INDIAN JOURNAL OF ANAESTHESIA, OCTOBER 2004400 PG ISSUE : PAED ANAESTHIndian J. Anaesth. 2004; 48 (5) : 400-405

COMPLICATIONS FOLLOWING GENERAL ANAESTHESIAIN PAEDIATRIC PATIENTS

Dr. Manjushree Ray1 Dr. Enakshi Saha2

Introduction“In anaesthesia, as in other areas of life, everything

does not always go as planned. Undesirable outcomes occurregardless of the quality of care provided.”

Posner KL, Cheney FW, Kroll DA1

Incidence of undesirable outcomes is more inpaediatric patients. In a retrospective study by KeenanRL and Boyan CP,2 higher incidence (three times) ofcardiac arrest was reported in children compared toadults. Complications leading to cardiac arrest in thisstudy were mostly due to perioperative laryngospasm,difficult intubation, pulmonary aspiration or halothaneoverdosage.3 Infants younger than 1 month old have thegreatest risk for perioperative complications becausethey are more likely to have major surgery and sickerthan older children. Prematurity further complicates thesituation. Therefore post general anaesthesia complicationsin paediatric patients may be discussed under followingheadings.

a. Complications due to prematurityb. Complications due to congenital anomalies

c. Complications due to genetic disorders

d. Complications related to anaesthetic techniques

e. Complications due to succinyl choline

A. Complications due to prematurityInfants are considered premature if they are born

before 37 weeks of gestation. Prematurity is one of theleading causes of perioperative mortality and morbidity.Incidence of anaesthetic morbidity increases directly withthe degree of prematurity. They are more prone toperioperative hypothermia, apnoea, respiratory distress,congestive heart failure, retinopathy and intracranialhaemorrhage.4

a. Impaired thermoregulationPremature infants are very much prone to hypothermia,

due to impaired thermoregulation. Consequences ofhypothermia are apnoea, bradycardia, metabolic acidosisand hypoglycaemia.

Causes of hypothermia :

- Lack of fat insulation

- Excessive heat loss due to increased surface to volumeratio

- Fewer brown fat cells

- Increased heat loss due to thin skin

To prevent hypothermia, premature infants should bekept in the incubator and operation theatre temperatureshould be raised during operation of such a baby.

b. ApnoeaSpells of apnoea is very common in premature infants.

The incidence of apnoic episodes is inversely related toconceptual age of the infants. It is rarely seen after 44-48weeks of conceptual age.5

Apnoea may be brief (respiratory pause <15 secondsand not associated with bradycardia) or it may be prolongedand life threatening. Life threatening apnoea is more than15 seconds of duration and usually associated withbradycardia (heart rate <100 beats min-1 for at least 5seconds),6

Several studies have demonstrated an increased riskfor postoperative apnoea in former preterm infants.5,6

Administration of different inhalational anaesthetics,sedatives, narcotics and muscle relaxants may increase theincidence of apnoea in postoperative period. This risk canbe minimized by:

• Perioperative administration of caffeine ortheophylline,6

• Use of spinal anaesthesia instead of general anaesthesia7

and

• Delaying the surgery, until the child is older than48-60 weeks post conceptual age.

400

1. M.B.B.S., M.D., MNAMS, Professor and Head2. M.B.B.S., PG student

Department of Anaesthesiology, Medical CollegeKolkata - 700 073.Correspond to :Dr.Manjushree RayE-mail : manjushriray@hotmail.com

RAY, SAHA : POST GENERAL ANAESTHETIC COMPLICATIONS 401

Use of caffeine 10 mgkg-1, as a premedicant virtuallyeliminate the postoperative apnoea. However, as aprecautionary measure, all premature infants should beadmitted for all surgery and should be monitored for12-24 hour following surgery to prevent apnoea andbradycardia. Infants more than 50 weeks of post conceptualage can be managed as ambulatory patients.5

c. Respiratory distress syndromeRespiratory distress syndrome is caused by deficiency

of surfactant resulting in alveolar collapse, right to leftshunt, hypoxaemia and metabolic acidosis. It is morecommon in neonates born by caesarean section before34 weeks of gestation. Administration of artificial surfactantimmediately after birth specially in high risk casessignificantly reduces the severity of illness.8

d. Retinopathy of prematurityPremature infants are susceptible to retinopathy. It

is inversely related to gestational age and birth weight ofthe infant. Incidence is highest in infants weighing less than1000 gms.

Various attempts were made to find out the role ofoxygen therapy in neonatal retinopathy, but failed todemonstrate clear cut relationship.9,10 Brief exposure to100% oxygen does not increase the incidence of ROP.However, every attempts should be made to controloxygenation by monitoring oxygen saturation and keeping itbetween 94 and 97 per cent.

e. Periventricular – intraventricular haemorrhageNewborn immaturity is the single most important

risk factor for intracranial haemorrhage. In majority ofcases, it occurs in first 72 hours of life and is rare after10 days. Neonatal hypoxia is another important cause ofintracranial haemorrhage. Hypoxia impairs cerebralautoregulation. As a result, any increase in systemic arterialpressure may increase the cerebral blood flow and maycause periventricular or intraventricular haemorrhage.Various anaesthetic procedures such as starting ofintravenous channel or awake intubation often inducesystemic hypertension and increase cerebral blood flowleading to intracranial haemorrhage.11 Therefore, everyprecaution should be taken to avoid hypoxaemia, hypercarbia,and cerebral hyperperfusion by maintaining bloodpressure in the normal range. All stressful proceduresshould be done under sedation or anaesthesia, unless theinfant is so critically ill which prevents the anaesthesiologistto do so.

Hyperosmolarity is another contributory factor forintracranial haemorrhage in premature baby. Hyperosmolar

fluids such as sodium bicarbonate should be avoided as faras possible or they should be diluted and administered slowlyto prevent such complications.

B. Complications due to congenital anomaliesAfter prematurity, congenital anomalies are the

second leading cause of mortality and morbidity in the first30 days of life. Common congenital anomalies associatedwith perioperative complications are congenital heart defects,congenital diaphragmatic hernia, tracheoesophageal fistulaand anterior abdominal wall defects.

a. Congenital heart diseaseCardiac murmurs are very common in children.

It may be either functional or pathological. Presence ofmurmur is not a contraindication for general anaesthesia,if the patient is clinically otherwise normal. However,presence of cyanosis, decreased exercise tolerance, poorweight gain, sweating, decreased femoral pulses andprecordial heave along with a cardiac murmur usuallyindicates some organic lesion in the heart. These patientsneed thorough preoperative evaluation and expertise opinionfrom paediatric cardiologist.

Hypoplastic left heart syndrome is a relatively rarecongenital defect, but it accounts for 15% of neonatal deathsassociated with congenital heart disease.12 It is oftenassociated with other congenital defects and carries highperioperative morbidity and mortality.

Intracardiac shunts: After birth, clamping of theumbilical cord and initiation of respiration producetremendous change in circulatory system of new born baby.Reduction in pulmonary vascular resistance is accompaniedby constriction of the ductus arteriosus due to increasedpartial pressure of oxygen in the blood. This increasespulmonary blood flow as well as left atrial pressure resultinginto functional closure of foramen ovale. These two neonatalshunts (ductus arteriosus and foramen ovale) may open duringanaesthesia if there is any alteration in cardiopulmonarymechanics.13

Rise in systemic vascular resistance caused bylighter plane of anaesthesia may increase left to rightintracardiac shunt and may produce pulmonaryovercirculation and failure. Similarly hypoxia, hypercarbia,acidosis, hypotension and hypothermia may increasethe pulmonary vascular resistance and may reverse thedirection of shunt (right to left) leading to hypoxaemia oracute corpulmonale.

b. Congenital diaphragmatic herniaCongenital diaphragmatic hernia is a surgical

emergency, often associated with other congenital anomalies

INDIAN JOURNAL OF ANAESTHESIA, OCTOBER 2004402 PG ISSUE : PAED ANAESTH

such as hydrocephalus, encephalopathy, intestinal atresia,atrial septal defect, ventricular septal defect, tetrology offallot and coarctation. It carries high mortality rate, inspite of intensive perioperative care. Postoperativerecovery depends on the degree of pulmonary hypertensionand pulmonary hypoplasia.14 Most infants suffer fromventilatory insufficiency in the postoperative period andneed ventilatory support. Long term sequelae includesbronchopulmonary dysplasia, pulmonary hypoperfusionand decreased FEV1 and ventilatory capacity.15

c. Tracheoesophageal fistulaThis is a surgical emergency of newborn baby.

Postoperative complications are mainly due to associatedprematurity and congenital heart defect, which is presentapproximately in 20-25% of cases.

There are two major complications of tracheoesophagealfistula; aspiration pneumonia and dehydration. Sometimesgastric juice reflux, aspiration and pneumonia is so severethat patient may need prolonged postoperative ventilatorysupport. Presence of congenital heart disease may furthercomplicate the situation. Tracheal compression secondaryto tracheomalacia and persistent gastroesophageal refluxdue to abnormal swallowing reflex may complicate thepostoperative period.

d. Anterior abdominal wall defectsOmphalocele and gastroschisis are the two congenital

anomalies associated with anterior abdominal wall defects.

Primary closure of defect may increase theintraabdominal pressure significantly and compromiseventilation.16 Hence ventilatory support may be requiredfor a period of 3-7 days following operation. Additionalcomplications include postoperative hypertension, oedemaof the extremities, prolonged ileus and compromisedhepatic clearance of the drugs.17 Increased intraabdominalpressure causes compression of IVC and impairedvisceral blood flow. Increased intraabdominal pressure canreduce the circulation to the kidneys resulting into releaseof rennin and activation of rennin – angiotensin – aldosteronesystem.

C. Complications due to Genetic DisordersVarious genetic disorders offer significant challenge

to the paediatric anaesthesiologist. One of the major problemis that they may remain unrecognized initially, till somecomplications manifest. Some of the common geneticdisorders associated with frequent postoperativecomplications are Trisomy-21, Duchenne’s musculardystrophy and sickle cell anaemia.

a . Trisomy-21Trisomy-21, commonly known as Down’s syndrome,

is the most common chromosomal anomaly. This ischaracterized by oblique palpabral fissures, flat facies,single palmer crease and dysplastic middle phalanx of thefifth digit. Major anaesthetic problems are mentalretardation, obesity, difficult airway and cardiac anomalies.Difficulty in intubation is because of narrow nasopharynx,large tonsils and adenoids, cervical spinal stenosis withatlanto axial subluxation and subglotic stenosis.18

Anaesthesiologist should take proper care duringendotracheal intubation to prevent hyperextension of cervicalspine.19 Care should also be taken during extubation asupper airway obstruction and postextubation stridor are verycommon.

Surgical correction of various cardiac defects inDown’s syndrome is often associated with postoperativerespiratory complication. Abnormal development of alveoliand the pulmonary vasculature predispose to developmentof pulmonary hypertension.18

Postoperative recovery may be prolonged due tounusual susceptibility of these patients to various anaestheticagents.

b. Genetic neuromuscular disordersDuchenne’s muscular dystrophy is a classical example

of a neuromuscular disorder which carries significantanaesthesia related mortality and morbidity. Altered musclecells of these patients produce a flux of K+ in response tosuccinyl choline, resulting into hyperkalaemia, severecirculatory instability or even cardiac arrest.20 Treatmentis directed towards the lowering of potassium level, whichincludes the administration of epinephrine and sodiumbicarbonate.

Another problem in children with Duchenne’smuscular dystrophy is higher incidence of malignanthyperthermia.

c. Sickle cell anaemiaChildren with sickle cell anaemia are at increased

risk for anaesthesia and surgery related complications.Sickling may precipitate with hypoxia, hypercarbia, acidosis,hypothermia, hypovolaemia and hypoperfusion states, all ofwhich is very common during perioperative period.

Patients are usually anaemic, hence preoperativetransfusion may be necessary.21

Sickle cell anaemia is very often associated withcardiomyopathy, nephropathy and respiratory dysfunction,which increase complications following general anaesthesia.

RAY, SAHA : POST GENERAL ANAESTHETIC COMPLICATIONS 403

D. Complications associated with anaesthetictechnique

Children experience greater anaesthetic risk thanadult. Most of the complications are either due to inadequateventilation or anaesthetic overdose. Mostly, complicationsoccur during early postoperative period. Hence intensivemonitoring is recommended during shifting of the baby fromoperation theatre to recovery room.

a. Emergence deliriumChildren are more prone to disorientation,

hallucinations and uncontrolled physical activity duringemergence from general anaesthesia. It is more commonlyseen in patients who have received potent inhalationalanaesthetic agents.22 Postoperative pain,sensory deprivation(e.g., eye bandages), residual effect of anaesthetic agents,unfriendly environment are other contributory factors.Occasionally this hyperexcitable state may persist forseveral hours, specially in anxious patients, who have notreceived any premedication.

b. Respiratory depressionRespiratory depression in children following general

anaesthesia may be because of residual effect of potentanaesthetic agents. Mechanical factors such as abdominaldistension or tight abdominal bandage may also be responsiblefor such complication.

Elevated PaCO2 not always indicates inadequateventilation. Respiratory depression should be suspectedwhen; (1) Tachycardia, dyspnoea, anxiety and labouredventilation is associated with respiratory acidosis, (2)hypercarbia reduces the arterial pH<7.25 or (3) PaCO2increases progressively along with decrease in arterial pH.23

Postoperative respiratory depression is usually dueto residual effects of muscle relaxants, intravenous orinhalational anaesthetic agents.24 Immediately afterextubation, ventilation may be normal but after sometimerespiratory depression may be evident. Due to absenceof noxious stimuli, residual effect of different anaestheticagent may be unmasked. Careful monitoring is necessaryduring early recovery phase to exclude such complication.

c. Postoperative hypoxaemiaIncidence of postoperative hypoxaemia is very high

in young children. In a study performed by Xue FS et al,25

SpO2 less than 90% was observed in 30% cases of less than1 year old children, 20% cases in 1-3 years and 14% casesin 3-14 years old children. In many occasions SpO2 was lessthan 85%.

Hypoxaemia most frequently occurs after terminationof anaesthesia during immediate postoperative period andthen later in the recovery room. The administration of100% oxygen at the end of anaesthesia have no effect onthe incidence of early hypoxaemia. Late hypoxaemia isusually associated with crying or breath holding, whichreduces significantly by supplemental oxygen.26 Intubation,use of muscle relaxants, intravenous induction and durationof anaesthesia more than 1 hour is associated with higherincidence of hypoxaemia.

In recovery room, the acceptable lower limit ofPaO2 is 80-100 mmHg which correspond to 93-97% of SpO2.However, adequate arterial oxygenation does not meanadequate tissue oxygenation. Sepsis, hypotension, anaemiaand CO-poisoning may hamper tissue oxygenation in spiteof good oxygenation.

Oxygen supplementation should be done in all highrisk patients or the patients with low SpO2 readings. Useof 100% oxygen for transient period does not produce anyharmful effect on newborn baby.27 Early signs of oxygentoxicity can only be seen after 72 hours.

d. Complications associated with intubation

a. Sore throatMany children complain of sore throat following

laryngoscopy and endotracheal intubation.28 Use of dryanaesthetic gases is another contributory factor. Incidenceof sore throat is less with laryngeal mask airway. Steaminhalation, cough lozenges and analgesics provide good relief.

b. Postextubation croupPostextubation croup is a well recognized complication

in children following endotracheal intubation.

Children are more prone to airway obstruction orcroup because they have narrow laryngeal and tracheallumen that may be blocked by mucosal oedema followingtrauma. Various precipitating factors are traumatic orrepeated intubations, coughing or bucking on the tube,changing the patient’s position after intubation and presenceof upper respiratory tract infection.29

The incidence of postextubation croup has beenreduced because of use of sterile, implanted testedendotracheal tube of proper size30 and use of heatedhumidified anaesthetic gases.

Treatment consists of humidified oxygen therapyand nebulized epinephrine. Role of corticosteroids iscontroversial.

INDIAN JOURNAL OF ANAESTHESIA, OCTOBER 2004404 PG ISSUE : PAED ANAESTH

e. Postoperative pulmonary oedemaPulmonary oedema in postoperative period occurs

mostly because of overhydration or airway obstruction.Postobstructive pulmonary oedema resolves quicklyautomatically. Treatment consists of positive pressureventilation with application of PEEP and diuretics.

f. Postoperative nausea vomitingPostoperative nausea vomiting (PONV) is the

commonest complication of general anaesthesia. It is notonly responsible for delayed discharge from PACU but alsofor unanticipated hospitalization.

Apart from unpleasantness for the patients, PONVincreases medical risks. Raised central venous pressureincreases morbidity after ocular, tympanic or intracranialprocedures. Increased intra abdominal pressure mayjeopardize suture lines.

Incidence of PONV is very high in childrenspecially following strabismus surgery, middle ear surgery,orchiopexy and umbilical hernia repair.31 Antiemetics canbe used prophylactically and also for treatment of PONV.Commonly used antiemetics are phenothiazines,butyrophenones, anticholinergics, benzamides and serotoninantagonists. All antiemetics except serotonin antagonists(e.g., ondansetron) produce sedation, which may delayrecovery of the patient. These antiemetics have differentsite of action, so combination therapy may provide betterresults by simultaneously treating two or more precipitatingfactors.32

g. Hepatic dysfunctionPostoperative hepatic dysfunction may be caused

by the surgical procedure, the stress of surgery, ischaemia,infection, preexisting undiagnosed liver disease or drugs.

Initial evaluation of the patient with hepaticdysfunction includes a thorough review of the past medicalhistory for any evidence of genetic disorders (e.g., glucuronyltransferase abnormality), blood transfusion (reaction,hepatitis) or exposure to drugs known to produce hepatitis.Medical record should be reviewed for any evidence ofsepsis, hypotension, hypoxaemia, shock or congestive heartfailure.

Although halothane hepatitis is rare in children,Kenna et al33 have reported few cases in their series.Anaesthetic related hepatitis is less likely to occur withnewer potent inhalational anaesthetic agents, such assevoflurane, isoflurane and desflurane because theirmetabolism is less than halothane.

5. Complications due to succinyl cholinea. Myalgia

Administration of succinyl choline in infants andsmall children causes damage of the muscle cells leadingto myalgia and increased plasma levels of creatininephosphokinase and myoglobin. This myalgia is intense andmay take several days to resolve. It can be minimized orprevented by pretreatment with non depolarizing musclerelaxants. Treatment is supportive and patients usuallyrecover spontaneously.

b. Masseter spasmTone of masseter muscle is increased following

administration of succinyl choline. This tone is maximumimmediately after the caesation of fasciculation. In somepatients it may be difficult to open the mouth because ofthe increased muscle tone, called masseter spasm. To avoidsuch complication two techniques have been adopted :

• Administration of larger dose of succinyl choline(2 mgkg-1)

• Waiting for twenty seconds after caesation offasciculation.

Littleford JA et al34 studied 57 children diagnosed asa case of isolated masseter muscle spasm. There was nolong term morbidity and no mortality. They concluded thatanaesthesia can be continued safely in cases of isolatedMMS, provided intensive perioperative monitoring is done.

ConclusionPaediatric patients in their first year of life are at

increased risk of anaesthesia related complications. Higherincidence of respiratory complications specially inadequateventilation and hypoxaemia have been observed in this groupof population. Prompt diagnosis and management can preventserious mishaps associated with these complications.

Hypoxaemia shortly after discontinuation ofanaesthesia is a constant problem in children. Therefore,oxygen supplementation and careful attention for clear airwayare essential during transport of the patient from operationtheatre to recovery room.

Although presence of URI is not a contraindicationfor general anaesthesia, it increases perioperativecomplications. Hence these children need intense perioperativemonitoring by experienced paediatric anaesthesiologist.

Thorough preoperative assessment is also mandatoryto exclude presence of any congenital abnormalities.

Strict application of these safety rules can reducethe rate of anaesthesia related complications and mishapsin paediatric population.

RAY, SAHA : POST GENERAL ANAESTHETIC COMPLICATIONS 405

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