In the developed parts of the world order cozaar canada blood glucose dangerous levels, where infants receive good health super- vision purchase 25 mg cozaar amex diabetes mellitus definition and types, the mortality diference is no longer a signifcant problem generic cozaar 50mg without a prescription diabete zucchero di canna. However, 327 A Clinical Guide for Contraception in the developing world, excess mortality due to early weaning continues to be high. The revival of breastfeeding can be attributed to the growth of knowl- edge regarding the health of infants. Breastfeeding has a child-spacing efect, which is very important in the developing world as a means of limiting family size and providing good nutrition for infants. Human milk prevents infections and illnesses in infants, both by the transmission of immunoglobulins and by modifying the bacte- rial fora of the infant’s gastrointestinal tract. Beginning in the 1960s, breastfeeding became more popular in the United States, Sweden, Canada, and the United Kingdom. But this upward trend in the United States peaked in 1982 (at 61% for initiation and 40% for 3 or more months). But the good news is that since the 1980s, there has been a steady and consistent increase in breastfeeding. Breast Physiology The basic component of the breast lobule is the hollow alveolus or milk gland lined by a single layer of milk-secreting epithelial cells, derived from an ingrowth of epidermis into the underlying mesenchyme at 10 to 12 weeks of gestation. Also surrounding the milk gland is a rich capillary the Postpartum Period, Breastfeeding, and Contraception network. The lumen of the alveolus connects to a collecting intralobular duct by means of a thin nonmuscular duct. Contractile muscle cells line the intralobular ducts that eventually reach the exterior via 15 to 20 collecting ducts in a radial arrangement, corresponding to the 15 to 20 distinct mam- mary lobules in the breast, each of which contains many alveoli. Growth of this milk-producing system is dependent on numerous hor- monal factors that occur in two sequences, frst at puberty and then in pregnancy. In most girls, the frst response to the increasing levels of estrogen is an increase in size and pigmentation of the areola and the formation of a mass of breast tissue just underneath the areola. The primary efect of estrogen in subprimate mammals is to stimulate growth of the ductal por- tion of the gland system. Full diferentiation of the gland requires insulin, cortisol, thyroxine, prolactin, and growth hormone. Nevertheless, experimental evidence in mice indicates that progesterone is the key hormone required for mammary growth and diferentiation; estro- gen is necessary because the synthesis of progesterone receptors requires the critical presence of estrogen. Dur- ing the normal menstrual cycle, estrogen receptors in mammary gland epi- thelium decrease in number during the luteal phase, whereas progesterone receptors remain at a high level throughout the cycle. However, important studies indicate that with increas- ing duration of exposure, progesterone imposes a limitation on breast cell proliferation. A Clinical Guide for Contraception Final diferentiation of the alveolar epithelial cell into a mature milk cell is accomplished by the gestational increase in estrogen and progesterone, combined with the presence of prolactin, but only afer prior exposure to cortisol and insulin. Tus, the endocrinologically intact individual in whom estrogen, progesterone, thyroxine, cortisol, insulin, prolactin, and growth hormone are available can have appropriate breast growth and function. During the frst trimester of pregnancy, growth and proliferation are maximal, changing to diferentiation and secretory activity as pregnancy progresses. As the years go by, the breasts contain progressively more fat, but afer menopause, this process accelerates so that soon into the postmenopausal years, the breast glandular tissue is mostly replaced by fat. Lactation During pregnancy, prolactin levels rise from the normal level of 10 to 25 ng/mL to high concentrations, beginning about 8 weeks and reaching a peak of 200 to 400 ng/mL at term. Although prolactin stimulates signifcant breast growth and is available for lactation, only colostrum (composed of desquamated epithelial cells and transudate) is produced during gestation. Full lactation is inhibited by progesterone, which interferes with prolactin action at the alveolar cell pro- lactin receptor level. Both estrogen and progesterone are necessary for the expression of the lactogenic receptor, but progesterone antagonizes the posi- tive action of prolactin on its own receptor while progesterone and pharma- cologic amounts of androgens reduce prolactin binding. With- out prolactin, synthesis of the primary protein, casein, will not occur, and the Postpartum Period, Breastfeeding, and Contraception true milk secretion will be impossible. The hormonal trigger for initiation of milk production within the alveolar cell and its secretion into the lumen of the gland is the rapid disappearance of estrogen and progesterone from the circulation afer delivery. The clearance of prolactin is much slower, requiring 7 days to reach nonpregnant levels in a nonbreastfeeding woman. Tese discordant hormonal events result in removal of the estrogen and pro- gesterone inhibition of prolactin action on the breast. Breast engorgement and milk secretion begin 3 to 4 days postpartum when steroids have been sufciently cleared. Maintenance of steroidal inhibition or rapid reduction of prolactin secretion (with a dopamine agonist) is efective in preventing postpartum milk synthesis and secretion. In the frst postpartum week, prolactin levels in breastfeeding women decline approximately 50% (to about 100 ng/mL). Until 2 to 3 months postpartum, basal levels are approximately 40 to 50 ng/mL, and there are large (about 10- to 20-fold) increases afer suckling. Troughout breastfeeding, baseline prolactin levels remain elevated, and suckling pro- duces a 2-fold increase that is essential for continuing milk production. The optimal quantity and the quality of milk are dependent upon the availability of thyroid, insulin, and the insulin-like growth factors, corti- sol, and the dietary intake of nutrients and fuids. Secretion of calcium into the milk of lactating women approximately doubles the daily loss of calcium. It is possible that recovery is impaired in women with inadequate calcium intake; total calcium intake during lactation should be at least 1,500 mg per day. Nevertheless, calcium supplementation has no efect on the calcium content of breast milk or on bone loss in lactating women who have normal diets. Human milk prevents infections in infants both by transmission of immunoglobulins and by modifying the bacterial fora of the infant’s gas- trointestinal tract. Viruses are transmitted in breast milk, and although the actual risks are unknown, women infected with cytomegalovirus, hepatitis B, or human immunodefciency virus are advised not to breastfeed. Vitamin A, vitamin B12, and folic acid are signifcantly reduced in the breast milk of women with poor dietary intake. In a study of Pima Indi- ans, exclusive breastfeeding for at least 2 months was associated with a lower rate of adult-onset non–insulin-dependent diabetes mellitus, partly because overfeeding and excess weight gain are more common with bottlefeeding. Indeed, afer the fourth postpartum month, suck- ling appears to be the only stimulant required; however, environmental and emotional states also are important for continued alveolar activity. Vigorous aerobic exercise does not afect the volume or composition of breast milk, and therefore infant weight gain is normal. However, the ejection of milk from the breast does not occur only as the result of a mechanically induced negative pressure produced by suckling. Tactile sensors concentrated in the areola activate, via thoracic sensory nerve roots 4, 5, and 6, an aferent sensory neural arc that stimulates the paraventricular and supraoptic nuclei of the hypothalamus to synthesize and transport oxytocin to the posterior pituitary. The eferent arc (oxytocin) is blood-borne to the breast alveolus-ductal systems to contract myoepithelial cells and empty the alveolar lumen. Oxytocin-like peptides exist in fsh, reptiles, and birds, and a role for oxytocin in maternal behavior may have existed before lactation evolved. The central nervous system can be conditioned to respond to the presence of the infant, or to the sound of the infant’s cry, by inducing activation of the eferent arc. Suckling, therefore, acts to refll the breast by activating both portions of the pituitary (anterior and posterior) causing the breast to produce new milk and to eject milk.
Calcium and other divalent cations also interfere with the absorption of these agents (ure 31 order discount cozaar online diabetes pills or insulin. Concentrations are high in bone purchase cozaar visa how does diabetes medications work, urine (except moxifloxacin) order cozaar uk diabetes joslin, kidney, prostatic tissue (but not prostatic fluid), and lungs as compared to serum. Accumulation in macrophages and polymorphonuclear leukocytes results in activity against intracellular organisms such as Listeria, Chlamydia, and Mycobacterium. Moxifloxacin is metabolized primarily by the liver, and while there is some renal excretion, no dose adjustment is required for renal impairment (see ure 31. Common adverse effects leading to discontinuation are nausea, vomiting, headache, and dizziness. Patients taking fluoroquinolones are at risk for phototoxicity resulting in exaggerated sunburn reactions. Arthropathy is uncommon, but arthralgia and arthritis are reported with fluoroquinolone use in pediatric patients. Use in the pediatric population should be limited to distinct clinical scenarios (for example, cystic fibrosis exacerbation). Hepatotoxicity or blood glucose disturbances (usually in diabetic patients receiving oral hypoglycemic agents or insulin) have been observed. Identification of any of these events should result in prompt removal of the agent. Serum concentrations of medications such as theophylline, tizanidine, warfarin, ropinirole, duloxetine, caffeine, sildenafil, and zolpidem may be increased (ure 31. Examples of clinically useful fluoroquinolones Due to increasing resistance and boxed warnings, fluoroquinolones should be used with caution in select circumstances. They may be considered in patients who do not tolerate other agents (for example, severe beta-lactam allergies) or as definitive therapy once susceptibilities are available. Ciprofloxacin is used in the treatment of traveler’s diarrhea, typhoid fever, and anthrax. It is a second-line agent for infections arising from intra-abdominal, lung, skin, or urine sources. Of note, high-dose therapy should be employed when treating Pseudomonas infections. It may be considered for mild-to-moderate intra- abdominal infections, but should be avoided if patients have fluoroquinolone exposure within previous three months, due to increasing B. Moxifloxacin may be considered as a second-line agent for management of drug-susceptible tuberculosis. Due to its spectrum of activity, it is an option for managing acute bacterial skin and skin structure infections. Humans use dietary folate to synthesize the critical folate derivative, tetrahydrofolic acid. By contrast, many bacteria are impermeable to folate derivatives, and rely on their ability to synthesize folate de novo (ure 31. Sulfonamides (sulfa drugs) are a family of antibiotics that inhibit de novo synthesis of folate. A second type of folate antagonist, trimethoprim, prevents microorganisms from converting dihydrofolic acid to tetrahydrofolic acid. The combination of the sulfonamide sulfamethoxazole with trimethoprim (the generic name for the combination is cotrimoxazole) provides a synergistic effect. Sulfonamides Sulfa drugs were among the first antibiotics used in clinical practice. Today, they are seldom prescribed alone except in developing countries, where they are employed because of low cost and efficacy. Antibacterial spectrum Sulfa drugs have in vitro activity against gram-negative and gram-positive organisms. Common organisms include Enterobacteriaceae, Haemophilus influenzae, Streptococcus spp. Resistance Bacteria that obtain folate from their environment are naturally resistant to sulfa drugs. Acquired bacterial resistance to the sulfa drugs can arise from plasmid transfers or random mutations. Absorption Most sulfa drugs are well absorbed following oral administration (ure 31. It is not absorbed when administered orally or as a suppository and, therefore, is reserved for treatment of chronic inflammatory bowel diseases. Absorption of sulfapyridine can lead to toxicity in patients who are slow acetylators. Because of the risk of sensitization, sulfa drugs are not usually applied topically. Distribution Sulfa drugs are bound to serum albumin in circulation and widely distribute throughout body tissues. Sulfa drugs penetrate well into cerebrospinal fluid (even in the absence of inflammation) and cross the placental barrier to enter fetal tissues. The acetylated product is devoid of antimicrobial activity but retains the toxic potential to precipitate at neutral or acidic pH. This causes crystalluria (“stone formation”; see below) and potential damage to the kidney. Excretion Unchanged sulfa drug and metabolites are eliminated via glomerular filtration and secretion, requiring dose adjustments with renal impairment. Adequate hydration and alkalinization of urine can prevent the problem by reducing the concentration of drug and promoting its ionization. Hypersensitivity Hypersensitivity reactions, such as rashes, angioedema, or Stevens-Johnson syndrome, may occur. When patients report previous sulfa allergies, it is paramount to acquire a description of the reaction to direct appropriate therapy. Fatal reactions have been reported from associated agranulocytosis, aplastic anemia, and other blood dyscrasias. Kernicterus Bilirubin-associated brain damage (kernicterus) may occur in newborns, because sulfa drugs displace bilirubin from binding sites on serum albumin. Contraindications Due to the danger of kernicterus, sulfa drugs should be avoided in newborns and infants less than 2 months of age, as well as in pregnant women at term. Sulfonamides should not be given to patients receiving methenamine, since they can crystallize in the presence of formaldehyde produced by this agent. Mechanism of action Trimethoprim is a potent inhibitor of bacterial dihydrofolate reductase (see ure 31. Inhibition of this enzyme prevents the formation of the metabolically active form of folic acid, tetrahydrofolic acid, and thus, interferes with normal bacterial cell functions. Trimethoprim binds to bacterial dihydrofolate reductase more readily than it does to human dihydrofolate reductase, which accounts for the selective toxicity of the drug. Antibacterial spectrum the antibacterial spectrum of trimethoprim is similar to that of sulfamethoxazole. Resistance Resistance in gram-negative bacteria is due to the presence of an altered dihydrofolate reductase that has a lower affinity for trimethoprim. Because the drug is a weak base, higher concentrations of trimethoprim are achieved in the relatively acidic prostatic and vaginal fluids.
In about 40% of cases buy cozaar 50 mg mastercard diabetes mellitus screening, fertility disorders are found serious medical conditions such as heart disease discount 50 mg cozaar visa diabetic diet juices, cancer purchase cozaar cheap diabetic diet vs atkins, in both the man and the woman. This does not mean there is no underlying problem and Definition: what is infertility? Unless the male partner has have assisted conception treatment, which is not only an suffered testicular failure and/or does not produce sperm effective treatment but also provides an informative or the woman is menopausal and/or does not have a assessment. It is the chance of conception that really defines fertility and this is very Ovulatory disorders much dependent on how long the couple have been try- ing, female age and the underlying cause. It is ovulation disorders into three groups based on serum Dewhurst’s Textbook of Obstetrics & Gynaecology, Ninth Edition. This group of disorders results in anovulatory oligomen- Prevalence (%) orrhoea, predominantly involving women with polycys- tic ovaries, which are present in about 80–90% of women Cause Primary Secondary with oligomenorrhoea and 30% of women with amenor- rhoea. Women with polycystic ovaries often have associ- Unexplained 25 20 ated clinical symptoms such hyperandrogenism Ovulatory disorders 25 15 presenting as hirsutism, acne or androgen‐dependent Tubal disease 20 40 alopecia. They are Tubal disease characterized by low gonadotrophins, a normal prolactin the incidence of tubal disease is very dependent on and low oestrogen levels. Three conditions are included: whether the woman has primary or secondary infertility. It is often caused by excessive cially those who have had an ectopic pregnancy, have a exercise, lean body mass, weight loss, severe dietary much higher incidence of tubal disease. The treatment must be aimed at the underlying Uterine and/or peritoneal disorders cause. Even with infection, brain/pituitary radiation, pituitary apoplexy, severe endometriosis, natural conception is still possible head trauma, and drugs such as glucocorticoids, narcot- and up to 70% of women with mild to moderate endome- ics and chemotherapy. However, up to Hypopituitarism is typically caused by a pituitary 30–50% of women with endometriosis may experience tumour or its treatment by surgery and/or radiotherapy infertility irrespective of the severity of the disease and but may be due to extra‐pituitary tumours, sarcoidosis, infertile women are six to eight times more likely to have haemochromatosis and Sheehan’s syndrome. Endometriosis is cal manifestations depend on the cause and both the thought to influence fertility in several ways, including type and degree of hormonal insufficiency. Patients may distorted pelvic anatomy, adhesions, pelvic inflamma- be asymptomatic or present with symptoms related to tion, altered immune system functioning and impaired hormone deficiency or a space‐occupying lesion. Adhesions are reported to be the leading cause of sec- They are characterized by normal oestrogen levels, ondary infertility in women and are thought to be Subfertility 693 responsible for approximately 22% (15–40%) of all infer- or chemotherapy, although in the majority of cases (66%) tility cases . Obstructive azoospermia is adnexal anatomy and the tubo‐ovarian relationship and/ uncommon, with a prevalence of less than 2%. It is often or by preventing or impairing the ability of the fallopian associated with congenital bilateral absence of vas defer- tube to pick up the oocyte at ovulation and then trans- ens, which itself is commonly associated with cystic port it. This may be due to the ovary being encapsulated fibrosis mutations or renal tract abnormality. The American Fertility Society classification uncommon but may result from spinal cord injury, pros- for adnexal adhesions  can be used to quantify the tatectomy, retroperitoneal lymph node dissection, dia- severity of the adhesions, which is predictive of term betes mellitus, transverse myelitis, multiple sclerosis, or pregnancy rates. Varicoceles are more common in men with abnormal Fibroids have been associated with infertility. It is unclear if, or why, varicoceles impair fertility recent data suggest that fibroids may still have a negative and spermatogenesis but any effect is likely to be due to effect on fertility even if the cavity appears hysteroscopi- elevated scrotal temperature and impaired semen cally normal due to effects on uterine blood flow, quality. Despite this, many women with relatively large fibroids conceive without difficulty. When asso- ciated with amenorrhoea, they are referred to as Given the various causes and presentations of infertility, Asherman’s syndrome. The adhesions lead to partial or it is essential that patients are managed as individuals complete obliteration of the uterine cavity and/or the from their initial referral through to their ultimate treat- cervical canal, resulting in menstrual abnormalities and/ ment. Secondary infertility is seen critical consideration of clinical features and used to in 43% of women with intrauterine adhesions and may be inform patient management and counselling. All health- due to obstruction of sperm into the cervix or prevention care practitioners working in fertility must therefore of embryo migration and/or implantation. However, typical management of a heterosexual couple for the impaired semen quality, azoospermia and inadequate simple reason that this reflects most referrals to second- coitus are contributing factors in nearly 50% of infertile ary care. Please mostly dysfunctional and unable to fertilize an oocyte substitute ‘no partner’ or ‘second female partner’ where but a proportion are often functionally normal. Take a critical history Azoospermia may be due to hypothalamic–pituitary failure, primary testicular failure (non‐obstructive azoo- Couples who experience problems in conceiving should spermia) or obstruction of the genital tract (obstructive be seen together because both partners are affected by azoospermia). Primary testicular failure is the most com- decisions surrounding investigation and treatment. It is important to specifically enquire about 694 Reproductive Problems sexual history, including the frequency and timing of bleeding could be hormonal or reflect local or endome- intercourse. Again, these symptoms would be an indi- to define ‘subfertility’ and therefore the need for investi- cation for pelvic and ultrasound examination possibly gation or treatment. Tubal disease the tests offered to the woman and her prognosis, while and adhesions that may impair the tubo‐ovarian rela- the presence of children invariably has implications for tionship are more common after pelvic infection, sexu- funding. It is also important to assess the couple’s life- ally transmitted infection, abdomino‐pelvic surgery, style as this impacts on their chance of natural concep- particularly that involving the pelvic organs, and ectopic tion and influences the success of treatment. They consider any religious or ethical objections the couple may also occur in women with endometriosis. This information is often volunteered and does not require Male direct questioning. The male history is often redundant, as most couples will Primary care physicians generally have a good under- be referred with the results of a seminal fluid analysis. Make sure these are available and confirm the value in taking a detailed history from the male partner. Missing a diagnosis of However, a specific enquiry regarding any psychosexual severe oligospermia or azoospermia or failing to realize problems including erectile or ejaculatory dysfunction is this until the end of the consultation will mean that much essential. Make sure you gather all clinically rele- those who have been shown to have abnormal results, a vant information and any test results before you see the more detailed history is indicated. A history of problems couple and share these with them at the appropriate time with testicular descent, puberty, trauma or surgery, depending on what they show and what the couple know. No cause will be identified in Female approximately 30–50% of men with poor semen Having already ascertained the woman’s age and parity, quality. Most Perform a relevant examination women (95%) who menstruate every 23–35 days are ovu- lating. Those with irregular menstrual cycles or who are Just like the clinical history, examination of the male and amenorrhoeic are not ovulating or, if they are, ovulate female partner is often unremarkable. These during the consultation and at examination, also pro- conditions may also be associated with chronic pelvic vides an opportunity to consider lifestyle issues such as pain and/or deep dyspareunia. Where relevant, a gen- Heavy periods may reflect dysfunctional uterine bleed- eral inspection should be conducted to look for signs of ing but could be due to fibroids, adenomyosis, endome- systemic disease, such as thyroid dysfunction, acromeg- triosis or endometrial polyps, all of which may impair aly and other endocrine disorders, and phenotypic implantation. More rarely, insulin resistance may lead to acanthosis nig- the levels of these hormones cannot be interpreted in ricans. Virilism can lead to male pattern baldness and the absence of serum estradiol and all three tests are clitoromegaly. Breast examination is often not indicated needed to assess hypothalamic–pituitary–ovarian func- but when performed should include Tanner’s staging. However, it is should be checked along with other hormones depend- rare to find an unexpected mass or demonstrate abdomi- ing on the clinical picture.
Preoxygenation is achieved by providing 100% oxygen at a high flow rate via a tight-fitting face mask for 3 buy cheap cozaar 25 mg line blood glucose 300 mg dl. Extending the time of preoxygenation from 4 to 8 minutes does not seem to increase the PaO to a clinically relevant extent and may actually reduce the PaO2 2 in the interval from 6 to 8 minutes in some patients  cozaar 50mg low cost diabetes type 1 forum. In patients who are being intubated for airway control order cozaar 50mg overnight delivery diabetes diet.org, preoxygenation is usually efficacious, whereas the value of preoxygenation in patients with acute lung injury is less certain . These approaches have been shown to be more effective than the standard approach in maintaining SpO values2 before, during, and even after the intubation procedure [25–27]. In obese patients, the use of the 25-degree head-up position improves the effectiveness of preoxygenation. In the unconscious patient in whom a secure airway must be established immediately, orotracheal intubation with direct visualization of the vocal cords is generally the preferred technique. In the conscious patient, direct laryngoscopy or awake fiberoptic intubation may be performed after obtaining adequate anesthesia of the airway. Alternatively, blind nasotracheal intubation is an option but requires significant skill by the clinician. Nasotracheal intubation should be avoided in patients with coagulopathies or those who are anticoagulated for medical indications. In the obese patient, employing the ramped position, whereby blankets are place under the head, shoulders, and upper back to insure that the tragus is at the level of the suprasternal notch, will increase the probability of a successful intubation. In trauma victims with extensive maxillary and mandibular fractures and inadequate ventilation or oxygenation, cricothyrotomy may be mandatory (see Chapter 9). In patients with cervical spine injury or decreased neck mobility, intubation using the flexible bronchoscope may be necessary. Many of these techniques require considerable skill and should be performed only by those who are experienced in airway management. B: After “ramping” with blankets beneath upper back and head, the tragus is at the level of the suprasternal notch. Traditional teaching dictates that successful orotracheal intubation requires alignment of the oral, pharyngeal, and laryngeal axes by putting the patient in the “sniffing position” in which the neck is flexed and the head is slightly extended about the atlanto-occipital joint. In addition, a randomized study in elective surgery patients examining the utility of the sniffing position as a means to facilitate orotracheal intubation failed to demonstrate that such positioning was superior to simple head extension [29,30]. In a patient with a full stomach, compressing the cricoid cartilage posteriorly against the vertebral body can reduce the diameter of the hypopharynx. This technique, known as Sellick maneuver, may prevent passive regurgitation of stomach contents into the trachea during intubation. Moreover, cricoid pressure increased the incidence of an unopposed esophagus by 50% and caused airway compression of greater than 1 mm in 81% of the volunteers . Consequently, compression of the alimentary tract was demonstrated with midline and lateral displacement of the cricoid cartilage relative to the underlying vertebral body . Cadaver studies have demonstrated the efficacy of cricoid pressure , and clinical studies have shown that gastric insufflation with gas during mask ventilation is reduced when cricoid pressure is applied . In aggregate, these data suggest that it is prudent to continue to use cricoid pressure in patients suspected of having full stomachs. In addition, placing the patient in the partial recumbent or reverse Trendelenburg position may reduce the risk of regurgitation and aspiration. The laryngoscope handle is grasped in the left hand whereas the patient’s mouth is opened with the gloved right hand. Often, when the head is extended in the unconscious patient, the mouth opens; if not, the thumb and index finger of the right hand are placed on the lower and upper incisors, respectively, and moved past each other in a scissor-like motion. The laryngoscope blade is inserted on the right side of the mouth and advanced to the base of the tongue, pushing it toward the left. With the blade in place, the operator should lift forward in a plane 45 degrees from the horizontal to expose the vocal cords (s. This motion decreases the risk of the blade striking the upper incisors and either chipping or dislodging teeth. The cuff is inflated with enough air to prevent a leak during positive-pressure ventilation with a bag valve device. The view of the glottis is usually very good, but intubation can sometimes be problematic because the proprietary stylets are rigid and cannot be molded to the optimal curvature. Complications can include mucosal damage or perforation of the palatoglossal arch, palatopharyngeal arch, or the retromolar trigone. A classification grading the view of the laryngeal aperture during direct laryngoscopy has been described  and is depicted in ure 8. This tube has a nylon cord running the length of the tube attached to a ring at the proximal end, which allows the operator to direct the tip of the tube anteriorly. If the attempt to intubate is still unsuccessful, the algorithm should be followed (see “Management of the Difficult Airway” section of this chapter). If the tube has been advanced too far, it will lodge in one of the main bronchi (particularly the right bronchus), and only one lung will be ventilated. A useful rule of thumb for tube placement in adults of average size is that the incisors should be at the 23-cm mark in men and the 21-cm mark in women. Alternatively, proper depth (5 cm above the carina) can be estimated using the following formula: (height in cm/5) − 13 . Palpation of the anterior trachea in the neck may detect cuff inflation because air is injected into the pilot tube and can serve as a means to ascertain correct tube position. Measurement of end-tidal carbon dioxide by standard capnography if available or by means of a calorimetric chemical detector of end-tidal carbon dioxide (e. If the tube is in the trachea, the bulb reexpands, and if the tube is in the esophagus, the bulb remains collapsed. After estimating proper tube placement clinically, it should be confirmed by chest radiograph or bronchoscopy because the tube may be malpositioned. It must be remembered that flexion or extension of the head can advance or withdraw the tube 2 to 5 cm, respectively. Nasotracheal Intubation Many of the considerations concerning patient preparation and positioning outlined for orotracheal intubation apply to nasal intubation as well. Blind nasal intubation is more difficult to perform than oral intubation because the tube cannot be observed directly as it passes between the vocal cords. Nasal intubation should not be attempted in patients with abnormal bleeding parameters, nasal polyps, extensive facial trauma, cerebrospinal rhinorrhea, sinusitis, or any anatomic abnormality that would inhibit atraumatic passage of the tube. As previously discussed in “Airway Adjuncts” section, after the operator has alternately occluded each nostril to ascertain that both are patent, a topical vasoconstrictor and anesthetic are applied to the nostril that will be intubated. The patient should be monitored with a pulse oximeter, and supplemental oxygen should be given as necessary. Here the tube operator must continually monitor for the presence of air movement through the tube by listening for breath sounds with the ear near the open end of the tube. The tube must never be forced or pushed forward if breath sounds are lost, because damage to the retropharyngeal mucosa can result.