Descriptive Study of Cases of Respiratory Distress in NICU in Ahmed Maher Teaching Hospital

Transcription

1 Med. J. Cairo Univ., Vol. 79, No. 1, September , Descriptive Study of Cases of Respiratory Distress in NICU in Ahmed Maher Teaching Hospital MOHAMMED HESHAM ZAAZOU, M.D.; MAHMOUD M. KAMAL, M.D.; RAGHDAA M. ALI, M.D.; NAGI A. EL-HUSSIENY, M.D. and MANAL EL-SAYED, M.D. The Department of Pediatrics, Ahmed Maher Teaching Hospital, Cairo Abstract Respiratory distress is one of the most common causes of admission in NICU. The aim of this work was to study the commonest causes of respiratory distress in NICU in Ahmed Maher Teaching Hospital, analysis of each cause, and to determine the strategic plan needed to improve the outcome of these cases. Patients and Methods: A retrospective study was conducted through the period from 1 st Jan. to 31 st Dec Data were collected from all patients files admitted in the unit during this period. Results: Total number of admissions was 233 cases, 206 cases were due to respiratory distress representing 88.4% of cases. The commonest causes of respiratory distress in our study were transient tachypnea of newborn (TTN) 78 cases (37.9%), respiratory distress syndrome () 64 cases (31%), meconium aspiration syndrome (MAS) 21 cases (10.2%), and perinatal asphyxia 15 cases (7.3%). Discussion: Ceserean section was the most common predisposing factor associated with the development of TTN and (the most 2 common causes of respiratory distress in our study). The overall mortality rate of cases of respiratory distress in our study was 18.9%. Cases with perinatal asphyxia were associated with the highest mortality rate (40%), (39%), and MAS (19%). Of the 4 most common causes, (178 cases) ventilatory support was needed in 76 cases (42.7%). 41 were put on nasal CPAP with survival rate of 85.4%, while 35 cases were put on IMV with a mortality rate of 80%. Recommendations: 1-Proper antenatal care 2-Use of surfactant 3-Use of high-frequency ventilators. Key Words: Respiratory distress NICU. Introduction RESPIRATORY distress is one of the commonest disorders encountered within the first hours of life. It occurs in approximately 0.96%-6% of live births, and is responsible for about 20% of neonatal mortality [1]. Correspondence to: Dr. Mohammed Hesham Zaazou, The Department of Pediatrics, Ahmed Maher Teaching Hospital, Cairo. The spectrum of respiratory distress in neonates includes transient tachypnea of newborn, respiratory distress syndrome, meconium aspiration syndrome, congenital pneumonia, congenital heart disease, perinatal asphyxia, and congenital anomalies as tracheo-oesophageal fistula, and congenital diaphragmatic hernia [2]. The aim of this study was to study the commonest causes of respiratory distress in NICU in Ahmed Maher Teaching Hospital, and to determine the strategic plan needed to improve the outcome of these cases. Patients and Methods A retrospective study was conducted in NICU in Ahmed Maher Teaching Hospital through the period from 1 st of January 2008 till 31 st of December Data were collected from all patient files admitted in the unit during this period. Inclusion criteria: All patients presented with respiratory distress on admission. Data collected included: 1- Obstetric history: Maternal diseases (diabetes mellitus-hypertension), premature rupture of membranes and mode of delivery. 2- Clinical examination data on admission included: Weight, sex, gestational age, vital signs, degree of respiratory distress, in addition to any positive clinical findings reported. 3- Radiological: Plain chest X-ray (routine). Plain X-ray abdomen, abdominal Ultra-sonography, ECHO, cranial Ultra- sonography if available. 441

2 442 Descriptive Study of Cases of Respiratory Distress in NICU 4- Laboratory evaluation; complete blood count with differential, reticulocytic count, blood culture and senstivity, electrolytes, blood sugar, blood gases. Results Total number of admissions during the studied period was 233 cases. Number of cases presented with respiratory distress was 206, representing 88.4% of all cases admitted. Number of cases with respiratory distress who died was 39 cases representing mortality rate of 18.9% of cases with respiratory distress. 121 cases were males while 85 cases were females representing male to female ratio 1.4:1. Weight of studied groups ranged from 600gm to 4500gm with mean of 2392gm. Gestational age of all neonates included in the study range from weeks with mean of 35.1 weeks. Table (1): Spectrum of diagnosis and mortality rate of cases with respiratory distress. Diagnosis Cases Mortality Number Percent (%) Number Percent (%) TTN TTN with sepsis TTN with CHD TTN with ICH with CHD with ICH with pneumothorax with NEC with sepsis with HIE MAS MAS with HIE MAS with pneumothorax MAS with CHD MAS with CHD and HIE Perinatal Asphyxia Perinatal asphyxia with pneumonia Perinatal asphyxia with ICH Perinatal asphyxia with CHD Congenital pneumonia Congenital pneumonia with CHD Congenital pneumonia with ICH CHD Tracheo-oesphageal fistula Referred Congenital diaphragmatic hernia Referred IDM (hypoglycemia) Metabolic acidosis Acute hemolytic anemia Total TTN : Transient tachypnea of newborn. : Respiratory distress syndrome. CHD : Congenital heart disease. ICH : Intra-cranial hemorrhage. NEC : Necrotizing enterocolitis. MAS : Meconium aspiration syndrome. IDM : Infant of a diabetic mother.

3 Mohammed H. Zaazou, et al. 443 Table (2): Clinical criteria-history-of the commonest causes of respiratory distress. Clinical criteria TTN Group I * Group II MAS Perinatal asphyxia GA (w) Range Mean Number of each group Percentage (%) Sex : ratio Weight (gm) Range Mean < : 1 1.5: 1 1.7: 1 1.6: 1 2.7: Mode of delivery Number (%) CS 66 (84.6) 25 (52) 10 (62.5) 3 (14.3) 7 (46.6) VD 12 (15.4) 23 (48) 6 (37.5) 18 (85.7) 8 (53.4) Maternal risk factors No (%) PROM 10 (12.8) 12 (25) 6 (37.5) 0 3 (20) Hypertension 5 (6.4) 6 (12.5) 3 (18.8) 2 (9.5) 1 (6.7) DM 3 (3.9) 3 (6.3) 1 (6.3) 0 0 Stained liquor (100) 5 (33.3) Twin 5 (6.4) 10 (20.8) 2 (12.5) 0 0 * was categorized into two groups according to gestational age; group I 25-<32 weeks and group II weeks. PROM= Premature rupture of membranes. DM= Diabetes mellitus. Table (3): Clinical examination of the commonest causes of respiratory distress. TTN Group I Group II MAS Perinatal asphyxia Grades of RD No (%) -- Grade I 31 (39.7) 1 (2.1) 2 (12.5) 2 (9.5) 4 (26.7) - Grade II 41 (52.6) 7 (14.6) 4 (25) 11 (52.5) 3 (20) - Grade III 6 (7.7) 30 (62.5) 8 (50) 4 (19) 6 (40) - Grade IV 0 10 (20.8) 2 (12.5) 4 (19) 2 (13.3) Auscultation No (%) - Fair air entry 72 (92.3) 0 6 (37.5) 3 (14.3) 12 (80) - Mild decrease air entry 6 (7.7) 0 10 (62.5) 6 (28.6) 3 (20) - Severe decrease air entry Crepitations 0 48 (100) 0 12 (57.1) 0 - Bronchial 27 (35.5) 6 (12.5) 1 (6.3) 11 (52.4) 0 breathing Table (4): Radiological findings no. (%) of the commonest causes of respiratory distress. Radiological findings TTN Group I Group II MAS Perinatal asphyxia Increase bronchovascular markings 31 (39.7) (33.3) Linear streaking at hilum 51 (65.4) Air bronchogram (37.5) 0 0 Fine reticulations 0 8 (16.7) 10 (62.5) 0 0 Ground glass appearance 0 40 (83.3) Atelectasis, hyperinflation (61.9) 0 Patchy infiltrates (38.1) 1 (6.7)

4 444 Descriptive Study of Cases of Respiratory Distress in NICU Table (5): Echo findings of congenital heart disease cases. No. (%) Transposition of great arteries Total anomalies pulmonary venous return Hypertrophic obstructive cardiomyopathy, pulmonary stenosis Pulmonary hypertension, patent ductus arteriosus, patent foramen ovale Ventricular septal defect, pulmonary hypertension Ventricular septal defect, patent ductus arteriosus Ventricular septal defect, patent ductus arteriosus, pulmonary hypertension Persistent pulmonary hypertension of newborn Pulmonary hypertension, patent ductus arteriosus, atrial septal defect Table (6): Ventilatory support no. (%) of commonest causes of respiratory distress. TTN Group I Group II MAS Perinatal asphyxia Nasal CPAP 9 (11.5) 15 (31.2) 10 (62.5) 4 (19) 3 (20) IMV 0 25 (52) 2 (12.5) 3 (14.3) 5 (33.3) IMV: Intermittent mechanical ventilation. CPAP: Continuous positive airway pressure. Table (7): Mortality of cases on ventilatory support no. (%). TTN MAS Perinatal asphyxia Group I Group II Nasal CPAP 0 2 (13.3) 2 (20) 2 (50) 0 IMV 0 19 (76) 2 (100) 3 (100) 4 (80) Table (8): Outcome of commonest causes of respiratory distress no. (%). TTN MAS Perinatal asphyxia Group I Group II Discharged 78 (100) 27 (56.2) 12 (75) 17 (81) 9 (60) Died 0 21 (43.8) 4 (25) 4 (19) 6 (40) Discussion The importance of Respiratory distress in neonates can be realized from the fact that the neonates with respiratory distress are 2-4 times more likely to die than those without respiratory distress [3]. Knowledge of the causes of respiratory distress is important for plan and provision of basic facilities for sick and low birth weight newborns [4]. In our study, respiratory distress constituted 88.4% of all cases admitted in the unit during the studied period. On the contrary, many other studies reported a much lower percentage of cases with respiratory distress in the admission of their NICU. Mathur el al., 2001 [5] found in their study that 29% of all the admissions to their neonatal unit were due to respiratory distress. This discrepancy could be explained on the basis that our unit is tertiary referral unit receiving mostly complicated cases, while in the study of Mathur in India, their neonatal unit was only a primary care unit and 51% of their neonates were delivered at home. The commonest causes of respiratory distress in our study were TTN (37.9%), (31 %), MAS (10.2%) and Perinatal Asphyxia (7.3%). Similar data were reported by Kumer and Bhat [6] who found that TTN was the most common cause of RD in their unit. It constituted >40% of their cases. Also Kasp et al., [7] stated that TTN represents 33-50% of RD in neonates. In our study, most causes of TTN were full terms with their mean GA 37.6 weeks, and their mean weight was 2893gm. There was nearly equal sex affection with to ratio of 1.2:1. Similarly; Raweling and Smith, [8] found that male sex and macrosomia have been associated with increased risk of TTN.

5 Mohammed H. Zaazou, et al. 445 By studying the predisposing factors, we found that cesarean section was the most common factor associated with development of TTN in neonates as 84.6% of cases in our study were delivered by CS. Milner et al., [9] noted that infants born by elective CS had much higher incidence of development of TTN. They attributed this mainly to that these infants had higher volumes of interstitial and alveolar fluid compared with those born vaginally. Other factors as premature rupture of membranes, maternal hypertension, twins or maternal diabetes mellitus had a much decreasing role in precipitating the occurrence of TTN. In our study most cases of TTN (92.3%) presented with mild degree of respiratory distress. 52.6% of cases presented with RD grade II, and 39.7% presented with RD grade I, and they had fair air entry on both lungs, while the remaining 7.7% of cases had only mild decrease in air entry. Bland [10] described TTN as quiet tachypnea with variable grunting, flaring and retractions. 65.4% of cases in our study had characteristic radiological findings of linear streaking at hilum. This coincides with the findings of Jain and Eaten [11] who reported that chest radiography is the diagnostic standard of TNN with prominent perihilar streaking that correlates with engorgement of lymphatic system with retained lung fluids. 11.5% of cases in our study needed ventilator support in the form of nasal CPAP; no single case needed IMV, all cases survived with no single mortality. Similarly, Helve et al., [12] stated that TTN is self resolving disorder with excellent prognosis and that rarely develops a worsening of picture of respiratory distress that may require more aggressive support including the use of CPAP or mechanical ventilation. Respiratory distress syndrome was the second most common respiratory distress in our study. It constituted 31% of cases. 75% of cases occurred in those with gestational age ranging from 26- <32weeks, their mean weight was 1256gm, while the remaining 25% of cases occurred in those with gestational age ranging from 32-36weeks, and their mean weight was 2037gm. There is preponderance of male affection in cases with respiratory distress syndrome with to ratio >1.5:1. In the United States, respiratory distress syndrome has been estimated to occur in newborn infants each year. Similar to our data, Hirtz et al., 2007 [13] reported that approximately 80% of neonates born at <32 weeks gestation develop respiratory distress syndrome, while it occurred in 50% of those born between weeks, and in <30% of those born at weeks gestation, and that the incidence rate of respiratory distress syndrome was 42% in infants weighing gm. 54.7% of cases were delivered by cesarean section, premature rupture of membranes >24hrs occurred in 25% of cases, twin delivery in 18.7% of cases, maternal hypertension in 14% of cases, while only 6.3% of cases had a history of maternal diabetes mellitus. Gerten et al., [14] reported that in addition to prematurity, the other risk factors for development of respiratory distress syndrome included maternal diabetes, cesarean section delivery, second born twins and asphyxia. Respiratory distress grade III was the most common clinical presentation of respiratory distress syndrome. It occurred in 62.5% cases with gestational age <32 weeks, and in 50% of those with gestational age between weeks. Fanaroff el al., [15] stated that neonates weighing <1000gm may have lungs so stiff, that they are unable to initiate or sustain respiration in delivery room as symptoms and signs include rapid, labored, grunting respirations appear immediately or within a few hours after delivery, with supra-sternal and sub-sternal retractions and flaring of ala nasai. As atelectasis and respiratory failure progress, symptoms worsen with cyanosis, lethargy, irregular breathing and apnea. Ground glass appearance was the most common radiological finding in cases with respiratory distress syndrome. It occurred in 62.5% of all cases of respiratory distress syndrome, and in 83.3% of cases with gestational age <32 week while a fine reticulation was the second most common radiological finding. It occurred in 28.1% of all cases, and 62.5% of cases with gestational age (32-37 weeks). In our study, ventilator support was needed in 83.2% of cases with gestational age <32weeks. 31.2% of cases needed nasal CPAP, while 52% of cases needed intermittent mandatory ventilation. Cases put on nasal CPAP had a survival rate of 86.7% while cases put on IMV had mortality rate of 76% while in those with gestational age (32-37 weeks), 75% of cases needed ventilator support.

6 446 Descriptive Study of Cases of Respiratory Distress in NICU 62.5% of cases needed nasal CPAP with survival rate of 80% while the remaining 12.5% of cases needed to be put on IMV, with a mortality rate of 100%. The over all mortality rate of cases with respiratory distress in our study was 39.5% (43.8% in cases <32 weeks gestation, and 25% in those with weeks gestation). This high mortality rate could be attributed to many factors; the most important of them is lack of surfactant replacement therapy in our unit. Steven el al., [16] reported that mortality rate of respiratory distress syndrome decreased by approximately 50% over the last decade with the advent of surfactant therapy. CPAP is adjuvant therapy given after surfactant if prolonged assistanted ventilation is not required. In a retrospective study, bubble nasal CPAP was successful in 76% of infants who weighed less than 1250gm and in 50% of infants who weighed less than 750 grams [17]. Kirbyetal, [18] several decades ago demonstrated that assisted ventilation further decreased respiratory distress syndrome-related morbidity and mortality. However, early ventilators were associated with complications such as air leak, bronchopulmonary dysplasia and intracranial haemorrhage. New ventilation techniques have been introduced to minimize the complications of conventional intermittent mandatory ventilation. Early use of high-frequency oscillatory ventilation was clearly superior to conventional ventilation [19]. Meconium aspiration syndrome (MAS) was the third most common cause of respiratory distress in our study (10.2%). Males were more affected with male/female ratio of 1.6:1. All cases (100%) had stained liqour at birth and 85.7% of cases were delivered vaginally. However, Mathur et al. [5], in their study of the causes of respiratory distress in neonates found that meconium aspiration syndrome represented only 4% of their cases. This could be explained that in developing countries with less availability of prenatal care, and where home births are common the incidence of meconium aspiration syndrome is thought to be higher than in industrialized world [20]. In our study, all cases were full term. Their mean GA was 38.6 weeks, and their mean weight was 2969 grams. This coincides with Singh et al., [21], who reported that meconium aspiration syndrome is exclusively a disease of newborns, especially those who are delivered at or after their due date. More than 50% of cases had RD grade II while 38% had severe RD (grade III, IV). Most cases (57%) had severe decrease in air entry and 52.4% had fine crepitations allover the chest. Dargaville and Copnell [22] stated that meconium aspiration syndrome may be presented with severe respiratory distress. Barrel chest, is associated with air trapping. Auscultatory rales and rhonchi are found in some cases. 61.9% of our cases had radiological findings in the form of areas of hyperinflation and atelectasis, while the remaining 38.1% had patchy infiltrates in both lungs. Similar findings were reported by Mellinda et al. [23]. All over mortality rate of cases of meconium aspiration in our study was 19%. Mellinda [23] stated that mortality rate for meconium aspiration syndrome resulting from severe parenchymal pulmonary disease and pulmonary hypertension is as high as 20%. 33.3% of cases needed ventilator support. 19% were put on nasal CPAP with mortality rate of 50% and 14.3% were put on IMV with mortality rate of 100%. Wiswell et al., [24] reported that mechanical ventilation is required by approximately 30% of infants with meconium aspiration syndrome. Collins et al., [25], added that although conventional ventilation commonly is initially used, high frequency oscillation and jet ventilation are alternate effective therapies. Perinatal asphyxia was the fourth most common cause of respiratory distress in our study. It constituted 7.3% of cases. Their mean gestational age was 36.8 weeks, and their mean weight was 2900 gm. Males are affected mainly with male to female ratio 2.7:1. Oswyn et al. [26] reported that the incidence of perinatal asphyxia in resource poor countries is high (5-10/1000 live births). However Jones et al., [27] stated that the true community incidence of perinatal asphyxia in resource poor countries is poorly estimated and understood.

7 Mohammed H. Zaazou, et al. 447 Grow and Barks [28] found that perinatal asphyxia most often occur in infants who are term at birth. In our study, fetal distress presenting with stained liquor was the most common predisposing factor for the development of perinatal asphyxia. It occurred in 33.3% of cases and premature rupture of membranes >24hs occurred in 20% of cases. Ellis et al., [29] stated that numerous causes of perinatal asphyxia include placental abruption, cord compression, intrauterine pneumonia or severe meconium aspiration. In our study >50% of cases presented with severe form of respiratory distress (grade III-IV). The mortality rate of perinatal asphyxia was 50%. Lawn et al., [30] reported that mortality rate in cases of perinatal asphyxia is as high as 25-50% of cases. 53.3% of cases in our study needed ventilator support. 20% of cases were put on nasal CPAP and were discharged. However, 33.3% of cases were put on intermittent mandatory ventilation. 80% of these cases died. This study does not reflect the true incidence of perinatal asphyxia as respiratory distress is not a common presentation of perinatal asphyxia. In putting the strategy for dealing with cases of respiratory distress in our NICU, we are interested in two factors: a- Cases that represent the higher incidence of occurrence and their main predisposing factors b- Cases associated with the higher mortality rate, and their management protocols. TTN, and were the most two common diagnoses (68.9%) of respiratory distress in our study, cesarean section was the most common predisposing factor associated with development of these conditions. Indication of ceserean section that represent most deliveries associated with development of TTN, and should be re-evaluated. Cases with perinatal asphyxia were associated with the highest mortality rate (40%), (39%), and MAS (19%). Of the four most common causes 178 cases (86.4%) of all cases of respiratory distress, ventilatory support was needed in 76 cases (42.7%). 41 cases were put on nasal CPAP with survival rate of 85.4%, while 35 cases were put on IMV with a mortality rate of 80%. Conclusion: Respiratory distress was the major cause of admission in our NICU. The most common causes of respiratory distress were TTN,, MAS, and perinatal asphyxia. Ceserean section was the most common predisposing factor associated with the development of respiratory distress in neonates. Mortality rate of cases of respiratory distress was 18.9%. Of the commonest causes of respiratory distress in our study, nasal CPAP was needed in 23% of cases with survival rate of 85.4%, while IMV was needed in 19.7% of cases with mortality rate of 80%. Recommendations: 1- Proper antenatal care to decrease the incidence of premature labour, evaluation of indication of ceserean section, and antenatal steriods for expected premature delivery. 2- Use of surfactant immedietly after delivery for all premature infants especially <32 weeks gestation. 3- Use of high-frequency oscillatory ventilators to counteract the high mortality rate associated with the use of conventional ventilators. References 1- Neonatal morbidity and mortality. Report of the national neonatal perinatal database. Indian Pediatrics, 34: , Am. Fam. Physician American Academy of Family Physicians, 76: , MISRA P.K.: Rrspiratory distress in newborn. Indian Pediatr., 24: 77-80, KHATUA S.P., GANGWAL A. and PATODHI P.K.R.: The incidence and etiology of respiratory distress in newborn. Indian Pediatr., 16: , N.B. MATHUR, K.GARG and S. KUMAR.: Respiratory distress in neonates with special reference to pneumonia. Indian Pediatrics, 39: , KUMAR A. and BHAT B.V.: Epidemiology of respiratory distress of newborns. Indian J. Pediatrics, 63: 93-8, KASAP B., DUMAN N., OZER E., TATLI M., KUMAR A. and OZKAN H.: Transient tachypnea of the newborn: Predictive factor for prolonged tachypnea. Pediatr. Int. Feb., 50 (1): 545-8, RAWLINGS J.S. and SMITH F.R.: Transient tacypnea of the newborn. An analysis of neonatal and obstetric risk factors. Am. J. Dis. Child. Sep.,138 (9): , MILNER A.D., SAUNDERS R.A. and HOPKIN I.E.: Effects of delivery by ceserean section on lung mechanics and lung volume in the human neonate. Arch. Dis. Child., 53 (7): 545-8, BLAND R.D.: Lung fluid balance during development. Neo. Reviews, 6 (6): e , 2005.

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