Respiratory failure due to hemorrhagic shock is a common yet underappreciated clinical syndrome. All forms of shock can cause respiratory failure, and its initial presentation may be subtle. Physicians may be eager to intubate early, but this intervention can be dangerous. Noninvasive techniques employed before or in the place of mechanical ventilation can help stabilize the patient and reduce the risk of hemodynamic collapse.
Joshua Davis, MD, a pulmonary and critical care physician at NewYork-Presbyterian and Weill Cornell Medicine, recently published a paper in the Annals of the American Thoracic Society outlining the challenges and optimal approaches to managing respiratory failure associated with hemorrhagic shock. Below he shares his advice for treating these patients in the safest way possible.
Exercise Caution
If a patient presents in respiratory failure due to hemorrhagic shock, the first thing we need to do is exercise caution in terms of how we manage their care. When someone is experiencing severe hemorrhage, they are in hypovolemic shock. Their total circulating blood volume is decreased. The ability of their heart to squeeze and maintain normal cardiac output is partially dependent upon how much the heart is stretched by the blood that's coming in. If there is less blood returning to the heart, there's less stretch of the heart, and it's not going to squeeze back as strongly as possible.
| Parameter | Severe Hemorrhagic Shock |
|---|---|
| Dead space fraction | Increased |
| Respiratory rate | Elevated Slower and erratic when cardiac arrest imminent |
| Mixed venous oxygen saturation of hemoglobin | Low |
| Partial pressure of O2 in arterial blood | Variable |
| Partial pressure of CO2 in arterial blood | Normal to elevated |
| End-tidal CO2 | Low |
A summary of the effects of hemorrhagic shock on respiratory parameters.
The condition of shock usually leads to an accumulation of acid in the blood, which often causes patients to breathe very hard. This breathing pattern is also advantageous because large deep breaths help pull more blood into the heart and chest and we don’t want to hinder that.
If you can avoid or delay intubation until the patient has been better resuscitated, it's going to be a lot safer for the patient overall.
— Dr. Joshua Davis
Delay Intubation and Mechanical Ventilation
Our instinct when someone is decompensating is to protect their airway, and we typically do that through intubation and mechanical ventilation. However, doing so in a patient in respiratory failure due to hemorrhagic shock can actually be dangerous. When we intubate a patient, we give them sedation and brief paralytic medications to minimize discomfort and facilitate the procedure. While those medications are often essential to safe intubation, they can disrupt the advantageous breathing pattern that is triggered by the state of shock and the patient can go into cardiac arrest.
When we intubate a patient, we are now blowing air into their chest, which increases pressure even more and prevents blood from returning to the heart. That, again, can cause cardiac arrest. If you can avoid or delay intubation until the patient has been better resuscitated, it's going to be a lot safer for the patient overall.
However, if you must intubate, ensure the ventilator is set to use the lowest amount of pressure possible to allow the most blood to return to the heart. We will often set positive end-expiratory pressure (PEEP) briefly at 0-cm H2O.
Try Noninvasive Approaches to Open the Airway
There are a number of noninvasive approaches that can help support a patient in respiratory failure, which carry much less risk than mechanical ventilation. With any case of shock, the blood pressure decreases, and the brain becomes under-perfused. The neural outflow from the brain to the muscles that keep the upper airway open decreases, which causes a picture similar to obstructive sleep apnea. Sometimes the smallest maneuvers to help open up the airway can be used to avoid intubation. Consider:
- Positioning the patient better in the bed so their head is not flopped over.
- Sitting the patient up, as opposed to having them lie flat.
- Using a nasopharyngeal airway — a small rubber tube that goes into the nose and helps open up that part of the airway.
- Using the jaw thrust maneuver: If the muscles in the upper airway are weak, the jaw may fall back. Placing gentle pressure at the angle of the jaw to take the weight off of the airway can relieve an obstruction and actually be lifesaving.
These techniques can often solve upper airway problems and give clinicians enough time to continue blood transfusions and resuscitate the patient to make intubation safer. Most of these patients will eventually need intubation for a procedure to stop the bleeding, such as emergency surgery, endoscopy, or interventional radiology. But the longer we can delay intubation, the better.
Monitor Closely
- When these patients come into your care, your first step should be to stop the bleeding if there’s obvious trauma that you can directly compress or put a tourniquet on. If you place a tourniquet, be sure to record the time you placed it.
- You also want to restore circulating blood volume. The loss of blood impairs the ability to deliver oxygen to the tissues, so give oxygen (even if the oxygen saturation is normal), while resuscitating with blood.
- Monitoring the patient's hemodynamics, respiratory drive, mental status, and gas exchange.
- During endotracheal intubation, monitoring systemic blood pressure frequently (such as every minute) or continuously using arterial catheterization, use vasopressors for life-threatening hypotension, and use lower doses of sedatives.
- Monitoring end-tidal CO2.
Take A Multidisciplinary Approach
At NewYork-Presbyterian, our trauma centers are equipped to provide specialized, multidisciplinary care for patients with respiratory failure due to hemorrhagic shock. Several of our hospitals feature medical, surgical, and neurologic intensive care units offering the latest evidence-based critical care.
Managing this condition involves doing a lot of things all at once, and we can’t do that without the involvement of other specialists and teams. These patients benefit greatly from a multidisciplinary approach that often includes a wide variety of specialists, ranging from acute care and trauma surgeons, interventional radiologists, gastroenterologists, and even pathologists (who work in our blood bank) who collaborate with the ER physicians, intensivists, and the ICU team to treat patients in hemorrhagic shock.
