Stages of Cough

Four stages are involved in producing an effective cough.¹⁴ The first stage requires inspiring enough air to provide the volume necessary for a forceful cough. Generally, adequate inspiratory volumes for a cough are noted to be at least 60% of the predicted vital capacity for that individual. The second stage involves the closing of the glottis (vocal folds) to prepare for the abdominal and intercostal muscles to produce positive intrathoracic pressure distal to the glottis. The third stage is the active contraction of these muscles. The fourth and final stage involves opening of the glottis and the forceful expulsion of the air. The patient usually is able to cough three to six times per expiratory effort. A minimal threshold of FEV₁ (forced expiratory volume in 1 second) of at least 60% of the patient’s actual vital capacity is a good indicator of adequate muscle strength necessary for effective expulsion (Figure 22-1). Bach and Saporito (1996)¹⁵ established a minimal peak cough flow rate (PCFR) of 160 L/min to effectively clear secretions and to predict successful decannulation for patients with neuromuscular conditions. The use of a simple peak flow meter can help assess the cough. Drops in peak flow have been correlated in children, patients with spinal cord injury, and older adults who have a decreased ability to cough. Assessing PCFR is a simple clinical test that can objectively measure the patient’s ability to provide the exhalation phase of the cough.^16–18 During a cough, alveolar, pleural, and subglottal pressures may rise as much as 200 cm H₂O.^14,19,20

It is also important to identify the stage of the cough cycle in which the patient is having difficulty. Only then can the appropriate therapeutic intervention be directed at correcting that deficit.

Stage 1: Adequate Inspiration

Did the patient spontaneously inspire a deep breath before coughing, or did he or she cough regardless of the inspiration or expiration cycle? Did the patient spontaneously use trunk extension, an upward eye gaze, or the arms to augment the inspiratory effort? Did the patient take enough time to inspire fully before coughing? If the patient inspires adequately, he or she should be able to sustain two to six coughs per expiratory effort for a cascade effect. Neurologically impaired patients who have inadequate inspiratory efforts usually present with only one or two coughs per breath and generally produce a quieter cough.²¹ If the patient cannot cough on demand (such as a young child or patient with cognitive impairment), ask the caretaker whether he or she has observed and/or heard the patient’s inspiratory breath and hold before a cough. If so, how effective did the patient’s process seem?

Stage 2: Glottal Closure

Did the patient hold his or her breath at the peak of inspiration before the expulsion phase, or did the patient go directly from inspiration to expiration? Did you hear a cough or a huff (a complete absence of a hold between inspiration and expiration)? If the patient intended to cough but instead produced a huff, this is an indication of insufficient glottal closure. This can result from a wide variety of situations, including glottal edema after prolonged intubation, partial or full paralysis of the vocal folds, hemiparesis of the vocal folds, or a timing or sequencing difficulty secondary to brain injuries, among other possibilities. A complete lack of glottal closure will not produce any cough sound because the vocal folds are not approximating (adducting). The huff technique may be encouraged when the patient tends to wheeze or after long-term intubation when there is vocal fold edema. However, in the “normal” population, a good hold and full cough are encouraged.

Stage 3: Building-Up of Intrathoracic and Intraabdominal Pressure

Did you see active contraction of the intercostal and abdominal muscles? Did the patient spontaneously move into trunk flexion during this phase? Did the cough have a low, resonant sound? Inadequate force is usually heard as a higher-pitched cough, often called a throaty cough. The sound is quieter overall and does not produce as many coughs per expiratory effort. It is sometimes associated with neck extension rather than flexion as the patient attempts to clear the upper airway only. The air appears to leak out rather than being propelled out of the larynx during the cough. As with inadequate lung volumes, inadequate pressure prevents the patient from coughing more than once or twice during one expiratory effort.

Pump Cough

The pump cough extends the huff technique and, clinically, is more effective. The patient is instructed to take three mid-sized huffs followed by three short, easy coughs at low lung volume, not deep breaths or deep lung volumes. Three or four sequences are performed: (1) huff, huff, huff; cough, cough, cough; (2) huff, huff, huff; cough, cough, cough; (3) huff, huff, huff; cough, cough, cough. Usually, if secretions are present, a spontaneous cough occurs, or the secretions will mobilize with the small coughs.

Series of Coughs

Another variation that decreases stress on the patient is to use a series of coughs consisting of a small breath and a small cough, then a medium breath and a medium cough, and finally a large breath and a large cough. This is a good technique to use with postoperative patients, who often become fatigued trying to cough maximally each time. For these patients, it is an effort to get air distal to the secretions in various parts of the lungs, a form of autogenic drainage.

Patients with Neuromuscular Weakness or Paralysis

For patients with transient or permanent neuromuscular weakness or paralysis, further instructions may be necessary.20,22–25 These patients must use every physical trait to maximize the function of each stage of the cough (see Figure 22-1). Physically assisting these patients during the expulsion stage of the cough addresses only one aspect.^26,27 Care must be taken to look at all four stages to maximize the airway clearance potential of any assistive cough technique. First, the patient must be positioned for success (stage 1). The beginning of any cough requires trunk extension or inspiratory movement to maximize inhalation, whereas the expulsion stage requires trunk flexion or expiratory movement to maximize exhalation.²⁸ Thus for any given posture, the clinician must assess the following:

When these questions have been answered satisfactorily, the clinician is ready to instruct the patient in the act of coughing. An example may provide the best illustration of these instructions. A clinician may pick a modified sitting position for a patient with generalized weakness (e.g., incomplete spinal cord injury, developmental delay, or temporary weakness or exhaustion after a medical or surgical procedure). The patient looks slumped, so the clinician places a lumbar support (e.g., a lumbar roll, a towel, or a pillow) behind the lower back to increase trunk extension in that position. The patient is asked whether he or she is comfortable and whether he or she can swallow safely. Next, the clinician tries to maximize the first cough stage by asking the patient to take a deep breath. Observing that the patient did not appear to take in as deep a breath as the clinician thought possible, the clinician adds further instructions, such as the following:

For patients with more limited arm function, apply appropriate ventilatory strategies detailed in Chapter 23. Very subtle movements can then be requested, such as the following:

Although less dramatic than the larger movements described previously, these subtle motions may significantly increase the patient’s inspiratory effort and provide a more active means for the patient to participate in his or her own coughing program.²⁹

Stage 2 involves closing the glottis. For some patients with weakness or timing problems, a sharp loud command to “hold it” at the peak of inspiration, may be sufficient to facilitate closure. Remember to allow enough time for the patient to take in a deep inspiratory effort before being asked to “hold.” Some clinicians rush the first phase by giving two instructions in quick succession, as in “Take a deep breath. Hold it.” This unintentionally limits the time of the inspiratory effort. A more appropriate verbal cue would be “Take a deep breath in … in … in … in … and now hold it,” allowing adequate time for the patient to inhale.

Stage 3 (building up pressure) and stage 4 (expulsion) are discussed together because their timing is interdependent. The patient now needs to move into trunk flexion, with or without the clinician’s assistance, to maximize expulsion. Patients who are able to assist can be asked to do the opposite of stage 1:

Likewise, patients with more limited arm function can be asked to do the following:

In this manner the clinician has used every conceivable resource to maximize a voluntary cough. Even the weakest cough can be made more effective by applying these simple concepts:

Objective and subjective assessments can confirm the improvement. However, even with excellent instructions, many patients with neurological disorders require a clinician’s physical assistance to inhale more deeply or to exhale more forcefully because of muscle weakness or paralysis.³⁰

Heimlich-Type (or Abdominal Thrust) Assist

The second technique is the Heimlich-type assist, also known as the abdominal thrust assist. This method requires the therapist to place the heel of his or her hand at about the level of the patient’s navel, taking care to avoid direct placement on the lower ribs (Figure 22-3). After appropriate positioning, the patient is instructed to “take in a deep breath and hold it.” The therapist can then facilitate the inspiration. As the patient is instructed to cough, the therapist quickly pushes up and in, under the diaphragm with the heel of his or her hand, as in a Heimlich maneuver. The patient is instructed to assist with appropriate trunk movements as much as possible. Technically, this procedure is very effective at forcefully expelling the air,²² as in a cough, but it can be extremely uncomfortable for the patient for several reasons:

Because of its limited usefulness, the Heimlich-type, or abdominal thrust, assist should be used only when the patient does not respond to other techniques and the need to produce an effective cough is great.

The therapist can use a combination of the costophrenic and the Heimlich-type assists simultaneously when the patient is in the side-lying position. If the patient has a hemiplegic deficit or has a unilateral lung or thorax disease or trauma, emphasizing one side of the thorax over the other may be an appropriate focus during airway clearance treatments. One upper extremity is used to perform the Heimlich-type assist while the other does a unilateral costophrenic assist. In this manner, the therapist can compress simultaneously all three planes of ventilation in the lower chest. The possibilities of combining techniques and positions are numerous once the therapist understands the principles on which they were developed.

Anterior Chest Compression Assist

The third assistive cough technique is called the anterior chest compression assist because it compresses both the upper and lower anterior chest during the coughing maneuver. This is the first single technique thus far to address the compression needs of the upper and lower chest in one maneuver. The therapist puts one arm across the patient’s pectoralis region to compress the upper chest; the other arm is placed parallel on the lower chest (avoiding the xiphoid process) or on the abdomen (Figure 22-4, A) or is placed as in the Heimlich-type maneuver (Figure 22-4, B). The commands are the same as in the other techniques. Because of the direct manual contact on the chest, inspiration can be easily facilitated first, followed by a “hold.” Thus the therapist can readily enhance the first two cough stages. The therapist then applies a quick force with both arms to simulate the force necessary during the expulsion phase. The directions of the force are:

When performed together, the compression force exerted by both arms forms the letter V.

The anterior chest compression technique is more effective than the costophrenic assist for patients with very weak chest wall muscles because of the added compression of the upper anterior chest wall. These authors have found the side-lying or three-quarter supine position to be the most effective position for this technique. However, the anterior chest compression technique is not appropriate for a patient with a cavus condition of the upper anterior chest because it promotes further collapsing of the anterior chest wall.

Counter-Rotation Assist

In these authors’ clinical experience, the most effective assistive-cough technique for the widest cross-section of patients with neurological disorders is the fourth and final method described: the side-lying counter-rotation assist.¹⁸ The positioning and procedures required for the counter-rotation technique (described in detail in Chapter 23) apply for both the patient and the therapist (Figure 22-5). The therapist should recall that orthopedic precautions for the spine, rib cage, shoulder, and pelvis also apply for this technique.

The therapist begins by following the patient’s breathing cycle, with his or her hands positioned over the patient’s shoulder and pelvis (see Figure 22-5). The therapist then gently assists the patient in inhalation and exhalation to promote better overall ventilation. This sequence is generally repeated for three to five cycles or until the patient appears to have achieved good ventilation to all lung segments.

At this point, the patient is ready to begin the coughing phase of the procedure. The patient is asked to take in as deep a breath as possible, with the therapist assisting the patient in chest expansion (see Figure 22-5, B). Next, the therapist instructs the patient to “hold it” at the end of maximal inspiration. The patient is then commanded to cough out as hard as possible while the therapist quickly and forcefully compresses the chest with his or her hands in their flexion phase positions (see Figure 22-5, A).

The importance of following a true diagonal plane of facilitation during both the flexion and extension phases of this technique cannot be overemphasized. Failure to do so will result in the shifting of the air within the chest cavity rather than the desired forcing out of the air. This air shifting can occur to varying degrees when the upper chest and lower chest are not used together, as in all the other assistive cough techniques. When done properly, the counter-rotation assist is the only technique to rapidly close off the chest cavity in all three planes of ventilation in all areas of the chest. Unless the patient voluntarily closes his or her glottis, it is impossible to prevent the air from being forcefully expelled. However, a common mistake made by the therapist is pulling the patient back into trunk extension during the expulsion phase rather than into trunk flexion. A good rule of thumb: if you can see your patient’s face when you are applying the compression force, you have pulled him or her into extension. The head and neck should stay forward and flexed so that only a facial profile can be seen.

Other effects of counter-rotation make this procedure particularly beneficial for patients with low levels of cognitive functioning:

The true beauty of the technique is the fact that no active participation on the part of the patient is required for success. Incoherent or unresponsive patients, such as patients with low functioning following a head trauma, CVA, or cerebral palsy, will still achieve good secretion clearance with this technique. The mechanics of the procedure dictate that the air within the lungs be rapidly and forcefully expelled, regardless of the patient’s level of active participation. Obviously, patient participation is desirable to clear secretions even more effectively and to teach the patient to eventually clear his or her own secretions, but it is not critical.

Clinical experience has demonstrated that in patients who have extremely tenacious secretions, the use of vibration may be more effective than quick chest compression during the cough itself. This prolongs the cough phase and gives the secretions time to be moved along the bronchi for successful expulsion. These patients may also require a series of three or four cough cycles before clearing most of their secretions. In general, patients from all the diagnostic groups discussed thus far, with or without good cognitive functioning, are appropriate candidates for this procedure. The majority of them find it to be the most comfortable and effective assistive means of expectorating secretions.

Prone-on-Elbows, Head-Flexion Self-Assisted Cough

The prone position is not commonly used as a posture for coughing because the position itself inhibits full use of the diaphragm by preventing lower anterior chest and abdominal excursion following a neurological insult. This forces the patient to use an alternative breathing pattern that facilitates greater use of accessory muscles. Because this change in breathing patterns often occurs spontaneously, prone on elbows can be an effective posture for promoting spontaneous use of the accessory muscles during a more difficult activity (coughing). However, without the full recruitment of the diaphragm, the resultant cough will be weaker than it would be in other postures. Prone on elbows should not be the exclusive posture for a self-assisted cough. After mastering the timing of the procedure, most patients move back to another posture, usually sitting or side-lying, and to other techniques to capitalize on the functional increase in chest expansion and compression. For the population of patients who can assume a prone-on-elbows posture independently (i.e., some patients with tetraplegia), this technique may be used functionally. In this position, they can assist their own coughs when the need arises, rather than wait for someone to assist them in a position change.

The head-flexion assist requires good use of head and neck musculature, seen in patients who have sustained a spinal level injury below C4 (e.g., spinal cord injuries [SCIs], spina bifida). It can be used either as a self-assisted or a therapist-assisted procedure, using the principles of trunk extension to facilitate inspiration and trunk flexion to facilitate expiration. With the patient prone on elbows, the therapist instructs him or her to bring the head and neck up and back as far as possible, inhaling maximally (Figure 22-6, A). The patient is then instructed to cough out as hard as possible while throwing the head forward and down (Figure 22-6, B). This head-and-neck pattern can initially be assisted by the therapist to establish the desired movement pattern and gradually progressed to a resisted pattern to promote increased accessory muscle participation and to strengthen those muscle groups.

Long-Sitting Self-Assisted Cough

There are two variations of this technique, one for tetraplegic patients and one for those who are paraplegic. For the tetraplegic version of the long-sitting self-assist, the patient is positioned on a mat in a long-sitting posture (legs straight out in front) and with upper extremity support. The therapist instructs the patient to extend his or her body backwards while inhaling maximally (Figure 22-7, A). The therapist then tells the patient to cough as the patient moves his or her upper body forward into a completely flexed posture, using shoulder internal rotation if possible (Figure 22-7, B). Once again, the extension aspect of the procedure is used to maximize inhalation, whereas the flexion aspect is used to maximize expiration. The self-directed chest compression occurs mainly on the superior-inferior plane of ventilation only.

The second procedure, the paraplegic version of the long-sit assist, uses the same principles as those described for the tetraplegic patient. However, paraplegic patients have active spinal extension musculature and can achieve greater trunk extension and flexion safely, thus achieving greater chest expansion before the cough and greater chest compression on a superior-inferior plane during the cough. The patient positions his or her upper extremities in a butterfly position or uses elbow retraction, depending on the level of injury (Figure 22-8, A). During the flexion phase, patients throw themselves onto their legs, thereby compressing both the upper and lower chest (Figure 22-8, B). This can be taught very successfully to patients with paraplegia, provided they have adequate trunk balance control. If the patient lacks hip flexion or is worried about bony contact or skin injury, place a pillow (or two as needed) on the legs. This will limit the hip flexion and minimize trauma from the quick thrust onto the legs.

Short-Sitting Self-Assisted Cough

A third assistive cough technique can be done with the patient sitting. The short-sitting self-assist is typically performed in a wheelchair or over the edge of a bed. The patient is instructed to place one hand over the other at the wrist and place them in his or her lap. As in the previous technique, the patient is then asked to extend the trunk backwards while inhaling maximally, followed by a strong voluntary cough. During the cough, the patient pulls his or her hands up and under the diaphragm, resembling the motion of a Heimlich maneuver (Figure 22-9). The hands mimic the abdominal muscles, which would ordinarily contract to push the intestinal contents up and under the diaphragm to aid its recoil ability. This short-sitting technique uses the diaphragm more substantially than the long-sitting procedure and is therefore generally more effective as an assistive cough. It is an effective self-assisted method for patients who have weak diaphragms or abdominal musculature. Most patients with SCI or spina bifida at C5 or below can learn this technique successfully. Patients with tetraplegia usually require trunk support and/or a seat belt from their wheelchairs to perform it independently and safely, whereas most patients with lower-level lesions resulting in paraplegia can perform it from an unsupported short-sitting position. Patients who lack good upper extremity coordination, such as many patients with Parkinson disease and multiple sclerosis (MS), cannot perform the procedure quickly or forcefully enough to make it effective and usually require assistance from another person.

Variations on all sitting techniques can be made readily. Clinicians are encouraged to use the concepts explained in the introduction to these cough techniques to develop techniques that work for their patients. For example, ask a patient in a wheelchair to lift his or her arms up while inhaling, hold, and then cough while throwing the arms down toward the feet or lap using maximum trunk flexion (use a seat belt for safety). Another idea is to have the patient hook one arm on a push handle of the wheelchair and move the other arm up and back (as in a pattern of shoulder flexion, abduction, and external rotation proprioceptive neuromuscular facilitation [PNF Pattern D2]);³⁵ make sure the patient’s moving hand maximizes trunk rotation; have the patient inhale during the movement, hold, and cough while throwing the trunk and arm down toward opposite knee. When devising the most appropriate self-assisted cough for your patient, remember to look for a combination of trunk, arm, head, neck, and eye patterns that will maximize all four phases of the cough.

Hands-Knees, Rocking Self-Assisted Cough

The last assistive cough to be discussed is performed most commonly as a multipurpose activity to increase the patient’s balance, strength, coordination, and functional use of breathing patterns (including quiet breathing and coughing) simultaneously. The patient assumes an all-fours position (hands-knees). He or she is then instructed to rock forward, looking up and breathing in while moving to a fully extended posture (Figure 22-10, A). After this, the patient is told to cough out as he or she quickly rocks backwards to the heels with a flexed head and neck (Figure 22-10, B). Once again, note the importance of the flexion and extension components of the cough. The rocking can be done with or without a therapist’s assistance. For patients with generalized or spotty weakness throughout (e.g., some patients with SCI, head trauma, Parkinson disease, MS, cerebral palsy, or spina bifida), this method is perfect for incorporating many functional goals into a single activity. It can help prepare them for the more challenging respiratory activities they will undoubtedly face after their discharge from a rehabilitation center.

For patients with limited lower extremity range of movement or skin concerns associated with a quick force, a pillow can be placed on the lower legs, thus restricting knee flexion and preventing direct contact of bony prominences.

Standing Self-Assisted Cough

Standing uses the same concepts as previously discussed and can be readily used for self-assisted coughs, provided the patient has adequate standing balance and upper extremity support. Any technique previously described can be modified for this posture. The number of possible combinations of trunk, head, and extremity movements during the cough maneuver is vast, so specific techniques are not detailed here.