Page 343 - ACCCN's Critical Care Nursing

320 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

Case study
Mr Martin is a 59-year-old patient admitted for elective aortic, On the basis of the PaCO 2 the SIMV rate was increased to 13 breaths
mitral and tricuspid valves surgery. His past history includes rheu- per minute, which corrected the PaCO 2 and pH. FiO 2 was progres-
matic heart diseases (severe mitral valve regurgitation, aortic ste- sively decreased from FiO 2 1.00 to 0.40 over the next hour while
nosis and aortic regurgitation, and moderate to severe tricuspid pulse oximetry revealed a SpO 2 greater than 98%.
valve regurgitation) and gout. He has had those valve problems Mr Martin was switched to CPAP/PS after 30 minutes of spontane-
for many years, but recently has developed exertional dyspnoea. ous ventilation on waking, where he sustained adequate ventila-
Coronary angiography was normal but left ventriculogram tion. He was assessed as suitable and extubated six hours post
reveals severe left ventricle systolic dysfunction. Preoperative tran- admission. After extubation supplemental face mask oxygen was
soesophageal echocardiography report reveals dilated left ventri- applied at 8 LPM to keep SaO 2 >97% and changed to nasal prong
cle with severe global systolic dysfunction, dilated right ventricle oxygen at 3LPM three hour post extubation. Lung recovery pro-
with moderately reduced systolic function, severe pulmonary gressed uneventfully, aided by twice-daily physiotherapy and
hypertension and confirmation of pathology of three valves.
mobilisation. Oxygen was discontinued on day 3.
Surgery was reported as uncomplicated. Aortic and mitral valves
were replaced with new mechanical valves and tricuspid valve was Cardiovascular
repaired with an annuloplasty ring. Cardiopulmonary bypass had Rhythm: Epicardial dual-chamber pacing wires were in place, but
been used for 180 minutes and aortic cross-clamp time was 149 pacing was provided in the AAI mode (demand atrial pacing) at 80
minutes. An intra-aortic balloon pump catheter was inserted at the beats/min, with no evidence of AV block. Pacing continued for 24
end of the case to assist with post operative left ventricle recovery. hours before sinus rhythm emerged above 80 beats/min, inhibiting
An infusion of glyceryl trinitrate (GTN) 20 mcg/min was the only the pacing. After 48 hours of sinus rhythm, the back-up pacing was
drug infusion in progress. turned off and the pacing wires isolated. These wires were removed
on day 5 without problems. Initially Mr Martin was normotensive
On admission to the ICU the patient was intubated and ventilated. with assistance of IABP (augmented diastolic pressure of 120, sys-
He had left radial arterial and pulmonary artery catheters (PAC) in tolic pressure of 110, diastolic pressure of 55 and mean arterial
situ. Two mediastinal and a pericardial drain tube had been placed pressure of 80 mmHg), with a cardiac index of 3.1L/min/m . Filling
2
and had drained 140 mL of blood to the time of admission. There pressures were kept at upper normal range with colloid administra-
was no air leak. A urinary catheter was also present. Early chest tion as he was vasodilated, with a SVR of 716 dynes/sec/cm . His
−5
X-rays confirmed ETT, PAC, chest tube and IABP catheter place- core temperature on admission was 36.3°C, not requiring active
ment. Lung fields were mildly congested and cardiomegaly was warming. Chest drainage remained modest, with total blood loss
present. of 150 mL in the first hour. Blood pressure and cardiac output
The main dimensions of Mr Martin’s progress, care and manage- remained within normal limits in first 24 hours. IABP was weaned
ment follow. (ratio wean) on day 1 post operative over a period of 6 hours
without any compromise, and the IABP catheter was removed 24
Neurological status hours post ICU admission.
Began to wake at 2 hours postoperatively, and was obeying com-
mands, able to move all limbs with equal strength. Pupils were Fluid balance
normal size and reactive to light. Pain was managed with regular Chest drainage for the first 4 hours was 400 mL and total drainage
intravenous tramadol, morphine (boluses) and paracetamol at 48 hours was 750 mL, at which time drains were removed. Mr
suppositories in initial phase and continued with IV tramadol for Martin’s urine output remained within 0.5–1 mL/kg/hr with normal
48 hours and oral paracetamol for 4 days post operative. serum urea and creatinine. Hourly fluid assessment was main-
Ventilation tained for the duration of ICU stay and a positive fluid balance was
Initial parameters: ETT secured at lip level 25 cm, equal air entry recorded on both days (1100 mL and 480 mL respectively). Oral
bilaterally. SIMV mode, tidal volume (VT) 720 mL (80 kg), rate fluids were commenced 3 hours post extubation and within 24
10/min, inspiratory flow 40 L/min, PEEP 5 cmH 2 O, FiO 2 1.00, pres- hours a light diet was being tolerated according to local practice,
sure support 10 cmH 2 O, producing acceptable peak inspiratory Mr Martin remained in the ICU until the second postoperative
pressures of 22–26 cmH 2 O. morning and was then discharged to the step-down unit after
removal of all lines and tubes. Mr Martin was started on warfarin
Admission ABG (after 20 minutes) revealed the following: tablets for his mechanical valves on day one post operative and the
● PaO 2 366 mmHg dosage was titrated by the cardiac team according to his INR
● PaCO 2 52 mmHg results. DVT prophylaxis (heparin) and gastric ulcer prophylaxis
● pH 7.34 (omeprazole) were continued up to day 7 postoperative when Mr
● HCO 3 25 mmol/L Martin was discharged from hospital with cardiac rehabilitation
−
● SaO 2 99.9%. program.