Principles of Preoperative & Operative Surgery (Part I)

Preoperative Evaluation-
Aim is not to screen broadly for undiagnosed disease but rather to identify and quantify any comorbidity that may have an impact on the operative outcome. Used to identify risk factors for postoperative morbidity and mortality. Communication between the surgeon and consultants is essential to define realistic goals and to expedite surgical management.


Cardiovascular:
ASA Classification for anesthetic risk has 5 strata:

I- Normal healthy patient
II- Patient with mild systemic disease
III- Patient with severe systemic disease that limits activity but is not incapacitating
IV- Patient who has incapacitating disease that is a constant threat to life
V- Moribund patient not expected to survive 24 hours with or without an operation

Cardiac Risk Indices-
Goldman Cardiac risk Index (1977), Detsky Modified Multifactorial Index (1986), Eagle’s Criteria for Cardiac Risk Assessment (1989), & Revised Cardiac Risk Index.

The current AHA/ACC recommendations are to start Beta-blockers therapy in the medium to high risk patients undergoing major to intermediate risk surgery as early as possible preoperatively and titrate to a heart rate of 60 beats/min.

An easy, inexpensive method to determine cardiopulmonary functional status for noncardiac surgery is the patient’s ability or inability to climb two flights of stairs. Two flights of stairs are needed because it requires greater than 4 metabolic equivalents (METs).


Pulmonary:

Preoperative evaluation of pulmonary function may be necessary for either thoracic or general surgical procedures.

Necessary tests include FEV1, FVC, and the diffusing capacity of carbon monoxide. Adults with an FEV1 of less than 0.8 L/sec, or 30% of predicted, have a high risk for complications and postoperative pulmonary insufficiency.

Preoperative interventions that decrease postoperative pulmonary complications include smoking cessation (>2 months before planned procedure), bronchodilator therapy, antibiotic therapy for preexisting infection, and pretreatment of asthmatic patients with steroids.
Perioperative strategies include the use of epidural anesthesia, vigorous pulmonary toilet and rehabilitation, and continued bronchodilator therapy.


Hepatobiliary:

Evidence of hepatic dysfunction may be seen on physical examination. Jaundice and sclera icterus may be evident with a serum bilirubin level greater than 3 mg/dL. Skin changes include spider angiomas, caput medusa, palmar erythema, and clubbing of the fingertips. Abdominal examination may reveal abdominal distention, evidence of fluid shift, and hepatomegaly. Encephalopathy or asterixis may be evident. Muscle wasting or cachexia can be prominent.

Here are ways to approach a patient with liver disease in selected cases:

Acute Hepatitis-
Postpone elective surgery at least until liver function tests have normalized.

Chronic Hepatitis-
Surgery is generally considered safe in these patients.

Obstructive Jaundice-
1) Perioperative fluid management to prevent renal dysfunction
2) No dopamine or mannitol
3) Lactulose may be helpful
4) Antibiotic prophylaxis
5) No routine preoperative biliary drainage
6) Check for abnormal coagulation parameters

Cirrhosis-
Child’s A and B- Treat ascites, coagulopathy and proceed to surgery
Child’s C- Postpone until the patient’s Child’s class could be improved or cancel surgery for conservative management

Coagulopathy- Target PT to be no more than 2 seconds above normal
1) Vitamin K- 10 mg subcutaneous
2) FFP if no improvement with Vit K
3) Give cryoprecipitate as needed

Ascites-
1) Fluid restriction
2) Diuretics- Furosemide and/or Spironolactone
3) Paracentesis- may be diagnostic or therapeutic with simultaneous administration of albumin

Encephalopathy-
1) Treat with lactulose
2) Prevent by treating precipitating conditions such as GI bleeding, alkalosis, uremia, avoidance of sedatives

Patients with cirrhosis may be assessed with the Child-Pugh classification, which stratifies operative risk according to a score based on several variables. Child’s class A, B, and C have mortality rates of 10%, 31%, and 76% respectfully during abdominal examinations.

Malnutrition is common in cirrhotic patients and is associated with reduction in hepatic glycogen stores and reduced hepatic protein synthesis.


References:
"Sabiston: Textbook of Surgery" Townsend, Elsevier. 2008

More to come soon...

Pediatrics- Ward Notes (Part IV)

Here are some notes from around the wards during my rotation in pediatrics. Enjoy:


Common causes of Hematuria:
Acute glomerulonephritis, IgA nephropathy, Stones, Urinary tract infection, Clotting disorders, Trauma, Drugs, PSGN

Severe complications of Acute GlomeruloNephritis:
Acute renal failure (anuria), Hypertensive encephalopathy, Left ventricular failure

During the 1st year of life, UTI is more common in males with an M to F ratio of 4:1.
Pyelonephritis characteristically presents with- Fever, Chills, Costovertebral tenderness

Strong indicators of UTI in a Urine D/R: (Multiple organisms usually indicate contamination)
Abnormal color or clarity, > 100,000 of the same organism/ ml, Nitrites +ve, Leukocyte esterase +ve
Damaged RBC casts in urine indicate Glomerular origin.
Creatinine is preferred over BUN because BUN is easily altered by dehydration and starvation while Creatinine is kidney function specific.

-Remember to ask about the number of stools/day because constipation is a risk factor for UTI. Examine the spinal cord.
-When did the child last urinate? If more than 6 hours, then suspect Acute Renal Failure.

Causes of Recurrent UTI:
Hypospadias, Meatal stenosis, Urethral/Ureteric stricture, Renal agenesis, Polycystic kidney disease, Horse-Shoe kidney, Obstruction at the PelvicUreteral Junction, Posterior Urethral Valve

When counseling for urine collection, ask mother if her child informs her when he wants to micturate.

Suprapubic Puncture: Procedure
Bladder should be full (>2 hours since last micturition). Palpate pubic symphysis and then puncture 2-3 cm above in the midline (avascular linea alba). The 10 gauge needle should be perpendicular. Next, aspirate urine out and then seal it. Remember, this is a blind procedure.
Complications- Infection, Trauma, Perforation

Posterior Urethral Valve:
Obstruction at the bladder neck because of posterior mucosal membranes. May present at any age despite being congenital.
Male child, Early presentation, Failure to grow, Oligohydramnios, Anemia, Acidosis, Increase in BP, Big bladder, Palpable kidneys

Investigations- CBC, Urine D/R, UCE, U/S KUB (echogenicity, corticomedullary differentiation, size, diameter, VUR), MCUG, DMSA scan (assess renal function)

Immediate treatment includes bladder decompression via catheterization. Surgical ablation via transurethral approach.

MCUG-
Investigation used for VesicoUreteral Reflux. One should look at the level of dilation of the ureter and the amount of dilation in the calyx and renal pelvis. Normally, contrast should not reflux into the ureters. Posterior urethral valves present as a black band (does not take up dye), between the bladder and urethra.
Urination begins in utero at the 12th week of gestation. Oligohydramnios may result in severe pulmonary hypoplasia. Therefore, a vesicoamniotic shunt should be created.

Ultrasound Kidney:
Echogenicity is compared to the echogenicity of the liver and spleen. The kidneys are normally less.
A dilated pelvis may indicate pelvoureteric stenosis.

DMSA Scan- Used to assess kidney function. A dye is taken up by the renal cortex.
DTPA- glomeruli
MAC 3- Tubules

Causes for Unilateral Kidney damage- Stones, Aberrant vasculature, Ureterocoele, abnormality of the PUJ (can be bilateral)

Grade I or II Hydronephrosis can be treated medically. The patient is advised to 'double micturate'.
Grade IV or V Hydronephrosis is treated surgically. Procedures include reimplantation of the ureters and Deflux surgery.

Management of VUR depends on the degree of damage. The bladder or urethra may need to be completely replaced.


Cesarean section and bottle fed babies are more prone to develop asthma when they grow up.
There is a high association between bronchiolitis and asthma.
A silent chest is a very severe condition.

Chest X-Ray in Asthma patients show streaky hilar shadows, hyperinflation, tubular heart
When Peak Expiratory Flow Rate is graphed, X-axis shows the value while the Height is plotted on the Y-axis.
Honey water or yakhni soup (Pakistani origin) can be given to clear secretions in mild asthma.
Asthma is diagnosed after the 3rd attack.
Status asthmaticus is diagnosed if the 3rd dose of short acting Beta agonists (bronchodilators) does not provide relief. Aminophyllin and steroids should be started.

Eosiniophilia in kids may be seen in:
Asthma, Ascaris infection, Loffler's syndrome, Hay fever, Hookworm infection

Differential Diagnosis for recurrent chest infections:
Cerebral palsy, GERD, Diaphragmatic hernia, DiGeorge’s syndrome, Fungal infection, Heart abnormalities, Pneumonia, Congenital bronchiectasis, Cystic fibrosis, Kartagener’s syndrome

Chest Physiotherapy- Since children under the age of 2 are unable to expectorate, physiotherapy is done to help remove secretions. Lay the child in the lateral tredelenburg position and percuss from below upwards on the chest. This is indicated in Bronchiectasis.

Neonatal Meningitis- E. coli, Group B streptococci, Klebsiella
Infantile Meningitis- H. influenza type B, S. pneumoniae, N. meningitidis
Tubercular Meningitis- glucose levels are low. Choroid Tubercles may be seen in the fundus of the eye
Viral- glucose levels are normal
Herpes- blood may be seen in the CSF
CSF- If there is an increase in lymphocytes, then the origin may be Tubercular, Viral, or partially treated bacterial. Glucose values are the last to change.

A single dose of antibiotics can render a Lumbar Puncture sterile. In such cases, Latex Particle AGglutination should be carried out.
Gram staining, and Herpes PCR can also be performed with CSF along with culture and sensitivity.

Band cells- Are immature neutrophils which signify overwhelming acute bacterial infection. Their nuclear material is arranged in a band within the cell.

Lymphocytic leukocytosis is seen in- Leukemia and Whooping cough

Chloride sweat test (uses pilocarpine) in a suspected Cystic Fibrosis case will be >80 mg/dL.

Barium meals show: Diaphragmatic hernia, Sliding hernia, Achalasia, Esophageal Stenosis/Atresia

Mumps- Advise not to eat sour foods. Complications include meningitis, otitis media, orchitis (males)

Flag sign- Seen in Kwashiorkor. Area of hyperpigmentation alongside an area of depigmentation

Cerebral Palsy- Non-progressive, permanent disorder of posture and movement that is usually a developmental problem. Mental retardation may be associated. Requires multi disciplinary management.

Ampicillin and Gentamycin are given prophylactically to cover gram +ve and gram -ve bacteria.

Dengue antibodies are seen 5 days after the fever begins.

Specific Typhoid investigations- Typhi dot and Bone marrow culture
Cross reactivity amongst Typhoid and Malaria is possible. Previous IgG typhoid is possible with vaccination.
Carriers for typhoid are identified as having three +ve consecutive stool cultures.

Causes of Pancytopenia:
Sepsis, HIV, Megaloblastic anemia, TB, Hypersplenism, Aplastic anemia

Thrombocytosis may be seen in Iron deficiency anemia and Kawasaki's disease.

Causes for Thrombocytopenia:
ITP, Sepsis, Malaria, Hemolytic ureamic syndrome, Hypersplenism, Dengue, TORCH infections, Iatrogenic, DIC, CLD, Hemangioma


Pakistan Statistics-
6 children are born every minute in Pakistan.

Neonatal Mortality rate is 40/1,000 live births, 20 of which are due to birth asphyxia.
Under 5 Mortality rate is 56/1,000 live births.
Perinatal Mortality rate (28 weeks gestation till 7 days after birth) is 60/1,000 live births.
Infant Mortality rate is 91/1,000 live births.
Maternal Mortality Ratio is 276/10,000.


Resuscitation Trolly:
Ambu bag (30-40 mm Hg pressure in infant type), Heater, ET tube (2.5 - 7.0), Laryngoscope, Mouthpiece, Epinephrine, Vitamin K, I/V chamber.

Incubators are used to regulate ventilation and temperature at 37 C degrees.
Blue light is usually used for phototherapy but cyanosis may not be seen. Hence, a yellow light may be used.

Babies at risk for Hypoglycemia- Birth asphyxia, Prematurity, Infants of Diabetic Mothers

If a neonate is limp, apply a painful stimuli. Start CPR when HR <>

Indomethacin is given for a duration of 3 days only after platelet and creatinine levels are termed normal.
Survanta- 4 mL/kG via endotracheal tube.

APGAR score of >7 is considered good.



As this is a series, there will be more to come soon!

Pediatrics- Ward Notes (Part III)

Here are some notes from around the wards during my rotation in pediatrics. Enjoy:


Hemolytic Uremic Syndrome:
Decreased platelets, Anemia, Peripheral film shows egg shaped cells/burr cells

Congenital Adrenal Hyperplasia:
21 alpha hydroxylase deficiencies are the most common. It causes virulization in females of feminization in males. Cortisol is not formed. Males are usually dehydrated. Urinary 17 ketoesterides is diagnostic. 17 hydroxyprogesterone levels in blood can be checked as well.

Global Retardation- Considered when all developmental parameters are deficient. Chronic Severe Malnutrition- Considered when all 3 growth parameters are <>

Complications of multiple blood transfusions:
Hemosidereosis, Blood group incompatibility, Splenomegaly
Treatment- Deferoxamine

Pneumonia:
Investigations- CBC, CXR, ABG’s (hypoxia, metabolic acidosis, hypercapnea), UCE, Blood culture, Tracheal swab/Bronchial lavage Immediate management- Oxygen, Electrolytes, Antibiotics
Pneumonia should be treated with antibiotics for 5-7 days. Identification of lobe involved can be checked by percussing laterally.
Atypical viral respiratory infections and Sarcoidosis can mimick Miliary TB in a CXR.

Causes of Microcephaly:
Trisomies, TORCH infections, CHARGE syndrome, Cruzen syndrome (early fusion of skull bones)

D/D for 1 day high grade fever with Neutrophilia- Bacterial tonsillitis, Pharyngitis, Otitis media, Urinary Tract Infection

Guillan Barre Syndrome is a lower motor neuron lesion.

Causes for a false -ve Monteux test- Steroid drugs (>20 mg/day for 2 weeks), Grade III malnutrition, Active measles infection

Rickets (Vitamin D deficiency in children):
Repeated chest infections, Craniotabes (ping pong head), Caput quadratum (square shaped head), Wide fontanelle, Frontal bossing (also seen in thalassemia), Pot belly, Widening of wrist, Harrison's sulcus, Rachitic rosary

In the history, ask about adequate sun exposure (UV rays do not penetrate household glass windows), ask about drinking cow's milk (high phosphate content in cow's milk binds to calcium and causes excretion).

Measles:
Fever, Maculopapular rash (appears at the hairline and behind the ears, extends downwards across the whole body, and then disappears in the same fashion of appearance), Cough, Coryza, Conjunctivitis, Koplik spots (white/sandy color spots found in the buccal mucosa in front of the lower molars. These appear before other symptoms). When the rash for Measles subsides, it leaves a dark, desquamated appearance. Measles antibodies may be seen 4-28 days after the rash appears. Ask about vaccination and drug history/allergies.

D/D Measles- Rubella, Scarlet fever, Meningococcemia, Typhoid (rose spots), Insect bites, Drug rash Measles is associated with a high grade fever while Rubella's fever is low grade with enlargement of the posterior auricular and occipital lymph nodes.
Scarlet fever has a dry, sand paper rash present on the upper limbs and trunk and is seen usually at 5-15 years of age.
Meningococcemia presents with meningeal irritation, petechial hemorrhage, and urological symptoms.

Complications of measles: Pneumonia, Laryngitis, Meningitis, Encephalitis, Otitis media, Diarrhea, Myocarditis, Encephalitis, Reactivation of primary Tuberculosis

Measles encephalitis is of 3 types: Measles encephalitis (viremia), Post measles encephalitis (autoimmune), Sub Sclerosing PanEncephalitis (may occur years later)

Measles treatment: Keep the patient at home, Antipyretics, Cough suppression, Nutrition (fluids and diet in short intervals), Antibiotics for superimposed infections.
Vitamin A should be given orally in all children with measles. 100,000 IU in children <>1 year.

Measles surveillance in Pakistan- Serology (2 cc) of patients with clinically diagnosed cases of measles are sent to Islamabad.

Daily requirement of Vitamin A is 1,500 IU. Vitamin A is not available over the counter in Pakistan. Thus, the multivitamin Rovigon (30,000 IU) is given instead.

Vit A deficiency- Night blindness, Xerosis conjunctiva, Xerosis cornea, Thisis bulba

Short Stature:
If systemic causes, then patient is short and thin. If endocrinological causes, then patient is short and obese. Height velocity is important.

Factors effecting growth in utero- Uterine size, Nutrition, Insulin, Insulin like growth factors.
Growth hormone and Thyroid hormone play a vital role in the post natal growth process.
Children whose absolute height is below 2 SD from the mean have pathological growth abnormalities.
Observe the child’s height over a period of at least 6 months. Precocious puberty can cause early bone fusion and a deranged bone age.

Target Height- Determines genetic growth potential. Calculate Mid-Parental height as well. Arm span may also be used if unable to obtain a standing height.

Short stature should be determined as proportionate or disproportionate.
Upper segment : Lower segment ratio- 1.7 at birth, 1.3 at 3 months, 1 at 10 years.
Skeletal dysplasias (spondylodysplasia) and Klinefelter’s syndrome are associated with a decreased U:L ratio. Achondroplasia is associated with an increased U:L ratio.

Proportionate with Increased Ht/Wt- Growth hormone deficiency, Hypothyroidism
Proportionate with Decreased Ht/Wt- Malnutrition, Renal disease, Chronic diseases/infections.

Normal variants of short stature include- Familial short stature and Constitutional growth delay.


As this is a series, there will be more to come soon!