Peak Inflation Research Articles

Prediction of prolonged ventilator dependence in preterm infants

Volutrauma is an important factor in the pathogenesis of bronchopulmonary dysplasia (BPD). Our aims were to identify risk factors in the first 24h for prolonged ventilator dependence and assess volume delivery and carbon dioxide levels in infants with evolving BPD. A retrospective study was undertaken of 41 infants born at less than 32weeks of gestational age (GA). A higher tidal volume, minute volume and resistance and a lower GA, birth weight and compliance were associated with a significantly higher risk of ventilator dependence at 28days. The strongest relationships were with birth weight (area under the receiver operating characteristic curve, AUROC = 0.771) and GA (AUROC = 0.813). Tidal volume remained significantly higher after adjusting for GA in those who remained ventilator dependent at 28days. The 18 who remained ventilator dependent at 28days had increased mean carbon dioxide (PCO2) levels with increasing age from a mean of 41mmHg in the first 24h to 65mmHg at 28days PMA (p < 0.001). The increase in PCO2 occurred despite increases in peak inflation pressures (p < 0.001), tidal volumes (p = 0.002) and minute volumes (p < 0.001).Conclusion: These results suggest that initial volutrauma may contribute to the development of chronic ventilator dependence. What is Known: • In prematurely born infants, excessive tidal volumes are important in the pathogenesis of bronchopulmonary dysplasia (BPD), but a tidal volume that is too low will increase the risk of atelectasis, work of breathing and energy expenditure. What is New: • A high tidal volume in the first 24h was associated with an increased risk of ventilator dependence at 28days, which remained significant after adjusting for gestational age. Carbon dioxide levels significantly increased over the first month despite increased pressures and volumes in those who remained ventilator dependent.

New Strategies of Pulmonary Protection of Preterm Infants in the Delivery Room with the Respiratory Function Monitoring.

To investigate if the use of a visible respiratory function monitor (RFM) to use lower tidal volumes (Vts) during positive pressure ventilation (PPV) in the delivery room (DR) reduces the need of surfactant administration and invasive mechanical ventilation during the first 72 hours after birth of preterm infants <32 weeks' gestational age (GA). Infants <32 weeks' GA (n = 106) requiring noninvasive PPV were monitored with a RFM at birth and randomized to visible (n = 54) or masked (n = 52) display on RFM. Pulmonary data were recorded during the first 10 minutes after birth. Secondary analysis stratified patients by GA (<28, 28-29+6, or ≥30 weeks). Median expiratory Vts during inflations were greater in the masked group (7 mL/kg) than in the visible group (5.8 mL/kg; p = 0.001) same as peak inflation pressure (PIP) administered (21.5 vs. 19.7 cmH2O; p < 0.001). Consequently, minute volumes were greater in the masked group (256 vs. 214 mL/kg/min; p < 0.001), with no differences in respiratory rate. These differences were higher in those <30 weeks' GA. There was no difference in the need of surfactant administration or intubation during the first 72 hours of age. Using a RFM in the DR prevents the use of large Vt and PIP during respiratory support inflations, mostly in the more immature newborn infants, but with no other short-term benefits.

FEM Simulation of Subintimal Angioplasty for the Treatment of Chronic Total Occlusions

Subintimal angioplasty is a highly challenging technique for percutaneous treatment of chronic total occlusion (CTO) in blood vessels, and the development of predictive tools for preliminary evaluation of potential outcomes and risks could be very useful for clinicians. While finite element (FE) simulation is a well-established approach to investigating partial occlusions, its extension to CTO has not been investigated yet, because of several additional issues that have to be addressed. In this work, we discuss the implementation of a FE model to simulate the main steps of the procedure, i.e., subintimal insertion of an initially folded balloon in a false lumen, inflation from eccentric position, deflation, and extraction. The model includes key morphological features of the CTO and possibility of varying spatial distribution of material properties to account for different constituents and degree of calcification. Both homogeneous and heterogeneous CTO configurations were analyzed, comparing arterial stress state, plaque compression, and postprocedural recoil. For a peak inflation pressure of 12 bar, the degree of lumen restoration was in the range 65-80%, depending on plaque heterogeneity. After balloon extraction, homogeneous highly calcified plaques exhibited substantial recovery of original shape. For homogeneous and heterogeneous CTO, values of peak von Mises stress in the arterial wall were of the same order of magnitude (range 1-1.1 MPa) but at different locations. Results compared favorably with data reported in literature for postprocedural lumen restoration and arterial stress data, confirming potential usefulness of the approach.

Inflation in Africa, 1960–2015

We present various stylized facts about annual CPI based inflation in 47 African countries. Some stylized facts concern time series properties for each of the series but also across series. To achieve a useful and relevant dataset, we impute all missing values in the sample 1960–2015 using a new method based on postage stamps prices. This results in a balanced panel of annual figures from 1960 to and including 2015 for 47 countries.The key conclusion from our tour around various data properties is that differences across the country-specific series are substantially larger than their common properties. These differences concern features like peak inflation rates, years of peak inflation, correlation with worldwide inflation figures and country-specific persistence. In one word, there is no such thing as “African inflation”, and we recommend that models for inflation in an African country should be designed one by one. When we correlate inflation features in a cross section with country-specific conditions, we see that more democracy, less corruption, and less religious fractionalization associate with lower inflation rates.

DURATION OF SUSTAINED INFLATION DURING SUSTAINED INFLATION AND CHEST COMPRESSION IN A PORCINE MODEL OF ASPHYXIA

Abstract BACKGROUND Current resuscitation guidelines recommend 3:1 C:V ratio, however the most effective C:V ratio in newborns remains controversial. We recently demonstrate that combining chest compressions (CC) with a sustained inflation (SI) (=CC+SI) significantly improves return of spontaneous circulation (ROSC) in asphyxiated newborn piglets compared to 3:1 C:V resuscitation. However, the optimal length of SI during CC+SI is unknown. OBJECTIVES To examine if a 60sec SI compared to a 20sec SI or 3:1 C:V will reduce will reduces ROSC during resuscitation in asphyxiated newborn piglets. DESIGN/METHODS Cardiac arrest with achieved was induced in newborn piglets and then randomized to receive either “3:1 C:V ratio, SI+CC-20sec” or “SS+CC-60sec”. Piglets randomized to “SI+CC+20sec” or “SI+CC+60sec” received 90/min CC during a SI of 20sec or 60sec. Piglets randomized to 3:1 C:V received 90/min CC and 30 inflations/min. The default settings for airway pressures were peak inflation pressure of 30 cm H2O and a positive end expiratory pressure of 6 cm H2O. The primary outcome was duration of CC to achieve ROSC. RESULTS Eight piglets were randomized to each group; the mean (SD) age and weight was similar between groups. Median (IQR) ROSC was significantly shorter in the SI+CC-20sec and SI+CC-60sec group with 96 (68–168) sec and 78 (60–91) sec compared to the 3:1 C:V group with 235 (182–347)sec (p=0.002). 5/8 in the SI+CC-60sec group, 7/8 in the SI+CC-20sec and 8/8 in the 3:1 C:V group received epinephrine (p=0.82). CONCLUSION Lengths of SI during CC+SI does not affect ROSC, however CC+SI compared to 3:1 C:V does improve ROSC in newborn piglets.

T-piece resuscitators: how do they compare?

BackgroundThe T-piece resuscitator (TPR) has seen increased use as a primary resuscitation device with newborns. Traditional TPR design uses a high resistance expiratory valve to produce positive end expiratory pressure...

Pressure-decay testing of pleural air leaks in intact murine lungs: evidence for peripheral airway regulation.

The critical care management of pleural air leaks can be challenging in all patients, but particularly in patients on mechanical ventilation. To investigate the effect of central airway pressure and pleural pressure on pulmonary air leaks, we studied orotracheally intubated mice with pleural injuries. We used clinically relevant variables – namely, airway pressure and pleural pressure – to investigate flow through peripheral air leaks. The model studied the pleural injuries using a pressure‐decay maneuver. The pressure‐decay maneuver involved a 3 sec ramp to 30 cmH20 followed by a 3 sec breath hold. After pleural injury, the pressure‐decay maneuver demonstrated a distinctive airway pressure time history. Peak inflation was followed by a rapid decrease to a lower plateau phase. The decay phase of the inflation maneuver was influenced by the injury area. The rate of pressure decline with multiple injuries (28 ± 8 cmH20/sec) was significantly greater than a single injury (12 ± 3 cmH2O/sec) (P < 0.05). In contrast, the plateau phase pressure was independent of injury surface area, but dependent upon transpulmonary pressure. The mean plateau transpulmonary pressure was 18 ± 0.7 cm H2O. Finally, analysis of the inflation ramp demonstrated that nearly all volume loss occurred at the end of inflation (P < 0.001). We conclude that the air flow through peripheral lung injuries was greatest at increased lung volumes and limited by peripheral airway closure. In addition to suggesting an intrinsic mechanism for limiting flow through peripheral air leaks, these findings suggest the utility of positive end‐expiratory pressure and negative pleural pressure to maintain lung volumes in patients with pleural injuries.

Transpulmonary Pressure‐Dependent Regulation of Air Leaks after Peripheral Lung Injury

To assess the pathophysiology of pulmonary air leaks, we studied orotracheally intubated mice on mechanical ventilation with pleural injuries produced by a 25g needle inserted 1–2 mm into the lung parenchyma. The pleural injuries were studied using a standard inflation maneuver involving a 3 second ramp to 30 cmH20 followed by a 3 second breath hold. After pleural injury, the inflation maneuver resulted in a distinctive airway pressure time history; that is, peak inflation was followed by a rapid decrease to a lower plateau phase. The decay phase of the inflation maneuver was influenced by the injury area; the rate of pressure decline with multiple injuries (28+8 cmH20/sec) was significantly greater than a single injury (12+3 cmH20/sec)(p&lt;.05). In contrast, the plateau phase pressure was independent of injury surface area, but dependent upon transpulmonary pressure. When the standard inflation maneuver was performed in a pressure‐regulated body box, the plateau transpulmonary pressures were a mean of 18+0.7 cm H2O regardless of the absolute pressures outside of the lung. Although the pleural injury resulted in a significant increase in delivered air volume (p&lt;.01), there was no significant difference in air leak volume between 1 and 5 injuries (p&gt;.05). These findings are consistent with the regulation of pleural air leaks by transpulmonary pressure‐dependent airway closure.Support or Funding InformationNIH Grant HL94567, HL134229, HL007734, CA009535, ES000002 and the German Research Foundation (SFB1066)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Elevated airway liquid volumes at birth: a potential cause of transient tachypnea of the newborn.

Excessive liquid in airways and/or distal lung tissue may underpin the respiratory morbidity associated with transient tachypnea of the newborn (TTN). However, its effects on lung aeration and respiratory function following birth are unknown. We investigated the effect of elevated airway liquid volumes on newborn respiratory function. Near-term rabbit kittens (30 days gestation; term ~32 days) were delivered, had their lung liquid-drained, and either had no liquid replaced (control; n = 7) or 30 ml/kg of liquid re-added to the airways [liquid added (LA); n = 7]. Kittens were mechanically ventilated in a plethysmograph. Measures of chest and lung parameters, uniformity of lung aeration, and airway size were analyzed using phase contrast X-ray imaging. The maximum peak inflation pressure required to recruit a tidal volume of 8 ml/kg was significantly greater in LA compared with control kittens (35.0 ± 0.7 vs. 26.8 ± 0.4 cmH2O, P < 0.001). LA kittens required greater time to achieve lung aeration (106 ± 14 vs. 60 ± 6 inflations, P = 0.03) and had expanded chest walls, as evidenced by an increased total chest area (32 ± 9%, P < 0.0001), lung height (17 ± 6%, P = 0.02), and curvature of the diaphragm (19 ± 8%, P = 0.04). LA kittens had lower functional residual capacity during stepwise changes in positive end-expiratory pressures (5, 3, 0, and 5 cmH20). Elevated lung liquid volumes had marked adverse effects on lung structure and function in the immediate neonatal period and reduced the ability of the lung to aerate efficiently. We speculate that elevated airway liquid volumes may underlie the initial morbidity in near-term babies with TTN after birth.NEW & NOTEWORTHY Transient tachypnea of the newborn reduces respiratory function in newborns and is thought to result due to elevated airway liquid volumes following birth. However, the effect of elevated airway liquid volumes on neonatal respiratory function is unknown. Using phase contrast X-ray imaging, we show that elevated airway liquid volumes have adverse effects on lung structure and function in the immediate newborn period, which may underlie the pathology of TTN in near-term babies after birth.

Inflation pressures and times during initial resuscitation in preterm infants.

The optimal combination of inflation pressures and times to produce adequate expiratory tidal volumes during initial resuscitation in prematurely born infants has not been determined. The aim of this study was therefore to assess combinations of inflation pressures and times and the resulting expiratory tidal volume levels using a respiratory function monitor. Sixty-four infants born before 34 weeks of gestation were studied. The infants were divided according to whether the inflation pressure (peak inflation pressure minus positive end expiratory pressure) was < or ≥20 cmH2 O during the first five inflations delivered by a face mask, and those groups were then subdivided according to whether the inflation time was < or ≥1.5 s. Inflation pressure ≥20 cmH2 O compared with lower pressure at both inflation times produced significantly higher expiratory tidal volume. Longer compared with shorter inflation times when the inflation pressure was ≥20 cmH2 O resulted in no significant difference in expiratory tidal volume. At <20 cmH2 O inflation pressure, longer inflation time overall resulted in higher end tidal volume, but the majority of infants had a tidal volume less than the anatomical dead space. At higher inflation pressure, a longer inflation time was not necessary to increase expiratory tidal volume.

Using exhaled CO2 to guide initial respiratory support at birth: a randomised controlled trial

ImportanceA sustained inflation (SI) provided at birth might reduce bronchopulmonary dysplasia (BPD).ObjectiveThis study aims to examine whether an SI-guided exhaled carbon dioxide (ECO2) compared with positive pressure ventilation (PPV) alone...

Neutrophil gelatinase‑associated lipocalin as a potential novel biomarker for ventilator‑associated lung injury.

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa protein of the lipocalin superfamily and its presence was initially observed in activated neutrophils. It has previously been demonstrated that the expression of NGAL is markedly increased in stimulated epithelia, and is important in the innate immunological response to various pathophysiological conditions, including infection, cancer, inflammation and kidney injury. The present study constructed a ventilator-associated lung injury model in mice. NGAL mRNA and protein expression levels in lung tissue were detected using reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. In addition, NGAL protein levels in bronchoalveolar lavage fluid and serum were measured via western blotting. The results of the present study suggested that NGAL expression increased under all mechanical ventilation treatments. The increase was most prominent in the high peak inflation pressure and high-volume mechanical ventilation groups, where there was the greatest extent of lung injury. In addition, NGAL expression increased in a time-dependent manner under high-volume mechanical ventilation, consistent with the degree of lung injury. These findings suggested that NGAL may serve as a potential novel biomarker in ventilator-associated lung injury.

Comparison of ventilation parameters and blood gas analysis in mechanically-ventilated children who received chest physiotherapy and suctioning vs. suctioning alone

Background Chest physiotherapy and suctioning are routine methods for airway clearance in mechanically-ventilated children. However, chest physiotherapy has not been confirmed to affect ventilation parameters, such as tidal volume (TV), peak inflation pressure (PIP), peak inspiratory flow (PIF), and peak expiratory flow (PEF), as well as blood gas analysis (BGA) values in pediatric intensive care unit (PICU) patients.Objective To determine the efficacy of chest physiotherapy and suctioning vs. suctioning alone for improving the mechanical ventilation parameters and BGA.Methods This randomized, single-blind, clinical trial was conducted from November 2012 to June 2013 in the PICU at Haji Adam Malik Hospital, Medan. A total of 40 mechanically-ventilated pediatric patients were enrolled and divided into either the chest physiotherapy and suctioning group (24 subjects) or the suctioning alone group (16 subjects). Subjects underwent treatment, followed by monitoring of their ventilation parameters and blood gas analyses. Data were analyzed by independent t-test and Mann-Whitney test.Results Subjects comprised of 23 boys and 17 girls, with an age range of 1–204 months. After the respective treatments (chest physiotherapy and suctioning vs. suctioning alone), the ventilation parameters were as follows: median TV (60.0 vs. 56.5 mL, respectively; P=0.838), median PEF (10.4 vs. 10.8 I/s, respectively; P=0.838), median PIF (7.4 vs. 8.2 I/s, respectively; P=0.469), and mean PIP (17.3 vs. 15.6 cmH2O, respectively; P=0.23). The BGA values were: median pH (7.4 vs. 7.3, respectively; P=0.838), median pCO2 (38.4 vs. 36.2 mmHg, respectively; P=1.000), mean pO2 (136.6 vs. 139.2 mmHg, respectively; P=0.834), median HCO3 (20.4 vs. 22.7 mmol/L, respectively; P=0.594), median TCO2 (22.0 vs. 23.7 mmol/L, respectively; P=0.672), mean BE (-4.3 vs. -3.1 mmol/L, respectively; P=0.629), and median O2 saturation (98.5 vs. 98.3 %, respectively; P=0.967).Conclusion In mechanically-ventilated children in the PICU, ventilation parameters and BGA values are not significantly different between subjects who received both chest physiotherapy and suctioning and those who received suctioning alone.

Can Ambu self-inflating bag and Neopuff infant resuscitator provide adequate and safe manual inflations for infants up to 10 kg weight?

BackgroundManual resuscitation devices for infants and newborns must be able to provide adequate ventilation in a safe and consistent manner across a wide range of patient sizes (0.5–10 kg) and...

Resuscitation of infants with congenital diaphragmatic hernia

ObjectiveTo determine whether the respiratory response to resuscitation in infants with congenital diaphragmatic hernia (CDH) as measured by a respiratory function monitor differed between those who did and did not...

A Novel Prototype Neonatal Resuscitator That Controls Tidal Volume and Ventilation Rate: A Comparative Study of Mask Ventilation in a Newborn Manikin.

The objective of this randomized controlled manikin trial was to examine tidal volume (VT) delivery and ventilation rate during mask positive pressure ventilation (PPV) with five different devices, including a volume-controlled prototype Next Step™ device for neonatal resuscitation. We hypothesized that VT and rate would be closest to target with the Next Step™. Twenty-five Neonatal Resuscitation Program providers provided mask PPV to a newborn manikin (simulated weight 1 kg) in a randomized order with a self-inflating bag (SIB), a disposable T-piece, a non-disposable T-piece, a stand-alone resuscitation system T-piece, and the Next Step™. All T-pieces used a peak inflation pressure of 20 cmH2O and a positive end-expiratory pressure of 5 cmH2O. The participants were instructed to deliver a 5 mL/kg VT (rate 40–60/min) for 1 min with each device and each of three test lungs with increasing compliance of 0.5, 1.0, and 2.0 mL/cmH2O. VT and ventilation rate were compared between devices and compliance levels (linear mixed model). All devices, except the Next Step™ delivered a too high VT, up to sixfold the target at the 2.0-mL/cmH2O compliance. The Next Step™ VT was 26% lower than the target in the low compliance. The ventilation rate was within target with the Next Step™ and SIB, and slightly lower with the T-pieces. In conclusion, routinely used newborn resuscitators over delivered VT, whereas the Next Step™ under delivered in the low compliant test lung. The SIB had higher VT and rate than the T-pieces. More research is needed on volume-controlled delivery room ventilation.

Mortality following congenital diaphragmatic hernia repair: the role of anesthesia.

Mortality following surgical repair of congenital diaphragmatic hernia (CDH) remains high. The volume and type of perioperative intravenous fluid administered, baro-trauma, oxygen toxicity, and the duration of anesthesia are thought to affect outcome in surgical populations. The aim of this retrospective observational study was to determine whether the perioperative volume or type of fluids and/or the duration of anesthesia were associated with postoperative mortality and if mortality was predicted by the oxygenation index (OI) prior to or following CDH surgical repair. The records of infants with a left-sided CDH and without other congenital anomalies, who underwent surgical repair between April 2009 and March 2015, were examined. The oxygenation index was used to "quantify" the severity of lung function abnormality and reported as the best OI on day 1 after birth (OIBEST ), the OI immediately prior to surgery (OIPRE ) and at 1, 6, 12, and 24h postsurgery (OI1h , OI6h , OI12h , OI24h ), respectively. The change in the OI index (delta OI) was calculated by subtracting OIPRE from postoperative OIs. The records of 37 CDH infants (median gestational age 35.8, range 31.5-41.4weeks) were assessed; six died postoperatively. Neither the duration of anesthesia, the volume of crystalloids or colloids administered, nor the peak inflation pressures used during surgical repair were significantly correlated with postoperative mortality. Neither fetal tracheal occlusion nor use of a parietal patch significantly influenced mortality. The postoperative OI1h , OI6h , OI12h showed weak evidence for a difference between survivors and nonsurvivors. An OI24h of ≥5.5 predicted mortality with 100% sensitivity (95% CI, confidence intervals (CI) 40-100) and 93.1% specificity (95% CI, 77-99). Neither the volume of intraoperative fluids administered nor the duration of anesthesia was associated with postoperative death. The OI 24h postsurgery was the best predictor of an increased risk of mortality.

The first breath during resuscitation of prematurely born infants

BackgroundThe first five initial inflation pressures and times during resuscitation of prematurely born infants are frequently lower than those recommended and rarely result in tidal volumes exceeding the anatomical dead space. Greater volumes were produced when the infant was provoked to inspire by an inflation (active inflation). AimsTo assess factors associated with a shorter time to the first active inflation. Study designRespiratory function monitoring was undertaken during resuscitation, peak inflation pressures (PIP), inflation times and the infant's respiratory activity were simultaneously recorded. SubjectsInfants with a gestational age<34weeks requiring resuscitation at birth. Outcome measuresThe relationships of the PIP and inflation time of the first five inflations and first active inflation to the time to the first active inflation. ResultsRecordings from 47 infants, median gestational age of 29 (23–34) weeks, were analysed. The median PIP of the first five inflations was 27 (range 9–37) cmH2O and inflation time 1.22 (range 0.32–4.08) s. The median PIP of the first active inflation was 25 (range 19–37) cmH2O and inflation time 1.35 (0.35–3.67) s. The median time to the first active inflation was 7 (range 0–50) seconds and was inversely correlated with the PIP (p=0.001) and inflation time (p=0.018) of the first five inflations and the PIP (p=0.001) and inflation time (p=0.008) of the first active inflation. ConclusionThe magnitude of the inflation pressures and times of the first five inflations inversely correlate with the time to the first breath during resuscitation.

Comparison of positive pressure ventilation devices in a newborn manikin

Objective: To compare tidal volume (VT) delivery and ventilation rate between devices for positive pressure ventilation (PPV) during newborn resuscitation.Methods: Neonatal resuscitation program providers (n = 25) delivered PPV to a newborn manikin in a randomized order with: a self-inflating bag (SIB), a disposable T-piece, a non-disposable T-piece, a stand-alone infant resuscitation system T-piece and the volume-controlled prototype Next StepTM device (KM Medical). All T-pieces used a peak inflation pressure of 20cmH2O and a 5cmH2O positive end-expiratory pressure (PEEP). The SIB neither had a PEEP valve nor manometer. The Next StepTM had a 5cmH2O PEEP valve. The participants aimed to deliver a 5 mL/kg VT (rate 40–60 min−1) for 1 min with each device and each of three compliances (0.5, 1.0 and 2.0 mL/cmH2O). VT and ventilation rate were compared between devices and compliance levels (ANOVA)Results: All devices, except the Next StepTM delivered a 4–5 mL/kg VT at the low compliance, but three- to four-fold that of the target at the higher compliance levels. The Next StepTM delivered a VT close to target at all compliance levels. The ventilation rate was within 40–60 min−1 with all devices and compliance levels.Conclusions: Routinely used ventilation devices for newborn resuscitation can triple intended VT and requires further investigation.

Reducing the within-patient variability of breathing for radiotherapy delivery in conscious, unsedated cancer patients using a mechanical ventilator

Objective:Variability in the breathing pattern of patients with cancer during radiotherapy requires mitigation, including enlargement of the planned treatment field, treatment gating and breathing guidance interventions. Here, we provide the first demonstration of how easy it is to mechanically ventilate patients with breast cancer while fully conscious and without sedation, and we quantify the resulting reduction in the variability of breathing.Methods:15 patients were trained for mechanical ventilation. Breathing was measured and the left breast anteroposterior displacement was measured using an Osiris surface-image mapping system (Qados Ltd, Sandhurst, UK).Results:Mechanical ventilation significantly reduced the within-breath variability of breathing frequency by 85% (p < 0.0001) and that of inflation volume by 29% (p < 0.006) when compared with their spontaneous breathing pattern. During mechanical ventilation, the mean amplitude of the left breast marker displacement was 5 ± 1 mm, the mean variability in its peak inflation position was 0.5 ± 0.1 mm and that in its trough inflation position was 0.4 ± 0.0 mm. Their mean drifts were not significantly different from 0 mm min−1 (peak drift was −0.1 ± 0.2 mm min−1 and trough drift was −0.3 ± 0.2 mm min−1). Patients had a normal resting mean systolic blood pressure (131 ± 5 mmHg) and mean heart rate [75 ± 2 beats per minute (bpm)] before mechanical ventilation. During mechanical ventilation, the mean blood pressure did not change significantly, mean heart rate fell by 2 bpm (p < 0.05) with pre-oxygenation and rose by only 4 bpm (p < 0.05) during pre-oxygenation with hypocapnia. No patients reported discomfort and all 15 patients were always willing to return to the laboratory on multiple occasions to continue the study.Conclusion:This simple technique for regularizing breathing may have important applications in radiotherapy.Advances in knowledge:Variations in the breathing pattern introduce major problems in imaging and radiotherapy planning and delivery and are currently addressed to only a limited extent by asking patients to breathe to auditory or visual guidelines. We provide the first demonstration that a completely different technique, of using a mechanical ventilator to take over the patients' breathing for them, is easy for patients who are conscious and unsedated and reduces the within-patient variability of breathing. This technique has potential advantages in radiotherapy over currently used breathing guidance interventions because it does not require any active participation from or feedback to the patient and is therefore worthy of further clinical evaluation.