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Aeromedical transfer of the

critically ill patientDr.Ebadi

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1-INTRODUCTION

-A model of timescale related to casualty death

-Primary,delayed primary,Secondary

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2-TEAM COMPOSITION

-Trained in anesthesia & intensive care

-Based on a full team

-Supplemented by additional personnel

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3-EQUIPMENT

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-Testing procedures

-Ventilators

-Monitors

-Pacemakers

-Syringe pumps and volumetric pumps

-Suction apparatus

-Blood analysis

-Peripheral nerve stimulators

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-Testing procedures :

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-Ventilators

-Continuous positive airways pressure (CPAP),

-Intermittent positive-pressure ventilation (IPPV),

- Positive end-expiratory pressure (PEEP)

-Alteration of the inspiratory to expiratory ratio

-Low power consumption

-Low oxygen consumption

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Univent Model 750 and Univent Eagle Model 754

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-Monitors

Blood Pressure:-palpated systolic BPs taken at the radial or brachial

site,

-Automated BP monitors using oscillometric

*Not ascultatory method

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-Doppler and pulse oximetry occlusion techniques

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-Invasive BP measurements such as the ProPaq Encore.

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ECG monitoring:

ProPaq Encore, provide an extended bandwidth where ST segments may be accurately displayed and printed.

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Oxygen Saturation: Pulse oximetry in the aeromedical evacuation

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End-tidal CO2(EtCO2) : EtCO 2 monitoring provides information on the adequacy of minute

ventilation and the position of the endotracheal tube.

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-Pacemakers

Temporary transvenous pacemakers

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-Syringe pumps and volumetric pumps

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-Suction apparatusSuction apparatus must be fully portable, have high flow capability and be able to collect fluid waste in a manner that protects staff and be safely disposable.

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-Blood analysisThe ability to perform blood gas, electrolyte, glucose, lactate.

Arterial oxygen, carbon dioxide, bicarbonate ,pH, glucose and potassium should be carried out at least every hour during transfer

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-Peripheral nerve stimulators

The ability to assess neuromuscular junction function is essential when using neuromuscular junction-blocking drugs.

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4-Cotaindications

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5-Check list

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6-EFFECT OF ALTITUDE

Common Problems Experienced

in Flight

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Special Problems

Experienced in Flight

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*Changes in pulmonary blood flow:

-may be due to abnormal responses to hypoxia

-reflection of the general state of the circulation

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*Intubated patient - The endotracheal tube should be

checked and a chest X-ray performed to determine the tube position.

-Endotracheal tube cuff pressures

should be checked and monitored during flight.

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*Tube thoracostomy:-They should be on free drainage, not be

clamped at any stage and remain dependent .

-If possible, systems that do not require fluid to function and have non-return systems should be used.

-The use of the Heimlich-type valve

incorporated in the system or certain types of emergency chest drainage systems, as used in acute trauma, may be problematic.

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*Tracheostomy -It is important to remember that this

is not without risk.-The patient should not be transferred

until the risk of immediate post-procedure haemorrhage has passed (at least 24 hours) and a tract has begun to form.

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*Air in the cerebrospinal fluid (CSF):

-expanding the skull can raise intracranial pressure.

*A sudden increase in volume skull:

-may lead to acute cardiovascular instability

-further neurological damage.

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*Air-containing cavities:-within the lung, bullae, post-surgery

or air leaks from trauma can lead to pneumothorax .

*Expanding air in the pleura or pericardium:

-may lead to the conversion of a simple pneumothorax or pneumopericardium to a tension pneumothorax or pneumopericardium,

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*Patients who are post-trauma, post-surgery:

-impaired gastric motility.

* Delayed gastric emptying: - raised gastric volume and nausea,

vomiting, regurgitation and electrolyte disturbances.

*Passive regurgitation in the unconscious patient:

-pulmonary aspiration and the risk of chemical pneumonitis and pulmonary sepsis

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*Surgery in the peritoneal cavity: -residual air trapped after closure

-In large amounts, it may lead to a rise in intra-abdominal pressure and a degree of intra-abdominal hypertension .

*Air or other gases within the lumen of the bowel:

-rise to pain and discomfort and put anastomotic suture lines at risk .

* Ileus or deranged bowel motility:-may also lead to raised intra-abdominal

pressure

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*Intra-abdominal hypertension :

-respiratory and cardiovascular dysfunction.

-renal function may be

impaired,with a rise in creatinine and urea.

- The liver is also vulnerable, and

deranged hepatic function may occur.

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-replacing losses and restricting fluids

-baseline maintenance requirements and insensible losses

* Fluid balance&resuscitation:

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-The circulation must be optimally filled in flight .

-Some patients,with major trauma or burns, may require additional fluids.

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-Continued resuscitation by large-bore cannulae.

-Vasoactive drugs require

administration via the central venous route ,

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-Inotropic sympathomimetics such as adrenaline (epinephrine), dopexamine, dobutamine and dopamine may already be in use.

-These drugs are life-vital components of care, as any sudden interruption in their administration may result in severe instability or cardiac arrest.

*sympathomimetics:

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-The circulation will also require optimal filling but may need increases in support from inotropic or vasoconstrictive drugs as transfer begins.

*SIRS:

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-The myocardium may be extremely irritable and prone to arrhythmias, which may precipitate cardiac arrest .

-Cardiac failure and cardiogenic shock may also occur.

*myocardial infarction:

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-A nasogastric drainage tube is normally a requirement for aeromedical transfers of critically ill patients .

*Stomach decompression :

-Feeding should be stopped a number of hours before transfer, in order to reduce the likelihood of reflux.

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-Nasogastric or orogastric tubes should be aspirated and then placed on free drainage, while remaining dependent.

-prokinetic drugs such as metoclopramide

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*Upper GI bleeding:

-H2 -receptor-blocking drugs,proton-pump inhibitors.

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-An intra-abdominal surgery and/or bowel surgery without sufficient time to allow anastomoses to heal, then sea-level cabin altitude should be requested.

*Intra-abdominal surgery :

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-In the critically ill patient, changes in blood flow, the presence of toxins and drugs in the circulation, and the direct effects of infectiveagents compromise hepatic function.

-Impaired hepatocyte function increases the potential for coagulopathy and for altered metabolism of drugs.

*Hepatic dysfunction

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-In practice, mildly deranged hepatic function is of little significance during transfer.

-In the case of acute hepatic failure, even

short-distance ground transfer may be extremely hazardous due to the circulatory and neurological effects associated with the condition.

-Transfer by air to enable the patient to receive hepatic transplantation may be justified and the attendant risk accepted.

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-Patients who are treated inadequately may be subject to changes in electrolytes during the flight, which will compromise their safety.

-If this occurs, then there is a limitedresponse available and the patient may suffer irreversible cardiac dysfunction.

*Renal dysfunction

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Urinary catheters need to be checked to ensure that there is free drainage. Urine output should be measured hourly, as in the ICU.

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*CNS problems: -If the level of consciousness is

reduced sufficiently, then it is associated with hypoventilation.

-Hypoventilation will lead initially to hypercarbia and then to hypoxia.

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-Hypercarbia leads to an increase in intracranial pressure,which may be critical for the already injured brain.

-Hypoxia will also lead to further neurological injury.

-The airway be maintained and ventilation is controlled.

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-Patients with a GCS of 8 or less should be intubated and ventilated.

-Vasodilation caused by induction agents may lead to hypotension and cerebral hypoperfusion.

--Conversely,intubation may lead to a marked sympathetic stimulation and a marked increase in intracranial pressure.

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-Injuries to the cervical and upper thoracic region may lead to cardiovascular instability due to loss of cardio-accelerator nerve .

-Below T5, sympathetic innervation of the myocardium is preserved.

-Ventilation and bronchomotor tone are also affected.

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-Ileus, urinary retention, gastric ulceration and haemorrhage may also occur in the early period.

-These patients have a markedly increased risk of deep venous thrombosis .

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-The patients with unopposed vagal influence due to high spinal-cord injury may be prone to profound bradycardia or even asystole when subjected to endobronchial suctioning.

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-Care must be taken to exclude compartment syndromes and any required fasciotomiesshould be undertaken pre-transfer.

-Fractures need to be stabilized adequately, preferably with a rigid fixation device.

-In the case of serious pelvic fracture, where there is risk of further haemorrhage, external fixation is also essential.

*limb trauma

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-Hypothermia interferes with normal metabolic processes, including the metabolism of drugs, and it can delay elimination of drugs.

-Hypothermia affects cardiovascular function; when severe,this leads to life-threatening arrhythmias.

-It also interferes with clotting mechanisms.

*Hypothermia

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-As a general principle, the patients should remain on an established regimen if they are stable and are suitable for transfer.

-This will normally include, at the very basic level, analgesia, sedation and often neuromuscular blockade.

*Therapeutic regimen

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-The critically ill patient requires other therapeutic agents such as antimicrobials, anticoagulants, antiarrhythmics and drugs to aid in the prevention of gastrointestinal haemorrhage.

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*TRANSFER-Short transfers by rotary-wing aircraft

or fixed-wing aircraft can be achieved by the minimum of a critical-care aeromedical physician and a critical-care aeromedical nurse .

-For longer, fixed-wing flights,technical support and additional logistic personnel should be included.

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