In performing a physical examination, the act of listening to sounds made by the body is known as

Dynamic Auscultation

Simple bedside maneuvers can help identify heart murmurs and characterize their significance [Table 10.7]. Right-sided events, except for the pulmonic ejection sound, increase with inspiration and decrease with expiration; left-sided events behave oppositely [100% sensitivity, 88% specificity]. The intensity of the murmurs associated with MR, VSD, and AR will increase in response to maneuvers that increase LV afterload [e.g., handgrip, vasopressor administration] and decrease after exposure to vasodilating agents [e.g., amyl nitrite]. The response of the murmur associated with MVP to standing and squatting has previously been described. The murmur of HOCM behaves in a directionally similar manner, becoming softer and shorter with squatting [95% sensitivity, 85% specificity] and longer and louder on rapid standing [95% sensitivity, 84% specificity]. The intensity of the murmur of HOCM also increases with the Valsalva maneuver [65% sensitivity, 95% specificity]. A change in the intensity of a systolic murmur in the first beat after a premature beat, or in the beat after a long cycle length in patients with AF, suggests aortic stenosis rather than MR, particularly in an older patient, in whom the murmur of aortic stenosis is well transmitted to the apex [Gallavardin effect]. Systolic murmurs caused by LV outflow obstruction, including those caused by aortic stenosis, will increase in intensity in the beat following a premature beat because of the combined effects of enhanced LV filling and postextrasystolic potentiation of contractile function. Forward flow accelerates, causing an increase in the gradient and a louder murmur. The intensity of the murmur of MR does not change in the post–premature beat, because relatively minimal further increase occurs in mitral valve flow or change in the LV-LA gradient.

Abstract

Auscultation is currently both a powerful screening tool, providing a cheap and quick initial assessment of a patient’s clinical condition, and a hard skill to master. Acquiring this skill is not only intrinsically difficult but our teaching methods are inadequate due to a variety of practical issues. In this chapter, we will discuss the difficulties of the art of auscultation, how we currently teach this skill and describe a novel simulation technology, IS4Learning, that can be used in three different teaching settings enabling us to train and evaluate students in the art of auscultation.

Observation of Touch, Reading or Listening to “Sensory” Words, Observing “Sensory Pictures,” and Mirror Visual Feedback

Activation of mirror neurons in the premotor cortex by the observation of hand activity is believed to play a fundamental role in both action and imitation.61 In addition, mirror neurons are thought to be involved in understanding the intention of actions.67 Reading or listening toaction words related to hand movements activates hand areas in the motor network,68 and hypothetically, reading or listening to “sensory” words or watching “sensory” pictures would activate the somatosensory cortex. Other ways to activate the somatosensory cortex include observing a body part being touched. Keysers and associates62 showed this duringobservation of touching the legs. It is suggested that the primary and secondary somatosensory cortices are related to the mirror neuron system.69,70 The patient’s observation of his or her hand being touched is one component of early sensory training the first days after surgery [Fig. 42.2].

The observational effect can be further enhanced by using mirror visual feedback.59,71 A mirror is placed transversally in front of thepatient with the nerve-injured hand hidden behind the mirror and the healthy hand being reflected in the position of the injured hand. Touching the healthy hand gives the illusion of touching the nerve-injured hand. In these training sessions, a clinical observation is that the patient often gets a perception of the tactile stimuli in the nerve-injured, insensate hand by the combined mirror illusion and the true touch of the healthy hand. [Fig. 42.3].

Auscultation.

Auscultation of an infant is at best a gross assessment of the lungs because of the thin chest wall, proximity of structures, and easy transmission of sounds. These problems are even more confounding when auscultating the chest of a premature infant or of an infant who is being mechanically ventilated.

The stethoscope used may vary according to the size of the infant or the personal preference of the therapist. Fig. 16-8 shows two sizes of commonly used pediatric stethoscopes. The stethoscope should have both a bell and a diaphragm, because it is often helpful to use both portions when listening to a neonate's chest.

Before attempting to auscultate an infant who is intubated or has a tracheostomy, the therapist should be sure to empty the corrugated ventilator tubing of all water that has precipitated from the humid water vapor delivered with inspired gases. Water that is bubbling in ventilator tubing can mask breath sounds and mimic adventitious sounds. A baby who is receiving intermittent mandatory ventilation [IMV] may be receiving as little as 2 breaths/min from the ventilator. It may be very difficult to hear breath sounds when the infant is breathing spontaneously. However, the mechanical breath often enhances breath sounds.

The therapist listens for normal and abnormal breath sounds, as well as for adventitious sounds [Figs. 16-9 and 16-10]. The terminology for normal, abnormal, and adventitious sounds in the infant is similar to that in an older child or adult [see Chapter 12]. Abnormal sounds can be distinguished from normal sounds by thorough and careful auscultation. It is also helpful to listen to breath sounds from corresponding areas of both lungs in a sequential manner to compare right and left lungs.

Whenever possible, the therapist should auscultate with the infant's head in the midline position, because turning the head to one side may cause decreased contralateral breath sounds. In infants, the relative thinness of the thorax may result in auscultation findings not necessarily corresponding with the condition of the underlying lung segment. It is extremely important to correlate physical signs, such as auscultation, with radiographic evidence of a pathological condition. The AP and lateral chest radiographs help localize areas of atelectasis, infiltrate, and pneumothorax, but these abnormalities are not always present. The therapist must often rely on auscultatory findings to indicate areas for treatment emphasis and to describe the results of bronchial drainage techniques, positioning to improve ventilation, and other therapeutic interventions. Auscultation is therefore an essential component of the chest examination of neonates.

Auscultation.

When chronic severe MR is caused by defective valve leaflets, S1, produced by mitral valve closure, is usually diminished. Wide splitting of S2 is common and results from the shortening of LV ejection and an earlier A2 because of reduced resistance to LV ejection. In patients with severe pulmonary hypertension, P2 is louder than A2. The abnormal increase in the flow rate across the mitral orifice during the rapid filling phase is often associated with a third heart sound [S3], which should not be interpreted as a feature of HF in these patients, and this may be accompanied by a brief diastolic rumble.

The systolic murmur is the most prominent physical finding; it must be differentiated from the systolic murmur of AS, tricuspid regurgitation [TR], and ventricular septal defect [VSD]. In most patients with severe MR, the systolic murmur commences immediately after the soft S1 and continues beyond and may obscure the A2 because of the persisting LV-LA pressure difference after aortic valve closure. The holosystolic murmur of chronic MR is usually constant in intensity, blowing, high-pitched, and loudest at the apex, with frequent radiation to the left axilla and left infrascapular area, particularly with posteriorly directed jets. Radiation toward the sternum or aortic area, however, may occur with abnormalities of the posterior leaflet and is particularly common in patients with MVP and flail involving this leaflet. The murmur shows little change, even in the presence of large beat-to-beat variations of LV stroke volume, as in AF. This finding contrasts with that in most midsystolic [ejection] murmurs, such as in AS, which vary greatly in intensity with stroke volume and therefore with the duration of diastole. Little correlation has been found between the intensity of the systolic murmur and severity of MR. In patients with severe MR caused by LV dilation, acute MI, or paraprosthetic valvular regurgitation, or in those who have marked emphysema, obesity, chest deformity, or a prosthetic heart valve, the systolic murmur may be barely audible or even absent, a condition referred to as “silent” MR.

The murmur of MR may be holosystolic, late systolic, or early systolic. When the murmur is confined to late systole, the regurgitation usually is secondary to MVP and may follow one or more midsystolic clicks and typically is not severe. Such late systolic MR is often associated with a normal S1 because initial closure of the mitral valve cusps may be unimpaired. Occasionally, a late systolic murmur of papillary muscle dysfunction may be noted, becoming louder or holosystolic during acute myocardial ischemia, and may disappear when ischemia is relieved. A midsystolic click preceding a mid- to late systolic murmur, and the response of that murmur to a number of maneuvers, helps establish the diagnosis of MVP [discussed later]. Early systolic murmurs are typical of acute MR. When the LAv wave is greatly elevated in acute MR, the murmur may diminish or disappear in late systole as the reverse pressure gradient declines. As noted, a short, low-pitched diastolic murmur following S3 may be audible in patients with severe MR, even without accompanying MS.

Separation of heart and lung sounds from digital auscultation

Auscultation of lung sounds is a useful procedure for detection of pulmonary diseases. Unfortunately, lung sounds are frequently corrupted by heart sounds, as both overlap in the time and frequency domains. However, due to the different origin of the two signals, their spectral content changes with different modulation frequencies; thus separability can be attained by filtering in the modulation spectrogram domain. Fig. 20A and B depict the modulation spectrogram for lung sounds, and lung sounds corrupted by heart sounds. The modulation-based analysis and synthesis of the auscultation sound signal to remove the heart sound provides an improvement in the separation of the lung and heart sounds compared with other utilized methods such as adaptive filtering, wavelet filtering, and independent component analysis, among others. A metric to compare the performance of the aforementioned separation methods is to measure the log-spectral distance [LSD] between the recovered lung sound and heart-sounds-free breathing sound. Comparing the modulation approach with wavelet filtering, the former achieves almost half the LSD value of wavelet filtering with almost 30 times lower signal processing time.

23 How is tracheal intubation confirmed?

Auscultation for bilateral breath sounds and absence of stomach inflation should be done after each intubation attempt. However, these signs may still be present with an esophageal intubation. Carbon dioxide capnography is one of the most reliable methods to confirm placement. The laryngoscopic view may be useful. If an experienced clinician clearly sees the tube between the vocal cords, this is definitive confirmation. The endotracheal tube itself commonly blocks sight of the vocal cords, and inexperienced clinicians may insert the tube in the esophagus despite having a good view of the larynx. Other confirmation methods include fiberoptic bronchoscopy or an esophageal detector device.

b Auscultation of Breath Sounds

Auscultation of bilateral breath sounds is the most common method used to ensure proper ETT placement. It can be done repeatedly anywhere endotracheal intubation is performed and whenever change in the position of the tube is suspected. In almost all cases, breath sounds heard near the midaxillary lines leave very little doubt regarding the position of the ETT. However, in numerous anecdotal reports, deceptive breath sounds were heard in cases that proved to be esophageal intubation.

There are several reasons why sounds heard with esophageal intubation may mimic breath sounds from the lungs. The combination of esophageal wall oscillations with gas movement and acoustic filtering can produce inspiratory or expiratory wheezes indistinguishable from sounds arising from gas movement in the airway.13,27,28 The high flow rate, distribution, and volume of gas delivered through the esophagus may lead to auscultation of predominantly bronchial breath sounds.13 In infants and children, esophageal sounds can be easily transmitted to wide areas of the chest wall.29 The quality of breath sounds may also differ depending on whether the chest is auscultated near the middle line or laterally near the axilla and may vary with the presence of pulmonary disease and from patient to patient.

Sounds retrieved by an esophageal stethoscope are different from those heard with a precordial stethoscope and should not be used to differentiate endotracheal from esophageal intuation.16,25 In patients with a thoracic stomach or hiatal hernia, many of the clinical signs of esophageal intubation may be obscured. Because of the intrathoracic location of a large distensible viscus, bilateral breath sounds may be heard during manual ventilation.12 For these reasons, whenever abnormal breath sounds are heard, they should not be relied on to confirm endotracheal intubations.30

Proper verification of ETT placement by auscultation is dependent on the clinician's experience.31 In one study in the critical care setting, experienced clinicians identified ETT location correctly, whereas inexperienced examiners were correct in only 68% of cases.31

C. Auscultation

Auscultation by itself does not determine the fetal position, but it may reinforce what the examiner suspects from palpation. In the vertex and breech positions, fetal heart tones are best heard through the fetal back, whereas in a face presentation, they are heard through the fetal thorax. In vertex presentations, heart tones are heard with maximal intensity between the umbilicus and the anterior superior iliac spine of the mother. In breech presentations, this point of maximal intensity is closer to the level of the umbilicus. In the more common occipitoanterior position, fetal heart tones are heard best near the midline, whereas in transverse presentations, they are more lateral; in posterior presentations, the point of maximal intensity is back toward the mother's flank.

Auscultation

Auscultation is the act of listening for sounds, often with a stethoscope, to denote the condition of the lungs, heart, pleura, abdomen, and other organs.5 The stethoscope does not magnify sound but rather blocks out extraneous room sounds. Of all the equipment used, the stethoscope quickly becomes a very personal instrument. Time should be taken to learn its features and make sure it is a good fit to the individual user. Auscultation is a skill that beginning examiners are eager to learn, but one that is difficult to master. First, the wide range of normal sounds must be learned. Once normal sounds are recognized, the clinician can begin to distinguish abnormal sounds.2

There are some general principles that apply to all auscultatory procedures. The environment should be quiet and free from distracting noises. The stethoscope should be placed on the naked skin because clothing obscures sound. The therapist should listen not only for the presence of sound but also its characteristics: intensity, pitch, duration, and quality. The sounds are often subtle or transitory, and intense listening is needed to hear the nuances. Closing the eyes may prevent distraction by visual stimuli and narrow the perceptual field to focus on the sound. The therapist should try to target and isolate each sound, concentrating on one sound at a time and taking enough time to identify all the characteristics of each sound.

One of the most difficult achievements in auscultation is learning to isolate sounds. Whether it is a breath sound or a heart beat in the sequence of respirations and heart beats, each segment of the cycle must be isolated and listened to specifically. After individual sounds are identified, they are put together in sequences. The clinician should not anticipate the next sound but rather concentrate on the one at hand.6

The patient should sit forward or, if this position is not possible, be placed in a side-lying position so that the upper and middle lung fields are exposed. The patient is reminded to breathe only through his mouth. First, he is asked to perform two repetitions of his normal breathing pattern: natural inspiration and expiration. Then systematically the stethoscope is placed over each of the auscultation landmarks [Figure 6-6], proceeding superior to inferior and evaluating at least one breath sound per pulmonary segment bilaterally.

The presence of abnormal breath sounds or the absence of breath sounds is noted and compared with the contralateral side. One or two repetitions of a maximal inspiration are taken at each landmark, again to note anything abnormal. Adventitious sounds such as crackles [rales] and wheezes [rhonchi] are also noted. Crackles may indicate the reopening of previously closed airways or, if nonrhythmic, may be a sign of fluid in the large airways. Wheezes are continuous and thought to be produced by air flowing through narrow airways at high velocities. Expiratory wheezes are associated with diffuse airway obstruction from extensive secretions in the airways [Figure 6-7].

Breath sounds are generated by air flow turbulence throughout the lung fields during inspiration and expiration. There are four types of breath sounds: tracheal, bronchial, vesicular, and bronchovesicular. Tracheal breath sounds are auscultated directly over the trachea. They are loud and high pitched with a pause of equal duration between inspiration and expiration. Bronchial breath sounds, which can be heard over the manubrium between the clavicles or posteriorly between the scapulae, are similar to tracheal breath sounds but the inspiration is shorter. Vesicular breath sounds can be heard over the peripheral lung fields and are identified by a long inspiration and short expiration with a faint, low-pitched sound and no pause between inspiration and expiration. Bronchovesicular breath sounds can be heard adjacent to the sternum or posteriorly between the scapulae and have a lower, medium-pitched sound with no pauses between inspiration and expiration; Table 6-1 illustrates and defines the difference.Auscultation should be carried out last, after other techniques have provided information that will assist in interpretation. Too often the temptation is to rush right in with the stethoscope, thereby missing the opportunity to gather other data that might be useful. Auscultation is also used to determine the type of treatment and breathing retraining necessary for each patient's best respiration outcomes. It may provide feedback about the continuing effectiveness of pulmonary treatment.

Indeed, clinicians must always be open to what has been described as the “clinical pearl of unexpected findings”7: the key [one among many] to a successful physical examination is to respect your judgment and your instinct whenever you find that which you had not expected to find—that is, when your sense of the expected or of what you might call the normal has been violated. Pay attention when that happens even if it doesn't seem to make sense or you can't explain it easily.