Photos/ Survival Flight Air Ambulance Company
Preface
Although mechanical circulatory support (MCS) management may be familiar to critical care and aeromedical teams, 911 EMS clinicians occasionally encounter these low-volume, high-stakes transfers that extend beyond routine practice. Many ground 911 EMS units now carry ventilators and infusion pumps, allowing broader critical care delivery, especially when rural transport times exceed 45 minutes.
This review emphasizes that mechanical ventilation is physiology in motion. During transport, clinicians must anticipate the clinical course, take all possible steps to prevent hemodynamic deterioration, clarify goals, preserve airway, breathing, and circulation, and provide analgesia and sedation while bridging the patient to definitive care. Critical care is not being paused but rather preserved during the continuum of transport from the sending hospital to the receiving specialty center.
The practical question is not whether one ventilator mode should be preferred in every MCS transfer, but how transport teams can recognize when a ventilator adjustment is becoming a circulatory intervention.
In rural, interfacility, or specialty-care transfers, the clinician managing the ventilator may also be the person interpreting blood pressure trends, ETCO₂ changes, infusion response, and device alarms. ETCO₂ is especially important in LVAD and Impella patients because low pulsatility can make conventional perfusion assessment, pulse checks, pulse oximetry reliability, and noninvasive blood pressure trends less dependable.
Because ETCO₂ reflects the interaction between ventilation, pulmonary blood flow, and cardiac output, trending ETCO₂ during MCS transport can provide an early warning of hypoventilation, worsening perfusion, reduced preload, or changing device effectiveness before oxygen saturation alone reveals deterioration.2,3 This makes a simple physiology-based framework especially useful for crews who may not transport Impella, LVAD, or IABP patients frequently.
Introduction
Critical care transport teams increasingly move patients receiving temporary or durable MCS between referring hospitals, specialty centers, and definitive-care destinations. During these transports, clinicians must preserve device function, gas exchange, and cardiovascular stability despite limited space, noise, vibration, handoffs, and evolving clinical information. Positive-pressure ventilation is central to this challenge because intrathoracic-pressure changes can affect pulmonary mechanics, venous return, RV afterload, LV afterload, and device preload.2,3
These effects vary by the patient’s clinical picture. Positive intrathoracic pressure may benefit LV-dominant failure by reducing LV transmural pressure and afterload, but excessive airway pressure or PEEP can reduce venous return and increase RV afterload.2-4 This is especially important in preload-dependent MCS, where reduced RV output decreases LV filling and blood volume available to an Impella or LVAD.2,3
Because comparative literature has not shown consistent clinical superiority of volume- or pressure-targeted ventilation when similar lung-protective goals are achieved, this study describes ventilator mode selection in an MCS transport cohort and interprets observed practice through heart-lung physiology, including permissive hypercapnia and RV vulnerability.1-7,9,10
The objective is to translate an observed transport practice pattern into clinically usable guidance for EMS and critical care transport teams. Rather than treating volume-targeted or pressure-targeted ventilation as competing defaults, this analysis emphasizes delivered tidal volume, minute ventilation, mean airway pressure, PEEP response, right-heart reserve, and device preload as the variables that should drive bedside decision-making.
Methods
A retrospective observational secondary analysis was performed using a locked MCS transport registry. The analytic cohort included 141 MCS cases: 64 LVAD, 45 Impella, and 32 IABP. Transport platforms included rotor-wing, fixed-wing, and specialty critical care ground transport.
Mechanical ventilation and available ventilator settings were abstracted using standardized airway definitions. Ventilator modes were grouped as volume-targeted/volume-set or pressure-control/pressure-aligned.
Conventional volume control, assist-control volume, and SIMV-volume were categorized as volume-targeted/volume-set. Pressure-control modes were categorized as pressure-control/pressure-aligned. Pressure-regulated volume control was treated as a hybrid mode and categorized according to its primary physiologic alignment for this analysis.
The analysis was descriptive. Ventilator modes were clinically selected and were neither randomized nor protocol-assigned; therefore, comparative effectiveness and causal associations between ventilator mode and outcomes could not be determined.
The study was reviewed and approved by the Institutional Review Board. Institutional Review Board approval was obtained (IRB No. 2026-004), and informed consent was waived due to the retrospective observational design. All data were de-identified before analysis to protect patient confidentiality.
Results
The results are presented as the proportion of MCS transports requiring invasive ventilation, ventilator-strategy distribution among ventilated transports, and device-specific clinical context from available records.
Of 141 included MCS cases, 24 (17.0%) received invasive mechanical ventilation during transport. These comprised 9 LVAD, 10 Impella, and 5 IABP transports.
A volume-targeted/volume-set strategy was used in 21 of 24 mechanically ventilated transports (87.5%; 88%). Three transports (12.5%) used pressure-control or pressure-aligned strategies. This observed practice pattern should not be interpreted as evidence that volume-targeted ventilation was superior to pressure-targeted ventilation.
Patient-level records showed heterogeneous ventilator mode documentation, including assist-control volume, SIMV-volume, conventional volume control, pressure-control strategies, and pressure-regulated volume control. For interpretive consistency, the pressure-regulated volume-control case was treated as pressure-aligned in this analysis because its pressure-limited behavior was considered more relevant to transport physiology than its volume target alone. One active transport transition from SIMV-volume to a pressure-targeted mode was also documented.
Table 1. Cohort and Mechanical Ventilation Characteristics
| Characteristic | LVAD | Impella | IABP | Overall |
| Included analytic cohort | 64 | 45 | 32 | 141 |
| Mechanical ventilation during transport | 9 | 10 | 5 | 24 |
| Ventilated proportion within device cohort | 14.1% | 22.2% | 15.6% | 17.0% |
Table 2. Ventilator Strategy Among Mechanically Ventilated MCS Transports
| Ventilator strategy | n | % of ventilated transports | Interpretation |
| Volume-targeted / volume-set | 21 | 87.5% | Predominant observed transport strategy |
| Pressure-control / pressure-aligned | 3 | 12.5% | Includes two pressure-control cases and one pressure-regulated volume-control case interpreted as
pressure-aligned |
| Total | 24 | 100% | Mechanically ventilated MCS transports |
Table 3 translates the cohort’s observed ventilator practice into a practical bedside framework for EMS and critical care transport clinicians. Rather than presenting volume-targeted or pressure-control/pressure-aligned ventilation as a fixed preference, it organizes mode selection around the patient’s physiology, device type, airway pressures, gas exchange, preload dependence, and monitoring reliability.
Before choosing or changing the ventilator mode, identify the MCS device and dominant physiology pattern, including Impella, LVAD, IABP, RV dysfunction, pulmonary hypertension, pulmonary edema, or ARDS physiology.
- Determine which variable is most vulnerable during movement: oxygenation, ventilation, RV output, LV filling, device preload, or low-pulsatility monitoring reliability.
- Set protective starting goals: lung-protective tidal volume, generally 6–8 mL/kg predicted body weight and closer to 6 mL/kg when ARDS physiology is present, with plateau pressure generally below 30 cm H₂O when measurable.
In general, volume-targeted ventilation may be reasonable when lung mechanics are stable and predictable minute ventilation is important, whereas pressure-control/pressure-aligned ventilation may be favored when limiting airway pressure, avoiding overdistention, or preserving preload becomes the priority. Regardless of mode, reassessment of ETCO₂, SpO₂, MAP, airway pressures, delivered tidal volume, and device-specific indicators should occur after any ventilator change.
Table 3. Physiology-Guided Ventilator Strategy During Cardiogenic Shock and MCS Transport
| Clinical situation | Volume-targeted ventilation may be reasonable when | Pressure-control / pressure-aligned ventilation may be favored when | EMS transport monitoring priority |
| No major pulmonary disease or stable lung mechanics | Compliance is stable, plateau pressure is low when measurable, oxygenation is adequate, and predictable tidal volume/minute ventilation is desired. | Less compelling unless airway pressures rise, dyssynchrony develops, or pressure limitation becomes the primary safety concern. | Trend peak/plateau pressure, exhaled tidal volume, ETCO₂, SpO₂, MAP, and device flow or alarms. |
| Cardiogenic shock or severe LV failure | May be practical when predictable minute ventilation is needed and mean airway pressure or PEEP is not compromising preload. | May be useful when pressure limitation or patient synchrony is prioritized, provided delivered tidal volume and ventilation remain adequate. | Reassess MAP, ETCO₂, oxygenation, vasoactive response, and signs of reduced venous return after any ventilator change. |
| IABP support | Often practical because IABP support depends heavily on native LV function and predictable gas exchange may support myocardial oxygen balance. | May be favored if pressure limitation is needed because of worsening compliance, high airway pressures, or pulmonary edema. | Monitor blood pressure, timing/augmentation, oxygenation, ETCO₂, airway pressures, and response to PEEP. |
| Impella support | May be acceptable when it provides stable | May be favored if pressure limitation | Trend ETCO₂, MAP, preload response, Impella |
| ventilation without increasing PEEP or mean airway pressure enough to reduce RV output, LV filling, or Impella preload. | helps preserve preload or reduce suction/low-flow physiology, but delivered volume must be monitored. | position/flow, suction alarms, SpO₂, and exhaled tidal volume. | |
| LVAD support | May be acceptable when tidal volume is lung protective and mean airway pressure does not reduce venous return, RV output, LV filling, or LVAD flow. | May be favored when pressure limitation helps avoid excessive intrathoracic pressure or suspected preload compromise. | Use ETCO₂ trends as part of multimodal assessment when pulses, SpO₂, or noninvasive blood pressure are unreliable; watch LVAD flow and pulsatility index when available. |
| RV dysfunction or pulmonary hypertension | Acceptable only if tidal volume, plateau pressure, PEEP, oxygenation, and CO₂ control avoid increasing pulmonary vascular resistance. | May be favored if pressure limitation reduces overdistention and RV afterload, provided ventilation and CO₂ clearance remain adequate. | Avoid hypoxemia, hypercapnia/acidemia, excessive PEEP, and overdistention; trend ETCO₂, MAP, SpO₂, and signs of RV compromise. |
| Pulmonary edema or worsening compliance | Can reveal deterioration through rising peak or plateau pressure while preserving minute ventilation, but
pressures must remain safe. |
May be favored when pressure limitation is needed; however, falling delivered tidal volume or minute ventilation must be detected quickly. | Compare set and exhaled tidal volume, minute ventilation, airway pressure trend, ETCO₂, SpO₂, breath sounds, and hemodynamic response. |
| ARDS physiology or high plateau/driving pressure | Only if lung-protective tidal volume is maintained and plateau/driving pressure remain acceptable. | May be favored when pressure limitation, synchrony, or recruitment strategy is prioritized, but minute ventilation may fall as compliance worsens. | Prioritize lung-protective ventilation, plateau pressure, driving pressure when available, PEEP response, ETCO₂/ABG data, and hemodynamics. |
Note: This table is intended as a transport decision-support example. It does not establish superiority of volume-targeted or pressure-targeted ventilation; mode selection should be individualized to delivered tidal volume, airway pressure, gas exchange, RV performance, preload dependence, and device response.
Discussion
Volume-targeted/volume-set ventilation was used in 88% of mechanically ventilated MCS transports in this cohort. For EMS and critical care transport clinicians, this finding identifies a common real-world strategy, not proof that one mode is superior. Its likely operational appeal is predictable tidal-volume and minute-ventilation delivery during high-acuity movement between care environments.
Volume control may be practical during transport because the team knows the intended tidal volume and minute ventilation.1 If compliance worsens from pulmonary edema, pneumothorax, mucus plugging, bronchospasm, or positioning, rising airway pressure may warn that respiratory mechanics are changing. Pressure-control ventilation limits set pressure, but delivered tidal volume and minute ventilation can fall as compliance deteriorates, requiring close monitoring.1 Stated simply, VCV guarantees volume with variable pressure, whereas PCV guarantees pressure with variable volume; neither guarantees cardiac stability.1-3
The cardiovascular response to ventilation matters more than the mode label. Positive-pressure ventilation increases intrathoracic pressure, decreases RV preload, and can increase RV afterload through changes in pulmonary vascular resistance.2,3 It can also decrease LV transmural pressure and LV stroke work.2,3 Thus, LV-dominant afterload-sensitive failure may respond differently from preload-dependent or RV-limited circulation.2-4
These interactions are central to MCS because Impella and LVAD support depend on adequate left-heart filling.2,3 Increased PEEP or mean intrathoracic pressure can reduce venous return, RV output, pulmonary venous return, LV filling, and ultimately device preload.2,3 In an Impella patient, poor LV filling may contribute to suction events and reduced flow; in an LVAD patient, reduced venous return and RV output may reduce effective flow. The present dataset did not directly test this pathway, so it should be viewed as mechanistic interpretation rather than observed outcome.
The RV-failure clinical picture deserves attention because ventilator strategy can influence pulmonary vascular resistance and RV afterload.2-5 Alveolar overdistention from excessive tidal volume or PEEP can worsen RV dilation, reduce LV preload, and decrease cardiac output.4,5 Hypoxemia, hypercapnia, and acidemia can also cause pulmonary vasoconstriction and increase PVR.4,5,9
Permissive hypercapnia requires interpretation based on the patient’s physiology pattern. It may help maintain lung-protective tidal volume and pressure targets, but in severe cardiac disease it is not uniformly benign.4,5,9 In severe ARDS, marked hypercapnia and acidemia have been associated with RV dilation and decreased cardiac index despite improved oxygenation and recruitment.4
For transport clinicians, permissive hypercapnia may be acceptable when modest and required for lung protection in a patient with adequate RV reserve. Tolerance should be lower when pulmonary hypertension, RV failure, or MCS preload dependence is present because hypoxemia, hypercapnia/acidemia, and excessive lung volume can converge to increase RV load and reduce device preload.2-5,9
These findings support a physiology-guided framework rather than a universal ventilator-mode prescription. Mode selection should be paired with surveillance of exhaled tidal volume, minute ventilation, peak and plateau pressure when available, PEEP, ETCO₂ or arterial blood gas data, oxygenation, MAP, RV physiology, and device performance.1-5,9 The appropriate mode is the one that achieves protective ventilation while preserving cardiopulmonary and device-specific physiology.1,6,7,10
A useful transport mindset is to treat the ventilator as part of the circulatory support system.2,3 Clinicians should prioritize lung-protective tidal volume, generally 6–8 mL/kg predicted body weight and closer to 6 mL/kg with ARDS physiology; plateau pressure generally below 30 cm H₂O when measurable; and individualized PEEP that balances oxygenation with hemodynamic response.1,4,5 After increasing PEEP or mean airway pressure, reassess MAP, pulse pressure, CVP if available, ETCO₂, oxygenation, device flow, Impella suction alarms, and LVAD flow or pulsatility index when applicable.2-5
Operationally, this supports a checklist mindset: confirm device type and preload dependence, review recent oxygenation and ventilation data, document baseline settings before departure, trend ETCO₂ and pulse oximetry during movement, and reassess blood pressure and device flow after any ventilator change. Mode changes and hemodynamic responses should be communicated clearly during handoff.
In practice, even small ventilator changes should be treated as reassessment points. A rise in airway pressure, fall in ETCO₂, new hypotension, narrowing pulse pressure, declining SpO₂, Impella suction alarm, or change in LVAD flow should prompt the crew to pause and reconsider both pulmonary mechanics and circulatory preload.
In low-pulsatility LVAD or Impella physiology, ETCO₂ trends may be particularly valuable because they can help corroborate perfusion and pulmonary blood-flow changes when peripheral pulses, pulse oximetry, or noninvasive blood pressure readings are difficult to interpret.2,3 This approach helps avoid anchoring on oxygen saturation alone when the more important problem may be RV strain, reduced venous return, or impaired device filling.
Clinical Takeaways for EMS Transport Teams
- Start with the mode that gives the most predictable cardiopulmonary interaction for the patient’s device and physiology; VCV is often practical during transport but is not inherently superior to PCV.
- VCV provides predictable tidal volume and minute ventilation with variable pressure; PCV limits pressure but tidal volume and minute ventilation may fall when compliance 1
- In LVAD and Impella patients, avoid ventilator changes that reduce venous return, worsen RV output, or decrease LV filling, because these changes can reduce device preload and effective flow.
- Use PEEP and airway pressure deliberately: they may improve oxygenation and LV loading conditions, but excessive pressure can compromise preload, RV performance, and device
- Be cautious with permissive hypercapnia when pulmonary hypertension, RV dysfunction, or MCS preload dependence is present; avoid the combination of hypoxemia, hypercapnia/acidemia, and excessive airway pressure.
- After increasing PEEP or mean airway pressure, reassess MAP, pulse pressure, ETCO₂, oxygenation, device flow, Impella suction alarms, and LVAD flow or pulsatility index when
These takeaways are intended to support field and transport judgment rather than replace local protocols, device-center recommendations, or medical-control direction. When uncertainty exists,
early consultation with the receiving MCS or cardiogenic-shock team can clarify acceptable oxygenation and ventilation targets, device-specific alarm response, and whether preload, afterload, or RV support should take priority during transport.
Limitations
This retrospective secondary analysis reflects practice within a single regional critical care transport system and includes only 24 mechanically ventilated MCS transports. Ventilator mode was selected clinically, creating confounding by indication and precluding causal comparison between modes.
Complete plateau pressure, driving pressure, arterial blood gas, echocardiographic RV-function, and serial device-flow data were not uniformly available.
Pressure-regulated volume control was treated as a hybrid mode and categorized as pressure-aligned for this analysis based on its pressure-limited behavior; therefore, the reported categories should be interpreted as transport-oriented physiologic groupings rather than strict ventilator engineering classifications. Established heart-lung physiology supports the physiologic links among ventilation, RV output, LV filling, and MCS flow, but this cohort did not directly test them.
Conclusion
Volume-targeted/volume-set ventilation was used in 21 of 24 mechanically ventilated MCS transports (87.5%; 88%), demonstrating a strong practice preference for predictable volume delivery in this high-risk critical care transport cohort. Three transports (12.5%) used pressure-control or pressure-aligned strategies, including one pressure-regulated volume-control case treated as pressure-aligned for physiologic interpretation.
The finding does not establish superiority over pressure-targeted ventilation.1,6,7,10 For EMS and transport clinicians, the practical takeaway is that ventilator mode should be selected and adjusted according to safe and effective delivery of tidal volume, airway pressure, PEEP, gas exchange, RV performance, blood pressure, and MCS preload.1-5,9 Permissive hypercapnia should be individualized and used cautiously when pulmonary hypertension, RV dysfunction, or device preload dependence is present.4,5,9
References
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2. Corp A, Thomas C, Adlam The cardiovascular effects of positive pressure ventilation. BJA Educ. 2021;21(6):202-209. doi:10.1016/j.bjae.2021.01.002.
3. Mahmood SS, Pinsky MR. Heart-lung interactions during mechanical ventilation: the basics. Ann Transl Med. 2018 Sep;6(18):349. doi: 10.21037/atm.2018.04.29. PMID: 30370276; PMCID: PMC6186561.
4. Mekontso Dessap A, Charron C, Devaquet J, et Impact of acute hypercapnia and augmented positive end-expiratory pressure on right ventricle function in severe acute respiratory distress syndrome. Intensive Care Med. 2009;35(11):1850-1858. doi:10.1007/s00134-009-1569-2.
5. Vieillard-Baron A, et Acute respiratory distress syndrome, mechanical ventilation, and right ventricular function. Curr Opin Crit Care. 2011. PMID:21157319.
6. Schick V, Dusse F, Eckardt R, et al. Comparison of volume-guaranteed or -targeted, pressure-controlled ventilation with volume-controlled ventilation during elective surgery: a systematic review and meta-analysis. J Clin Med. 2021;10(6):1276. doi:10.3390/jcm10061276.
7. Jiang J, Li B, Kang N, Wu A, Yue Pressure-controlled versus volume-controlled ventilation for surgical patients: a systematic review and meta-analysis. J Cardiothorac Vasc Anesth. 2016;30(2):501-514. doi:10.1053/j.jvca.2015.05.199.
8. Wiesen J, Ornstein M, Tonelli AR, Menon V, Ashton RW. State of the evidence: mechanical ventilation with PEEP in patients with cardiogenic shock. Heart. 2013 Dec;99(24):1812-7. doi: 10.1136/heartjnl-2013-303642. Epub 2013 Mar 28. PMID: 23539555; PMCID: PMC4096289.
9. Mekontso Dessap A, Gendreau S, Vieillard-Baron Respective roles of hypercapnia and acidosis in acute respiratory distress syndrome. Intensive Care Med. 2022;48(6):787-788. doi:10.1007/s00134-022-06709-x.
10. Richard JM, Beloncle FM, Béduneau G, Mortaza S, Ehrmann S, Diehl JL, Prat G, Jaber S, Rahmani H, Reignier J, Boulain T, Yonis H, Richecoeur J, Thille AW, Declercq PL, Antok E, Carteaux G, Vielle B, Brochard L, Mercat A; REVA network. Pressure control plus spontaneous ventilation versus volume assist-control ventilation in acute respiratory distress syndrome. A randomised clinical trial. Intensive Care Med. 2024 Oct;50(10):1647-1656. doi: 10.1007/s00134-024-07612-3. Epub 2024 Sep 17. PMID: 39287651; PMCID: PMC11457688.
Gregory Proctor, FP-C, EMT-P, is a flight paramedic, medical student, and EMS researcher with more than two decades of experience in fire and emergency medical services. His clinical and research interests include critical care transport, airway management, mechanical circulatory support, cardiovascular emergencies, and the integration of prehospital and hospital-based critical care.
