What are the primary factors that contribute to the initiation of the newborns respirations?

Lungs and Respiration

The respiratory examination begins with observation of the color of the skin and mucous membranes, respiratory rate, breathing pattern, and work of breathing. Respiratory problems are unlikely to be found in a newborn who is centrally pink and breathing comfortably at a normal rate.

In the normal newborn, the abdomen expands smoothly with each contraction of the diaphragm, while the chest moves inward slightly.

The respiratory rate of the newborn is highly variable when the newborn is awake and changes with activity such as feeding and crying. Tachypnea during sleep is more clearly associated with respiratory problems than tachypnea when awake. During an examination the respiratory rate should be determined if tachypnea or hypopnea is evident. Because short pauses and brief periods of rapid breathing are common in normal newborns, accurate measurement of the respiratory rate requires at least a 60-second assessment, preferably when the newborn is asleep or at least not crying. During crying the quality and vigor of vocalization are assessed, and the newborn is observed for changes in color and perfusion. Central cyanosis that appears during crying may indicate cardiac or respiratory disease and requires further evaluation. Cyanosis that resolves during crying may be due to choanal atresia/stenosis, apnea, or hypoventilation.

The classic signs of neonatal respiratory distress are nasal flaring, grunting, and retractions. Nasal flaring and mild grunting are common in the immediate postnatal period but should resolve within 15–20 minutes after birth. Increasing respiratory distress caused by decreasing lung compliance is typically characterized by a progression in severity of these classic symptoms. The respiratory rate generally decreases as the work or effort of breathing increases, as indicated by the development of grunting and increasing retractions. When respiratory distress is mild, intermittent grunting at a slower respiratory rate may alternate with periods of mild tachypnea. As grunting worsens, the expiratory phase becomes more prolonged. The length of the grunt, rather than its loudness, correlates with the severity of distress. Intermittent mild grunting can be misinterpreted by parents as crying or singing. The rhythm of grunting and its occurrence at the end of expiration are key features that help distinguish grunting from other vocalizations. Retractions require a forceful inspiratory effort and decreased lung compliance, and they may be absent or less prominent than expected in a newborn with neuromuscular depression.

Nasal congestion, airway obstruction, and airway secretions can produce sounds that are audible without a stethoscope. Noisy or congested nasal breathing and intermittent sneezing not associated with upper respiratory tract infection are common in the first few days after birth. A hoarse cry suggests an abnormality affecting the vocal cords. Because intubation of vigorous newborns born through meconium-stained amniotic fluid is no longer routine (Halliday and Sweet, 2001), hoarseness or stridor caused by vocal cord trauma in healthy term newborns has become less common. Inspiratory stridor is due to narrowing or partial obstruction of the upper airway. The presence and loudness of stridor depend on respiratory effort as well as the extent of airway narrowing, so stridor typically worsens with forceful inspiration during crying. Stridor during crying in a newborn with no respiratory distress when quiet is often due to tracheolaryngomalacia (usually benign). Stridor that is present during quiet breathing or present throughout inspiration and expiration suggests the presence of a more significant airway obstruction that requires further evaluation.

A brief chest auscultation of the newborn who is observed to be centrally pink and breathing comfortably in room air is usually sufficient to ensure that breath sounds are clear and that air entry is adequate and equal bilaterally. Breath sounds are not well localized in the newborn, and the newborn might not remain quiet for long, so delineating the quality of breath sounds is usually more helpful than attempting to compare multiple sites. Detection of abnormal sounds such as crackles, wheezes, or rhonchi requires further assessment. If a more detailed examination is indicated, one should auscultate over the four major quadrants anteriorly, on both sides, and on the upper and lower back bilaterally. Diaphragmatic hernia presenting in the neonatal period usually causes significant respiratory distress. Rarely, a small diaphragmatic hernia is detected by the presence of bowel sounds in the chest of an asymptomatic newborn. Spontaneous cough is abnormal in newborns and is most commonly caused by infection or aspiration.

Although rarely done, percussion of the chest can be useful for estimating the position of the upper margin of the liver. Percussion can also be used to detect a large pleural effusion or lung consolidation, but newborns with these conditions will have other signs of respiratory distress, so the diagnosis will rely on imaging studies and not the physical examination. Transillumination can be useful for supporting a rapid diagnosis of pneumothorax in a distressed newborn, but it is not reliable for detecting a small pneumothorax that produces minimal symptoms.

Respiratory signs are sensitive but nonspecific indicators of illness in the newborn. Alterations in respiration (including apnea) can accompany illness of many different causes. Common causes of subtle or mild respiratory distress detected in routine evaluation include retained fetal lung fluid (transient tachypnea of the newborn), spontaneous pneumothorax, neonatal sepsis, pneumonia, meconium or amniotic fluid aspiration, and congenital heart disease. Any newborn with respiratory distress should be transferred to a NICU or observation nursery for further evaluation, monitoring, and treatment.

Lungs and Respiration

The respiratory examination begins with observing the color of the tongue and mucous membranes, respiratory rate, breathing pattern, and work of breathing. Respiratory problems are unlikely to be found in an infant who is centrally pink and breathing comfortably at a relaxed rate. In the normal newborn, the abdomen expands smoothly with each contraction of the diaphragm, while the chest moves inward slightly.

The respiratory rate of the newborn infant is highly variable when the infant is awake, changing with activity such as feeding and crying. Tachypnea during sleep is more clearly associated with respiratory problems than is tachypnea during awake states. During a routine examination of the healthy infant, it is not necessary to measure the exact respiratory rate, as long as it is clearly within a normal range in an asymptomatic infant, but the respiratory rate should be determined if tachypnea or an unusually slow rate is seen. Because short pauses and brief periods of rapid breathing are common in normal newborns, accurate measurement of the respiratory rate requires counting for a full minute, preferably when the infant is asleep or at least not crying. During crying, the quality and vigor of vocalization are assessed, and the infant is observed for changes in color and perfusion. Central cyanosis that only appears during crying may be caused by cardiac or respiratory disease and requires further evaluation. Cyanosis that resolves during crying may be due to choanal atresia or stenosis, apnea, or hypoventilation.

The classic symptoms of respiratory distress are nasal flaring, grunting, and retractions. Nasal flaring and mild grunting are common in the immediate postnatal period, but in the healthy newborn they should resolve within 15 to 20 minutes after birth. Increasing respiratory distress caused by decreasing lung compliance is typically reflected in a progression from nasal flaring, or mild tachypnea, or both; to nasal flaring plus mild or intermittent grunting; and then to flaring, grunting, and increasingly severe retractions. The respiratory rate generally decreases as the work or effort of breathing increases, as indicated by the development of grunting and increasing retractions. When respiratory distress is mild, intermittent grunting at a slower respiratory rate may alternate with periods of mild tachypnea. As grunting becomes more severe, the expiratory phase becomes increasingly prolonged. The length of the grunt, rather than its loudness, correlates with the severity of distress. Intermittent mild grunting can be misinterpreted by parents as crying. The rhythm of grunting and its occurrence at the end of expiration are key features that help to distinguish it from other vocalizations. Retractions require a forceful inspiratory effort and decreased lung compliance, and they may be absent or less prominent than expected in an infant with neuromuscular depression.

Nasal congestion, airway obstruction, and airway secretions can produce sounds that are audible without a stethoscope. Noisy or congested nasal breathing and intermittent sneezing not associated with upper respiratory infection is common in the first few days after birth. A hoarse cry suggests an abnormality affecting the vocal cords. Because intubation of vigorous infants born through meconium-stained amniotic fluid is no longer routine (Halliday and Sweet, 2001), hoarseness or stridor caused by vocal cord trauma in healthy term infants is less common than previously. Inspiratory stridor is due to narrowing or partial obstruction of the upper airway. The presence and loudness of the stridor depends on respiratory effort as well as the extent of airway narrowing, so that stridor worsens with forceful inspiration during crying. Stridor during crying in an infant with no respiratory distress when quiet is often due to tracheolaryngomalacia, and it is usually benign. Stridor that is present during quiet breathing or present during both inspiration and expiration suggests the presence of a more significant airway obstruction that requires further evaluation.

In the routine examination of the infant who is observed to be centrally pink and breathing comfortably in room air, brief auscultation of the chest of a sleeping or quiet infant is usually sufficient to ensure that the breath sounds are clear, and that air entry is adequate and equal bilaterally. Sounds are not well localized in the neonate, and the infant might not remain quiet for long, so attention to the quality of the breath sounds is usually more helpful than attempting to compare multiple sites. Detection of abnormal lung sounds including crackles, wheezes, and rhonchi requires further assessment. If more detailed examination is indicated, auscultate over the four major quadrants anteriorly, on the sides, and on the upper and lower back bilaterally. Diaphragmatic hernia manifesting in the neonatal period usually causes significant respiratory distress, but rarely a small diaphragmatic hernia is detected by the presence of bowel sounds in the chest in an asymptomatic infant. Spontaneous cough, which is abnormal in neonates, is most commonly caused by infection or aspiration.

Percussion of the chest, rarely done as part of routine examination of newborn, can be useful for estimating the position of the upper margin of the liver. Percussion can also be used to detect a large effusion or lung consolidation, but infants with these conditions will have other symptoms of respiratory distress, so the diagnosis will rely on imaging studies and not the physical examination. Transillumination can be useful for supporting a rapid diagnosis of pneumothorax in a distressed infant, but it is not reliable for detecting a small pneumothorax that produces minimal symptoms.

Respiratory symptoms are sensitive but nonspecific indicators of illness in the newborn, because alterations in respiration (including apnea) can accompany illness of many different etiologies. Common causes of subtle or mild respiratory distress detected in the routine evaluation include retained fetal lung fluid (transient tachypnea of the newborn), spontaneous pneumothorax, neonatal sepsis, pneumonia, meconium or amniotic fluid aspiration, and congenital heart disease. Any infant with respiratory distress should be transferred to an NICU or observation nursery for further evaluation, monitoring, and treatment.

Physical Examination

A complete cardiovascular, respiratory, and abdominal examination should be performed. The physical examination of the patient presenting with chest pain should initially focus on the vital signs. After documenting a stable regular heart rate and rhythm, respirations, and blood pressure, a thorough physical examination should focus on finding noncardiac causes. The initial evaluation should include inspecting for evidence of trauma, bruises, or abrasions on the chest wall. Palpation should focus on bony abnormalities and localized chest swellings and on the site of the pain indicated by the patient. There should be an attempt to reproduce the pain by palpation of the location indicated by the patient. Reproducible pain, particularly at the costochondral junction or over a rib, points to costochondritis as the etiology of the pain.

PALPATION

Although more generally thought of in terms of the abdominal examination, palpation is important in the respiratory examination as well. It is used to confirm the visual observations of chest wall shape and excursion. Palpation is performed by placing the entire hand on the chest and feeling with the palm and fingertips. Friction rubs may be felt as high-frequency vibrations in synchrony with the respiratory pattern. Tactile fremitus, the transmission of vibrations associated with vocalization, is at times difficult to assess in children because of a lack of cooperation and a higher-pitched voice; lower-pitched vocalization is more effectively transmitted. It is best felt with the palmar aspects of the metacarpal and phalangeal joints on the costal interspaces. Decreased fremitus suggests airway obstruction, pleural fluid, or pleural thickening, whereas increased fremitus is associated with parenchymal consolidation. Occasionally a “thud” can be felt high in the chest or in the neck, a finding suggestive of a free tracheal foreign body. One can also assess chest excursion by placing the hands with the fingertips anterior and thumbs posterior and noting the degree of chest wall movement, comparing excursion of one side with the other by noting the movement of the thumbs away from the midline (the spinous processes). The point of maximal impulse, frequently shifted to the left in cardiac disease, may be shifted inferiorly and to the right in severe asthma, a large left-sided pleural effusion, or a tension pneumothorax. With massive left-sided atelectasis, it may be shifted to the left.

Pneumocystis jiroveci pneumonitis

Interstitial pneumonitis due to Pneumocystis jiroveci presents as subacute progressive dyspnoea, non-productive cough and fever. Respiratory examination reveals fever and tachypnoea; however, focal signs are uncommon. The critical finding is that of hypoxia. The chest X-ray or CT scan classically demonstrates interstitial ‘ground glass’ infiltrates but can be normal. A definitive diagnosis is made by demonstrating Pneumocystis cysts in an induced sputum specimen, bronchoalveolar lavage fluid or a transbronchial biopsy.

Severe PJP is best treated with high-dose intravenous co-trimoxazole (trimethoprim-sulfamethoxazole). Many patients develop a hypersensitivity reaction to co-trimoxazole; only severe reactions necessitate changing to intravenous pentamidine. Steroid therapy must be used if the

Patients with a CD4 T-cell count of <200/mL should receive PJP prophylaxis; most effective is co-trimoxazole, which has added benefit in protecting against other bacterial infections and cerebral toxoplasmosis.16

Patient Education

Fearing that a dizziness attack will come on or that they will fall, many older persons with dizziness give up activities crucial to their independence and self-image, such as going to church, shopping, visiting friends, and driving. For these reasons, the effective management of dizziness requires counseling the patient and family about these issues. Patients should be given basic education regarding the pathophysiology of dizziness and its provocation to help the patient understand, and therefore be more realistic and less anxious about dizziness. At times, modifying activities is indicated; for example, in case of postural dizziness, patients should be instructed to rise slowly from the sitting or supine position. Deconditioning plays an important role in the persistence of symptoms; accordingly, activities are to be encouraged. Finally, dizzy patients should avoid over-the-counter sleeping pills or cold medicines, and their prescription medications should be carefully reviewed.

POSTTEST

You are asked to evaluate to see an 80-year-old man, a nursing home resident with past medical history of mild Alzheimer's disease, hypertension, and reflux oesophagitis, who complained of feeling dizzy, a sensation of about to pass out on the dining table after eating his breakfast. He had similar episodes in the past after finishing his meals. He denies any chest pain or shortness of breath. On examination, he is alert, awake, oriented to person and place. Vital signs show heart rate of 74 per minute and blood pressure of 110/70. His vital signs in the morning at 7 AM were heart rate 70 per minute and blood pressure 130/80. Other system examination was unremarkable. No recent medication changes were made. What is the most likely diagnosis?

Cerebrovascular stroke

Recurrent vestibulopathy

Postprandial hypotension

Benign paroxysmal positional vertigo

Mr. K.G. is a 68-year-old retired insurance salesman with a 2-day history of dizziness. He describes a lightheaded sensation as though he is about to pass out, that occurs whenever he is standing or walking. He has a milder sensation in the sitting position and is completely relieved when he lies down. There is no sense of spinning accompanying this sensation. What is the likely physiologic mechanism underlying Mr. K.G.'s dizziness?

Depression or anxiety

Diminished oxygenation of the cerebral cortex

Cardiac dysrhythmia

Stimulation of the vestibular system when he stands

Irritation of neck proprioceptive fibers

What laboratory test provides the best method of screening for an acoustic neuroma?

Magnetic resonance imaging of the head

Computerized tomography of the head

Brainstem-evoked potentials

Electroencephalography

Audiometry with speech discrimination

A 74-year-old man is brought to your office by his concerned wife. At about 2:30 this morning he got up to go to the bathroom, feeling a little lightheaded. He sat on the toilet, but even as he did so he could feel himself blacking out. His wife heard a thud and found him unconscious. He became conscious in about 10 to 15 seconds. He did not feel chest pain or palpitations before or after the episode, and he was not incontinent. On further questioning, he states that he has had a cold for the past 4 days, for which he has taken a combination medication containing pseudoephedrine and chlorpheniramine. Rarely an alcohol drinker, he admits to having few beers last evening while watching Monday night football with his son, who is visiting. He does not have a history of seizures. Four months ago, he had a normal cardiac treadmill test performed by his cardiologist as part of a routine evaluation. Other than the cold preparation and one aspirin a day, he is not taking medication.

Which of the following conditions contributed to this episode of vasovagal dizziness and syncope?

History of alcohol intake last night

Common cold for 4 days, probably viral illness

Use of medications containing pseudoephedrine and chlorpheniramine

Postural hypotension secondary to rapidly getting up from lying-down position

All of the above

PRETEST ANSWERS

d

c

d

b

POSTTEST ANSWERS

c

b

e

e

Recurrent Pneumonia

The child with a history of more than one episode of pneumonia may require further evaluation. A single episode of pneumonia is usually not a cause for concern in a child, but more that one episode in a year, or three during childhood, should provoke further evaluation14. Some studies have suggested that an underlying illness will be found as frequently as 80% of the time in these patients15 (Table 1-4).

Chemotherapy

The primary offending agents include bleomycin and nitrosourea, with clinical manifestations usually occurring months after a critical cumulative dose is reached or exceeded. Busulfan is also associated with pulmonary fibrosis, with the greatest risk in patients who have received more than 500 mg. Pulmonary toxicity is increased when any of these agents are given in combination with radiation therapy to the lungs or chest. Children who have undergone transplant are at risk for chronic pulmonary issues such as graft versus host disease (GVHD) of the lungs and bronchiolitis obliterans organizing pneumonia, known as BOOP.

Diagnosis

The diagnosis of apnea of prematurity is made by excluding all other causes of neonatal apnea. The etiologies of neonatal apnea include infection, metabolic disorders, thermal instability, gastroesophageal reflux, and neurologic causes (Box 3-3). The infant's history should include prenatal, perinatal, and postnatal information to guide the clinician to a specific disease entity. Physical examination should focus on the infant's breathing pattern during awake and sleep periods, including a complete respiratory, cardiac, and neurologic examination. Although clinical observation can give some clue to the diagnosis, studies have shown that a large percentage of apnea episodes were not detected by nursing staff.64,65 Nursing detection not only identified significantly less true apnea and bradycardia but also misclassified the type of events in a significant number of infants.66

An overnight polysomnographic study is the most complete test for evaluation of infant apnea. The standard infant montage includes assessment of the following parameters: body position, left and right electrooculogram, central and occipital electroencephalogram (C3A1, C4A1), chin electromyogram, electrocardiogram, pulse oximetry and pulse waveform, thoracic and abdominal inductance plethysmography, airflow, end-tidal CO2, and transcutaneous Po2 and Pco2. The study allows accurate assessment of apnea and its effect on cardiovascular and pulmonary function (Fig. 3-3). It provides not only data on cardiorespiratory events but also information on sleep architecture, sleep organization, and the relationship between sleep states and apnea (Figs. 3-4, 3-5, 3-6). Many clinicians, however, elect to perform four or five channel pneumocardiograms, which include heart and respiratory rates, oxygen saturation, nasal airflow, and possibly esophageal pH as the first step in the diagnosis and management of AOP. As a diagnostic tool, pneumocardiogram can objectively quantify rate of respiration, respiratory rhythm, the relative amplitude of respiratory activity, and the incidence of apnea, as well as any resultant bradycardia. This tool, however, does not differentiate among the various types of apnea nor does it detect alveolar hypoventilation as would a polysomnogram.

CLINICAL FEATURES