With this rise in altitude, the intravenous (IV) flow will increase, necessitating modifications to the flow rate. When feasible, a pump that adjusts to maintain a specific flow rate should be employed since barometric pressure impacts the flow rate. The barometric pressure drops as the altitude rises, and the increased flow in the IV tubing is made possible by the lower pressure. This may impact the dosage of IV drugs given. Cabins for fixed-wing aircraft traveling at high altitudes are pressurized, but only to a height of 6000–8000 feet, not sea level.
Bicarbonate (HCO3-) less than 22 mEq/L and a pH less than 7.35 are consistent with metabolic acidosis, which may result from severe diarrhea, starvation, diabetic ketoacidosis, kidney failure, and aspirin toxicity. Symptoms may include headache, altered consciousness, and agitation from lethargy to coma. Cardiac dysrhythmias and Kussmaul respirations are common. The other readings listed in the question indicate the following:
‥ HCO3 of more than 26 mEq/L and a pH of more than 7.45 are consistent with metabolic alkalosis
‥ PaCO2 of 35–45 mmHg and PaO of 80 mmHg or more are normal adult readings
‥ PaCO2 more than 55 mmHg and PaO2 less than 60 mmHg are consistent with acute respiratory failure in a previously healthy adult.
The newborn or infants may still be viable if the mother is in active preterm labor with a singleton or multiple deliveries at 22 weeks or more gestation. Burns that entail an explosion with respiratory difficulty or disorientation, unconsciousness, or burns that cover 18% or more of the body surface area (second or third-degree burns), must be transported by air. A fracture may be rendered immobile for land transportation. Injury to a limb is less urgent unless combined with extensive bleeding or compromised circulation. Penetrating injuries (such as shrapnel, gunshot wounds, or stabbing) to the head or trunk frequently necessitates air transfer, especially with prolonged unconsciousness.
Systolic blood pressure measurements are used to examine pulsus paradoxus. When breathing normally, the blood pressure slightly drops during intake while the heart rate rises and rises slightly during expiration as the heart rate falls. The pulsus paradoxus, assessed by identifying the initial systolic reading during exhale and reducing blood pressure cuff measurements until the systolic pressure can be heard during both cycles, exaggerates this. Positive for pulsus paradoxus is a more than 10 mmHg difference between the systolic reading taken during expiration alone and the reading taken between inhalation and exhalation.
N-acetylcysteine best protects the liver if administered within 8 hours of acetaminophen intoxication. Since 8 hours have passed in the scenario outlined in the question, the antidote must be administered immediately because it reduces hepatotoxicity even after 24 hours. Although activated charcoal may have some protective benefits if administered within 4 hours of intake, gastrointestinal decontamination is most successful when done within 1 hour of administration. The Rumack-Matthew nomogram illustrates toxicity, with serum levels greater than 150 mg necessitating an antidote. The initial dosage of the 72-hour N-acetylcysteine regimen is 140 mg/kg (PO), followed by 17 further doses of 70 mg/kg every 4 hours (orally or intravenously).
In order to protect personal safety as well as the safety of the medical and flight crew, patients who are aggressive or confrontational need be physically confined for transport and may also need chemical restraints. It is not a good idea to leave the patient in the hospital because the majority of rural hospitals lack the expertise and equipment necessary to perform limb reattachments. The likelihood of a successful reattachment may be lowered if ground transportation is delayed by waiting or making other arrangements.
