Ventilation by external high-frequency oscillation in cats

1985 ◽  
Vol 58 (4) ◽  
pp. 1390-1399 ◽  
Author(s):  
H. E. Ward ◽  
J. Armengol ◽  
R. L. Jones
Keyword(s):  
High Frequency ◽  
Spontaneous Breathing ◽  
Random Order ◽  
High Frequency Oscillation ◽  
Chamber Pressure ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Residual Capacity ◽  
Highly Correlated

Eight anesthetized tracheostomized cats were placed in an 8.2-liter airtight chamber with the trachea connected to the exterior. Thirty-two combinations of high-frequency oscillations (HFO) (0.5–30 Hz; 25–100 ml) were delivered for 10 min each in random order into the chamber. Arterial blood gas tensions during oscillation were compared with control measurements made after 10 min of spontaneous breathing without oscillation when the mean arterial PCO2 (PaCO2) was 30.1 Torr. Ventilation due to spontaneous breathing (Vs) and oscillation (Vo) were derived from the chamber pressure trace and a pneumotachograph, respectively. As the oscillation frequency increased, oscillated tidal volume (Vo) decreased from a mean of 39 (0.5 Hz) to 3.3 ml (30 Hz) when 100 ml was delivered to the chamber. From 6–25 Hz, apnea occurred with Vo less than estimated respiratory dead space (VD); the minimum effective Vo/VD ratio was 0.37 +/- 0.05. Although Vo was maximal at 10 Hz at each oscillation volume, the lowest PaCO2 occurred at 2–6 Hz, and arterial PO2 rose as expected during hypocapnia. Above 10 Hz, PaCO2 was determined by Vo and was independent of frequency, whereas at lower frequencies, PaCO2 was related to Vo; below 6 Hz, PaCO2 varied inversely with the calculated alveolar ventilation. As oscillations became more effective, both PaCO2 and Vs fell progressively and were highly correlated; apnea occurred when PaCO2 was reduced by a mean of 4.5 Torr. Mean chamber pressure remained near zero up to 15 Hz, indicating functional residual capacity did not change. We conclude that externally applied HFO can readily maintain gas exchange in vivo, with Vo less than VD at frequencies over 2 Hz.

Lung volume recruitment during high-frequency oscillation in atelectasis-prone rabbits

1988 ◽  
Vol 64 (4) ◽  
pp. 1607-1614 ◽  
Author(s):  
L. J. Byford ◽  
J. H. Finkler ◽  
A. B. Froese
Keyword(s):  
Lung Volume ◽  
High Frequency ◽  
Airway Pressure ◽  
Random Order ◽  
High Frequency Oscillation ◽  
Mean Airway Pressure ◽  
Mean Pressure ◽  
Residual Capacity ◽  
Lung Volume Recruitment ◽  
Arterial Po2

In diffuse lung injury, optimal oxygenation occurs with high-frequency oscillatory ventilation (HFO-A, where A is active expiratory phase) when sustained inflations (SI) are applied periodically to recruit lung volume. Theoretically pulsed pressures may be safer and more effective than static pressures for reexpanding alveoli. We compared the increases in lung volume and arterial PO2 (PaO2) induced by 30-s increases in mean airway pressure in six New Zealand White rabbits made atelectasis prone by saline lavage plus 1 h of conventional ventilation. Pulsatile SI's (HFO-A left on during increase in mean pressure) of delta PSI = 5, 10, and 15 cmH2O and static SI's (HFO-A off during SI) of delta PSI = 5, 10, 15, and 20 cmH2O were delivered in random order. Lungs were ventilated at 15 Hz, inspired fractional concentration of O2 = 1.0, and mean airway pressure 15-20 cmH2O between test periods and deflated to functional residual capacity before each SI to standardize volume history. With both maneuvers, increases in lung volume and PaO2 induced by SI's were proportional to the magnitude of the SI (P less than 0.001) in all cases. Pulsatile SI's consistently increased lung volume and PaO2 more than static SI's having the same delta PSI (P less than 0.005) such that any given target PaO2 or change in volume (delta V) was achieved at 5 cmH2O less mean pressure with the pulsatile maneuver. Respiratory system compliance increased after both types of SI. Oxygenation and lung volume changes at 5 min were related with r = 0.58 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Dilutional Acidosis following Hetastarch or Albumin in Healthy Volunteers

2000 ◽  
Vol 93 (5) ◽  
pp. 1184-1187 ◽  
Author(s):  
Jonathan H. Waters ◽  
Clifford A. Bernstein
Keyword(s):  
Healthy Volunteers ◽  
Repeated Measures ◽  
Base Excess ◽  
Rank Test ◽  
Albumin Concentration ◽  
Acid Base Balance ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
The Impact

Background The intent of this study was to evaluate the impact of the commonly used colloids-hetastarch and albumin-on in vivo acid-base balance. From this evaluation, a better understanding of the mechanism of dilutional acidosis was expected. Methods In a prospective, randomized fashion, 11 healthy volunteers were administered 15 ml/kg hetastarch solution, 6%, or 15 ml/kg albumin, 5%, intravenously over 30 min. Four weeks later, the study subjects were administered the other colloid. Arterial blood gas and electrolyte parameters were measured at baseline and at 30, 60, 90, 120, 210, and 300 min after colloid administration. Pre- and postlaboratory values were compared within groups using a paired t test and a Wilcoxon signed rank test and between groups using repeated-measures analysis of variance and a Wilcoxon rank sum test. Results Thirty min after infusion, subjects who were administered hetastarch showed statistically significant changes (P < 0.05) in base excess (from 2.5 +/- 0.9 mEq/l to 0.7 +/- 1.1 mEq/l), HCO3- concentration (from 27 +/- 1.0 mEq/l to 25 +/- 1.3 mEq/l), Cl- concentration (from 108 +/- 2 mEq/l to 112 +/- 2 mEq/l), albumin concentration (from 4.4 +/- 0.2 g/dl to 3.5 +/- 0.5 g/dl), and arterial carbon dioxide tension (Paco2; from 40.8 +/- 2.3 mmHg to 39. 2 +/- 3.2 mmHg), whereas only the albumin concentration (from 4.4 +/- 0.2 g/dl to 4.8 +/- 0.6 g/dl) changed significantly in the albumin-treated group. Conclusions Decreases in base excess were observed for 210 min after hetastarch administration but not after albumin. The mechanism for this difference is discussed.

scholarly journals Physiologic Evaluation of Ventilation Perfusion Mismatch and Respiratory Mechanics at Different Positive End-expiratory Pressure in Patients Undergoing Protective One-lung Ventilation

2018 ◽  
Vol 128 (3) ◽  
pp. 531-538 ◽  
Author(s):  
Savino Spadaro ◽  
Salvatore Grasso ◽  
Dan Stieper Karbing ◽  
Alberto Fogagnolo ◽  
Marco Contoli ◽  
...  
Keyword(s):  
Respiratory Mechanics ◽  
Lung Ventilation ◽  
Random Order ◽  
Driving Pressure ◽  
Shunt Fraction ◽  
Positive End Expiratory Pressure ◽  
One Lung Ventilation ◽  
Predicted Body Weight ◽  
Arterial Blood Gas ◽  
Arterial Blood

Abstract Background Arterial oxygenation is often impaired during one-lung ventilation, due to both pulmonary shunt and atelectasis. The use of low tidal volume (VT) (5 ml/kg predicted body weight) in the context of a lung-protective approach exacerbates atelectasis. This study sought to determine the combined physiologic effects of positive end-expiratory pressure and low VT during one-lung ventilation. Methods Data from 41 patients studied during general anesthesia for thoracic surgery were collected and analyzed. Shunt fraction, high V/Q and respiratory mechanics were measured at positive end-expiratory pressure 0 cm H2O during bilateral lung ventilation and one-lung ventilation and, subsequently, during one-lung ventilation at 5 or 10 cm H2O of positive end-expiratory pressure. Shunt fraction and high V/Q were measured using variation of inspired oxygen fraction and measurement of respiratory gas concentration and arterial blood gas. The level of positive end-expiratory pressure was applied in random order and maintained for 15 min before measurements. Results During one-lung ventilation, increasing positive end-expiratory pressure from 0 cm H2O to 5 cm H2O and 10 cm H2O resulted in a shunt fraction decrease of 5% (0 to 11) and 11% (5 to 16), respectively (P < 0.001). The Pao2/Fio2 ratio increased significantly only at a positive end-expiratory pressure of 10 cm H2O (P < 0.001). Driving pressure decreased from 16 ± 3 cm H2O at a positive end-expiratory pressure of 0 cm H2O to 12 ± 3 cm H2O at a positive end-expiratory pressure of 10 cm H2O (P < 0.001). The high V/Q ratio did not change. Conclusions During low VT one-lung ventilation, high positive end-expiratory pressure levels improve pulmonary function without increasing high V/Q and reduce driving pressure.

Responses of pulmonary vagal mechanoreceptors to high-frequency oscillatory ventilation

1988 ◽  
Vol 65 (2) ◽  
pp. 633-639 ◽  
Author(s):  
J. A. Wozniak ◽  
P. W. Davenport ◽  
P. C. Kosch
Keyword(s):  
High Frequency ◽  
Spontaneous Breathing ◽  
High Frequency Oscillatory Ventilation ◽  
Oscillatory Ventilation ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
Residual Capacity ◽  
Anesthetized Dogs ◽  
Increased Activity ◽  
High Frequency Oscillatory

The discharge of 57 slowly adapting pulmonary stretch receptors (PSR's) and 16 rapidly adapting receptors (RAR's) was recorded from thin vagal filaments in anesthetized dogs. The receptors were localized and separated into three groups: extrathoracic tracheal, intrathoracic tracheal, and intrapulmonary receptors. The influence of high-frequency oscillatory ventilation (HFO) at 29 Hz on receptor discharge was analyzed by separating the response to the associated shift in functional residual capacity (FRC) from the oscillatory component of the response. PSR activity during HFO was increased from spontaneous breathing (49%) and from the static FRC shift (25%). PSR activity during the static inflation was increased 19% over spontaneous breathing. RAR activity was also increased with HFO. These results demonstrate that 1) the increased activity of PSR and RAR during HFO is due primarily to the oscillating action of the ventilator and secondarily to the shift in FRC associated with HFO, 2) the increased PSR activity during HFO may account for the observed apneic response, and 3) PSR response generally decreases with increasing distance from the tracheal opening.

scholarly journals High frequency jet ventilation through mask contribute to oxygen therapy in patients undergoing bronchoscopic intervention under deep sedation

2020 ◽  
Author(s):  
Mingyuan Yang ◽  
Bin Wang ◽  
Qingwu Hou ◽  
Yunzhi Zhou ◽  
Na Li ◽  
...  
Keyword(s):  
High Frequency ◽  
Oxygen Therapy ◽  
Deep Sedation ◽  
Blood Gas ◽  
Jet Ventilation ◽  
Arterial Blood Gas ◽  
Airway Stenosis ◽  
High Frequency Jet Ventilation ◽  
Arterial Blood ◽  
Procedure Duration

Abstract Background: High frequency jet ventilation (HFJV) is an open ventilating technique to maintain ventilation for emergency or difficult airway. However, it is unclear whether jet ventilation or conventional oxygen therapy (COT) is more effectively and safely to maintain adequate oxygenation in patients with airway stenosis during bronchoscopic intervention (BI) under deep sedation.Methods: A prospective randomized cohort study was conducted to compare HFJV with normal frequency jet ventilation (NFJV) and COT (high flow oxygen) in oxygen supplementation during BI under deep sedation from March 2020 to August 2020. Patients receiving BI under deep sedation were randomly divided into 3 parallel groups of 50 patients each: the COT group (FiO21.0, 12 L/min), the NFJV Group (FiO2 1.0, driving pressure 0.1MPa, respiratory rate (RR) 15bpm) and HFJV Group (FiO2 1.0, driving pressure 0.1MPa, RR 1200bpm). SpO2, MBP and HR were recorded during the whole procedure. Arterial blood gas was examined and recorded at 15 minutes after initiation of procedure. Procedure duration, dose of anesthetics and adverse events during BI in the three groups were also recorded.Results: A total of 161 patients were enrolled with 11 patients excluded. Clinical characteristics were similar among the three groups. PaO2 of HFJV group was significantly higher than that of COT and NFJV group (P<0.001). PaO2 was significantly correlated with ventilation mode (P<0.001), BMI (P=0.019) and procedure duration (P=0.001). Multiple linear regression showed that only BMI and procedure duration were independent influencing factors of arterial blood gas PaO2 (P=0.040, P=0.002). The location of airway lesions and severity of airway stenosis were no statistical correlation with PaCO2 and PaO2.Conclusions: HFJV can effectively and safely improve intra-operative PaO2 in patients with airway stenosis during BI in deep sedation, and doesn’t increase intra-operative PaCO2 and the risk of hypercapnia. The location of airway lesions and severity of airway stenosis may not affect oxygenation maintain during basic and some advanced BI.Trial registration: Chinese Clinical Trial Registry. Registration number, ChiCTR2000031110, registered on March 22, 2020.

scholarly journals Physiological Effects of Different Recruitment Maneuvers in a Pig Model of ARDS

2020 ◽  
Author(s):  
Feiping Xia ◽  
Chun Pan ◽  
Lihui Wang ◽  
Ling Liu ◽  
Songqiao Liu ◽  
...  
Keyword(s):  
Random Order ◽  
Pig Model ◽  
Physiological Effects ◽  
Impedance Tomography ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Recruitment Maneuvers ◽  
Sustained Inflation ◽  
Significant Difference ◽  
Before And After

Abstract Background: In acute respiratory distress syndrome (ARDS), lung recruitment maneuvers can recruit collapsed alveoli in gravity-dependent lung regions, improving the homogeneity of ventilation distribution. This study used electrical impedance tomography (EIT) to investigate the physiological effects of different recruitment maneuvers for alveolar recruitment in a pig model of ARDS. Methods: ARDS was induced in ten healthy male pigs with repeated bronchoalveolar lavage until the arterial partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) (P/F ratio) was < 100 mmHg and remained stable for 30 minutes (TARDS). ARDS pigs underwent three sequential recruitment maneuvers, including sustained inflation (SI), increments of positive end-expiratory pressure (PEEP) (IP), and pressure-controlled ventilation (PCV) applied in random order, with 30 mins at a PEEP of 5 cmH2O between maneuvers. Respiratory mechanics, hemodynamics, arterial blood gas, and EIT were recorded at baseline, TARDS, and before and after each recruitment maneuver.Results: In all ten pigs, ARDS was successfully induced with a mean 2.8±1.03L (2800±1032.80ml) bronchoalveolar lavages. PaO2, SO2, P/F, and compliance were significantly improved after recruitment with SI, IP or PCV (all p<0.05), and there were no significant differences between maneuvers. Global inhomogeneity (GI) was significantly decreased after recruitment with SI, IP, or PCV. There were no significant differences in GI before or after recruitment with the different maneuvers. The decrease in GI (ΔGI) was significantly greater after recruitment with IP compared to SI (p=0.023), but there was no significant difference in ΔGI between IP and PCV.Conclusion: SI, IP, and PCV increased oxygenation, and regional and global compliance of the respiratory system, and decreased inhomogeneous gas distribution in ARDS pigs. IP significantly improved inhomogeneity of the lung compared to SI.

Lung pressures and gas transport during high-frequency airway and chest wall oscillation

1989 ◽  
Vol 67 (3) ◽  
pp. 985-992 ◽  
Author(s):  
M. C. Khoo ◽  
T. H. Ye ◽  
N. H. Tran
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
High Frequency ◽  
Blood Gases ◽  
Small Degree ◽  
Conventional Mechanical Ventilation ◽  
Positive Pressure ◽  
Arterial Blood ◽  
Residual Capacity ◽  
Wall Oscillation

The major goal of this study was to compare gas exchange, tidal volume (VT), and dynamic lung pressures resulting from high-frequency airway oscillation (HFAO) with the corresponding effects in high-frequency chest wall oscillation (HFCWO). Eight anesthetized paralyzed dogs were maintained eucapnic with HFAO and HFCWO at frequencies ranging from 1 to 16 Hz in the former and 0.5 to 8 Hz in the latter. Tracheal (delta Ptr) and esophageal (delta Pes) pressure swings, VT, and arterial blood gases were measured in addition to respiratory impedance and static pressure-volume curves. Mean positive pressure (25–30 cmH2O) in the chest cuff associated with HFCWO generation decreased lung volume by approximately 200 ml and increased pulmonary impedance significantly. Aside from this decrease in functional residual capacity (FRC), no change in lung volume occurred as a result of dynamic factors during the course of HFCWO application. With HFAO, a small degree of hyperinflation occurred only at 16 Hz. Arterial PO2 decreased by 5 Torr on average during HFCWO. VT decreased with increasing frequency in both cases, but VT during HFCWO was smaller over the range of frequencies compared with HFAO. delta Pes and delta Ptr between 1 and 8 Hz were lower than the corresponding pressure swings obtained with conventional mechanical ventilation (CMV) applied at 0.25 Hz. delta Pes was minimized at 1 Hz during HFCWO; however, delta Ptr decreased continuously with decreasing frequency and, below 2 Hz, became progressively smaller than the corresponding values obtained with HFAO and CMV.

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