Chapter 41 David J. Hirsch Evaluation and treatment of the pregnant patient represent a challenge for all levels of medical providers, from first responder through EMS physician. Thankfully, major complications and acute life-threatening illnesses are rare. However, when they occur, many special considerations must be taken into account in order to provide the best medical care. This chapter will provide an overview of physiological changes in pregnancy and their implications for prehospital care. Although many of the conditions require further diagnostic testing and treatment beyond the current capabilities of EMS, familiarization by EMS providers and EMS medical directors is critical. This will enable EMS providers to consider life-threatening conditions that require immediate intervention, formulate a preliminary differential diagnosis, initiate treatment, and make the best determination for transport destination. The anatomical changes that a woman undergoes during pregnancy are not confined to the reproductive organs. One of the most apparent changes is weight gain. By full term, a woman of average weight should be expected to gain between 25–35 pounds (11.5–16 kg) [1]. Most of this weight is made up of the fetus and uterus, but contributions are also made by the breasts and additional fluid in the form of blood volume and extracellular fluid. This additional weight, particularly its distribution, provides distinct challenges for EMS providers in certain circumstances such as airway management and traumatic injury, which will be discussed in detail later. Innumerable physiological changes occur during pregnancy. Discussion will be limited to those with the most direct prehospital effects. The increase in blood volume, on average 48% above that of a non-pregnant patient, is one of the most dramatic changes. This is an absolute increase of about 1500 mL [2]. This increased volume improves blood flow and provides nutrients to the growing uterus and fetus, protects the fetus from impaired venous return from maternal supine position, and protects the mother from the effects of blood loss during delivery [3]. Other notable changes include increased baseline heart rate, increased cardiac output, and normal to low blood pressure (Box 41.1). The core of any EMS provider’s training is based on initial evaluation and stabilization of the most critically ill or injured patient. This is best accomplished by using a systematic method such as the ABCs (airway, breathing, circulation). The pregnant patient should be approached in a similar manner, with specific additional considerations. Any resuscitation during pregnancy places at least two lives at stake, considering the mother and one or more fetuses. Airway management is among the most critical skills for the EMS provider to master. Without proper airway maintenance, a patient has a small chance of even arriving at the hospital alive. Several anatomical changes to the airway during pregnancy can complicate airway management in the prehospital setting [4]. Edema, caused by increased extracellular fluid volume, can lead to more profound airway obstruction in states of decreased responsiveness, complicating basic airway maneuvers such as bag-valve-mask ventilation. Edema may also lead to swelling of the glottic structures, causing a decreased glottic opening and complicating advanced airway interventions. Additional important considerations are listed in Box 41.2. Emergency medical services providers must anticipate these issues, and pay close attention to basic airway techniques, with more liberal use of airway adjuncts such as oral or nasal airways as appropriate. Suctioning devices must be ready and available at all times to address vomiting. For advanced airway interventions, ALS providers should perform an airway assessment using standardized scoring systems such as Mallampati to help predict the presence of a difficult airway. A smaller sized endotracheal tube than anticipated should be kept on hand in case of difficulty passing the tube through the glottic opening. Standard monitoring such as oxygen saturation and waveform capnography is critical. The gravid uterus causes significant upward displacement of the diaphragm, restricting lung function. Functional residual capacity is decreased by approximately 20% in pregnancy [4]. This, in combination with increased oxygen consumption of 30–60% and decreased venous return due to inferior vena cava compression, can lead to rapid desaturation with any medical or traumatic insult. The patient with respiratory distress or who is requiring ventilation should be placed as upright as feasible to decrease abdominal pressure on the thorax. Oxygen should be used more liberally to ensure the fetus is receiving adequate oxygenation. As described earlier, pregnancy is accompanied by increased blood volume which may allow initial compensation for even major blood loss, followed by rapid deterioration. Given this, patients should be treated aggressively with fluid resuscitation for potential hypovolemic states. The shift toward a permissive hypotension approach to trauma patients should likely not be applied to pregnant patients, though data on this are lacking. Given the relative anemia of pregnancy, blood transfusion may be necessary earlier in resuscitative efforts than in a non-pregnant patient. Vasopressors may be used if necessary to correct shock. Complications such as pulmonary edema and third spacing with crystalloid infusions due to lower oncotic pressure should be anticipated. Patients with hypotension and/or those who are supine should always be placed tilted to the left 15–30° using sandbags or pillows. This allows the gravid uterus to be moved off the inferior vena cava, improving venous return to the heart. In the preceding section, the evaluation and management of the pregnant patient in extremis
Physiology of pregnancy: EMS implications
Introduction
General considerations
Anatomical
Physiological
Critical care and trauma
Airway
Breathing
Circulation
Disease states by system
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