air volume flow rates requires careful design of air distribution system. This study aims to find velocity and temperature distribution in the room towards this end.

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Effects of three controlled mechanical ventilation modes on rat lung hydrogen peroxide and apoptosis during hemorrhagic shock

Open Journal of Molecular and Integrative Physiology ◽

10.4236/ojmip.2013.31005 ◽

2013 ◽

Vol 03 (01) ◽

pp. 27-35

Author(s):

Amanda R. Thimmesch ◽

Qiuhua Shen ◽

Richard L. Clancy ◽

Janet D. Pierce

Keyword(s):

Hydrogen Peroxide ◽

Mechanical Ventilation ◽

Hemorrhagic Shock ◽

Rat Lung ◽

Ventilation Modes ◽

Controlled Mechanical Ventilation

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Mechanical ventilation

10.1093/med/9780199687039.003.0024_update_001 ◽

2016 ◽

Author(s):

Robert O Grounds ◽

Andrew Rhodes

Keyword(s):

Mechanical Ventilation ◽

Lung Injury ◽

Gas Flow ◽

Spontaneous Respiration ◽

Positive Pressure ◽

International Consensus ◽

Ventilation Modes ◽

Protective Strategies ◽

Pressure Controlled

Mechanical ventilation is used to assist or replace spontaneous respiration. Gas flow can be generated by negative pressure techniques, but it is positive pressure ventilation that is the most efficacious in intensive care. There are numerous pulmonary and extrapulmonary indications for mechanical ventilation, and it is the underlying pathology that will determine the duration of ventilation required. Ventilation modes can broadly be classified as volume- or pressure-controlled, but modern ventilators combine the characteristics of both in order to complement the diverse requirements of individual patients. To avoid confusion, it is important to appreciate that there is no international consensus on the classification of ventilation modes. Ventilator manufacturers can use terms that are similar to those used by others that describe very different modes or have completely different names for similar modes. It is well established that ventilation in itself can cause or exacerbate lung injury, so the evidence-based lung-protective strategies should be adhered to. The term acute lung injury has been abolished, whilst a new definition and classification for the acute respiratory distress syndrome has been defined.

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Ventilator induced Diaphragmatic Dysfunction assessed by Ultrasonography and its impact on Weaning outcome

QJM ◽

10.1093/qjmed/hcaa039.066 ◽

2020 ◽

Vol 113 (Supplement_1) ◽

Author(s):

H M A Fawzy ◽

M H M Hassan ◽

A A M Alkholy

Keyword(s):

Mechanical Ventilation ◽

Operating Characteristics ◽

Diaphragmatic Dysfunction ◽

Rapid Shallow Breathing Index ◽

Weaning Failure ◽

Significant Difference ◽

Shallow Breathing ◽

Ventilation Modes ◽

Weaning Outcome ◽

Rapid Shallow Breathing

Abstract Background Ventilator induced diaphragmatic dysfunction (VIDD), as a loss of diaphragmatic force generating capacity due to the use of mechanical ventilation. Difficulties in discontinuing ventilatory support are encountered in 20–25% of mechanically ventilated patients, with a staggering 40% of time spent in the intensive care unit being devoted to weaning. M-mode ultrasonography is now an accepted qualitative method of assessing diaphragmatic motion in normal and pathological conditions. In this study, we evaluated whether diaphragmatic excursion (DE) as measured by M-mode sonography can be a predictor of weaning and diagnosis of VIDD. Aim The aim of this study is to determine the presence of ventilator induced diaphragmatic dysfunction (VIDD) diagnosed by M-mode ultrasonography and its impact on weaning outcome. Methodology This study was conducted prospectively in critical care unit in Ain Shams Hospital, a university-affiliated, tertiary referral center in Cairo, Egypt. Study subjects included 78 patients between August 2017 to August 2018. who required mechanical ventilation ≥72hrs. who fulfilled the spontaneous breath trial (SBT) criteria, at the start of a 1-hr SBT, each hemidiaphragm was evaluated M-mode sonography with the patient in the supine position. Rapid shallow Breathing index (RSBI) was simultaneously calculated at the bedside. Ultrasonographic Diaphragmatic Dysfunction (DD) was diagnosed if an Diaphragmatic Excursion (DE) was <10 mm or negative, the latter indicating paradoxical diaphragmatic movement. Results Diaphragmatic Dysfunction (DD) among the eligible 78 patients was 48% (n = 37). DD group had longer weaning time [39,2 (26-56) hrs. vs. 22.3 (30-16) hrs. p = 0.001) in DD vs. NDD group respectively and total ventilation time [140 (130-150) hrs. vs. 130 (120–140) hrs. p > 0.05) in DD vs. NDD group respectively. Weaning failure was (45.8% vs. 30.8%, p=0.01) in DD vs. NDD group respectively. In NDD group Rt. DE, mean 25.4 ±4.1 mm. While Lt. side was 25.3±4.6 mm, 11.25mm and 22mm (45-15) respectively. In DD group Rt. DE, mean 7.6 ±2.02mm, IQR 2.4 mm and median 8.2mm (10-1.9). While Lt. side was 9.2±0.8mm, 4.3mm and 8.9mm (9.8-5.7) respectively. The area under the receiver operating characteristics curve (ROC) of ultrasonographic criteria in predicting weaning failure was near similar to that of rapid shallow breathing index. Hypercapenic acidosis in NDD group might protect them from VIDD Conclusions DD is present in a significant percentage 48% (nearly half) of our medical ICU patients on MV ≥ 72 hrs which largely account for weaning failure. DD was associated with a significant longer weaning time, and ICU stay, with no significant difference in 30 day mortality Recommendations DE by US measurements is a valuable tool and is recommended as an adjunctive weaning index to aid prediction of weaning outcome. Evaluating the role of spontaneous ventilation modes and advanced ventilation modes as PAV and NAVA effects on decreas ing VIDD versus controlled modes.

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