scholarly journals Mechanical ventilation. Part II: Basic principles and function of ventilators.

2017 ◽  
Vol 62 (4) ◽  
pp. 334
Author(s):  
K. PAVLIDOU (Κ. ΠΑΥΛΙΔΟΥ) ◽  
I. SAVVAS (Ι. ΣΑΒΒΑΣ) ◽  
T. ANAGNOSTOU (Τ. ΑΝΑΓΝΩΣΤΟΥ)
Keyword(s):  
Mechanical Ventilation ◽  
Tidal Volume ◽  
Respiratory Rate ◽  
Positive Pressure Ventilation ◽  
Anaesthetic Management ◽  
Intermittent Positive Pressure Ventilation ◽  
Assisted Ventilation ◽  
Inspiratory Pressure ◽  
Positive Pressure ◽  
Continuous Positive Pressure

Mechanical ventilation is the process of supporting respiration by manual or mechanical means. When normal breathing is inefficient or has stopped, mechanical ventilation is life-saving and should be applied at once. The ventilator increases the patient's ventilation by inflating the lungs with oxygen or a mixture of air and oxygen. Ventilators play an important role in the anaesthetic management of patients, as well as in the treatment of patients in the ICU. However, there are differences between the anaesthetic ventilators and the ventilators in ICU. The main indication for mechanical ventilation is difficulty in ventilation and/or oxygenation of the patient because of any respiratory or other disease. The aims of mechanical ventilation are to supply adequate oxygen to patients with a limited vital capacity, to treat ventilatory failure, to reduce dyspnoea and to facilitate rest of fatigued breathing muscles. Depression of the central nervous system function is a pre-requirement for mechanical ventilation. Some times, opioids or muscle relaxants can be used in order to depress patient's breathing. Mechanical ventilation can be applied using many different modes: assisted ventilation, controlled ventilation, continuous positive pressure ventilation, intermittent positive pressure ventilation and jet ventilation. Furthermore, there are different types of automatic ventilators built to provide positive pressure ventilation in anaesthetized or heavily sedated or comatose patients: manual ventilators (Ambu-bag), volumecontrolled ventilators with pressure cycling, volume-controlled ventilators with time cycling and pressure-controlled ventilators. In veterinary practice, the ventilator should be portable, compact and easy to operate. The controls on most anaesthetic ventilators include settings for tidal volume, inspiratory time, inspiratory pressure, respiratory rate and inspiration: expiration (I:E) ratio. The initial settings should be between 10-20 ml/kg for tidal volume, 12-30 cmH2 0 for the inspiratory pressure and 8-15 breaths/min for the respiratory rate. Mechanical ventilation is a very important part of treatment in the ICU, but many problems may arise during application of mechanical ventilation in critically ill patients. All connections should be checked in advance and periodically for mechanical problems like leaks. Moreover, complications like lung injury, pneumonia, pneumothorax, myopathy and respiratory failure can occur during the course of mechanical ventilation causing difficulty in weaning.

Effects of nasal positive-pressure hyperventilation on the glottis in normal awake subjects

1995 ◽  
Vol 79 (1) ◽  
pp. 176-185 ◽  
Author(s):  
V. Jounieaux ◽  
G. Aubert ◽  
M. Dury ◽  
P. Delguste ◽  
D. O. Rodenstein
Keyword(s):  
Tidal Volume ◽  
Positive Pressure Ventilation ◽  
Anterior Commissure ◽  
Minute Ventilation ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Vocal Cords ◽  
Diaphragmatic Muscle ◽  
Inspiratory Resistance ◽  
Cyclic Changes

We have recently observed obstructive apneas during nasal intermittent positive-pressure ventilation (nIPPV) and suggested that they were due to hypocapnia-induced glottic closure. To confirm this hypothesis, we studied seven healthy subjects and submitted them to nIPPV while their glottis was continuously monitored through a fiber-optic bronchoscope. During wakefulness, we measured breath by breath the widest inspiratory angle formed by the vocal cords at the anterior commissure along with several other indexes. Mechanical ventilation was progressively increased up to 30 l/min. In the absence of diaphragmatic activity, increases in delivered minute ventilation resulted in progressive narrowing of the vocal cords, with an increase in inspiratory resistance and a progressive reduction in the percentage of the delivered tidal volume effectively reaching the lungs. Adding CO2 to the inspired gas led to partial widening of the glottis in two of three subjects. Moreover, activation of the diaphragmatic muscle was always associated with a significant inspiratory abduction of the vocal cords. Sporadically, complete adduction of the vocal cords was directly responsible for obstructive laryngeal apneas and cyclic changes in the glottic aperture resulted in waxing and waning of tidal volume. We conclude that in awake humans passive ventilation with nIPPV results in vocal cord adduction that depends partly on hypocapnia, but our results suggest that other factors may also influence glottic width.

Effects of continuous positive-pressure ventilation in experimental pulmonary edema

1976 ◽  
Vol 40 (4) ◽  
pp. 568-574 ◽  
Author(s):  
P. C. Hopewell ◽  
J. F. Murray
Keyword(s):  
Pulmonary Edema ◽  
Left Atrial ◽  
Positive Pressure Ventilation ◽  
Colloid Osmotic Pressure ◽  
Intermittent Positive Pressure Ventilation ◽  
Water Volume ◽  
Positive Pressure ◽  
Positive End Expiratory Pressure ◽  
Continuous Positive Pressure ◽  
Double Isotope

We compared the effects of continuous positive-pressure ventilation (CPPV), using 10 cmH2O positive end-expiratory pressure (PEEP), with intermittent positive-pressure ventilation (IPPV), on pulmonary extravascular water volume (PEWV) and lung function in dogs with pulmonary edema caused by elevated left atrial pressure and decreased colloid osmotic pressure. The PEWV was measured by gravimetric and double-isotope indicator dilution methods. Animals with high (22–33 mmHg), moderately elevated (12–20 mmHg), and normal (3–11 mmHg) left atrial pressures (Pla) were studied. The PEWV by both methods was significantly increased in the high and moderate Pla groups, the former greater than the latter (P less than 0.05). There was no difference in the PEWV between animals receiving CPPV and those receiving IPPV in both the high and moderately elevated Pla groups. However, in animals with high Pla, the Pao2 was significantly better maintained and the inflation pressure required to deliver a tidal volume of 12 ml/kg was significantly less with the use of CPPV than with IPPV. We conclude that in pulmonary edema associated with high Pla, PEEP does not reduce PEWV but does improve pulmonary function.

Continuous positive-pressure ventilation does not alter ventricular pressure-volume relationship

1981 ◽  
Vol 240 (6) ◽  
pp. H821-H826 ◽  
Author(s):  
J. E. Fewell ◽  
D. R. Abendschein ◽  
C. J. Carlson ◽  
E. Rapaport ◽  
J. F. Murray
Keyword(s):  
Mechanical Properties ◽  
Positive Pressure Ventilation ◽  
Venous Return ◽  
Intermittent Positive Pressure Ventilation ◽  
Left Ventricular ◽  
Positive Pressure ◽  
Volume Relationship ◽  
Pressure Volume Relationship ◽  
The Right ◽  
Continuous Positive Pressure

To determine whether alterations in the mechanical properties (i.e., stiffening) of the right and left ventricles contribute to the decrease in right and left ventricular end-diastolic volumes during continuous positive-pressure ventilation (CPPV), we studied six dogs anesthetized with chloralose urethane and ventilated with a volume ventilator. We varied ventricular volumes by withdrawing or infusing blood. Pressure-volume curves, constructed by plotting transmural ventricular end-diastolic pressures against ventricular end-diastolic volumes, did not change during CPPV (12 cmH2O positive end-expiratory pressure) compared to intermittent positive-pressure ventilation (IPPV, 0 cmH2O end-expiratory pressure). We conclude that decreased ventricular end-diastolic volumes during CPPV result primarily from a decrease in venous return. Alterations in the mechanical properties of the ventricles do not play a significant role in this response.

Comparison of Early Nasal Intermittent Positive Pressure Ventilation and Nasal Continuous Positive Airway Pressure in Preterm Infants with Respiratory Distress Syndrome

2018 ◽  
Vol 65 (4) ◽  
pp. 352-360 ◽  
Author(s):  
Mesut Dursun ◽  
Sinan Uslu ◽  
Ali Bulbul ◽  
Muhittin Celik ◽  
Umut Zubarioglu ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Continuous Positive Airway Pressure ◽  
Respiratory Distress Syndrome ◽  
Airway Pressure ◽  
Positive Pressure Ventilation ◽  
Distress Syndrome ◽  
Positive Airway Pressure ◽  
Invasive Mechanical Ventilation ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure

Abstract Aims To compare the effect of early nasal intermittent positive pressure ventilation (nIPPV) and nasal continuous positive airway pressure (nCPAP) in terms of the need for endotracheal ventilation in the treatment of respiratory distress syndrome (RDS) in preterm infants born between 24 and 32 gestational weeks. Methods This is a randomized, controlled, prospective, single-centered study. Forty-two infants were randomized to nIPPV and 42 comparable infants to nCPAP (birth weight 1356 ± 295 and 1359 ± 246 g and gestational age 29.2 ± 1.7 and 29.4 ± 1.5 weeks, respectively). Results The need for endotracheal intubation and invasive mechanical ventilation was significantly lower in the nIPPV group than the nCPAP group (11.9% and 40.5%, respectively, p < 0.05). There were no differences in the duration of total nasal respiratory support, duration of invasive mechanical ventilation, bronchopulmonary dysplasia or other early morbidities. Conclusion nIPPV compared with nCPAP reduced the need for endotracheal intubation and invasive mechanical ventilation in premature infants with RDS.

Lung Ventilation: Natural and Mechanical

2017 ◽  
Author(s):  
Yuan Lei
Keyword(s):  
Mechanical Ventilation ◽  
Critical Care ◽  
Respiratory System ◽  
Positive Pressure Ventilation ◽  
Lung Ventilation ◽  
Intermittent Positive Pressure Ventilation ◽  
Artificial Lung ◽  
Positive Pressure ◽  
Anatomy And Physiology ◽  
Artificial Lung Ventilation

‘Lung Ventilation: Natural and Mechanical’ describes the processes of respiration and lung ventilation, focusing on those issues related directly to mechanical ventilation. The chapter starts by discussing the anatomy and physiology of respiration, and the involvement of the lungs and the entire respiratory system. It continues by introducing the three operating principles of mechanical ventilation. It then narrows its focus to intermittent positive pressure ventilation (IPPV), the operating principle of most modern critical care ventilators, explaining the pneumatic process of IPPV. The chapter ends by comparing natural and mechanical/artificial lung ventilation.

Medical Ventilator System Basics: A clinical guide

2017 ◽  
Author(s):  
Yuan Lei
Keyword(s):  
Mechanical Ventilation ◽  
Positive Pressure Ventilation ◽  
Breathing Circuit ◽  
Building Blocks ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Control Parameters ◽  
Anatomy And Physiology ◽  
Ventilation Modes ◽  
Therapy Education

Medical Ventilator System Basics: A clinical guide—unlike books that focus on clinical applications, or that provide specifics about individual ventilator models, this is a practical guide about the equipment used for positive pressure mechanical ventilation. This book provides the information a clinician needs every day: how to assemble a ventilator system, how to determine appropriate ventilator settings, how to make sense of monitored data, how to respond to alarms, and how to troubleshoot ventilation problems. The book applies to all ventilators based on the intermittent positive pressure ventilation (IPPV) operating principle. In a systematic and comprehensive way, the book steps the user through the ventilator system, starting with its pneumatic principles to an explanation of the anatomy and physiology of respiration. It describes the system components, including the ventilator, breathing circuit, humidifier, and nebulizer. The book then introduces ventilation modes, starting with an explanation of the building blocks of breath variables and breath types. It describes the major ventilator functions, including control parameters, monitoring, and alarms. Along the way the book provides much practical troubleshooting information. Clearly written and generously illustrated, the book is a handy reference for anyone involved with mechanical ventilation, clinicians and non-clinicians alike. It is suitable as a teaching aid for respiratory therapy education and as a practical handbook in clinical practice.

End-respiratory pressure ventilation and sulfobromophthalein sodium excretion in dogs

1977 ◽  
Vol 43 (4) ◽  
pp. 714-720 ◽  
Author(s):  
E. E. Johnson ◽  
J. Hedley-Whyte ◽  
S. V. Hall
Keyword(s):  
Positive Pressure Ventilation ◽  
Total Concentration ◽  
Venous Pressure ◽  
Serum Levels ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Central Venous ◽  
Serum Samples ◽  
Cholecystokinin Octapeptide ◽  
Continuous Positive Pressure

Sulfobromophthalein sodium (BSP) 25 mg/kg body wt was given as a single iv injection to 32 fasted dogs. Serum samples at 3, 5, 10, 20, 30, 45, 60, 80, and 120 min postinjection were analyzed for total concentration of BSP and from 30 to 120 min for percent conjugated BSP. Four groups were compared: spontaneous ventilation; intermittent positive-pressure ventilation (IPPV) and continuous positive-pressure ventilation (CPPV) (2 groups). During CPPV, one group of dogs was given a continuous infusion of cholecystokinin octapeptide (CCK-8, 1 ng/kg per min). Central venous pressure averaged 11.3 +/- 0.7 (SE) cmH2O in dogs with CPPV + CCK-8 and 11.8 +/- 0.8 (SE) cmH2O in dogs with CPPV alone. At 3, 5, and 10 min postinjection serum BSP levels were similar in all groups. From 30 to 120 min postinjection serum levels of both free and conjugated BSP were higher in dogs ventilated with CPPV alone than in any other group (P less than 0.01). Dogs given CCK-8 during CPPV had serum BSP levels that were statistically similar to dogs breathing spontaneously or ventilated with IPPV. We conclude that CPPV impairs BSP excretion. This effect is counteracted by CCK-8.

Chronic Pulmonary Disease in Neonates With Assisted Ventilation

PEDIATRICS ◽  
1975 ◽  
Vol 55 (6) ◽  
pp. 788-796
Author(s):  
Philip G. Rhodes ◽  
Robert T. Hall ◽  
John C. Leonidas
Keyword(s):  
Lung Disease ◽  
Chronic Lung Disease ◽  
Positive Pressure Ventilation ◽  
Clinical Signs ◽  
Intermittent Positive Pressure Ventilation ◽  
Assisted Ventilation ◽  
Positive Pressure ◽  
Radiographic Appearance ◽  
Idiopathic Respiratory Distress Syndrome ◽  
Inspired Oxygen

Chronic lung disease in the form of stage III or IV bronchopulmonary dysplasia (BPD) was found to occur among nine of 188 infants receiving intermittent positive pressure ventilation for respiratory insufficiency. None occurred in infants ventilated with a mask alone. The duration of endotracheal intubation was not significantly longer in patients developing BPD; however, the duration of exposure to inspired oxygen &gt; 60% was significantly longer in that group (mean, 141 hours.). A previously undescribed form of chronic lung disease was found to occur among nine of 150 infants ventilated because of underlying idiopathic respiratory distress syndrome. A radiographic appearance of diffuse haziness with loss of identifiable lung markings occurred at 5 to 15 days of age and was not associated with clinical signs or symptoms or increased oxygen needs. These changes disappeared in one to five days.

Effects of nasal positive-pressure hyperventilation on the glottis in normal sleeping subjects

1995 ◽  
Vol 79 (1) ◽  
pp. 186-193 ◽  
Author(s):  
V. Jounieaux ◽  
G. Aubert ◽  
M. Dury ◽  
P. Delguste ◽  
D. O. Rodenstein
Keyword(s):  
Tidal Volume ◽  
Positive Pressure Ventilation ◽  
Sleep Stage ◽  
Minute Ventilation ◽  
Significant Negative Correlation ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Rapid Eye Movement Sleep ◽  
Inspiratory Resistance ◽  
Co2 Level

We have previously observed that, in normal awake subjects passively hyperventilated with intermittent positive-pressure ventilation delivered through nasal access (nIPPV), the glottis could interfere with the ventilation. We report on data obtained in the same subjects during stable sleep. In all cases, the glottis was continuously observed through a fiber-optic bronchoscope, and other indexes were also continuously recorded. Mechanical ventilation was progressively increased up to 30 l/min. We have observed during passive nIPPV in stable sleep that increases in delivered minute ventilation (VEd) resulted in progressive narrowing of the glottic aperture, with increases in inspiratory resistance and progressive reductions in the percentage of the delivered tidal volume effectively reaching the lungs. For a given level of VEd, comparisons showed that the glottis was significantly narrower during sleep than during wakefulness and that the glottis was significantly narrower during stage 2 than during stages 3/4 non-rapid-eye-movement sleep. Moreover, when CO2 is added to the inspired air, glottic aperture increased in five of nine trials without changes in sleep stage. We also observed a significant negative correlation between glottic width and the VED, independent of the CO2 level. We conclude that during nIPPV glottis narrowing results in a decrease in the proportion of the delivered tidal volume reaching the lungs.

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