History of Intermittent Mandatory Ventilation prior to 1972. Part one. Special Article

Medical history is often overlooked as advances keep moving forward. Seldom is it that advances in medicine are truly new, unique ideas, but rather built on ideas that have been considered before. Even our latest developments will become history or forgotten as science and medicine advance. This history of intermittent mandatory ventilation (IMV) is a two-part article in which the first part attempts to show that the concepts and apparatus that involve the now common mode of ventilation have been considered and described for nearly 200 years, if not earlier. This older history is not brought forward to diminish what has been done in the last 50 years, but to enhance awareness of how ideas and even mechanical ventilators change over time. The second part will describe how those ideas and mechanics changed into what we now call IMV in its many forms. Keywords: Intermittent Mandatory Ventilation, IMV, History of mechanical ventilation

Changes of Physiological parameters of the patient during laparoscopic gynaecology

Analysing and fusing data from the medical devices of different disciplines (anaesthesiology and surgery) inside the operating rooms may promote awareness during surgical procedures. In this work, the changes of physiological parameters of patients undergoing laparoscopic gynaecology procedures were analysed. The statistical relationship between the intra-abdominal pressure and airway peak pressure was evaluated. Patients ventilated with pressure-controlled ventilation (PCV) and intermittent mandatory ventilation (IMV) were included. The results demonstrated that increasing the intra-abdominal pressure (IAP) resulted in increasing the airway peak pressure and decreasing the lung compliance. The Pearson correlation coefficient between the IAP and the airway peak pressure was 0.910 in PCV-patients and 0.952 in IMV-patients when changes of the ventilation settings were considered. Additionally, major hemodynamic changes included alterations in the mean blood pressure (MBP), where the MBP increased after insufflating the abdomen and decreased after abdomen deflation.

Four Truths of Mechanical Ventilation and the Ten-Fold Path to Enlightenment

The Four Truths 1. The truth of confusion 2. The truth of the origin of confusion 3. The truth of the cessation of confusion 4. The truth of the path leading to the cessation of confusion The 10-Fold Path 1. A breath is one cycle of positive flow (inspiration) and negative flow (expiration) defined in terms of the flow-time curve. 2. A breath is assisted if the ventilator does work on the patient. 3. A ventilator assists breathing using either pressure control or volume control based on the equation of motion for the respiratory system. 4. Breaths are classified by the criteria that trigger (start) and cycle (stop) inspiration 5. Trigger and cycle events can be initiated by the patient or the machine. 6. Breaths are classified as spontaneous or mandatory based on both the trigger and cycle events. 7. There are 3 breath sequences: Continuous mandatory ventilation (CMV), Intermittent Mandatory Ventilation (IMV), and Continuous Spontaneous Ventilation (CSV). 8. There are 5 basic ventilatory patterns: VC-CMV, VC-IMV, PC-CMV, PC-IMV, and PC-CSV: 9. Within each ventilatory pattern there are several variations that can be distinguished by their targeting scheme(s). 10. A mode of ventilation is classified according to its control variable, breath sequence, and targeting scheme(s). Keywords: Breath. Trigger, Cycle, Breath sequences, Ventilatory patterns, Mode of ventilation

Neurally Adjusted Ventilatory Assistance and Synchronized Intermittend Mandatory Ventilation in Children Assessed by Electrical Impedance Segmentography: A Prospective Randomized Case-Control Crossover Trial

Background: Assessing relative differences of integrated impedance as a surrogate of volume changes between neurally adjusted ventilatory assist (NAVA) and synchronized intermittent mandatory ventilation (SIMV) by using electric impedance segmentography in children.Methods: Performed as a prospective randomized case-control crossover trial in a pediatric intensive care unit of a tertiary center including eight mechanically-ventilated children, four sequences of two different ventilation modes were consecutively applied. The children were randomized in two groups; one that was started on neurally adjusted ventilatory assist and the other on synchronized intermittent mandatory ventilation. During ventilation, electric impedance segmentography measurements were recorded.Results: The relative difference of vertical impedance between both ventilatory modes was measured (median 0.52, IQR 0-0.87). These differences in left apical lung segments were present during the first (median 0.58, IQR 0-0.89, p=0.04) and second crossover (median 0.50, IQR 0-0.88, p=0.05) as well as across total impedance (0.52 IQR 0-0.87; p=0.002). During neurally adjusted ventilatory assist children showed a shift of impedance towards caudal lung segments, compared to synchronized intermittent mandatory ventilation.Conclusion: Electrical impedance segmentography enables dynamic monitoring of transthoracic impedance. Segmental measurements, however, were of low reproducibility due to various limiting factors in its application. For further evaluation, larger prospective clinical trials are necessary.